Flight Testing : Report Citation Wayne, Jay C. and Walkowicz, Teddy F. (1944) Flight Testing : Report. Master's thesis, California Institute of Technology. doi:10.7907/xez2-cg73. https://resolver.caltech.edu/CaltechTHESIS:06102025-185052730 Abstract No abstract. Item Type: Thesis (Master's thesis) Subject Keywords: (Aeronautics) Degree Grantor: California Institute of Technology Division: Engineering and Applied Science Major Option: Aeronautics Thesis Availability: Public (worldwide access) Research Advisor(s): Millikan, Clark Blanchard Thesis Committee: Unknown, Unknown Defense Date: 1 June 1944 Record Number: CaltechTHESIS:06102025-185052730 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:06102025-185052730 DOI: 10.7907/xez2-cg73 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 17442 Collection: CaltechTHESIS Deposited By: Benjamin Perez Deposited On: 18 Jun 2025 17:27 Last Modified: 18 Jun 2025 17:34 Thesis Files PDF - Final Version See Usage Policy. 58MB Repository Staff Only: item control page

FLIGHT TESTING Report by J. c. Wayne, Capt. A. c. .and T.• F. Walkowioz, Capt. A. c. California Institute of TeohnoloGY Pasadena, California June 1944 'I'he nufoors ,dsh to cx;: ress their c- / ;ireci , tion to Dr. C. B. Millikim of the CDli fornh Institute of 'Technology :nd to ii r. J . C. fl.eed for their kind ' i:;dvice .: nd frequent ,,ssir; t,r nc e during the µrepc1rr. tion of this tJ.1 es is. WAS Ee.ch of the .following orgrnizc~ ticn s ~ rr:ost hel;:, ful in ex- pla.ining their procedures, lo oning r e::,ort_s E:nd photogr,::;•hs, f, nd contributing gemertlly to the_ information contd ned . herein: Northro p Aircrcft, Inc. Lockheed-Vegt.. Jdrcrt.ft Corp. Douglns Aircr&ft Co., Inc. Consolid ;;;, ted-Vul tee .Hrcrc ft Corp . ,_i 'The Civil .Aer-on c: utics 1:dministri:; tion rnd the Glenn L. '.;1: rtin Comp i.,ny supplied mrny he,lpful reports in 1,ns wE r to 1,;,ri t tcr:i r er::ue:-.: ts. He.wk s, Chief of the Engin eerin g Divi f:i (m Lid son Section, V , e s tern ?rocurement Distr-ict, 1',fr: teriel Comm r ncl , '-::11: s of gr eL t r.s s isknce in mekin g the necessc ry con t acts ,nd r rr;:-n 6 in r: f at· th e visits which the euthot"s mace to study the flight tc t t org, ni::.;r L·:ms i:t the vi;.rious e:ircr1dt :;:.il an ts - Title Pa.1-t i I l 1 1. OPRRr TIO:iAT... TgwrmG 1 2 3. 'J'F:.:1 1'8 1'0 DY'i' : :~~It!;IT:; co~:iPLIJ; :\CF: t\"I '.rH Ui\JOTI §P'f:ciFfCATIOU HF;~n n .tJ:~ • s b. FLY.nm QUi1.LITir~ 3 3 3 4. Rh~St:A.Ft~ }{ Vt,I C¾TIT ?.FS r 1:/G 1 A fasrt;t; i•·tn cTr,'.ir F"I,r ··;}~T ·rE~J-TIJ:"tC· l\.S --- 6 10 11 ll 2·. c~\llH I ED (JUT ~'i 1T}J t1'\.3:.I tJ1_IT! J-t -.(ir~r.r, FOF SJ>.FL;fY - -- - - 13 14 14 14 15 17 17 2. c 0n?-';_r:y 0 O1,:rcrns c;cr.1 : .-r·r;c FJ;;:;1rT T1-• sr 7d~'rrnnts • 19 a.. b. mI''': LD F'LIG'IT 'f?f,'f'I?W BD A sunDIVISitl'J or TlL; r 1JGFL ;;! T '.G DET'A ? T'':' -~;<T OTI. SE :.::ffJ1 .. T~ I T B?.~. 3~"T ·up O., ~ fr_-iE :;1\:1;; ORC'JI." IZNt'Ll'rAL L7 ''H, ;:._3 TI!F fflGI'. TF'}{F lG PEPh R'ftf."-'1X T? THE ORGi\'<'! ZA.TTOHAL .GOUHECTIO'.r BETl}El~J FLIGHT TBSTr 'G !i.}lD A, l'.Oi:Y;::1u·1rcs e. 19 2S mtsP<Y·iSIBILlTI ;'.S A?:"D LI MlT:3 'JF AU'l'i i'JPI 'T.'Y OF TlTE FLIGET ·r LS T ORGi\T-:IZA.·ncn 24 1. 23 General Diseussion. 2. Pla.nn.:ing the Test Progra.rn and Establishment of Pr:i.o-ritios for Ve.r-5.ous 'I'ests. 27 s. The ilainta...a..11ee and Instrumentation of Test Airorn:f't. 29 4. P.xeeution of the Flight Test Program. 31 5. Determi.."ling Chru ,ges Necessary to neuiedy Unsatisfaoto:ry Items Fol.ID.d D~ing 'F'light Tests. 33 d. PRRSommL POLICIES 35 'l. Health of Flie.~ht Test Personnel 35 2. Eng;ineer1.ng Test Pilots s. Working Hours • 36 37 38 38 a. SAF}•,;ry OF FLIGiIT T°l':S'[' P; Fwo,-.;N; ;L ,\ND EQUIP!7 1·!T 38 ·13 45 d. e.. T·J1~1.1lTC1'1J)!',J oi:· l?!.,-(Gr~··.r .TJ::·~·:;T D.ll~~}\. .A\ LD DISSJ::l:~J N.\ '?IC_l;\r (t?· E: <SI;J..i?S 48 PH'';\TISI(J!-I Of' 1\.D}.\ i.!}t_.rrr: 1;·uor.1T SGJt r.:r\ :J_J~;s P,.r~Tn ! :'_1-·co~'I?iS 50 Title Part f. TEL FILIN G SYS 'f GM - Par;e 51 53 1. GK''' RA.L 53 54 3. Pf.N tN "T G Mm CATrnYrnG OUT .'f,!m FLIGHT TEST PtoGR,\r.1 a. 56 I t I'fIATTm OF THE TF:GT A' :D ACTIVTl'I ;·,s UP TO 'l'HE '.rl'. 1L T!L"c T 'l':ff.: AIRPL/i.NI~ IS PIU!-,. PA I'ff!D FOR ·rm,; 'rF:ST 56 b. CARRY H:G (Jl;T ~:m FLIGH'r TI: S'.i' 1-'HOGTIAT,1 60 o. TYPICAL SAVi,;<l'Y PF'I~CAlJI'I Ot:S 63 64 LIST 01'"' FIGUHJ<:S 'FOR PAHT 1 66 F'IGUR:•:S FOH PAF.T I II D :S'fRUM.EH TATI ON 68 A. 68 PLMiNING 1. TYrn CiF AinPJ.A!TE 69 2. TYPE OF T1'.~~JT 70 s. QlIA Li T"( O:F 11!\.TA 71 73 . 1. STRi\I:.: GAGES I 74 74 b. APPLICA'l'I01JS 76 78 d. STRJ.-.. IN IH DICATOR 80 Part Title - Pag;e 81 3. Pims nF? F:j_;_t\_ ~~UHF'- :'.)"::rJTG -- 85 88 89 6. A'1"TITUDE HSTRUMEN'l'S 91 91 8. .A.. UT0'J\ TIC EF:CO1 ' DFG 92 a. co:rs 'I'HtTC'n >N 94 b. LIGHTIWG 96 96 d. CCr!TPOL A: ,D COERBIATI OJ'} 97 e. PlIOTOGRt.. PHI:rn r.m AII!PI.!1' 'E 99 99 100 103 104 105 !It 106 106 107 108 HI BLI ()G HA PHY PAFT I 109 PART II 110 INTHODDCTIO.N Until cornp r r e, ti vely recentl y, flight te s ting i,.:.. s us<fd onl~'. to · insure the proper functioning of tn ll.ircrt-ft 1:.nd its com~onen t _piirts in night end to give nn E-.pp roxim::,te indic£, ti(-.n of the performcnce c ape.bili tiee of the aircrPft. Under the impetus of i.;.J.-ie wa r, flight testing techniques f nd methods of instrurnentr:tion end reduction of dv t;:-, have imp roved t:-nd progressed r r,~:,idly to the point whe-re f1.ight testing must now be con side red .lit leest ;:; co,:,plemen t to wind tunnel testing in providing the J.eron t.uticd I!hgine e'r' with va rious dr:.t F for use in the development of future aircrRft. I ctunlly, flight te s ting is unic:ue in cerwin c&sea such E, s the determina tion of dyn tcmic Bir and hnding loads and their . true effect on the aircraft s ti:-uctut'e. By no other method c.m the a ctu,.:l dyn a;nic lor ds be properly epplied t•nd mes.sured 6 t the prese.nt time. N<;> e. ttemp t is ;nade in this thesis to contribute l'nY new v,o-rk to the field of flight testing, bect:.: use of the rd r; . tive. inexpe rience of t he authors. Xhe concerted efforts of m.rny le:::rn ed men have f dvenced the t~rt to its present s t r: te and this pc.per does not presume to instruct thene men in their own fields of ende1.wor. Re,the -r, the purpo se of this report. is three-fold. 1. To pres ent in convenient form what · might be con:Jidered fi basic m~mut:1 on fJ.ight testing. 2. To s timule te the thinking of both the mEJnufr. cturers i:nd the using agenci~s c:long lines 'of stcmdt,rdization 1md pos ::,i ble simpHfic i tion of cet'ts in ba sic flight test procedures . i J. To discuss t ny er.,:--1f,.1:'en t trends 1n the development cf the 0 t,rt of flight testing. In attempting to write & basic rMnud on Flight Testing, the I &.u thors had originelly intended to cover the .Philoso phy of F1ight Testing, the Instrumentction of F'light Test 1,ircrr ft, rnd the Reduction of Dak. How~iver, ..Army /dr forces fechnic nl 8..eport No. 5069, by Mr. P. F. ~ikle, entitled 11 Performrnce Flight Testing /!.ethods in Use by the Flight Section, Yiright Field", wi:·s publishf,d r: few months B.e:,,ort deds p rincipr1ly with Reduc.tion of D&tc:, the GU tho rs decided to leave out this ;)&rt. 'Iherefore, this thesis fo i collection znd d~scussfon of those idei,s in connection with the i'hi::l.oso;,hy of Flight ·resting end the Instrumentetion of Flight Test Jdrcrr.ft ,~hicp ar.\)es r to hEve been ruost successful in producing the gre:: test wnount of relil>ble end useful engineering datt, per dolhr invested in fl~ght testing. In conjunction with 1'1\F'TR. 5069, ,0.erhsps it will be of some value in those orgemi zations where the const.:nt ·need for tr, ining 0 nev; flight test personnel is e mr.jor probl~m~ 'I'he f.eron:,utics De- ., pr:rt.'l'len ts in eome colleges •;Jhich ore considering giving courses in Flir.ht Test Engineering mcy find this thesis of interest. Strnd1rdi ze.tion of procedures in cny co;::plex Gmd r 1. pidly improving c:rt such cs flight testing is ;)ossible but m . turdly c1ifficul t. 1,. ny r:trnd rrdi zing procesr would ht•.ve to be well-con side red, rnd soecii--1 sefegu1::rds would ·hr,ve to be tr;ken to insure the t tl;16 fiE:ld of fli ght ter.ting v.ns not deprived of the vclur,ble be,nefits of inti.ividu ;:l irii th.tive emong the vi:,ricus E.ircrrft. Comp.?nies. ii However, the i·.d - \rnn te_ges to be g,dn€!d from strnd.::', rdization of certein bs sic ;) ht➔ ses of flight testing a.re so grer, t DS to make worth-while f:: com plete imd thorough investige,.tion of this possibi.l i ty. Direct compyris9n of the performwce l:nd flying qualities of v<:irious aircr1:St, without l'\ ny cuestion a.s to the r eliability of .my of the dc-_tt: or the Ulet.½ods by v.Jiich they were obt; ined, lcnd elimination, of· fa grei,.t mnount of the duplicution of ter:rting between the mmufc,cturers c.nd the services would be two inunediste benefits derived from e. stEnd£,rdi.za.tion proj ec't. These benefits would rwturdly 6asume more value after the ws.r Vihen tl-.e S8le of aircrf,ft to commercin1 airlines becomes possible ;;nd when the funds available both to t.1-le industry rnd to "the services for the development of eircreft may be e.J1.-pected to be somewht.t -restricted. lilld Army Air Forces 'l'echnict:cl Report No. 5069 1is an excellent importrnt step in the direction of stenderdization. It is in• teresting to note the.t s.11 of. the flight test org~iza.tions visited by the authors were either phmning to prepare or rctui,lly ;; re1nri;ng a mu1ut-ll describing their otm flight test methods. Certrin trends in the development of the ~:rt of flight testing have become a. pp e rent to the t::uthors during the survey of various flight test orgenHmtiona. The le Gt p1:,.rt of this paper- discusses those trends rnd attempts to point out their import:nce to the future progress of the aircr1:,. ft industry. The t.;uthors will be he.ppy to discuss further, with 1,nyone in .. terested, t.rie m~teriF.,l preeen t ed rnd to be informed of any errors which rnb.y be found in this thesis. iii W 11ere controv,cirsid que ;=.; tLms are involved, .especially in the part on Philosophy of Flight Testing, the views presented l ' t'e those of the 11uthors. I, PHlLOS-O?HY Of ¥' '~1GH'1 'IE.S TING Flig_ht te r ting can be divided into the folloidnr, di s tinct ' pht ses: 1. Oper&.tbn«,1 te~ting 2.. Jiccelereted service testing 3. ·ree.ts to determine corliplience wi tb nF.,,jcr s ;:,ecific-:,tion re0 ui rem en ts with re gi, rd to : •4. Eta ?erformtmce b. flying qucli ti0.s c. ?owtH' plmt coo1:J,ng and opert,tion d. Op c r n tion of accessories Research flight testing, i.e. flight te " ting ,, s e de :;ign function 1. O.PYRb'rIONLL TES'I'I~l G, Oper.s.tiohd te::ting gener1:clly consists· of ti:xiing te:.: t;:;, :dmulcsted t t: keoffs, c:nd then the fir:ot fe ., flights of a ne,1 1: ircr f t. Vari0us comi)onents of t..11.e 1':ircrrft /.',re oper: ted for the f'ir ~t time during t : :xiing t~ ;:; ts rnd ~.imulnted-ttkeoff run r; in l,n e. ttempt to determine ..;tiether or not the~rr~ t.re ~1ny serious mechinic•:l dif f icu} tie s . When sucn items l'.S power ph.nt, propeller, hydri; u1ic system, . controls, brekes, etc. R9per r to be functioning srti s ft;ctorily, the ini ti r.l . flights ere mr de. Thir :)h1:,ce of .f'J.i rht te::"ting r<:'C'Uires tne utmoi: t in diligence on the ;_; ~ rt of ~.-.1 1 ;:ier-sonnel connected 'Ni th th e , ctucl tef,t flif.,:i ts. Car-eful procedures ht ve to be phnn<:::d u1d v,orked out in i>dvr. nce to insure th~; t &11 of the co:nr on en ts of the E·irCI?,ft f;nd bll r ~ight test eaui , ,.,·,men t ere properly o~~ere ted h .,v e, reldively un- fvmilin.r crew end thr. t eny unsatisf&ctocy or d,,ngol'ous Condition which may develop during a flight will im:nedhtely be detected ,md brought to the attention of the pilot. The i:ircreft is given a thorough and rigid inspection on the ground aftet' eEch flight to insure th&.t everything is still in proper order. phc se of .fLight testing 'I'he objective of this is to aiscover ond cor-cE,ct those difficul tie.s i,nd •f1;,ul ts in the design which, if they exist, will become re;:. dily u:~;wrent rnd will 9revent t.11.e further s, .fe o perf tion of the ,~ircnft. 1'.ccelereted service tE:sting begins rs soon i.s it is E•viden t thr, t the continued sd 'e ope ?:'f; ti :'. n of the e.i rcr: ft is )O ssible. A stnfall number of the pc.rticuJ. r:. r ,drplcme tyi;e .a re flo,~n pnctically continuously, undergoing rigid t nd complete periodic inspections. The insoections generrlly follow some 1)redete rmined ph.n, being more , freouent rnd complete during the firr;t few hDurs of flying time. This . ph Fse of the test progrsm determines which of tJie vcricus components 'of the ctirc.rcft would not sknd up under re pe£ted use rnd v,..nulc reouire e:xc_ef!sive me: intenance or would hBV€ to be rE·desif'Tled nt some later dt,te if the E•ircrr.ft were i:nmedil~tely '.)reduced in cutin ti ty rnd put in to service. It brings out the differe:1ce between a custom- built p rototyp e, main tdned by a st, ff of exn ertf•:, rnd i=, rYroductirm aircri ft which hns to be kept flying by personnel of so:ne~.'h: t lower oaliber. Thus,, insofar as the operator . of the airoraft· is oonoemed, a.ooelere.ted service testinr; reduces mintenanoe ooa-ts and maintenance time, and outs down the number of perso,mal and spare parts necessary • to keep the aircraft in nying shape. Also, it helps the aircraft manufe.gturer avoid those costl~• production stoppa.ges wh1oh will occur if serfous aerviee diffioulties a.re encountered with a new airora.f't after produc>tio.n has beg:w1. a. PERFO H.l&\NCl~ • The third phase of fliglrb testing deter• mines the bo.sio ohartu~to:rist:l. cs of' the alro~rt. Testa are rtm to establish Quch perfoM!llnoe items ae ta._lce•o:f't distances. m:idm.um rate . of olimb, speeds at various powers and altitudes, .ro.ngo, n_nd land:lng dista:nees. Often; some of these tests are repeated to dot- mine the effeets of different groas vteights of the airora.ft or of one or more inoperative engines. It is obvi'ous that almost M infinite amount of fli~ht testing would have to be done to deto:rmine specifically all of the perfornnnoe da·ta.. To avoid auoh a tirne-eonsumi:q!; a.nd oos tly procedure; onl:r c:,erts.in basio perfoma.nce date. e.ro obta.h1ed from fli ght tests. These basic data aro then interpreted properly to give tha actual perfornru100 of the aircraft at any ,wei ght or e.1 ti tude, u.-ridor ony conditions • . b. FLYI~''.G QUALITIES, • The flying qualities of an air,plane indicate the relative ease an.d safety with whioh it ean be f'l0\'1!1-. The;z also shdW whether o:r not the airplane is stdta.ble for the ~ission for which it was designed. t-iueh items as stability., nnnouverability, and stall charactel:"istios, for example, are cansiderod r_nrt of the flytng qual:1.ties of the ~i.rcl'l'.ft. For long-range trru,sport or bom- ba.rdr.lent a.irore.:f't satisfactory stability is of pri::iary intcres't , · whereas for a fighter t"l;pe considerable flight test time has to be expended to show that its maneuverability oh.ara.cteristios n:ake i t satisfaoto:ry for combat use. o. POWER P!..Alrl' COOLIN(} AJ'JD OP:i:'.!ATIOrJ • The power plant DB.:rn.u'a.eturer generelly apecifLs maximum temperatures . . .for .sa.f.'e, coo.• tinuous operetim of the engines. The cooling tests are l'!'lf).de to show that these ma.ximum safe tellI'i.')era tures are not exceeded under the moat oritioe.1 oo:itd.itiori. For single-engined aircraft, the critical condi- tion will e;enerally• oocur with maximum conti.l'luous power at speed for best :rate of ()limb. I1'or a multi-e:n.gined airplru:ie, tho test will genera 1 ly be oondueted with o:1e or more engine a inope:ro. ti ve. Engine ooolir .g during ground operation is frequently eritioo.l with some aircraft designs. In addition to the cooling tests, further · tests are neoes~ry to insure that the fuel, oil, and ignition systems wiJ.1 function sat1o.fe.ctor1ly at a.11 a.lti·cudes and under all conditions. d. OPI~P.A.TI01',T OF' Af:CBSSORV S • The electrical and hydre.ulio systems, ee.bin hen.tors, deicers, radio equipment, and rrnny other items ~re tested under vnrfous conditions i n conjunction with the p0rfo:rmanee, flyirg qualitities, a.nd engir:e eoolir:p; tests. All of those phases. of fli g-, ht testing are carried ' out in SG>r,1e lot:ieal soquenee, ma.ny of them simul,to..VJ.eously, a.11d the results comr:nred with various safot-y reguluti.ons o.nd specifiootion requirem1:mts. It is obvious the.t, a.t any st.age i n this prooess, m1sa.tisfactory openatin[', characteristics or items which do not oonfon:n to speeifi• ¢a.tion requiremanta mtl.Y be anoountcrad. 'l'his will complicate matters, for the test p:ro~m must then be cha.'1. ged and replannecl to al low· for the testing of modifioati.ortS which vd.11 be ma.de to correct the un-sa.tisfactory item.s. ,Frequently, one of t he norlit.'ioa:hi ons tested roo.y be suoh as to o.f'i'ec·t the e.irspef;'ld aa.librntio:o of th<:i tewc ahora.tt, ' • mnkir:~ a. reoo.J.ibra:bion necessary to insure 'che vnlidity of da.to. which .will be taken d'l:U"ing subsaqu~t flight tests. If' the unsntiafactory item be a rn,ior one, a. good portion of the t ost prof1;ro..m ntuat often bo I repeatod because of :the foterrelation of tho -various oharaotoristioe of the niroraft. For example• a ma,jol" chnnge in oowl desie;n to i.m.prove entsine oooli:ng will probably necessitate the repetition of oertain performance tos-ts. Tha actual sequence of' tests will be different for each nfi1 prototype. depending rrninly on tho type of aircrn rt, the purpose tor vlhioh :lt vm.s dosif.,r.ted• amJ on the previous exper:lonoe of the pa:rticula.r aircraft Corr!pany. In the case of a pt-ototype dosir:;ned during wnrtime to meet nn ureent oan.bat need, the oper.s.tionnl and a.ccele1·a t ed senrloo test phe.sos might be emphasized al'.ld expedited at the expense of tests to determine oonplitil.nce with ma..ior specifioat:tm·. requir~nents. 'l'he mame m:te;ht also be true b tho case of a me.Jor modif':loo.tlon of an e:xist:h1g 1 suooessful, mil ital"'J airo?'ll:ft. IIei-e the s equonoa of flight teats will b@ governed by the ext ent to whioh the modified aircraft departs from the e:x1st1nc• pr?ven design. Ch the other h6.nd, an e·xpex-ien ced a ircroft company, during norn:nl time fl, w-0uld be moBt anxious to determine the perfOl"!OOnce charaoteristics . of' a new tl"ansp¢:rt airers.ft desig;n. It would thus be able to deter--- m.inc probable operating costs, and •obtain a meQ.Su:ra of ,t;he success of the new desig.'l be.fore investing ~o heavily in the . eost of e.dditloral flight teats. Hero, o.lao, sm.11e of the aeoelerated eervioe testing might be oam.bined with a.ctual demonstro.t~on of the new transport to airlines. Any numlJer of varla.tions exist, but in the final anaJysis, the suooeasful &iroraf't will have gone through the first three phases of flight testi.11g outl lned. 4. RJ~JY..RCH FLlGHT TES TING • FLIGHT TES 'fnYG AS A 1)BSIGN FUl:CTIOl'T• It is often presumed tht,.t the i'lil")'at testing of a new e.i:raraft en!,i,s when the apeoifioa.tio:n requirements have been oheoked, with the · possible. exception of further ~esta of V\\rious modifi~Mons or now type aooessor;i.es. Guoh, however; is- not the ease. 'hi.e f'li~ht test:lng of a new air'oraft ahoul d never b~ considered finished until eu£f1oient data have beon e;athcre.d to emble· the design engin~or to cheok the validity and ac,curaoy ot a.11 of the rre.jor assumptions !'lade in desi@:).ing the a.irera.ft. The najor e.ssumpti?P,t will generally be those made in trying to force the new clesign to reach beyond the boundaries of pre.se-nt aaeronauttoo.l progress. The enginee.r must know to wio.t excent he was suocessf.ul in his ls..st dosit,i. if' he is to suoeead i n his next - design. Eoweve1<, here the quest ion of' oost must 1Je considered. It will be l10ted that, up ·!;o this po -; nt, tho cost' question has :.:ot been, d1$cussed. The reason for this iii obvi0wJ. The flight tests outlined thus f'a.r aro actually pa.rt of the work ot developing an a.ir• o:ra.tt a nd• ae such. are paid for direotly by the organiza tior~ for which the airoraf't is being developed. I'b is often a.r -s:ued that 'these flip;ht te~rt;s are l';('A1.ere.lly so pr~UJ$L"1.g and i nvolved as to preclude the ga.therine; of add:l·bio1ml data for- re-$ oaroh purposes. Thus. research flir,;ht testing is left to be done at a later data or:, more ofteri-, left tri'idor.o. There a.p!>eo.rs to be o. certain amount of a.version t-o i'l ig,J1t testfrg for reaee.roh purposes when, ·tho o. il·oraft manufaotm·er himself is paying the prioe. This a.version seems to be the oo'nsequenoa of a feeling that over~zealoue flirrpt test personnel often attenpt to rnoaeure or dGtennine by flight tests ()erbl.in variables whioh are either inconsequential or ot lloodemio interes·t only. or eourse. fli~t testing for research purposes must be undertaken, like resear-oh in any other ind.us-try, only when thero app~-are to be ·a n assurance that the potential gain will be worth the o.etunl investr.wnt. Eowever. the task o:f' improving the modern a.1 :r,criaf't can be OOT"'.pa.re<l wi ·th tho s olutfon of a riddle consisting of a. mte of inter;ralated effects e...'l"ld -eorr.pro:misos. The solutior1 of this riddle will often r(~uil"EI extensive :'i.11.strumenta:tion e.nd oorefully controlled flight tests to det€rmine the small e:f'feets of severo.1 variables. By itself, e.ny one of these variables my well e.;:,per:t r to be unimportant, hut vmen studied' togother small Vts.ria.blea can often give important answers. many answers e,nd r,ill'ly solutions to tho riddle. Jiowaver, thei•e e.re Researoh flie:ht testing must tsola.te the principal ones. That is. resenroh flight testing must conoern itself with those factors which are potentially most oapa.blo of inor-oo.sil::g the economic value of the present e.iro1-aft as well as tha.t of' the next nm1 design. The recent paper by J. n•. . Kendrick& on uAero-toanomios" indicates an approo.oh to the nroblem, . ' of nirore.:f't development from the economic poi:nt of view. Wlth this sort or ~ a.pproo.ch to the problem Qi' research :!'light testing, the~ need not be· any question as to economic juistifioation. Then the entire flight raaea.~oh tes·ting program oo.n invariably be planned and axe• outed at a.n oo.rlier <i'° te and a.t a lower total cost than if only certain isolated phases of it are carried out at some la.tor data, when it becomes impero.tiv-e to ans-uer the demand from design eng1.nee1·s for addi tionn.l de.ta which are needed in designilig the next now prototy-pe. Researoh f'Hght testine_: can be discussed from another point of view. It is eoonom:ioally sound. to test a. prototype airplnne only if the prooo.bili ty of having a serious accident occur is below a oertain m:xi1num. Although it -.vouid be difficult to express thia "accident prooo.bility" as a. nU,-.ncrica~ reln tion, it obv:i.ously n:oes up a.s the number o!' new, 8xperimental itol'.Tls a nd innovations in d9sign on the prototype increases. If a. particular aircraft design i.s of a highly e:xperimrn:1te.l 0n d risky ri..a.ture, the t\1robab1li ty of accideEt" oo.n be reduced in two different ways. One way eomiiste of tra.1°sportil'g tho aircraft ·to a. large, suitably-flat and unobstructed area, suoh as a dry ?ake, and there gradually ''feeling out" the airplane i n extensivo -re.xiin& ar~d 0 short-hop1t tests. This method .lowers the risk of accident somewmt. but it ear.;. become prohibitively expensive from the poi:nt of viert ot tiine oons'twed a.s well a.a a.otoo.l cost. Another way of re duoin ~ t he 11 probabili ty of acoidEl'llt" consists • of t esti:ng various oompo:·,ents of a n~, deisir;n on a piece""'lnoal basis• by i nsw.lling them on an older aircraft of prov-en d csi;g1. 'rhis method becomes of !?;roat i mportance if it be gi n.s as ,soon as the work of desi1'7l.i nt; t,he prototype is s-t-nrtod. Heseo.rc.11 fli ght t e sting then\. be,. oomes a design fun ction, i.e.• it beoomea one of the tools which the design engineer can use to obtain solutions to current desi gn problems. Flight ·testfue performs best as a. d osit.11 funotim when fli i.llt test pe1·sonnel are used in a.n advisory oo.paoi ty i n eonneotion with new projects. Frequently; t heir prlil.ctioal a dvice 11 builda into .t he new airplane" the lessons of a. great a mount of flying experience which are apt to be remote from ·oh e · des1[111 enginter. Jj\xpe dm~ntal desif.P. features and new type accessories a.re tested i.Y>. flight as soon a.a they make their appea.ranoe o:n tho desi@rl angi1:eor's drafting boo.rd. Flig)lt tasti ng as a desi r:;n £\motion greatly reduces the "pro• be.bill ty of aco1dent". . It also <.,-uts. down the total a mount of fl i t~t testi n g necessary after the p rototype is rea dy a nd elimi r.ie.tos, a 101? of unsatisfaotory item.a whieh ".just g;et by 11 l'iecause it is too un-eoor!omica l to elimir.a te t h an late r o.n. cori sidaring the t1.me ~deb 'Y()Uld be . required to do so. Tli.e B-ln; airplane was an outata.'l'.l di n~; e:x£l&-i,ple of t ho use of fli gpt testfog as a desi g,i func t i on. ready for s. oceptt1.n oe de,nonstretions one waek - 'f hi s airplane was t01'1 hours of fly ing time .... after completion of the prototype. In another notable caae, the o~nnpleto engine and cowl installation for the 11 Con1!3tella.tian. 11 va.s flight tested on a twin-engine medium ban.bar. 5. Sln!1\.'lfi.RY OF OBJECTIVF:s. Keep:bJf'; in mind the vtirious phases of fli1:,ht testing v.hich have been discussed, it is possible to summarize o.s i'Qllows the prtn.cipal objectives of flight testing• a. To determine a11d eliminate any i.mdesira.ble ehn.:m.cteristics which a prototype aircraft may have. (This must be dor e with •ximtim regs.rd for the safety of the flight test a.ircra.rt and crew.) b. To test a prototype exhaustively in as short a time as possible. so as to reduce to a minimum the a.mount of l'!fl.intem:lce work . necessary to keep the aircraf t flying nnd the number of produotion s~ppages due to the discovery of unsa. tis factory items -when the a.iroraft is put into reg;uhi.r use. o. To gather (and present in some suitable form) all data. whioh the services or a connneroial ooera.tor will need to. operate the a.iroraft safely and eff_ioiently. d. To provide the desir,n enginocr with sufficient fli r, ht resee.rch data to permit him to oheok tho val:l,di ty 1;1.n d a~euro.cy of his solutions of important new . problems encountered. in the design of a prototype and, insofar as it is possible, to help him. solve current problems which cor.to up as tho dcsigti of the next new prototype progresses. Only when flight testing attempts to :reach all of these objectives, does it beoome of rr,axit,ium value to an airorn ft compeny. n. at\SIC RRQUISITFS OF GOOD FLI GHT TEST H G. 1 . •GENERAL. Modern aero:nautioal a cienoe has progressod to the point where the suooesaf'ul a.eranautiaal mgineer must avail hiniself of every possible souroe of design information in a.tte1~)ting to develop a nevi. su1:>erior aircraft. These sources or w..f orna tion will generally in- clude a a.. '.i'he le.t@st resea.roh ca ta available from ·w'i nd tunnel tests. fli ght tests, a nd laboratory tests conducted by h i s pa.:rti' oula.r om1pany o·r . by 11arious resroroh a q; e:ncies. b. Dvery latest refinement in methods of :mc.the~.tioo.l a.n&ly sis. o. His .f'und of pra.otioe.l k nowledge based a;1 . ?:'-ft experience. > In us1.nr; all of this· design infornation,. the enginecl' will invariably have to ~ e many assumptions and e xtrapolations -in order to apply it i.'l'l some ne\v way or ir.i. regi.mea n ot yet compl ot~ly explored. Further, the progress of. a.eror.au tiea has made the modern aircraft so complex, that the ae1·Qiiaut.ioal engineer is constantly fuoed with the necessj_ty of maki nr; a. s e :riea or compromises between ·various con• flioting factors i ri e.tte1:.ptbg 'bo so.tisfy all of the s pecification. requ i rements. - The relativ-e i!.1porui.noe of perfo:rro n ce chnractoristios, safety reqi,irmen t s.it S~f"'Tioeahilit~,r, ease of p roduction, and :oany other factors muet repentedly be wei ghed agah.c t each other e.s the design of an aireraf't proe:reesas. The protot~ which is finally l!8nufactured represeh~ the desi~ engineer's solution of the problem of at.>plying bas1o id'ormtion ru:,d rce.ldng a eeriee of oot'lpranises in en e. ttompt to find th• best an~\'Ver to e. set of 1nter•depe:n dent require- menta. In general. before e.n airers.ft (H)l"rpt\.ny oon ree.lize a p?'Ofit en ittl invesilnoot in the design and manui'e.oture of a p~tot'l.fPe, the company must be able to prove two things, a. 'l'ha.t the air'cn.ft is saf$ to fly and poeeoases no s e rious und~a1rable ohare.oteri1rtios. b. • That it oan perf'om. a certain task or mission more effioiently 'bb&n a.ny other airom.ft, i.e.,_ that it aa.n meet or exoeed • speeifioat1on reqtd.rement.e. The future ~ the design• of"tan even the future of' the airere.ft canpa.ny 1 tself; depends on the fir:al answers whloh are obte.i :.ed to t~se two questions. • Flig]lt teeti.ng is important because it ansvrers these two questions. It i$ the critique whioh measures the success or f'a.11Ul'e of the oo::-1pn11y•s attempt to develop an aircraft vmioh will find e. re»:i.dy market. Thie uniqu.e respor;sibi.lity (!f fl i rr:ht testing imln$dia.tely attaches to this fun6tion cer-tnin basio requirements. • •lt must be : a. Carried out with naximum rer;ard for -the safety of f'lig;M; test e.irera:f't and flight teat erewe. b. Reliable and a.ocura. to. o. rxsou~d a.a r&pidly as :gossiblEi. . d. As complete and exhaustive as possible, -0on si,dor:i.ng the ti.me available and the cost faotor. e. Absolutely 1.,npartia.l in judging and rnssin g upon the merits of various components a.11d charact0rist ioa of the airers.rt. 2. CARRIED OUT VHTH rU', XIMmn REC'.A.RD FOE SAFB'l'Y• The disruptix1g effeota of the loss of a flight test aircraft and erew hardly need be mentioned. The prototype airoraft inval"is.bly represents a oons1dol"t'. ble inve&tll'l$!1t,. It is a oustom.. built artiole, involving the high oosts of extensive special ma.chining, jigs and I fixtures ,vhioh may be used only a few times, ~nd rrnny expensive i-tems such as en gines, propallere • o.nd various aooessorios. Fli r;ht test orewe generally beoome of value to a company only after eonsiderable . . time tmd mo,7 ey Me been Bpent giving them a dditi one.1 training. In the cnse of engineering; test pilots, i t ia oft:e41 axoept:1.ona.lly diffi oul t to find nev,r personnel who aro sui te.bly qiwl ified. Thua, the loss of a hee.vy £!na.no1e.l irrvestment, tho job of finding e.nd training replacer~ents for impo1-te.nt personnel, a n d the inco.loula.blfJ effects of. tho delay enoouutered before a seeonc1 protot;y1.>e i s roody to fly - t\ny of the se factors nny Trell be the ber3;innin g of the end for nn aircraft compo.ny. I t is thorof'o:re a:x:imnatic that nothing should ever ba don e i n flight t e sting v1hieh will compromise safety cor!.Sidere.-- tions to even the snnlleot extent. ~. HR LIABU~ AND ACCURf,. TE. Unrel1.able or haoourate fli f::,ht test data., althour,h they may be unwitth :,f.:;ly used as helpful evidenoe in the sale o:f qu,mtitioa of airoreft to a custome:r 1 can only lend to grief. Where the customer wJly be a oommercial ope:rator-. the !:rief· will e:xpress itself as a fi~cinl loss to the operator. with eventual disorodit to the e.iro.raf't ni.nuincturer. In the ease of m!litn:ry e.1roraft 1 .flight tests made · by the semoes will ,i rivariably $how up the questionable nt.!.ture of' the ~nufaoturer 'a data. • The ensuing negot:iati ons oon ofter: oo.st a shad!,'JW on the reputation of 8.J1 nirornft rrnnufacturer fo:r a l ong tir-te. 4. E:XACU'C'RD EA PIDLY. Such rapid strides are being mad~ in the developm.oo.t of new aircraft tha't t.he obsole$moe ra t e has been gi"€X<l.tly incroe.sed. New discoveries and teohn.ical i"nprovem.ents. constantly tend to deer-ease the useful, ef'fioient aptw; of life of 11\o<lem aircraft. Consided 'e tho new desig;n orily from the time it has rmohed the prototype state 1 it ie neoessa.ry toot everythi:"1.r, possible ba done to i n crease tho period of' uoeful:ness of' thn t aircraft. This oan be done b-J eu·tting dmm on the i'lifr,ht teot ti!,10, i.e.• by eorrect u 1g any deSieifl futilts which r:ny be discovered, d0t(.lrrn'lninr:; optimum ope r.atinr~ cl1araeteristioa of the a.iroraf't, and making it avai la.ble fo:r servioe use 1.n as short a tit.:e as possible . fa ·the final nmtlysis, the r e-a.son f c,r the ustatiom.1.ry 6\ssembly linc 11 , with all aircrf.l. ft of a pa:r•t i cula.1" type 0roun ded, can often 'be traced oook to the flight test whioh ·was never ma.de or is still beinc; planned. There tnay, of oourse, be !m.ny very :real re1.tscns why the flight test ,ma r:ot made or we.a dekyed. Further, it must be expected , that abnormal use under vmrti -.,e conditions will e.lvmys continue to produce ser.rice difficulties or failures~ However, it r~ins true that if the inttial flight tests are as complete and exhaustive as possible, a grei:.. t P"roentae;e of the produotio11 stoppages due to ser-· vice difficulties~ be eliminated.. An additional u1vestme:nt in flight test instruraente.tion and even a.d<li ti-anal test £1 :te)tts in the first place will ~ less e:>..vetl.Sive tho.n the so.me flight test later on, when service troubleli nake. them necessary. Furthermore, dis ... looa.tions :in the prQduotion schedule are invariably vecy expeneive~ 6.. I MPARTIAL• The buyo:r of ~ ?lew aircraft will ~nerelly demand that it meet all of'hia speoifioatione. Fli ;;ht testing must _therefore be com- pletely 1r.1pru-tial in prov-ir:p; the relia.bility and determining the chara.otoristics of all of the oomponents of the airora-ft. The high perf'orr.nnce aircraft is not useful if a faul ~r fuel system prevents operation at . high altitude~. Likewise, e. low landing spt)ed with flaps extm1ded is not completely ae.tisfactory if' each extension of the fh\ps requires servicing of th0 flap actuating meoharJ.am. or 1 course, the qua.li ty of the wo-:-k done bY'"the design engineer is the pri~ary a:r>...d nw.jor factor in detemb i ng how well t..he various oom.ponente of the airom:f.t fu..""lction. ' But fli ght, testing tnust definitely prove that ur;tdar all conditions of uso the operat:i.on of all of the cor.1• pO!!ents of the airoro.ft satisfies the buyer's speoif'ioatim:.s. C. ORGAUIZ,; TIO'N nF FLI GHT TB? T A.CTIVI1'IL0 . The follovring two pr.oble'7:a must be considered in a diseussion of the orr-;ariization of fli ~ht t"st a,ctivities1 Coro.pi:my policies governing . fli{!')lt to~t aot:l. •1ities .... these a. ' policiee dete:rro:i.ne the looation of the f l i ght test organiza.tlon With' respeot to :the subdivi$ions of :the oor,:rxcny as a whole and they outline the relationships whioh ohou : d o:riat between fli;;ht test h ,g 1:1.nd tb~so subdivisionss they also :set forth the reaponsihili ties and lir,: iits of authority of the fl:J. i,:.h.t test org)lri.ization. b. Policies ,•tltrdn the fl i ,d it test org,-a:n:lza:tio-a ..... those poli... oies outline the ~n1cr in whioh t he fl i r;ht test orgru1izat:ion will opornte to properly disoharge a.11 of tta respo:n• sihili ties, The exte1it to whioh fli 7,ht test:i.r.t is sn ccesaful a.,1a. of ·,;ulue to the con1mrw depei:i ds minly up011 the ~dsdom with which these various poliefoa are established.. '.!.'her e are p robably no q~asti nns i n connectlon with i'lif ht tosti!1g; whieh would he discussed ,µ1d even contested with 1:10ro vigor tho.n those oor,cern i ng the proper or~nn:i. iatiou of fli ght test o.ctivi-t.;i es. ronsona for this a.re r_eadily a.ppo.:rant. 'I'he Orgp.rd w.t i ons f.u•e <level oped prinnrily with ro {~;t-i. rd to peculiar oor. diti f;ns within a particular bus Loss. Aotual a pplications of the fu.nda• 110r:.tals of good or[')L"i. tza t ion •di.ffi)r widely in t~o dif'fere:n.t oonptmioa, size in pm'"ticule.r hav:Lng a marked effect on the way in which an organi w.t:ton develops. The growth of various airer.e.ft companies• especially during the pa.st five yea.rs, baa not been a stoo.ey, prediotable prooeas. Som:e entire campa.'1ies have doubled and tripled in $1Se practically ove-rnight. The produc~io.."l depar-t.nents of oertain concerns have groi.m. trem.endously with little change in -the size or structure of the en• pa.rtmentt3 have grovm. in step with the ge~:ral company expe.:r:sion. It is a well-knovm. fa.ct that during time21 of a bnormal and unusual ex• pe.nsJ.en, especially in a 001.:i.[.$.ratively new industry, there is fr&.. quently little experience upon which to be.$~ organizational decisions. The problem of, pEirson,alitiea then takes an .g reater importance and baoomes a ~overning fe.etor in the resolution of org;ad P,t1:cional , problems. J:'urther; certain unµsu.e.1 events in the history of a. oompan;y often l->Ave a profound influence op; the orgar.liiatior4:tl development of' the com.pany. For exarnple·• the airoNf't company which. durir:g the pre,,,.war period., rray have· suffered severe setbauks beoouse of loss of prototype a.iroraft during flie;M; tests 1e very apt ·to J:....ave a strong, wall de, '' velopad n i&:;h t test ore;a.nizatior1 today. On the other' hand, a compara- tively small o~pany wh :>lile engirieeri. 21g deparQ!lent ·was suooessful in developing nev,· military aircraft e. few years ago .,..;. designs so superior as to meet vdth imrnedia.te ~coeptanoe by the services •- might be expeotod to be well developed todo.y from a productior, s t o.r1dpobt, but not necessarily insofar as flight test1ng is conoerned. '.l'hese two ea.sea a.re , extremes between which lie the aotual courses followed by ~1:lrious aircra ft c0:.1panie$ i."l the historioal development of th0ir fli1tht teat departnlcnts. Of ooursa, tho factors which have, been rn.en• tioned will id.'luenee riot only the . fli r,ht test function but oi'ton tho entire organizational s_truoture of the co~~pa.ny., However, onl:il t heir offs ots on the fli ~~ht tost orgnni~tion EU·e pertinent here. 'l'hus,. since coM.panies of' various sizes e.:re involved, with different personalities problcns in ea.oh company and with different cour·ses of historical dmrelopment~ it is natural th.at differences of opid.nn shou:1 d exist a~ to tho tH·opt?r orr,an:tza. ti ·,n or the .i'lir:ht test fu11otion. Ho-waver, it rennins possible to discuss soma of those policies and pre.ct:tces which appear to to.aka a fli s ht test organize.tior: or gre~ltest w.lue ~m the point of view of effioient an<l complete 0:1: tainrnent or its objectives. A complete disouasion of this s~bject would na.tu~lly be -.;rery lengthy and far beyond tµe soope of this work. Tien oe; on ly some of tho more irl.portn..11 t que6tior:ilfl are eoueidered. I n the actual applioe.tia:1 of these policies and pra.otic0t: there will be as many aotual detailed solut'i.on.s to the problem of o:rgani zing flight test a.(rtivities aa the1·e ar~ oornpan:l.es of diffe~·mt sit.e;i with different persone.lities problem.s; objectives• a nd :N...-ria.neial problems. 2. CO' lPAHY POLICll~S GOVRHWntO FLIGF. T 'l'YG T AG'rIVITI LS. a. SHOULD FLIG!iT TEfl TH;iG HE A EJ!JDDIVI~i1 0.? OF T:-m 1-:NGINIV1-n ro Dli:PART!mJT OR STI0DLD I1' BB SI;T UP O"! T'H? Ml.II.f,; ORGAi" U:ATI CNAL Ll~VRL AS 'l'Im }~i!GI HF:\HIN'G r,:sPAHTt,TI~HT? • It is ps.rti oula.rly difficult to discuss this ques'cion. slrice ao rtu1ny of the faoto:rs i nvolved depend on peculiar conditions within ~oh company. In one sense. fli ght test :hig is a mere continua. tion of, a nd of time only a smll pa rt of• the work done by the engineorin1:: departmant. Yat. fl 1cht testinc i s a very ii::po:rtan.t ~n:: of' -the dav0lcrpt11Emt of o.n aircreft simply be-ci:rnsa it is the final part. It is a "oateh~lln• the oorapa.ny's last ehe.nce.. to discover and correct hid.den inadequa.oies in deSit?Jl, r,hich rrs.y prove damgin~ to its reputation and future if the aircraft is put irito eervioa before they are eli.-ni.nated. In this respect, the relations betrwen flight test:ing and engineering :may be eon1pa.red to those existing bet.veon inspection and production. Flight testinG oonsti• tutea a, "final inspection" for each nevr work of the on~ineering de- pa.rtment. There is no longer any question L'l'l ra.iroraft companies that oontbued h_igh q-mlity of produetion requi.ret3 an inspeoticn departmont which is ;a.utonomotis insofar _as its relations with the produoticn depart0 ment are concerned. nowever, in tho oo.se of flig;ht tosting versus engine~"1r:l2ig 11 other factors tend to ocmplieate the issue. 'l'r.te axiOlll of "two head.a are better · than one" is readily E\.;)plioe.ble when ndvooo.ting the_ use of an ir,dependent fliir)1t test organisation, instead ot ono which ia part of the engineering det~rtment, for ma.king the final adjustments which insm·e that a new a.ircre.:f.'t will be lafe to f~-y a.t1d will m.eot all spoeifi~tion roquirem.ents. It will be admitted that a ma."'l, who 1s engrossed with the t!mltiple details of a naw design over a pex·,.od of ti~• sometimes loses sight of the main objectives and frequently becomes prejudiced i:n r-ecard to certain phnsos of the ~esif91 • . Suoh a !rl:l.n will fbd it very difficult to make the correct olnnges and prop<,r compromises ,;,then flight testing re-voe.ls a flaw in one of his pl"Qjudiees. Thia fuct 0.ppet1.rs to be e. major influence i11 :favor of' an independent fl.if)lt test department~ m: n pa.r v.r:l i:;h the a"l.gineo ring de~l"tment, pa.:rti oule.rly in the oase of the larger oo.mpt.\:t'l.ies. cnly an ~l"'Mo.1 judge, he.vinrt; none of the prejudice~ whicll often spring from prwious oonnaotion with the de- tailed dasie:n or o.n air-craft, oan be completely sw,cesafUl ui evaluating t.'1-ie prototrJpe and ma.king thooe ahang{)s and oompromisea ·which will . il!lke it aQeepto.ble to the blJUer. But, flight testing is more than a final phase in the de"itelopment of a new desif1). or e.: measu:re of the sucoens of tho onf:;inoering de• parttnent. ' The design of new aircraft ~!' of modifion:tions of existing airers.ft ve!""J frequently depends on the availe.bili ty of· onginecl'inr; data which can be obtained only from reser:1 roh flight tostint;. Often data whioh are obtained from wind tu.nnol tests or :f'rom niathen~tioe.1 . analysis 68.tttlot be used with full oonf1denoe in tho design of new e.iroraft -Yri.thout Sbtne •preliminary oo:rrel.ation with research f'U.r)l.t tetJts results. Furthermore, flii:;ht testing often produo~s new in- formation which tn0.y a.lt<-ir the very basio of eertn:i.n ded~ pra.otioes. L'l'l the sense tha.t it performs e.11 of these functions, flight testing is fuen e. otually a. pl-iase of-engineering. However• beoaus e of oost oorisideraM.o:r.s, resoo.~·ch flight tastil1g, i.e., flight testing ·as a design ftmction, has to be oorried on together wi1:;h and as a part of i'lif!,ht tests which a.re m.ade to test and develop specific airetaft. Furthermore, tho amount of reset:;,rch flight tGt~tine; has to be ca.re.fully controlled a.nd limit,ed to itenw which a.re really necessary and i:m.por• tan t for, otherwise, expend:t turos for re$.ee.l"oh fl i1:.ht teating · .. ,..- ' can. -- -•~ ; easily become unroa.sonable. It ia trut'3 ·that the amount and ne.ture of reaearoh fli r:;ht testing can be controlled sa.tisfaotorily, if proper safeguards a:re ta.s • reg;ar dless of the position of the· flight test organieation. However, it is significa:::i.t that the necessity for providing t!i.is eontrol over· 1·esearoh f1 i r;ht testing appears to hav-e produced a trend in the direction of a stronger, more n early aU:to:.:, cmous flight test orge.n~za.tion. An arrangement involving an indepe11dent flight test ore;aniza.t:lcn is potentially ver3 ht.uo.rdous in that it e;r.e v,tly inoroases the possi• bilities of ftiiotion and crui deprive the eriginet~:ring denartment of • C the sense and. se.ti°sfa.otion of doinr, a oomplete job. Speoi.o.l safe• guards have to be tnken to insure thci t the qua.li t;y and quantity of work dpne by both departments ara not diminished because of misu:nde:r• ste.:.,dings a.."1d le.ck of e.pprecis. tion. of es.eh o·thar 's problems o.ncl responsibili ties. If an independ~t flight test o:r:ganizatlon e:dats. the question of design cho.nr;es when major diffioulties are encountered in the teats or airore.ft, the overall direotion of the en tire fl ig;ht test program so thn t it is of lll\Xinum value to the cov:1po.ny-, the correlation or important wind tunnel test da ·t;a and the cheeking of the :results of theol"etio~l a..nal;-{888 by means of fli~ht tests, all of these que ~tiona should beoo:me agenda. for a "flight testh,,g de1~rt!!lent • engi11eerh,g department oommittee 0 • . The com, itte.e v.ro:rk fosters n . proper group spirit among members of the two departM.onts, the spirit •of !1elpir~g oo.oh other, for the good of the entorprisa. b. . THE ORGANIL::ATiff:AL (",-ONNF.: CTI ()11 TI!:~TWEE:~~ FLI GHT TI•:sr:r. :NG AND AERC}!IDW.!f~CS • Flight testing and e.erod.yx:am.ios are f~quently Ho-wewr,. thie ap pears to b~ an outgrowth assoeia.ted: with each other,. of histo:rioa.l development rather than of pmotieal naeessity. ln its early ste. e;~s, flight testing oonsisted .of ma.king a eom.para.tively simple airplane safe to fly and then gathering some a.ppro.xims.te pe?. fo:rma:noe de.ta.. !J!ost •of the work done re.quired a good aerody:r.:amioa ba.okground, hence the reason for oombinint; a.erody:na.mios and f'li 6 ht test. • nut it appears that ·o:f,' all of the flight test work which lie.a to be done on a modern e.irpla.ri e; •perhflps lesi than 355; requires e. erod:ymmi o inte:rpretat :1 on. The oombb..a.ticn ~f aerodyn8lllioe a1Jd fli r,ht testing ~y be ad'V&n• tageous in a. amal,.l eam.pany whore the:re is an .i nsufficient; amount ot work to warre.n1f the tull-time employment of c:me good a.erodynti.mioist . ' on fli ght test wor-k, ,,-and another one on theoretical e.erodyliamio~ in :: . . . eonneotion with dedgn work. ~ ·However, as a com.pony grows, the com- binatic:n -of flight ·testing and a erodynarnios is apt to beoome soniewhe.t r'isky, whet.lier the combina,t ion be r-:rt of the engine(!; ring department or s.ape.ra ted :from it. An aerodyzamioist is not al-we.ye oritioally observant of tho por• f'orme.nee of all of the oorn:ponents of rui aircraft. Ile t.requently cooocntre:bea on such 1tEe.e e.s dl'.9-C and propeller efficiency and overlooks itEmie suoh as the fuel system and the electrical . system. H.ia flight teatin& ·1 s a.pt te become acadamio in naoo:re. with the i nclusion of many teet items .vhioh could not be oonsldered "e.erereoonanio" • or oourse., these e:f'fe~ts ean be,. and are. m.inimhed ~' keeping the I functions of flight testing an.a. a.erodynantles distinct tram oooh other and, as the organi2:a.tion grows, by ad.di.TJ.g flif;ht test personnel who are &pecialists in the analys1.$ of the various componen ts of an a.ircro.rt. However, in th~ oase of largt1' eom.paniea whore flight testing is not pa.t't of et1gin$ering, there does n9t a r,nmr to be any justifi• •ce.tion for 1Mk1nt, 121e engineerin~: deparbment dependent upon £'..notho)" de~rtrnem.t for theoretical aerody!,Jirniee work whioh is res. Uy part of the :job of designin g a new a. iroraft. 'r ho solution of this ,,oroblem appears to ;tie in .the provision of a truffiofont number of qualified aerodY11,run.ioists in both the fli r;ht tEi $t EL"'l.d engine Pri.'1. 6 o.epe. rtme nts, permitting eaoh organization to perform the aerodynamics work which falls in its own Bphei-e of influence. The wol"k of the two groups should be coordinated and. results eor-1}:Xil.r$d frequently by a su.itable oomr111ttee. There ,votild be no reason fQr competition between the two aerodynamics e;roups, and a re p;ular intorchnnge or a orodyr,amios per• sonnel between the fli itht tei;ti:ng and en gir~eeri:nr,; dopartmonts would probably be or oonside:rable V'O.lue in proraot1ng coordir.!llted effort and a spirit of eooperatton. m~SPO'.'lSBILIT n:s A.HD LIMITS OF AF THOIUTY OF 'l'IfE T' LI GHT TEST 6r1CTAN'l2~vflI ott. • , •• I l. General Discussion• One of the f'irgt rules which is . apparently followed 1n .organizing flight test .activi tie::: is the lumping c. of responsibiL ty for all of tho variouo phases of flig)lt testing in one orr~1ization. T'ais is dono rer~rdless of the nature oi' the test item or the aircraft oomnonent with which it is co:r.oe:rned. Flight· tasting bee'.:>PlOS 0.r1 org;an.izntio:n of specialized skills for dobJS, o.ny flir;ht tost ,iob se.fely_. aooure.tely and completely, ra pidly, and at mini.mum cost-. In the past, speofo.lited f1 ight test projt)cta have occasionally - been put ir1 the ha.ids of VQ.rioos speo:tn.liats who ,we1·e not me:::'.b ers of the f'li f,ht test organi~tion. For exru-o.ple, a stability nnd control ' en gineer, re,I:u larly assigned to the engineering clopar't,u0nt, mip:ht be givm the task of carry i ng out flight t ests on a ner,... t y-pe flap, relying an the ref:;ule.r flit.,ht test organization only for assi r;o.!:1ent of pilota and some administrathre o.ssistr. .noe inu e:etting the te--st a.irpJ.ane into the airst and having the required test porformed. 'l'he special• ist with hia special :f'light ta::rb problem becomes n.n .in.trudor i.t... o~r as the regular r'outine of the fli ght test orf:P,niza.tior! is eoneerr.ed, espeoia.lly if he is only one of a. group of mon with vari ous n.ssigprnents ' or a. similar nature. Muoh sad expe rienoe bas ar~1a:r,fL tly caused the disoo:nti nuanoo of tM.s praotiee.. Primarily• disorganized fli ght testing booomes prohibitively expensive a nd complicated. One aircraft mf'>.y be flown for rnahy hours at 1_1:rea t oost to fir1d the a.?11:r,.vei- to only one question, wheree.a 1.1n:th carefully integrated tests, the fl i z,hts could have yielded the a.n :swers to ma.ey additional questio ns r.t muoh l01 rer 1 east per anSWC3r. (The actual value of the 1:1.r.swor obtf:l.ined ie '.often lhnited by virtue 0£ the f'a.ot that it was i mpoaa:tble to obtain the sa111e pilot to run tho whole s eries of tests.) Thun, with disor::_~r, ized flight testir1g, the amount of dntt, obtained pei- hcur of flying time cfeoreasos and the nur:1bar of test a.i rcr•nft :r;ecessa:ry to do a certain amount of work in.crea.ses. As the number of test . a.irorof't :increases., the problem of e.ssir;o.ing a x,d keepbg trnok of priorities 1nagnifies itself, and mainte:n.anoe a.n d inatallation work bee<Jt1ea oon fuood a n d invol:ved .hooouse of a mtlltiplioit-J of orde rs arid a. f.:N ltlte r number of a.iroro.f t. Sometimes there is o. belief that an importan t s peoial teak oo.n be performed more rapidly by the assi~nt of a specio.list outside of the fl i r,~ht test organization. not the case. This is Vt.•!"IJ frequer. tly Fli f~ht testin tr ie a. suffieier:.tly epocia.lized ;i ob in itself so-that it carin ot be "just picked up". • T'ne multiple dete.ils of prepari11;g 6.."l e.irort1. ft •for a f li ght test, dett.-1. ils oi' test i nstru• mentntion 1,·1 ithout whioh. tha fli 6ht tosts will sel dom. be oi' any a ,)pre- ciable value• ce.r1 be 1m:ndle-o. most e f fio:i._ently by an organizat ion set- _ up to tnko care of them in a routi :,e rnn n.10r. The s pecialist has to fi n(l out a.bout, perf orm, and worry about detailed r(fl.ttara which, ordinarily, would pave boon ta.ken oara of rap i dly ru.1d. .e.utcna tica.lly by the fli rt,ht tost organ iz.at:i.on. Furthorn'l.Ore, wh ile ho is doir,e; theso thin.is, the theo:re-t.ioal or othor work which he io host qualified to do a nd f'or which the eompa.1w is pe.y i nt; him, is be:i.1:r; ne glected. The oo.se of accele reted service ·testing i s a possible exoeptioo. By its nature~ accelerated serr lce tes tfr,g is soraewha.t diff erent from a ny other phase of' fl itht toat :lnr:;. It do es not require any speoial h :strumerrta.t:'i.on· arHl does ;'.1ot have to be perforrned under i deal wenther con ditions. Thus, it is freq ue ntly or f:1'-nized e.s a distinot a.nci sepe. rote functi on . Eormve r., clooe liaison must be min.• to. LYJ.etl betwo e:n fli p;ht testing proper n nd n.co el En·Ht ocl ser v ice te s t ing -21- to insure t:.'ta.t any basio, diffioul tie a encountered durinr, accelerated serv'ioe tests are promptly i.nveatife.tcd and eliminnted. A good example or the type- of dif'ficul ty which is s~eti mes enoountered is ~he case of a protot-ype aireroft whioh suooessfully passes all ori~ gi.."W.l • flutter_ teats. Aocelex-ated service ttilsts begtn and shortly thcreo.fbe:r flutter difficulties develop, c'l.ue to e.n inoreased a.mount of play, es.used by woo.:r, in the control aystem. The flight test department muet be mde a~re of such dif"ficul ties as soou as they ooour &nd it r:iuet determine and £lie:-J1t test t ·h e proper o,orre<stive design !lhan~es a.a seen e..s possible. Thus • with the pot:rn i ble exoapt1Qrl pofa te d •out in tl1.e pre .. ceding paragraph, effective fl ig,ht testing must be oon.plotely orguni zed• And this eon:i..plete organization must at'tlloh to fli r.;ht testing at least tho following responsib:lH t~es • a. The deta1led planning of the entire flight test program, includil~ the est.a'bl.i shmont of priorities for various t&sts. b. The maL"lte,na.nee and instrumentat i on of te!lt a.ircraft. o. Execution of tho actual test program. d,. Pet1:wmininr; tho ohari,.r,es 1.lGOOSSQ.ry to remedy items ,llh.ich are i'oum'l unee.tisfu.oto~ during the course of flir:,ht teats. 2. Planning tho 'l'est Program a.Ed r~t.rta.bUshl:nent of Priorities for Various Teats .. The oor,1 plete utili 1110.tion of every mL,ute of ex- pcr1aive flyine time requirea that ea.ch test flight be oarafully and oompletely plaruied. A single flif)lt my ®Ver a variety of iteras which }lave to be tested at difforent a.l ti tudes a.nd under dif'f.e1~e:nt condi'cions. Careful plann:i.ni~ will integ_t'ate ·thes¢_ varim.u\l test · itemi:; so tha·t a.11 of the tests a.re mnde and the required dn.ta obtained 1n a. minimum Rnount of :fHr.,ht tine. r"'urthermore, in the case of' large ro.rcrnrt to be tested at hiir,h altitudl,s, another- raetor must be oonsiclorod. The testing of a lar£;$ airero.ft generally involv-es a. considerable nuri.1be1· of people. Considerable work has to be ~one by ground personnel to insure that the aircraft a21.d. th~ flie;ht test equ:i.oment are functlonine satisfactorily. The fli/!,ht test orew, numberi.1'lg often as many as ten people; has to spend some time re~ding Q:itygen equ:i.pr,w nt and under• going denitrogeni~tion. With all of this work to be dor.,(l in prepare.• tion for a test flight, it :i.s gonora.lly U.'18<><:-atmioa•i to !!".s.ke flights of less thari aevo:ral hours t duration • .. The -pla.""ln:tng of a. fl i~ht test program requires the estab1 ishment of prlo:riths for the order in which th(:) vmrk will be per• formed. This ia especially true in tine of wnr., when the volume of work to oo done by a. g.roup of i?dividuala generally multiplies oon• siderably. i:a.ny :&i.oto.r s have to be eonsido:red 'besides the ovom.11 i.-rnportanQ.e of a parti~1lar projeot, v.hen establhh,ing priorities for. different flight te$ts in a eoro.pany. The relative in.portanoe of · the projeet,. ~e ai:rcruft which Ytill be available to perfom the test, the amount of time neoeesa.ry to J1Jake the required test installatio:ns in the airora.rt, types of tests to be ~de o.nd amount .of f'l i,[~ht time required, ,a.1 titudo at which t.vie test mm:it be cor::duotefc1, and nu.'1.y other facto~ must be oons:i.dered if a..11 efi'ioiont, eoonomieal II and ,rell"'r , tegrated test program is to be ple.rraed. The entire process of' setting priori t:tes o.n d platining tests can be han dled properly only by: &omem1e who is intin-e-tely conneoted vtith all of the fli r)lt test pro;je>ots a nd a-ware of all of the factors wM.eh muat be considered. It ls an easy ma.tter for any one ;J.ndivi"' dual to fi nd enough 1'Elasona why his ~rticular project should be t~iven first priority and the~fora eanpleted i nrnediately, by itself. to tho oxclus:i..011 of all. others. But such action ru ;_:, idly makes flight testing pt•ohiM.tively expensive ·:rrom t...11e poirit of view of' the amount of equl pment an.d number oi' personnel required to do a certain a.mount Rx:pe.rie:n.ee appenre to •indicat e that tho entire fl'icht test pr·oga.m in A. J)fll.rticiila.r 0.iro:ra.ft oom~y cn.n he planned and carried out with 'IT.IEl.ximum effieienoy when the fli t)1t teat orgp.r.i ea tion is govorned. by only the .moat general type of priorities pol:toy ancl alltAVad to us~ its <:Nm judgement in detc ~mi.."lfr.g the order of various teGts. 'l'he general prioritios policy (usually S C; t up by ::iarlfl.ff;Sment) should speoif'IJ, at rnost, the :relal;ive impor'bl.nee of only the mjor flight test projects. 3. The Jtnintena.noe a :r;d Instrumon-ta tion of Test A:i.rorart • Compe.J"Eld with ai?"line i'lying or r>roduction fli f;ht testin g , e:cporwntal ' . flight teatinp; is never routine,, it always involves samethinc differ• ent, somethin g noo. lt requires a different type of me:,ta.li ty, a dit'f'erent a.pproaeh to the problem of a. flying· ai:rplune. Good flight testing derm:nds meticulous a.tton~on to details r;,t airer-a.ft main.. tenarioe and i nstallation of .flight test eqtJipment. • With this attention; flight testing is sucoesr;;f'ulJ without it• flight testi."'lg be• oom.es just so mt1c.l1 very expensive flying. For exnwple, mny da.ya af propara tion and lOO.nY hours of flying can be rnade valueless by SO'C'!O• thing as simple as- a leajk in the e.irspEted system. .A(~in, a -whole . series or tests to determine &ileran e:f'fectii;rEmaas may ho.ve to be repeated because o:f a minor change in configuration of the wi.ng for• ward of the ailerons l something as minor as a muddy wi..ng may have a marked and measurable effeot. The proper control of these factors requires more "br"'-inS in the rr.inke0 th.an is required £'or routine airline or produotion test flying nninterJ.Q.r1oe wo:rk, i.e. it requires a higher level of intellige:nee a."nong the men who minta.in .:f'lir.Jit teat aireraf.t e..nd install and l'!B.intain fli;,;ht test instrmnentation and equipment. It is alm:QIJt impossible to obtain. e.rnl keep a. high le~el of intelligenoe among these men if they a.r(!) under 't..lie supeMrision of someone \Vh() i8 :not connected with exporimen-ml flight testing, I if they are frequently shifted a.round, and nre not given the oppor- tunity to get the continuous, speo!al5.zed train'ing n.nd experience ,ilioh they need to become profiQient in doing work on flip.;ht test ai:ro:ro.ft. True, it is quite possible, to simplify the me.intone.nee of :f.'lif}lt test, pt"Oducti on,. and oompa.ny air-oraf't (used for personnel I trn..."1sports) a.nd to show e. definite saving in cost by combil'l.ing all :rm.1-nte.110.11c,e nnd service e..otivities under ono department. However, it is easier sti11 to prove that the ooat of one rui~ed test fli£.9.1t • will ofte..T'l be gr<1e:ter tl.ru1 the total yearly expendi'.l;uro f'or sepe.rate mn.intenanoe ft\oilities for flight test niroro.£t would be. Furthermore, a.side from measurable oqst oon~idera tions, the delay involved in making a test n:tr)lt over ngiin to get urf~eritly needed data ~y often prove da.rrnging insofar as thG production schedule is eonoerned. 4. El!;ec,~tion oi' the Flight Test Progrnm .. The flight test organization must be given the unqualified responsibilit-y for carrying out the a(rtual test flights in the n,a.nner deemed mo.st suitable · f'or prO(luoil~g the required raeul ts. •Good flight testlnr:, invol-:;-e-s oo.reful teelmioo.l preparn tions, pe.instaking atterocion to :minor details, a:nd well---oontrolled test flights ·whioh invariably have to be oe.rried out urider special vreather oondit1.ona. •In the onae of one company whieh the authors considered to be well-orr,a.nized, it vas found tlw.t, O"V"er a porl.od of th)."~e months .. -approximately 75 llV3...'1. hours of ma:i.nte..nanoe tllld instrumentation work and 27 man hours of ei1g5.:naerir1g work were required per hour of flying time. These facts are often • forgottei1 or overlooked in a. spirit o:f' eagerness to r;et the job done. This f.'orgetfulneos ofte11 lends to admlnistrative oontrole or poli• oies which e.re tnos.nt to nset the po.oe" for ..,;he fl Lt.ht test orga11izatbn. The-mo.re oom:non of these are, o. tendence t .o jud~ the per·ormanoe of the flight test orc;trniza'ticn 011 the basis of test· hours flown, or even a requirement apeoify:tng tho number of test hours to be fl owa. in a oeri::.,"l.in period of tL"'1le; and a tendency to require cor:1ple'bion of certain project.$ Yrithin e. specified period ?f time~ without a thorough oqnsidere.tion of the problems which ~y be enoountered. . . If they are not used with oonside?'able la:lowladge and judg• mertt. suoh administrative controls e&11 only lead to grief :in the long . rt111. ,Fli.~ t teat proj~ets, like ~y other :research projects. should ' • • be retd.mv$d periodically o.nd cheoked f'or satiifB,otory progress. Ho~er, nn uninformed., arM.trary requirement thi1t 'they be completed at a certai.'l time ah.n result in the . expenditure of oonsidere.ble otfort • ' to explti.in why the requirement ~not be met, or it oan lend to futile attempts to perf orm satis.fact.ory :l'lfr,ht t:ests with inadequate inet.rtt-,, mentatian undei' questionable weather conditions. ~ di-.ater. It oo..n also lead Sa.f~ty demnd:$ that flight testing he carried out in a deliberate l!J;\.nn,er,. by per11crmel who ~t'e :not tired from. overwork and are given time to Qorupulouely a:void taking u,nnecessary obn.noas, even if a1rore,rt h~ve to be grounded for me.ir:tenanoe work exid important tests delayed., A design dTe.rts.man who mti.kes o. ,mistake o!" overlooks something can mke oorrectier.is 'aeveral de.~ b.ter. Howe•er, mistakes . or -ove.-s:1.ghta in. .f'lir)lt 'besting generally have fri ghtfully final .re- 'Po require an arbitNu•y amount of flying involves the r.tsk of b.e:i.ng oa,ui~t .-w.t th 9.n aircraft needing nnintenance work at a tilne I 1.vhen • combination or r;ood weather and more a(lequate i r:,strumentat:i..on would have made posaibl$ a test flight w:i.th sa.tisfs.dtor'IJ nnd oonpl0te results. netel"lld.ning Cl:tru.1f.$S Neoeufsaey to Re?.'ledy t'naatis:faotory 5. Items Found Duri.ng Flight 'l'ests • ..,W1th the advent of the 1ndep8ll4ent I • I • .• flJ..gh.t test otg&niza. tion, ilhe,:,e ha$ been SQt:'l& telndenoy to consider f'Hr)it testi~r, as a service :f'uno~:tor:, authoristed only to coll eot fl lght test de.~ f'o-r, w.rioua oubdivUU.ons ot the ~ngin~~ing depal!'tment. The rea,ponsib1li ty to'r ll1~tiatiug ·heats and taking oof'reottve measu:res whtm ur1aat:\.araoto1')1' li;etri,8 are enc<tUntered Qn an e.1.romft ls as.signed to the engineering d~pa.rtln&nt. Such an a,rra.nge-ment may be the only altel."!Uitive it it u ~()rutide:red unw:tee or im?OSElible to assign _the NJq_uir$d numbot of qualified flight 'be.s t e:ngi..neer-$ to the. fH mht test otga.niza.tion., However •. it may be"ome unsa.t1sfe.otory for a.-:zy- or the :f'a11ow1ng i'e&.aonss a. 'l'he adV&.!1'tl\ge:,a ot havhg ."two bralns" e-.ttack a cronw.,on • probiffin are 1--edµttely l()st in such an arrangement, :Flit.ht testing should brir,g to the O.evetopment of ai:roraft e. strong, . ., . . 1mpartia1 d$GiT..- to 11ee the customer•s spec,ifioa.tions satH.tf1ed• Ith-.$ been poiltted out previously that it ii generally more difrtoul t fo1· the eneineering dep&l'ltnwnt •to apprai_se its work er1tioally e.."ld im.t,Qrtinlly, from the customer's point or view. b. Unusual and oostly delaY'f) a.re often encountered 1then :flight· testing perfoms merely as a eeMriGe i'unotion,. It is V'El~/ difficult -at times to adoquately de$or1'b¢ an unU$ml phenomenon whti:th _oe-oura in the air dur-ing a _flight test. Considerable time my el.apse befbre tl;e required data are e:va.ilable in. euoh form aud in suffioient quantity ao thnt the en@tineering department can understand oam..,letely just what ia hn.pneni.ne;. Test fl ighta then may have to he re-,. peat-etl to , permit engineering dapa.rtnent personnel to actually observe the di.fficul ty •s j t ooour-o. The entire process is one ~'lioh requires a r;:roo.t deal more time then · it would require_ 1i' proper decisions conoemirig oorrootive measures wera na-de shortly atter the flight during whieh the trouble is encountered. o. ' Under eut,h an arrangement. flight test personnel be• come u.nmfonned• they dG- l:lOt al-.ys tmderstand. and appre• oiat-e What they a.re <loing, and they loae their SEil s-e of doing a. complet.e and ~onttruotive job. ¥fuE11 the amount of' flight t•eting inor-ee.,ua.., the Elllg:ineering department iray coounter a gnwing reluetanoe on the part of the fl.igbt te&'I er~niaation to perform importa:nt :f'l.ight ~e.te without •~•ndve queatiOl.\ing and arguing about their ne~esalty $id. !mportance. All ot thesi, factors._ if they were premitted to e,xist simulte,n$ouoly • cc-u1d so Nduoe the o-treotivent,as of flight testing as to make i.t preotioally ,.-s-eleas as a tool in the develo~mt of new aircraft.. Thus the flight ~st or{1tniae,tion should never. be permitted to beorn:~e solely e. dam oolle.ctirig agonoy. Howove~, the fli"1t test (n•gai11zation should not oonsider .authority to imke oorreotive dasig_n chQ.?1p.;0s -. as a lioense to do ~$ it sees fit, by itself', without any consideration of' engineering or production problems. In suoh a ce.ae, flight test1.ng becomes guU ty ot deprivine,: the company t;,f the benefits of having umore than one heQ.d'' work 01 a common problem:. Whan design difficulties are encountered, :the important quest;l.on ie not "t1ho will decid~ vrbat to do?", but rather, "-What is the best \18.y of eliminating the difficul ty? 11 'l"he final de• oision should naturally be n:iade by the flight test organization beoause, in the final analysis, it is the responsibility of this ·Or!!Jlni.;. zation to insure that the airere.ft is what the customer vrants. But the deoision cen be. and should be based upon e.chrio.e from engineering and production personnel whieh should be a,ro,ile.ble to and taken ad• va...l'.ltQ.ge of by r:tir,ht test p,:;raoimel. "Flif,ht teatin.p;, engineering, and production" committoe action on more important desir;i chru1~s will go far to improve working relations between these departmen~s. It will give the ene;:tnooririg department the sa.tiefaotion of doing a. ' complete ,job• result ~ deai~ -ehanbes which meet with r~.dy aeoepte.nee by the produotian department, ' a.".ld · still develop an airomft whioh will be aooeptable to the buyer. d. PT-T'SC1-U{r,;L POLICIES. • l. Ht.'l1l-lth, of Flieht •.res.t PerEJomel ... Safety considemticn.s demnd thnt all of' the members of a flight tost crew perform their respective duties p!·operly a.t all times. Aasum.ine; a knowledg~ of correct operating teol).niqnes• the perforroo.noo of the flip:ht test orew depencls largely on their physioo.l oonditiori. This is especially true when a groat deal of test flyin.g is done o.t high al ~i:tudos. The servio~e of e. flir:;ht ·surgeon ,r~raed in a:vio:tion aadioi:ne should be e:ve.,ilable at all t ir.&s to fl:t ,::ht test orews. A hi v.) 1• altitude Qhe.mber is indispens~ble if flie.;ht tests o.re golng to be . performe~ .at hitJl altitudes. The best in h1£'.:h-""8.l titude flying su1. ts,. oxygen r.ia.sks, and oxyge:n equipment should be provided. In general, . any reasoriable investment which the company CM. JIil.kc to ·promote the physico.1 vrell•being of flight test crews will be worthwhile. If pro- per preventa biva moo.1;,ures a.re ta.ken, ·iih.ere should nev1:1r 'be tiXJ.y occasion to terminate an important e.nd expensive test flight because of phy- sical moo.paoity of a crew member• . 2. Engineering 'l' est Pilots ... Mo den, flight testing deme.nd.s that the test pilot be primarily &:good pilot, with a more-thtm•usual ' aoount of' ability to· do precision flying. However, modern test flying . ' also demands tha.t ha be an engineer, preferably an o.eronautioal engineer. The only accepta.ble substitute,. in place of ~ .for-aal ~nf,lneering eduaation, appears to be a considerable amount or teat-flying; exper• : ienoet eouplod ,.with an open mind and a vtillinr,iess to admit tmt good instrumentation is in"Xlri&.bly mo:re aoeurate than a. 11 calibrated test pilot"•, Whenever the rare combination of good pilct, good aeronautioal • engineer, and good exeou ti'7'0 osn be found, it is. 001111~,on. pra oti c e to , ohoo~ suoh e. n~i1 as the hoo.d of the flight test deparbnent. , Other- wi~e, the e.ngineerfog test pilot~ are macle ?).rt of the flight test department, responsible to the direotor · of that department whether or not he be a pilot. 'This a.rrant~ement app~rs to. be Wl"'J satisfuotory f'rom the st..<tndpo1nt of enabling test pilots a.fld fl ie;ht test engineors to m>rk together olosely a.s a. team, with :mutUlil.l respect f9r and e.ppreoiation of each other•.s abilities. It o.lso eliminates a t\On• siderable amount of the fr:letfon which is bou.."'ld to ooour if na."le.gement :receives uncoordina. ted flight test reports from t·wo different sou rons, from the teat pilots and from the flight teat orga.niza-ci on. , • 3. Working Hours .. Fli.fJ1t t&l!!ting depends to a. 'groot ex- tent on the availability of good flieht test weather. Tha flight test organisation whicli does little flying for~ time beonuse of 'ood -weat.1-ier m.a.y oud~enly be called uµon to spmd whole days flying ,.d1en the weather becomes suitable.. lt is generally advisable, be()f.rnse of.health and safety, oonsidero.tions, to limit the :n,..ax:lmum contlnuous working period of flight erew members and to require reporting to work later t.l,w.n usual the following morning wh~ a test flight 1.a.sts late into the even:i,ng. mten flight osting is in progresa, it is advisable to have maintenance 01'8\YB at work early in the morning so thAt test aircraft rray b~ given a. pre•flimt inspection 0.ll.d be ?!8de ready for use b;r 1:he time the flight crews report for duty. Also,. if flights a.re g;oi?,r; to last i~ta 1.n·t o the evG:r-4,ng, it is well to have stenografil:i.e help • available &O that important flight test results 06\n 1'll'l'Jl$diataly be dictated end typed, in prelimin&.ey form, ready for distribution 00.rly· the next momint• ln geneMl, the entire matter of working hours for flif;ht test pert,onnel should bee. flexible one, left up to t,he discrotion of the direotor of the flir)\t test dapnrtment. A rigid work:i.n:g•hour sahedule and eff1o16nt operation of the night test orr;nnizat5.on are :i.nco111patible 11 especie.Uy if the worlcing hours b.e ..set b.y company policy without due ree,i.r.d f'or the requirements of tho fli tJ1.t test organization. e. COST CO!TT:ROL • Cost control by menns of a. .budget is one of tho mo~t effective tools available to nll.nagemant and needs little oomment here. The cost sySteI!J. should provide for tho co~lection of data on various expenditures fol" ea.oh fU.f,,ht test project. re.ta on expendi turos-to-date should be, a~il.a.ble and oonsul ted whmever flight test projeoto are bei.ng revi.awed for progress. ' ' ' f,. • ACCI DENT DO.A.RD • An .Aeoident Boa.rd oo.n be orga.nized in a vary short time and will save a company ri:tuoh grief' if it is ever- needed. Speoifio 1nstruotions should be l11S'tUid to the telephone svd tchboard operator, oovari:!'Jg the l'!l\nner in which e.11 members of the Aoeiden-b Board,. or thoir alternat.es. ~ should be contacted in an emerge-nay. The BoM•d should be ready to a.et at a moomnt•s notice, hn.vme; set prooed.u res for the f'ollowi.ri.g1 insuring thRt medioa.l a.id e.nd fire equi;rnont is dispatched to the proper location J oonduoting an invest1• . ga.tian; e;uardirig the damaged ai:r<1ra:ftJ handing out inforrns.tion to the pressJ and answering telephone calls. Geneni.lly, the Accident Board should funotion under the direction of a member of the Flight • Test Department and should include EU'l engineering test pilot, the project eng1~er, the flight .surgeon, and rep;resentati·vea of ma.nufa.oturing, p~blio :relations. plant prote~~on, the le&il eta.ff, and the services. 3. POLICIES WITHm THE FLX GHT Tg ;JT oEGANIZATH.N,. is. a soienee in whioh there is no aubsti ·cui;>e far experience. The judf}rl.ent r;md deoi.eicns of an experienced m.n will invariably be tem-, pered· by the thoughts of many incidents which; with a little l&s.s luck, Night \Vall have bean diaa.stroue. One of the prinwu-:, requisites for h1sur:ing aa.tety in Ii flight test ~ganiza.tion is on adm.inlstra.t!.ve policy whieh defi.ni tely pla.oes the resp·o:r ieibili ty for an important V decisions in the hands or the experienced• key pet•c-nnel • • For e:ita.mple, th• detailed plans for ea.oh te.et flight should be eubj~ot to rigid inspeot:i.on and approval by the chief flight test engineer and by th• ohief' engineering test pilot (oT their fir-s t assistants), prior t~ ea.eh flight. tested. This is especially impo...,-eant when new au-ore.ft a.re being I . D6viatio.."l8 from flight plans. during th~ test -flights should be allowei only in the oa.se of minor items·, except on those flights whet'& one of th$ k:ey men is noting either as ongin.eerir;e teat pilot or flight teat $:rlgineer. The detailed i ns te.lla tioo <l _.ings tor flight test instru- mentation should also be oh~oke4 closely by exper1enood personnel. especially where the instrumentation involves the power _p lant eontroll!J ' or the prlr.nry flight . control system. All such inetruinen-mtion should be desig;ned so as 'f» give the pilot e.11 available control of the air• plane• should he require it 1n an emergency. For e,a-rn.ple, in. f'Uel oonsumption t~sts., it should be possible for, the p:llot to instM• taneously switch on a by-pass for ·the e1'l};ine fuel supply 1.n the event of failure of the tuel~f'low measurir.,g system. Where tests are being oonduoted to check the struotu:ral integi-ity of certain pol"tions of the aircraft, every effort should. be nade to pro'Vide tho pilot v,"i. th sµitable warning devices so that he knows whe:n neo.r-oritiool loads ,,; . are being enoo1mtored. lt should be constantly remembered that the . safety or the flight 'orsw a.nd test aircraft lies entirely pilot's m.nds during fA. test .flight. in the His responsibil:i. ty is a great one and every attempt ahoul.d be made to assist him in disoharging it properly. La.ck of e:xperienae among engineers o~en results in a ls.ck of' appreoi~tion of the pilot 1 s task whieh should ne~er be perrniti:~d to mn1fest itself in the :f"ol"!!l of experimental insbtlla tions whioh hamper or limit the pilot in exerciaiug complete control over the test aircraft. A ey&te!IJ.\.tio training pragre.m for flight orews should be a. pel"!Mnent part of every flight test organ1-.tion. The program should include flight training for pilot$ and co-pilots~ wider the di reotion of the chi.ef engineer :i..ng test . pilot, and eri.gineering tro.ini:ng for .9.11 fU.e;ht orew mem'bers,. undel' tht, direetion of the chief flight test engineer. In addition, every attempt should be 11_1ade to p;ivo ~eoial enginee?'ing training to pilots who do not h&ve a f'OJ"rnal eng\neerin.g eduoo.ticn as pnrt of their 1-okground. These tf'ainirg programs should be ocntinuous, cilthough they may be sohedtL1ed at irregular intt,rvals to take advantage of sl•ok periods when good flight tost wee..t:r..er ie not available. Nothing 'should be left to chenoe; no an .lhould be . permitted to perf.'onn .a· pa.l"ticular fu...71.ctio:n during an aotunl test f'light m t:11 he haa previ o\lSly demopstra ted his a.bill ty to do it satisfactorily w.i th complete safety to himfllelr • to other m&mbers of the orew, and to the tes~ airers.rt. a.s poao:i.ble. The training pl'ognuu ~hould be as pre.otioa.1' Fer e»1mple, a fuel flO'ffl!leter opera.tor should be ;equired to deraonstrnte his ability to perform satisfactorily whi ! e dressed in hi1:)1 altitude flying olothea. weari..i-ig his parachute and oxygan equipmnnt. Tho .principe.l objeoti ve of the training proira.m should be to insure that all members of a fli ght crew· are unquestionably qua.li:f.'ied to per form safely and properly the duties which are assi 1~0d to them. A ri gid oontrol over all work which is done on flight test a.ircrn.f't is necessary. It ahould include maintenance ,Nork as well as bstallations of special equ'>.prne:rrt and iri.a·t;rumenta. This control shouJ.d l"Sst :in. one individual, generally the fli e,h t tes·b engineer assi£;n.ed to o. particular nircrn ft. The m.eth od of control ahould be suoh thP.t before a f1ir)lt the test pilot can readily dotomine what work has been dor.e on the airorn ft since the last fli cht. 'l'ha preflif..,ht inapecti011 of the airplo.ne should include a check of s.11 s ixioio.l. • flig-)1t test equipnent and in3tr1..1mentation. (In additio ,, to safety: oon• siderationa, the i."!lporta.nce of gathering us muoh us·erul and reliable data a.a possible on: eaoh fli r:;ht r~kes the pra--flight ahecking of all fli sht test equip1!1ent absolutely necessary.) Before ea.oh fli g;ht, the pilot ond flight test engh:eor should have -definite evidenoe that the complote aircraft and all installations have boen :bspectad. and Qhecked :f'or satisfactory or,omti.on by quali_fied personnel. FliV1t test personnel must ab'lo.ys remerr.b @r that fli r-, ht testine: is seldom routine, The desi 2:n of' each now s.iroreft consists of a series of oompromises botweon weir71t a:."lcl structtirnl reliability, betweor... simplicity and satis:fact,ory op0:ro. tion under all o.pecified conditions. 'r heoo compromises der\lin d ·t11i\t t~he oa.pa.bilitiee of an aircraft be determined gradually. They dae1and that n.o naJ n oomponant or a nevi design be tested under woret possihle oon<litions wit..hout first ooin e operated successfully wider leSB-aevere oiroumstances. Finally, the ux1expected must always be a.:n.tioipl ted o.nd provided for. 1.hergenoy procedures should be established and pra cticed at frequent i ntervals by a.11 flig.'1-it ore,v mo.:tb(rs. These cnnorg8'loy procedures should cover failure oi' oxygen rupplyat high altitucfos, :first;...e.id treatment of personnel ·who become physioally disabled d'uring high a~titude flir!hts, and order and rr£trmer of. oo.U-ou·t. Common sense requires tha.t e.s fevr key persormcl of the flight test orga.niza.tioo. as possible should take po.rt in tha same test flight., especially during opem ti anal te.sts of a new vrototype., • Considerable- good judgement hn.s to be usod i n esto.blishing • a.dministrntive policies a.nd oont:t"ols ·which will insuro -chat safety requirements and safety considerations are never neglected in the execution of tho fli r ht test prog>!'flm. The fixed polio1es an d oon- . t:rolo must natu rally r;et more inclusive and more dorra. ::1ding as they ei'f'eot the activities of personnel with less experience. However, they must be limited only to items of impo:rtar;ce and so used as to holp the inexperianoed man dis()hargo a.11 of hi.s 1-espcrisibilities more rapi dly, k a sys-te,,-atio fashion. These · polfoios an d oontrols must be reviewed ·frequently and revised whenever r!eoessary so a.s to encoura ge l"ather than l:imit -the use of' i n itiative on the pa.rt of the young engineer v.ii1.o is governed hy them and who. most freqmmtly., will be the first ta detect their inadequacies e. ril. l:i.mito.tions. H~vsr, the strict adherei,ee to established po1ioiss must be den~ n ded f or, without it, the less-experienced personnel will be aki.ng decisions which my ee..s ily loo.d to lc,ss of valuable personnel and equipment. A ppi:rit of teamwork must pr.e ve.U arid each rrte·01ber of the flight test organ i~tion must 'know his own limitations a.nd aooept administrative . policies as the best 1:nsu:ranoe of safety, rather than regard them as neeessary evils. b. TTIE BTTGUIEF'riPIG Tl~ST PILOT • The engineering test pilot gane:rally brin gs with him a vast fund of practioo.1 knowledge and \ experience ,vhich oa.n be of immen.ie value to the fli{'.',ht teat arge.,niza.,. tion. Prinl:\.rily,. of course~ the pilot possesses a hiq11 degree of skill in the pr6'lCision i'lying of vario~s types of aircraft. However• so.me companies have often hired test pilots whose flying technique needed additional davelornent and improvewm.t when those pilots possessed other qual ifioe. tions which made them of' still -gren.ter value to the organization. This has been espec:d~lly true when the pilots . in question have hact a formal engineering education. The good pilot-engineer is a ra?"e individual. Every attempt should be made to insure · tho.t both his fiying and enl)inee ring e.bili ties a.re fully utilized. . Frequentiy, he will be found most va.lmble as a teat pilot of' smgle•sea ter a.iror£tft where he ea.n also perform as a qualified engineer:l.n.g observer. He is -pa.rtieularly val ua.ble when• because of la.ek of h :strum.enta.tion, only qua.litati ve tests are ba:lng •made to determine the flying qua.l ities of an aircraft. A te st pilot- engineer m.11 save t,he oon l'.'l\ny much tiroo o.n d mor1ey ty befag able to \ I speak the ae:rodynrunieist •s lanpge in describin~ def'ioienoies in' the . oont :rol system end suf;r;osti:ng methods or eliminati ng .tho diff ·ioulties. Ch the ground, he ·.should be allowed to play a po.rt b tho approval of detailed flight test plans and installation drawfrf~S of flir,,ht teat equipment a.."ld mat:rurneri'bltian, especially where ·t:he engine con• trols or the prinary flir:;ht oontrol system is ooneierned. His jude,oont 9,,.'1.d advice will often help the fli r:;ht test organization avoid rrmiy expensive hours or grief in the air durine; flic,ht ·t:asts. Teat pilots who a~ not engil'leora will .f'roqu0ntly he found qualified to perform eomo ground function ir. co:.! llection v1ith the administration or the experimental flirr,ht opemtioo.s offioe. It is important th.at ail of the abilities of test pilots be fully utilized, not only to keep them busy while not flyi.'r1g, but to insure that they acquire a- genuine i..11terest in and becorne thorour;hly e..cqun.inted With the rre.ny engineering ElJJ.d proctionl problems whioh have to be eo~"Js mr:tly solved to nnke flirht test:i.rg of wl.uo. Only when the pilot' work ver:;1 closely with these problems will their fund of practiool !c.:i.ow• ledge and experience play a pa1·t in and be of valuE! in the daily aotivitios of the flight test orge..nba.tio:n. Of course, whenever a pilot is assi©-1ed respcnsib1lit1os of a continuous nature, it is ' • importnnt that m.rosures be taken to prev,,nt hi$ work from beooming a bottl~meok when ho h called upon to do a lot or flyihg. S:i.nce tt:.:;t flying ie not a.lvmye very regular insofar as the individual pilot is oon<lerned, t,his problem has frequently H ni tod pilots to non•flyinr:: a.ssir.;nmonta of o.n advisory nature only. A oomnon· problm in f'li t ht test organbntions ia the one of dividing responsibility between the test pilot and flight test l. engfr.eer so e.s to insure e. ~ amount of oooperation and a. minimum amount of froiotion. The idee.l solution to this problem . is found when a sufficient number of pilQt-enginsers are available for assignmm.t ' to the '1a.rious test airerart 1 with the flight tes t er:gh1eers as their a.s sistants. The pilot then becr:imeei r esponsible for e.11 of the details of plann i.ng and earr.1in g out teste e.ssi f::?1-ed to his aircraft. . Un. fortunatoly, e. sufficient numbel" of pilot•eng :i neero can rarely be found. It appears . to be oom1lon prao.t i ce in such, CQt:Jes to make the fli ght teat engineor responsible for the dcetailed planning arid pre·parntion ot e.ucraft for the tests e.aai gned. During an actual test flight~ the test pilot is respnnsible tor all decisions on matters of safet;,, but he is required ~ follow the b etr;uotioos o.f the flight test enginec,r insofar a.a . the details of <:,onductbg the tet;t a.re oon• earned. Such an arrapgement is freqoontly unavoidable• but it is an unhappy one, at best_. an d SOF.:18times lead~ to friction over a period or time, 'until both pilot ant engine er learn to appreciate ea.oh other's abilities and begin to realize their own lim11iati011s. o. PLAHJ!ING .Mm CARRYHlG OUT T:IB F1.. I GHT '!'EST PROGRA.1.(. • It vould be an ' endless task to. discuss the multiple problems wh;ch ru-e gonerally eneountered iu planning a sound,. sensible flight test pror,rnm. In addition to the teats found neeessa.rJ a nd - planned by the flit~ht test department, requests for various tests a.re received :f'rom many sources among 'ffllioh rre.y be project engineers, the production de-- par~nt, a11d the e.'erodyl'ia.mios or the win d tunnel subdivis:ions of the $tlgineering department. All of these teat requests or "test items'' a.re assigned proper prloritie~, the major o::nas in. accorda.nce with prevailing company policies a.s to their reli➔.tive importance. Suoh fao-tors as i.ustrumoo~ticn time and flight time are then oonsi dered and bale.noed against the priorities. The "test it8L'ls 11 a.re e.asir;.ned to various test .a ircraft in such a me.nnor as to insure full utilization of oach tes-t airaroft; both on the ground e.nd in the air., and yet minimize interferences between various test items which migh~ seriously delay a high--prior1ty test for one of lmver priority.. the "flight test team" scheme appoors to have been Sllcoessfully applied by most flie.ht teat organho.ttons for perfonning the detailed work &f planning ea.oh test flight, preparh{~ the particular airoraft for the tests, and actually oa.rrying out the test flights. The "flight test team" g;enernlly consists of pilot, oo-pilot, fli~t test engineer, instrumentation engineer and fli@11t test obse:rvors. Qualified flight ,test engineers are oceasione.lly givon flight training and "oheoked out" aa oo-•pilots en aircraft whioh have completed the operational phase or flir,ht testh1g, thus permitting them to act· as flight test e nglneer•oo•pilot. (Instrume:nta tion and inatal la ti on meoha.n.ios and me.Lr1tena:nee mechruiics are sometimes considered part of the team when . the test e.irora.!'t 18 a large one.) 'I'his nflight test te8.t!l 0 is assigned one or more flight test aircraft and, insofar n.s possible, they are kept workil1g together on the va.rlous flight tests pel"fonned ori those airernft. Etft,her the pilot, i t he be a qualified engine~r, or the flight test enf~ineer is made :responsible for th~ aotiVities of this r;roup and all work on. the teat aircraft is per• formed through orders issued owr his signature. subject to proper approw.l by hig-)la:r authority if neeease.ry. The nrlight test toam" has the pt'inoipa.l advantage of bringing pilot and fli[?lt test eng ineer 1 eloaer together and p@rmitting ea.oh of them to apply his specialized ability tove.rds the solutim of the various problems which are en• ooun~rac,. when test flights are being planned. It alao reduces the .• amount of oonfu&ion which is sm.etbes oree.t,ed when ma.i.ntennnoe personnel. rGoeived uncoo-rd1 fi.ated orders for work to be porformed on the same test e.irpla.7l.e fran pilots .. flight test mg:ineera, and in• strumentation engineers. One or the ma,jor factors m _ioh will greatly u1eroo.se the oost ot flight tests is the a.coum.oy whioh is r equired. As instrumen• taticn methods improve o.nd develop, the snroo investment will naturally provide bet-ter, more aeoum te instrumentation. However, the grenter tho desired &.oeuro.cy of resul ta, generally the more flight time will be required tif produae them. It is important that this problem be oonsid84'ed oaoh time new tests are en~ou:ntered and t hat it be a.pproaohed with the ••mx1mum permissible error" outlook ratht3:r tl1."3.n with the desire for' unaximum possible accuracy." This e.pproaoh will frequently gi'V8 the desired results e.t muoh lower cost~ But ea.re must be axer• oioed' lest the a.pproaoh bo pe,rmitted to im.pc ir the e.oouraoy of l:aaio tests, suah o.e power oalibre.tiona. where aoouraoy is essential. All of the members of 11. flie-.ht test orew should be required to attend a. pre-flight and post•fli!_!')lt oonferenoe i.'11 oomection with ea.oh test fl'i p,ht. The pre•fli t ht eonfercnoe n.ffo:rds an opportunity . to discuss the e ntire plar.\ of test a..vid insure that oo.ch crow member kn~ wmt will happen and what will be expeoted of him during ea.ch . . phas-e of the test fU.ght.. At the post~flight eonferenoe, the results of thlJ test flight a.re diao.ussed .and each orew member ia reqitired to . . present his "squawk sheet", listing• any items of equipment and in• . ' atrumenta:tion which did. not o~n.te during the flig')-rb. The flight test engineer is thus able to detennlne whioh test items sy have to be repeated and how mcm maintenance work will be nooeesa.ry <n the airplane and teat equipment before the next £'light 0$.n be 'tffl·d•• . . . . Strict discipline should be exercieed in the natto:r of pranpt atten• dance a. t . these eonferenee,. ?1othing oa.n be more :~li1ing tlan to he.ve the joint work or o. group of' men repeatedly held up ,.. the te.rdi• nesa ot one individual.. ri. REDUGTl<Jl 01'' F'LIGHT TEST DATA JJ\WD DISSt1M1HATIOU OF RT$SU11rS. • Speed 18 the major oonsideration in reduoing f'li~t test data ~d •disseminating flight test. reaults, assuming that the z.-eduo,.. ·.:O.. ti<11 methods used are ma.th8lllltioa.lly sound and su:t':f'ioiently a.ooura.te.: A£ter the ~st flight is oompleted, nothing should be allowed to in• terfere with th& job ttf' making the results f:\.VB.iJ,&ble in usable form as soon as. possible. ?ta.ny !'light test orga.r:d.zatims consider this problem 'When the inst~tatiol'i. f'or a particular flight test 1$ being Every effort ie •de to make speoial fli@lt teat ins~ents ., ' • direot-reading when they ~re ca.libl"ated. For example,. a control sur-- planned. J faoe position indica.tor should show. direotly the auri\l.oe position . . in c1egrees, rath~r than an e.bs~4:iot numbe-r ·which then has to be eon• verted to degrees by referring; ta· an appropriate oalibrntion cu~. This practice saves an enonnoua aroou..llt of time in data redu,ction and is very effective if it does not ino1·ease the time requii-&d tor 1n.. strumenta tion to any great extent. Irnportant instrW!lenta are oftctn duplicated on the pilot'• and fli(iht test ena;ineer•s pan-el. It is thus possible to plot the· res~l ta of certain phases of the tests being conducted while the test flight is still :i.n. progress. • Thie permits immediate rechecks of. en ta whioh apr.,.ee.:r to be inaocurn ts and makes the more impo:rtn.nt datii. immediately avail,able fo:r use- t'fhen the airora:f't lRnds. In pfJ.rtioula.rly urf~ent ,oe.ees, the data rrAy be_ radioed dmsn to a ground station bofore completio11 ot: the test flight. A najv portim of flight test de.ta is, 1.11. most cases., re• eordced by autoroa·bie photo-observex-a. Every flight test or£!P-1tlratim should make provisions for 1"8.pid ha.ndling of' the photo..obee:rver f'ilm.. Sorr.e companies pr9vide for the oomplete'f'inishing of this film within one hour after completi.on of flight tests. De.ta-recorders a.re then employed on a.:n evening shift to read the film nnd plot all data s~ that it j,s available for fli~t test engineers early the following morning. The :rosulte of rl.i~ht tests should be promptly 1D.o.de available to all parties concerned. This is especially true when the particular test item is at1 attempt to correct service difficulties v.tlioh haw e.ffeoted the produotior- schedule. In general, a preliminary report, giving at le~st the raw fligit test dtl.ta, should be in the hands of the person requesting; the test within twenty•four hours of the oompleti on of a i'light covering the test item. fl lght te8t resu 1ts does two things• This p:rcrnpt distribut:lon of 1. It koeps everyone informed of the p1...ogress boir..g nnde on particular tests. 2. Frequently, i t results in the oa...'loellation of part of e. test when prelimJnary results ei th.er give a satis. • factory answer or indioate immediately tmt the parti- cular test itan should not be tested further. e. PEOTISIOF OF AD E{lUATE FLIGtIT sc ;;l;1)1_: rns AF D RECORDS. • At 1E¥tst two different flight scl1odules should be provided. The first of these should list the entire flight test program, sho,,'f.L.,,_g the priorities of the various test items, and the airo:ruft to which they have bem: ass5.gned. It should also gbre. an est:lmntG of the probable con pletion date for the various test i tams and the causes for delnys when they a.re encotmtered. Suoh a schedule is very valuable in pro .. vidiqt ma.ne. 1,;ement, the enginem:•i nc dep'2~ rtment, the fl i_cht test de- partmerrt, 0.!1d others with a grr:1.phio and conplete picture of the entire flight test p1•ogra,':'l. It ina.kes th~ mo.tter of pl"iorities an open one and , in .alJ. frdrnoss., giires r£1a nugement and other ixrteroste d depo.r'bnents an opportun5- ty to question priorities vthich a.re established. T'ne second flight schedule- should 1)e a. schec1:u1e of actual flight oporations for the period which i t covers. The period may vary frcrn 011e day in the case of e. large flight tost orga:nizaticn to several days in. the rose of a smll orga:nizatio:n· where only a. limU.ed amount of flying is done. This seom:d schedule, when properly dis• tributed, will always eave fli r)lt test peraoimel a. considerable a.mount of time \Vhioh would otharwise be spent givlng flight plans verbe.1 ly to tho5e ,r.ho request them. , 'fypioa.1 'e:xamples of tl1ese two ffight schedules are given in Sec.· D , ff Operating Proeed~:res." - r Adequate reoords of work and flight time performed under each test item should be ·. -ref'ully kept since theY, form the basis of . cost control. Muoh time• aa.n o-ften be saved in aul.rai tting cost es• • tine.tee for flight test prognun$ 8.lld the estizrates tha:nselves will be m-0%"e 'aocura.te if oo.refully :rooorded data are available• covering work done an progX"fl,ms of a similar nature in the ?&St. Cost date. are also in'tJ8.luable for .b lllaneing flight res~t"Oh coats a~inat the potential p?"of'it or ga.L'l'l tram the de.ta whioh are being ob~ med. f~ Tins FILPIG SYSTEM• • The story of lost or misplaood. data . ' . is so conman ·and vrell-knqwn that pemapa even the wildest eatinate of' time o.nd mcney lost beoe,uee of 1t 'M>Uld probably be coose.rvatiy-e. A rigid, cor.aistent syste;1 o'r filing various data o:n fli ght t(;tsts which are in prog;ress shbul d be maintained. Data: which are haphaaardly file-d or kept by ',several persona oo.n seldom be quickly. located whm they are needed in cionferenoes or in &nS"Wering urgent telephone .calla or 0-9rrespondenoe. The f 11 i."1g system must obviously be ei.mpl e and strair,htfonm-d, for othervrise it vrl.11 tax the valuable time of engi11eers who use the "ooua. in proe&ss'~. A typiool filing aystan fa;; · ourrent ' flight test date. is given in Seo. D. , A oross-irtdexed filin.g Gystem should be kept Qf a.11 reporte oove:riz:lg work whi.ch has been done by the fl i f,ht test organize. tion. • ' . Problems OdOS.Si;onally repeat themselves and 8. past report v1hich .oen be easily found for refe1'8floe will often saw muoh time, effort, and . mCJney. Some of the larger f1ight test orgn niza.-tio:0.s find it adv isable and profitable to employ a. full-time librarian to insure continual proper handling of the report filing system. -ssD. OPFR!sTIHG PROCET)\J~{BS • 1. . GF1mRAL. 'l'he opera.ting prooeduree for any particular flie::ht test orga.nizatioo must be outlined speoifioo.lly to fit that or~:nizati an. Methods of opera t:l.on ·will ve.r,1 with the sizo (tnd che.racteristica of the air• ore.ft company e...n d the fli ght test organ iznt': on. a.nd i:hey will also vary with the types a:nd sizes of airplar1es to be tested. The ba.sio p:r:inoiples u.'1derlyi:rig opera.ti ne; p-rocoduroa were prose,,ted c;en~n·al ly . in preoedinr; seotl. on-s. Th:i.s sectim~ disoussos s0100 of t.11.e pmctioes which can be followed and standard forms wh:i.oh oan be used in the applioa:tion of basic principles -to routj_ z:e flieht test R·ctiviti00. Stnn.dal"d forms do three importn11t thii::.gs: n. They outl:i.ne e. pa.:rt:i eula.r task co,;,o lately .so thnt the ra• cipient 111..ay properly do everythi~g required of him, accordLr1p.; to established policies. b. They permit the executives in e.n ore,-anizati on to for&-et about routine e.otivi tios and concentrate ·cheir time and efforts an important current problems and problems which may a.rise in the future. o. When properly filed• they form o. com:) lete historical record of the more L-nporto..:nt a.ctivit:i.ea of e.n orr;aI.,:i.zn.t ion . Over a period of time, such a record ee.n bnco:":e irvahn· -:10 as a. cuide in tho establishrnont of new po·1ioies~ The success of a:n orgar,ization frequontly depmda m! the e xtent to which executives can stundnrd:lze routine a.ctivitios, without burden• i q:; their persmmel ,-rlt..h n.n. exoessive wwun t of "paper work". 2. ORGA2TT.ZA.TI ON CHART FOR TTT.B FLIGHT TE::rr DEPAR'l'HENT. For purposes of this diseuHion, a typical organization oruirt fol" a. Fl i~t Tes-t Department 1s preseri·ced il1 Figure l. - The oh.art sham would be suitable fol' a large company. In the Oil.Se of a smllor company, the same prinotpiee would e.pply but just. a few individuals would be performing a.11 or the f'unctiona listed. The fol.lawi ng important ·f-.ture& of' the organi.,t:l.on Qhart; should he no.~ d, a. The Flir:;ht Test Department reporta di_reotly to tsnagement. The actual off1aia1 to wham the Fl i ght Test Department re• ports might be a 0 vioe..Proaideo.t in Charge of Research" in a large oampany, or the President in a enall c ompany. In . both oases 1 however, th& Flight Test Departme!..tt would be •tndepe:ndfmt ot . . ·iu·s.d cm the ·se.m& O!'f11.lnizational level as-· the F'lngineering Department which designs the a. ircrart to ,be tested. b. An "F.ingi.neer-irig•Flight Test-Produotiontt Cor.mtittee is used ,to oheck: on the impoMan.0$ of \18.rious fli ght researoh pro- jects., to insure 'bhe oorrelatict1. of important wind tunnel and theoretical data. by means of' fli ght tests# and to ex.. p&di te any - t'l i~t tests vhioh might affeet the prodUO'b1m s<'lhedule. o. The Flight Test Planning Fnr,ineers, 1n eaneul tation with the Director of the Flight Test Depe.rtt1)9nt, plan the OV'e:mll flight test program. They determine priorities :for various tests• prepare i'l ir,,ht schedules,. and insure that equipment and personnel are utilized with nax:bnum. e.f'fici~cy in carry- ing out the flight test program. d. The EngL11eering Sta.ff aots irl an advisory oapaoity, a.saisting Flight Test Y•lngin.eera in the solution of speoia.lized problems 1n oonneotian with power plants, propellers, hydraulic systems, t\nd the 1 ike. e. The Fligh~ Test Teams plan each test flight, issue the orders to prepare the airplanes for each test fl:1.g.11t, and then onrry out th,() tests. 1\'aoh team is oomposed of an ~gineeril';g Test Pilot• Flight Test Engi110er, Co-pilot, Instrumentation Jsngineer. Da:t,a. ltrialyst, and other neeesso.ry £light test crew members. Either the Engineer:i.ng; Test Pilot or the Flight Test Rngineer ia responsible for the actual activities of ea.c.'1 team. The Chief lnstt-umentatian Engirmr and Chief' Data Analyst exercise teohnical supEc,rvi• s:too over ~e work ·or the Instrumentation Engineers arid Data ' Amlysts e.aaigned to the various Flight Test T!:&ns. t. 'M1e· Director- of the Flight Teet Depe.ri:ment exercises super- vieim, through the Chief of He.intenance and Installations, over all ma.intone.nee and installation work done on flir;ht test e.irorai't arid over the persormel (foremen. meohanios, eto..) who do the l'tork. The :f\tnet,1.ons or· all of' the various units into which the Flir;ht Test De1_.i-tment is divided and the duties of a.11 key personnel should be closely defined so that there is no overlapp:l.q_,; ?f responsibility. Figure 2 givos an example of the "ffl'1Y. i:n which the duties of the Flight Test F.ngineol" might be defined. 3. PWrnrnG AND CA}1RYrm OUT THB FLIGHT 'l'E!3T PROGRl\JJ. Thie outline of operating procedures has been dividecl into the following four parts, a. Initiation of the test and a(ltivi ties up to the time that ; the airpla..".l.e is prepared for the test. b. Carrying out the flight test. program. o. '1.'ypioal safety preaautions. ·d . A filing system. a. rnTJATIOlJ OF Tim TE~1T A:HD ACTIVnn:s .TJP TO TIIF TI!SE THll.T IS PJ?J!:PAmm FOR Tim TEST. "' All of these activities Tm} AlRPlANE and the nenner in whioh .they affeet various individuals are pictured g;ro.phioo.lly in Figure 3, "Preparation.a for a Test }'light." I l. . Request fo~ fest. The request for test m.y origma ts in any one ot the principal. depar'bnents of the co:npany and i t is Jsent to the Direot.or of Flight TGst:. However, before- it is even transmitted., the· request should be carefully evaluated for its n~oeasi-ty, its sitn11arity to other tests, its singularity of purpose, a..~d the possibili~ that the dosired inforrru,tion might be more quiclcly ,. and more accurately obtained f'ran other souroes. The request for tt,st should atate as e<rpletely and as oonoisoly as possible the items to be i1westie;t:i. ted and the aocuraoy with "'llmich they a.re to be determined. V.!h.ere exceptional acouraoy is required, reasons for the requi.rem<m,t should be given,. The Direotor or Fti~t Test will examine the ?"oq_uast e.ni:J., U' it appears logiet.l• he will fol"\'$.rd i t to the Flight 'l'est Planning :&-:ngineet' together 'V'rith a.n.y re oommanao.... tions whieh he T!lly have as to the a etian to be talren. 2. A B&19le Flight Test Order. • The Ple.nning Engineer then oon• s.iders the nat'l,lre of th• test, the priority Whioh it de1wves. the G.il"J?lane cm which it can be performed;. the possibility that it can be combined with t:tth~r tests, and the amount ot grouttd work and flying time wh:tah will be r,equired to complete ths test. The Budget. Controller uses these da:ta. to estimate the eost of performing the test. Ir it appears that the ooat w:tll not lM, excessive• the Director of Fli~t Test will approv~ the test, The Planning Bng:ineer will th$Il assign th~ test to a. particular Flight Te1:,t Team by issuing a Flight Test Order Vihich authorizes the Team to perform the test. Figurt:J 5 ShOfflJ a typioo.l simple Flight Test Order. On the be.sis .of e.11 of the Flight Test Orders isslled, the Plannir:g lihgineer pre- pares an appropriate schedule of the Fl i.ght Test PTogra,m. Tho flight schedule is revised at frequent intervals and distributed to all ( s. Configure. tt on Sheet. • The Flight 'i'est Engineer of 'bhat particular Flight Test Team then ·G'lmrts his work on the test. He firGt consults with the ln.strumenta.tion Engineer a.nd Data Analyst ef his tea.'l'l. in determ:ln ing the gunnti-ty arid type of the in$trumanta• tian which will be required tor the test. With these itemized data a.nd a oor;.oeption of the particular oondi tion of the e..irpla.no which ie required fb r the test• he prepares a configuration sheet. <kl. this sheet he lfsts the instrumentation and the alterations of the e.ir• plane whioh will be required for the teat. Thi~, sheet is first coordinated within his O\-¥n team and then with the Director of Flight Teat.. '.?hl. s fortn is primarily tor file and record but it is also useful in helping Maintenance and Installs.. tions personnel plan their work and pre:p;t.re a preliminary eatin:f\te of the time which will be required to prepo.re the aircraft for the test. An outline of a. oanfigurntion sheet is given in llic;ure a. 4. Test Conference• The Project Engineer then holds e. conference with the Director of Flight Teat-. the Chief' :Elngi:ne~,ring Test Pilot• the Flight Test Tea...m~ and the Requestor's Representative. At this oon:f'er~noe the complete outline or program of this !)Qrtioular teat is discussed. This outline will sane e.s a basis for l)el"forming the '"«> rk required by the Flie,ht Test Order• but it is subject to modification if' the results of' any of' the individual teat flights ~rrant a ohe.nge. Speoifieally" the decisions rea.ohed in this con- fe:re.nae are as follow t a. The items ,mioh are to be moo.sured on eaoh flight. s l<"'rom a. oanplete eonsideration of tall of' the iterne an e/.• titnate of the nUlllbe:r of flie-)lts .and the rlying hours should be possible. b. The instrumentation which will be required to secure the data. c •. An itemized list of the work n.eoessary on. the airplane and an estimats of the time that the airplane will have to be grounded to be prepared for the test. d. A liEJt of the persons who will form the orew for eaoh - flir)lt. '.1.'hie list should a,lso include persons frem other depa.rtmente v1ho my have a valid :reason for witness111g the tests. e. A plan for the preparation of the report, i.e. whe'f;her • e. preliminary or a ccmplete report is necessary, what persons outside of the flight test tet..m will be :needed to assist in the preparation of· the report. eto. If the frequenoy of oonf'erenoes of this $a.rt shouJ. d warrant, it. may be adviso.'ble to hold regular meetings at which test items may be discussed a.long with other topics. Some flight test org_nn1• zations hold daily "morning oonferances" which serve this purpoQe. The Planning Eng-lneer attend$ these oanferanoes and is thus able to keep the flit)it schedule accurate ineof.a.r as mtes for the perform• a.nee of the various test flights are conoerned• . 5. Service Orders .... 'l'he writine; of Somce Orders is the respo..~eibilH,-y of the Flight Test Engineer. (Ocoos:lom.lly, service orde~·e are ,v-ritten b-,1 .the Instrumentation Engineer• but these must be ooordinated by the Fliirht Test · Engineex-.) Ail se;rvice orders should be ooordincited by th& Director of Flight Test. A. "oheok-off list" should be a ttaohed to the airple.ne as it enters the ,hangp,r and each servioo order is enter-ed on this list and initialed by the Sel"Vioe Foreman as it is received. Ho change, whether it be alteration of the airplane or ta.ddition or removal of equipr., ent should be made unless an appropriate written order is first ooor.,. dinated by the' Fli[glt Tost Engineer. The rigorous applioation of this rule is vital to the euocess.ful exeeution of a. flight test. The Fl:i.gh:t; Test Engineer must be in oonstan:t touch with the oondi~ tion or his airplane.. This is neees:aary not only for safety con- siderations but Q.lso for a.n a.oourate control of the airplane oan• figuration and of the weight and be.lance. It possible. the Sex-vice Ordan should be issued in a group, before the e.irplane is sent to the servioe hangar-, in order that the Service 1Foranen may sohedul~ the w<>rk and complete it in the shortest possible time. Before the airplane leaves the service hangar. the Flig,ht .Test Engineer should mspeot the a1rpla.ne with t.lie Service Foremn to see that the airplane has been wei ghed, properl_y blllla.sted, M._d that all of the work and only that work 'Which has been entered and ohecked m the "check-off list" has been This inspection should be performed in e.ddi tion to ·bhe perf ormed. / safety lnepection whieh ·will no:nnl\l ly be performed by the regular Inspection l)epe.rtment. The service orders and the 11 oheok-off list" should then be filed by the Flight Test Engineer. The I nstrumenta- tion l!1n:g ineer should oheok tho instrumentation to. :insure that it half bean b. properly iruJtalled a.nd ee.lib:rated. CA..RRYr1G OUT TliR F'LlGHT TEST PROGRAM. • Figure 7 gi we a graphic picture of act'ivities from the time the o.irpll'\.ne is roo.dy for a test flight until the final report b written. 1. Test Flight Plan. • A ty piaal '.i.'est Flight Plan is presented in Fig. a. ft:Jr ea.oh flight. These are prepared by the Flight Test. Engineer• The Plans e.rn.nge tho VS:rioua tests in such order as to take ~dw.nte.g;e of e,rery minute of flybg time. They must be sufficiently complete and olear to insure that all erew members will know when to operate the photo obsorven and other apeoio.1 instrumentation. 2. Pre-flif!)lt Inspeot:i.on. • Se.rvioe orders are issued to the Maintenance and Installations Unit and to the !nspectian Department, shmvi;ng the &"-t)ected tii-r.e of take-off, the names of the orew, e.nd the purpose of the test'. It is then the duty of those or~"lit:atio:rus,. be.rrlng; irregularities, to have the airplane r eady for the flir,ht. T'ne pre•flie.,it inspeGtion i s pa.rtfoula.rly important and should be performed ·with oe.reful attention to details. To assist the orew chief o.n.d the Inspector in t.~eir jobs and to assure the Pilot and Flight Test Engineer that overything is in order. a speoial flight inspeot:1.on sheet is prepared and m1:1st be signed as il1spectior:.s a.re performed. • The 1nstru.'1lent mechanic a.lao inspaots; tests. a....-id "oheoks off" the flight test instrumo:ntation prior to flight, usil,g nn "Instrumentation Chech-off · List11 which is prepared for him. The Flight •r(')st Engineer also prepares data sheets for - ma."ltw.l reoording of j_rnportant da.tn. Sin oe some time may elapse be.fore automatic oboerver data is :roody for use, mam.:ally recorded elate. will ehre an approxirm tion of the more import.ant results of the test flight and will expedite plo.rnlng of subsequent flights. The· data sheets should consist of a vellum original o.nd a oo.rbon oopy of' ea.ch sheet,. . The carbon copy serves a.s insure.nee age i:cst the loss of ir.tpo2•mnt data i£ the vellum should be deatroyed. 3. Airore.ft release. • The Engir.earinr; Test Pilot (or his co.pilot) is responsible tor filling out the necessary forms to obtain au-oraft olee.~noe e.nd for cheeking the weather. sample form for airoro.rt release is shown in Fig. 9. A Copies of' this form are usually n0oessary for the Budget Controller, Flie;ht Opara• ti.one, Inau:ra.."'.lee~ a.nd FHgb.t Test li'nee. 4. Pre•flight Conf'erenoe ... A pre•flig;ht conference for the flight crew i .s usttttll;v held one _hour before take-off time. In this oonfe!'ence• the Test Flight Plan ia discussed in detail• the duties of ea.oh crew member a.re enumerated, and the data sheets are distributed. 5. Test Flight. • The test flight is then performed. Ea.eh crG\v member keeps in ooneta:r.t _communication with the Flight Test :E'ngi:neer to reoeive instructions . or to re ;?ort a.ny irregular.itiee. Also, ee.ch crew member keeps a.Ii individual "sqt1a.wk" sheet on which he notes any malfunctioning of equipment or instnu::tents v.hioh he 0 may notice. (For e. more complete cliscuasion of procedures i'or actually porf'oming the test flight, the reader is referred to nFlight Test Organhation, Procedures, and Crevr Tro.inine;" by A. c. Reed and r.r. F. !Jilliken.) 6. Pos.t-Flight Co!lferenoe. • After the fli ght is co::,plated, a. post-flight oonferenoe is held i'or the flight orew and en.y p~rsons intereBted in the inunediate reaul ts of the test. . The test flight is disouased and in,egularlties are considered, givi.'rlg the Flight Test &1gineer B..."l'l. idea. •s to the success ,vith which the vo.rlous phases of th& test .f'lif.,ht were carried out. !>J1y rnalfunetiming of the instrumentation or the airplane is :noted and entered on a oair, posite "squawk" sheet \'illioh is g;ivon to the maintenance -orew. fhe flight de.ta sheets are ooordinated a.--id given to the Data Analyst. 7. Prelhninary Re port... The Pilot &.nd the i~t~ineor usually dictate a Pralimina.ry Report immediately afte r the post•flight oon.- In a. few cases this wi 11 be suffioient t rand no othe1" re- ferencc. ports will be necessary. In a tne.jority of cases, howe'Ver, these PrelL"lli~ry Reports will be used ae referenoea in the preparation of the Final Roport. 8. ll'inal Renart. • ¥,'hen the Da_.ta Analyst has finished his work, he submits it to the Flight Test Engineer who uses it; as a basis for writing the Flight Test Report. This report 1s ooordino.ted properly 8...Yld sent to the Requestor. ' c. TYPICAL Sfu'E'l'Y PFECAUTIONS. • The onre.ful eonsideration of ... a...~d planning for ovary eventimlity i ·s or primary importance in the prevention or acoi'dents. However, after thia has been done 1 pre- voo.table accidents oo.n still occur through ovorsi{."J'i.t ~ negleot of some duty. A particularly effective method of oontrolling this last factor is the extensive use of 0 oh.eck•off'' lists. '!'heir use to insure complete pre-flight inspections of both the airplane e..nd the flight t 0~t instrurfl8ntation ha.s a.lroe.dy been ment i oned. The eerviees find "oheak-off11 lists vary useful for reminding pilots of the proper p:rooedures to be followed while flyi·1. g ~:rticufor airplanes. Che_c lc•off lists are applicable to the duties of flight teat engilieers and other f litr..ht orew members, not only :in the air but also on the ground. Sinoe tho prepare. tions which are required for a·high altitude fl:ir:;ht are -mueh more involved tl'lrul those for on ordinary low-e.l_titude terrb1 °: the follovdng examples of check-off lists gi"lre!l here arE;) f'or hip-Ji-altitude fl:i.ghtsi Figu1-e 10 .,. ·Flight .Bnginear•s Cheek--off List. Figure 11 ,. Flir.,ht Crow Hmnbor,'s Pre~Fli eht Chook List. Figul"e 12 • Eirlergeney Pl;"ooedure.i,. All of these are to.ken di raotly from the papa r on "FU i!ht Test c. Reed and Orgt:muation, Prooodur~s• and Crew Tt•ainil'1g11 by A. W. F. Milliken. d. FIL:UJG SYSTEM. • It is 1.1eoessary that carof'u; :files be kept of the var1.oua orders, work sheets, correspondenee., e.nd other de.ta pertinent to u flight test airpl~"le ,vhen tests a.re in progress. The plan of hav-inr, ea.oh Flight T.est Engineer keep the files for his po.rtioular e.:l q, la.."1e or airpla:nes . is one which aeems to be vor-y successful. It has e.lso been folmd advisable to sta."1dardiz.e the system of keep:i.ng these :files. This ·is valuable in a.ssistinp; any• 011e who is familiar with the system in using any of the files as . . reference. The fili ng system which is presented here is only one of many. but is the one whioh upper.red to be moat sa.tisf'a.etory. 'l'h:i.s system ; consists of a. series of' eleven folders for every fli r.i1t test o.i rpln.ne or mAjor test itmi. Should a. tet~t item be too srrnll ·co ~rre.nt o.n extensive file. it is kept i.1~ a sinr5le folder whioh is subdivided according to this system.. The folders are used a.a follows 1 Folder Ho. 1 • l)aily L,og Thia folder eon't:n. ~ns a complete day•by-day log 0£ flight time; purpose of fli1:..ht, changes of the ai'tplane 'L'feieht· and be.lanoe, and othor pertinent notee. The carbon copy of ea.eh de.ta shoet and one print of each automQ.tio observer data sheet are also kept ill this f'older. -F older ?fo. 2 - tut.a Sheets The origj_na..l vellums 0£ both the r~nue..1 and the autarat1e . obaervor dtlta shoots e.i·e filed i..'l'l th1$ folder. Fo-lder Ho. 3 • Standard Fonns In this folder the vt1..rious s ·ta:ndi:lrd forms suoh a .a flight. tost o?'ders, Sel"Vioe orders. flight requeHta, eto. are filed. Folder 'No. 4 • Correspondor,oe 'l'1w oorrospondence ooneerning the teat items is filed in this folder., Folder No. 5 • Instrunents and c~ . librat:lons The serial numbe:--s, purposes, and all aal ibrat o::1s for the . . instrW;1ents used to eolleot the elate. are filed in this folder. Folder No. 6 - Ca.loulatio:u s. Curveo, and Results All of the oo.loulat:io:r,s 1 curves, resu lts an d the e..no.zysis ot .resul ta are filed in this folder. Folder No. 7 • Test Flight Plans Thia folder shonld eon:ba 1n all of ·the test flight plnns. it is eonvenient to file the planES for the conploJced tests on one side a nd th(>Se fQr the pro ,10sad tests on the other side of the f'older. -aaFolder No. 8 ., Weight and &le.nee The original weir,ht data and a complete tabulation of all of the equipment which \98.S :i.xicluded in· tho original wi s hing to- gether with the c omputa t:i. ons of weight and balance i' o:t ea ah f li c;ht are filed in this folder. Folder No. 9 • Configuration This folder should conta:in intornation, such as photographs. sketches. eto., oonoorn:ing the configurations of the airplane a.a 'bes·ted. Folder Na. 10 - Miscellaneous Any miscellaneous infornr;ltio:n or dA ta which mAy oo per- tinent to the test, &.nd which does not prop~rly belong in e.ny of the other folders, ehould be filed here. Folder JJ.o . 11 • Final Report • All information thn t is to be used ln the fitie.1 report should eventual]¥ end up il'l this folder. Some organ izations prefer a , "90:imal iystem •hioh gives a more exact design.a.ti.on to ·the looation of ee.oh bit of data. Thie EJyatem is more adaptable to variations in tests than the one presented, but the extensive division of the file is likely to lead to duplication or records, merely to keep ea.eh file complete, and the filing system is apt to oansume too muoh of tho Engineer's time. Figure 1• • Organizati<>n Cha.rt, F'li g.ht Test Department Figure 2. .. Hespooaibilitias of Flight Teet Engineers Figure 3. • Preparations tor a Test Flight :Figure 4.. • Fl 1.ght Test Re.quest Figure 5. • Flight Test Order Figure a. • Confie;~ration Sheet Figure 7. • C-an-yj.ng Out the Fliir, ht Test Program • Figure a. ""' Test Flight Pl.an Figure 9. • Aii-craft Helease . Figure 10. • Fliriit Engineer's Cheok--off List FigUre 11. • Flight Crew Membor•s Pre-Flight Cheek List . Fic;ure 12 .... .Emergenoy Proc-edui-es MA IU\.GEl'.'iENT PRODUCTION., ETCo FLIGHT TEST DEPARTMENT • - I I SECRET.A.RY s AND cmrTROL CLERICAL I FLIGHT TEST BUDGET PLi\1' 'FJG E!rGDTEERS F ENG II:JEEFnTG STAFF I I ]f11 MAHITEYAS CE EPGI YEERllJG AND r;.:sTALIATIOlJS DATA Mll\LYSIS IHSTRUT/EHTATION TEST PILOTS I FLIGHT TEST ENG HJ:i:FR I FLIG7iT TEST F: NGH~F R I FLIGHT TE!~ T TEAT!'. FLIGHT TEST ENGH EER I FLIGHT TE:'; T TE Al'·' Fig. l FLIGIIT TL ST TElUl I I F L I G II T T E S T· R N G I lT E E R S The Flight Test Enginee r 's duti e s a nd r e sponsibilities shall be as follows: 1. To coordinate all flight test operati ons on a particular airplane. This function i ncludes t he p reliminary pla.1cning; and clarification of the test to sat i sfy a particular Flight Test Order which will n onnally require the close coopero tion of the Fli ght Engi neer, the Requester's Representative, the Instrumentation Engineer, and the Data Anal y st. 2. To prepare the final Plan of •res t and schedule the Pre-flight Conference betv-reen the Flight Tes t Team, the Requestor's Representative, and the Ch ief En gi neerin g Test Pilot. 3. To be responsible for the con duct of the fli ght test fasofar as the particular investigations discussed in the Pre-flight Conference are concerne d. It should be n oted, however, that when any situation arises in v!.hich there is a question of the safety of the airplane or cr ew, the pilot has absolute authority to tennina te the flight. 4. To issue all Service Orders n ecessary to prepare .the airplane for the particula r fli ght test. 5. To be responsible for the preparation of Pla n of Test, Pre- liminary Re p ort of the Test, and Final Re port of Test. 6. To be responsible for mainto. i ning a 0hotogra. phic record of all major test configura tions or: his airplane. 7. To be at all times completely familiar with functional aspects of his airplane which in any way affect flight testine; . 8. To keep a Weekly Log of test work c onduct ed on each test airpla.ne. This Log should include reference Flit;ht Test Orders, length of flight, and brief remarks on fli ght conditions, • actu.e,lly investi gated, and any difficulties encounte red. * * * He may allocate work to other flight engi neers under his direction in orde r to fulfill the responsibilities 1 isted above. Fig. 2 '"lj Cl) 0 1,.;..; 0.., ,-, :cu ~ <:! ;;a 0 Q ,...., H H t?j ~ >-3 0 !:tJ H t:J t:,J g .·c"-4 ~ Cl) •-> L::.J :7J >-3 'zj I-'• aq •· Ul t"' H ,S.1_, t--3 t--3 ,-, 1-3 t.c:'. 0 I . . I r3 ~ ._,. ;:_.,, I f I I 0 H I I I I 0 H I I > 1-(j I I I I I H H I I I I 1. 0 I I 0 I 1-v 1-i j 0 ¢l ;;;,,. 'O 'i 0 ~ I-' > Q CT I-'• § > 0 H I I 0 0 0 H ~ I-'· p.. I-'· '1 I-'• ctf,) ~ ct- CT (/] I"' (l) • 0 I I I I 0 0 I I I Ol EJ1GrTEERHJG DEPARTMENT PROJECT :SIJG Hfi;FR OTHER bEPTS., CQ!f,'.': I TTEES , ETC . DIREC TOR OF FLIGHT TEST PLA.NI'JETG ENG I FE1-'R BUDGET CONTROL MAINTEITAl'JCE & INSTALIATIONS I 0 FLIGHT TEST EIIGINEER ":r.j t"' H 0 ......, >-'-i r3 EHGI i!ESRH!G TI>, T ? ILOT t--3 L':l CJ) t--3 I'TS'.i:'RUJ:~SlfTATIO::~ ENGI7 'ET;'R t--3 ~ ;:.:..-, I 0 ~ >-< (l) I 0 40 , I 0 I I I . > 1-tJ ,.J... . h ·< L, CJ) H ~ > 0 ., 0 0 I . :cu H I H Al dc.cj I I 0 0 I I I I 0 >-;j '"C 0 0 > 'U > ('") r3 :cu I ~ l:i::l r3 I I I c::: 1--3 1-(j I ~ ,. J tc:J C,) > 1-(j I I _ ~ c.• . .J CJ) :C,j CJ) •·--< >-:-c:J I:"' 1--1 c, ..,.. DA TA AHALYS T FLIGHT TE::, T REQl!l::ST Submit in triplicate Th i s fo :rm to be used for all tests, only one test i tern to be requested on this sheet, I Model ----- Flight Test ----- Gr oung Test ----- Date----- Test of: Reason for Test: Exact information required from test, state accuracy required: (Use reverse side of sheet if necessary) Parts and Special F:quinment for Test may be obta med from: -------- Witnesses to be present: Ih.te desired: ------------------------- ------ Requested by:------ Approved by:------ This inforAirplane Ho. _ _..,,.......,.._will be available on.,..,,.._.,..__ _,..for test. 'Test will be conducted: In conjunction with othe r tests • mation is • Flig;ht time estimate_ _ _ _ _Proba'Si"e" to be filled Special flight in by Flight completion dat-;-Te s t Deps.rtComments: ment ______ Signed: • F li gh""t_T,_e_s_,,t....,P""'l_an_n,..i_n_g_En_g'""i_n_e_e_r ---------- Authorized by Director of Flt. Test: By ----Time is to be charged to Charge No. Time is to be charged to Schedule ?------o,· Time is entered on Master Schedule by------ Date Start Date Hours Flown Estimated Cost ------ Finish Date Fig. 4 FLIGHT TEST ORDER To Be Performed an ------- Test Item No. --------- Time Charge No. Airplane n o. -------- Priority _ _ _ _(,..,T....o._.b_e_en--.-te-re_cf......,b_y_B.,..u-,d~g-e.,.t_,,..C-01-1t-r-r-o-.1,..,J.------- Discussion of Test: Flight Test Plannmg Engineer Fig. 5 cm FIGURATION SHEET 1 ELIGRT TEST ORDlill ---------- ---------- ,D ate -Engineer Airplane Model .no. ----- Purpose of Test --------------------------- Flight No. or Nos. _ _ _ _ _ _ __ l. Special Conditions as follows: 2. Installations: ~. Instrumentation : ------------- Approved Fig. 6 ~ I I - FIHAL REPORT SQUAWK" SHEE T DA TA SHEETS 11 P EE:LIHHJARY REPOR T -- -AP ~ 0 H ; tr;:;; ; a ~ § E-t H H @ 0 ""-~ ,-..:i i- AP p H r.-' t:.,q 0 E-< r:i::: 0 f:5 >JC.< H 0 P~ p-~ H ~ - 0 ·~~ ;.,~ '· E-l H Cl) a.. ~;; r,:i H 8 0 ~ 0 ~~ $ zH :;,.; ~ <,:; C='.1 0 :~ i ~~ H ~; (/) E-< ,-.:i j E-l -- --- - - >JC.< H ,-..:i p:! c.'J E-1 0 P.. ~ f.rl E-< 0 ~-.; Cf) ~ - - - - - - - - - - - AC - C- - C- - C - H ~;-.• Cl) E-< p::; f-;:; p ~ <: ~ ..,,,.... r=~ r:i::: ,-1 c..) H ,_:i '""' ~ ..i! µ:; E-1 C:J t/2 ...,., r:c: '11 E-< @ Cl) ~ r, E-1 ;:r~ Cl) '="' 5 H • AC - -I Fig. 7 - C - . - - - - - - - - AP - -- -- I - AC C E-t µ'.l Cl) E-< ~ 2, -...;, lf.) µ..l 5E-< - - - - - - - - . AC - - - - - - - - - AP I - - I - - - - - - . AP - - - - - -II - - I - - I - - - .. - - - - - AC I - SERVICE ORDER FOR PE8FLI CHT INSPl~ CTI ow FLI GHT CL FJ-1.I?AHCE I r,:.. ,_:i H e., E-< µ:1 E-l ~: :>-< U) E-1 E-i ..::;1 E--< H ...,. ~ 1-l c., E-< • ~~ µ:, :,-;::; ~ U) (/) ~-::; c.:i E-< c., H a.. 1-i ~ ,._. /:::i 0 ,-..:i pc. f;j J.:1 E-< 0 -., p::; FLI GHT TES T TEA1! TE:.:T FLI GE T PIAN Fff?Jvf AP - App roval AC - Action C - Coordinates I - I:ni t i a. tes KEY TEST FLIGHT PLA.N AFPLANE DATE -----TEST no. FLirrrlT - - - - - - PURPOSE A. B. C. D. E. F. G. H. I. Elevator operation with· no packing in boost valve (trim & friction) and direct cable system. Tail cone flap loads with a.ft end sealed vs. Vi. ·water dUi-np out of right hand chute. Ventilation with new scoop. Empennage de-icer direct inlet 11 q 11 • Aileron operation with direct cable system. Right hand mai.n landing gear check. CO measurements at wing lea ding edg;e in boo. rd of in board eng ines. nai n brake system i"eturn pressure. 1..A·. B. C. TAXI - take CO samples TAIIB-OFF 2600 rpm. 46 11 Hg. - Take CO sa mples Climb to 10,000 feet at 2400 rpm. 40 11 Hg- - 160 Vi - Take CO s aL1ples. 2-WATL:R DUI? OliT OF EIGi'IT rIAHD DUJ,:P CHUTE I ? CLIMB a. - b. c-. d. e. f. g. h. i. Fly at 160 Vi Have ri ght hand side of ship LYJ. the sun Open ri ght hand dump chute and ri g,ht hand water valve Turn camera an (right hand) Time water flow Leave dmnn valve do,,m for at least 5 minutes after dumping Slow dovm to 120 mph and shut chute Observe and n ote water from streamlined bump window Pump water from lines back to tank No. 7 3-TAIL COHE ?LAP LOADS AUXILIARY VE:•fTIIATION E1\1PFJFAGE D}:~-ICER DUC T INLET 11 q 11 a. b. A. Outflow valves open position (forward ) - aux. vent exit operi. scoop closed Alcitude 10,000 feet 1800 rpm with power to give 160 Vi - cowl flaps open 4J2 and 1(3 . pressure bulkhead seale d a. b. c. d. e. Take CO samples. T.1easure veloci.ty distribution at duct outlet at 2, q., 8 , 11, 14, 17.., 20 illches along outlet. Bea.sure velocity with the anemometer at stations 500, 600., 700, 800, and 900 i nches, a.long the cente r of tho s hip a pp rox. 4 feet above the floor level. Ree. d for one mi nu te at each sta tian. Observe tufts and n ote . Road tail cone flap loa d. - - - - - - - - - - - - ._,_ __ F'..g . 8 _......_ _ _ _ _ B. a. b. c. - - - -- - - - Repeat items (b) (c) and (d) of Part A. Plug up duct outlet and note noise diffe'r ence. 1800 rpm at 140 BlfilP, pressure bulkhead sealed. a. D. ---- ----- -- 1800 rpm with power to give 160, pressure bulkhead holes open Repeat items (a) (b) (c) (d) and (e) of Pa.rt A. 1800 rpm at 140 BJIBP, pressure bulkhead holes open. a. b. Repeat items (b) ( c) and ( d) of Part A. Plug up duct outlet and note noise difference 2200 rpm at 140 BJ'!EP., pressure bulkhead sea.led. a. Repeat items (a) (b) (c) (d) and (e) of Part A . 4-EIBVAT0R 0PF?.ATI0N A. F PICT ION a·. b_. c. d. B. STA BILITY a. b~ c·. d. C. Fly at 1600 rpm, 14.0 Vi at 10.,000'. Trim airplane (note' os cilla. ti ons). Move elevator tab slowly up at a steady rate of approx. 1/2°/sec. until elevator moves - :r:ote angle. Same as II c" with down tab. Fly at 2200 rpm, 140 BJ..IBP, at 10.,000'. Trim airplane. Pull up to 20% lower speed. Push down to 20% higher speed. FEEL CQiTTR0LS A}ID H0TE RESULTS 5-AIL?R0W 0P:rnA TI0N WITH DIREC T CABLE SYSTEI'J A. Stabil:i.ty • a. b. Fly at 2200 rpm, 140 BMEP Feel aileron control 6-GEAR CTIECK A. B. Lower the gear If the right hand main gear doesn't lock at first., -vve.it seve ral minutes . ........ _______ - --- · - - - Fig. 8 (Contd) - - - - - - -..-. - - ----------- -----Crew - stay at follovting stations except one test. l. -----Pilot 7. 4. -----Radio Operator 10. -----Over fire bottles 11. ----At stress table -----Eng~ A.O. 2. s. -----Co-pilot -----1.lia.ster A.O. 3. -----Flight Test Engineer 9. -----Over fire bottles 5. -----Flight Station ,,t 6. At Flight Sta.. Door ----- 12. AAF Insp. - Seat half'way· back in cabin - R.H. side Fig. 8 (Contd) REQ1:JEST FOR FLIGHT MT D AIRClAF T REI.EASE DATE AIRCRAFT MFG. SERIAL NO. AIR CRAFT CUSTOl.mR OR LICENSE NO. FLIGHT CIA SSIFICATION PURPOSE OF FLIGHT INTENDED DATE AND TEIB OF FLIGHT TAKE: OFF FHOM ------------------------------ Lli.NDI NG AT INSTRUCT IO:-JS : PASSENGERS : ' 1. NAME IDENTIFICA TION NA:ME I DSHTIF ICATION 2. 3. IDENTIFICATION CHECK FOR ALL FLIGHTS ----COHTHACT FLIGHT ---. COMPANY PILOT ----BEFORE FD:AL ACCEPTANCE ---NOH- CCHTRACT FLIGHT---CUSTOMER PILOT---AFT:SR FINAL ACCEPTAlTCE ABOVE FLIGHT IS AUT!:iORIZf.D subject to provisions of FLIGHT COHTROL REGULA TIONS Yfork order chl?.rg;e. number CREDIT AF D FINAHCE DIVISION RELEASE (FOR DL'LIV:•:HY FLIGH'fS OR DELIVY.RY ) 'By_ _ _ _ _ _ _ _ _ _ _ _ _ _ __ l.ffi.HAGER By -~-u_p_p-le--m- e_n_t~a-!j-,-s-i_gn_a_t_ur_e_v~m_e_n_r_e_q_u~ired Fig. 9 • FLIGHi:r EIJGINEER'S CHECK-OFF LIST AT OFFICE 1. 2. 3·. 4. s·. 6. 7. 8. 9. Test schedule - make out. Test plan - prepare. Flight physical insurance and instruction of crew·. Tentative crew notifioa tion exclusive of Weights Dept. Rep. Status of airplane. Note sigriificant changes since previous flight. Decision on time of flight from Chi'ef Test Pilot. Order lunches or milk if required. (Engineering Flight Clerk) Final crew notification, including Weight Dept., Flight Data Analyst, Instrumentation Rep., Supt. Ground Operation, and Director F. & A. Asser.ible personal and engineering equipment for flight. AT HA.NGAR 10'. 11~ 12. 13. 14. 15. 16. 17. 18. 19·. 20. 21. 22. Distribute flight plans to crew. Put own equipment in plane. a. Pad of paper and 3 x 5 cards. b. Stop watch. o~ Spare bailout bottle. d. Standby mask. e. Data. board and sheets prepared. f. Graph pa.per. g. Calibration. h. Blank squawk sheet. i~ Double headset. j. Pencils (~ or more). k. Helium-oxygen mixture. 1. Medical set. (1) Hypodermic ( 2) Ammonia. (3) Charcoal pills ( 4) Na.sale. tor Put pilot's equipment in plane. Round up crew for pre-flight conference. Ground Check-off Lists - Distribute a.nd collect. Distribute Flight Check-off Lists to ne:w men. Glucose capsules. Check out flash lights if night. Charcoal pills. Announce standard time, coord:i.m te watches. Obtain weight sheet. Instruct crew, put equipment in plane. Call nurse (8155) ~vr1en denitrogenation is bagu..~. rn AI RPIANE BEFORE FLIGHT 23. 24. Set co-pilot's altimeter ·to standard and record P.A. Record ground temperature. ____,, _ _ _ _ _ _ _ " Fig. 10 ----:.---- 25. · 26. - - - - ----- - - ----- . Standard time check if not done before - set cockpit clock a.nd wind. Check test equipment. IN FLIGHT 27·. 21:f. 29. 30. 31.. 32·. 33. Remind c r ew to get as many de.ta. as possible. Keep crew informed. Fuel readings - level. Remind pilot to go through check-off list. Fuel readings - radio to hangar just before landing. Radio OAT to Weather Bureau. ~lucose capsules. rn AIRPI.AlJE, AF'TER FLIGHT 34. 35. Unfasten sliding windshield locks. Tur.n off special autosyn, waste gate indicator, and genera.tor switches. 36. • Fill out nForm l. 11 37. Collect squawl~s. POST-FLIGHT DUTIES 38. 39. 40'. · 41. 42. 43. 44. 45·,. 46·. , 47·. 48. 49. Phone for nurse after denitrogenation flights, if one is not present. Classify and deliver squawks to Instrumentation Clerk for typing before de.ta. sheets. Roun·d up crew for conference. Collect fL~al weight sh~et and data sheet. Che·ck in flash lights if night. Decision on next flight. Phone Senior Flight Engineer. Test schedule• make out. Check in flight test equipment to locker. Signature of pilot on squawks. Dictate "Report of Test. n Check rough draft of test report. Fig. 10 (Contd) FLIGHT CRE\'1 Iv!El.IBER 'S PRE-FLIGHT CHECK LIST 1. 2. 3. 4. 5. 6. 7. . a. Physical Examination - regular semi-annual flight physical, including electrocardiograph with:in six mohths preceding flight. ge_e.E_- good night's sleep before flight. ~ i t u t e in case of illness - make arrangements with fli ght engineer as far J.n ,advance as possible for substitute, if you have a cold or ear trouble or other illness. Mee.l - if you have not ea ten within the pa.st threei hours, eat a light lunch high in carbohydrate content, or at l east a candy bar. Emergency Alarm Bells - one bell, stana by; three bells, jump. ~mergency Exits - learn location and operation. Oxyg~n Equipment and Supply• . a·. <hcyg;en pressure at 1200 psi or more. b~ Ma sk sponge valve dry. c. Plug in bottom of re-breathe r ba.g. d. Re-breather bag for tears. e. Flomete r for sticking, connections, etc. f. Rubber tubing for holes, connections, etc. g. Auxilial"'J oxygen outlet on regulator turned off. h. Adjust straps on regular and bailout masks. i. Check ba~~out bottle at 1800 psi or more • Emergency· - if a parachute jump is necessary, the order of exit will be • 9. Designation of Emergency Exits to be Used for this Flight -------- First Choice 10. Alternate Parachute Equipment ~-:-Parachute was last repa:cked_______l94 (must be within 60 days.) b. Parachute pack cover flaps - see that flaps have not worked loose exposing silk canopy. c. Rip cord and pins• see that the rip cord is free and rip cord pins are enga. e,;ed in their studs. d. Harness - adjust to fit snugly, s e eing that no straps a.re twisted or crossed. e. Rip cord i n place - see that rip cord ring is in its faoric pocket and clear of the horizontal chest strap. f. Protruding straps - see that shoulder and chest straps do not project in such a ma.rarer as to be easily caught on protuberances in the airplane. Signature -------------- Test No. Model Date Ser. No. Fig. 11 ------------ EMERGENCY PROCEDURES I. PROCEDURE IN CASE OF BMERGEHCY (MEHORIZE) 1. Stand By in Emergency. {l bell on emergency ala:nn system) a. b. 2. Safety belt - unfasten. Doors - open all doors inside airplane (unless doors :in airplane are needed to isolate fire.} Emergen cy Requiring a Jump. a. Oxygen - turn on emergency sup !_)ly. b~ •Mask - remove. • c. Ilou'thpiece - place emergency oxygen m·outhpiece in mouth. pinch nose., ~nd breathe through mouth. d. Goggles - place over eyes. e. Exits to be used for this flight: First choice Alternate Jump after crew member Clear the airplane. h. Rip cord - delay pulling until certain of clearing airplane and/or until reaching a warmer altitude. i. Direction - try if possible to land facing the direction in which you are drifting. ,j. Leg straps - unfasten leg straps as water is ap p roached, m case a water landing is evident. Cross the feet e.nd keep the legs together to a void straddling trees or fences. k. Tow a.shore - if wind is litht, and from sea to shore, hold to ·parachute to tow ashore. Note: If no "standby11 order is given before the co:mmand to jump. open all doors inside airplane before turning on emergency oxygen supply. • f. g. II. PROCEDUP.E FOR FAILURE OF YOUR OXYGEN SUPPLY (J',IBHOR IZE) · 1·. • 2. 3. Signal other . crew member. • Oxygen valve - open slightly and tap it lightly. Standby Mask - put on •spare mask if regular supply cannot be fixed immedia tely. See that va.lve is on. Help will be given by other crew members. Alternate: 4. Transfer oxygen mask tube from regular supply to auxiliary outlet on standby supply • . Emergency Bailout Oxygen - if standby oxygen system is defective or i n use, turn on ·emergency bailout oxygen. put mouthpiece in mouth. pi..Y1ch nose., an:d breathe through mouth. Help ' ·will be given by other cr ew members. Fig. 12 II. IIISTlH!MEll TA'l'IOH lt '\IVS.8 pointed_ out in Part l th!tt one of ·the requ ireme:nts for the solution of' the "riddle of the lT!Odem aircraft" is extensive instrumentati on .. The instrumentation of the flight test a. _irplt:n.e is the oosis upo:n which the _qua.l itative analysis 01' any type of airplane is prediootod. l The very va. lue of flight teatinr, lies in the faot that e.11 of the conditions, loo.ds and forces which a.re to be utudiod are actually applied and n.ot assumed. However, the value of this adva r:-tur;e is diminished g!":.,atly by a lack of the proper instrumenta. tion with which to collect informs. tion necessa~; to oval ua.te the reaction of the airplane to the ,ra:riables. Flight test instrumentation bas s )-,ovm steady :L'llprovament bot_h in quality and in scope irt ~te p with t he progression of the aeronautio~.1 a.rt. Standard instruments have been modified and improved to give the accuracy and l' olia.bility r equired of tost equ.i y.Ynent and new or particular :Lristrume:i::rtntion hao bef;rn devised to measure other quant1.tiea a.s they are required. A. -- PLil.~J:.I nm. Tho fi-.rst problem to oonf'ront the Instrumentation F.~1gireer is that of planning. The emour,t of planning; ·will vary fran test to test, but t he instrumentation should be planned as ce.rly as possiblo. J.n this rr:a·•mer a..YJ.y special problem oo.n be foreseen and r:iven due considera ti Ctn ·without delaying: the ter.t. In the event of tests of a new protot-ype airplane_. the instrumc:n.te.-cion may ·well be pla,::::.:ed even r..s the airplane is beinr, desirgied and built. Speeie.1 tubi11g, wiring, or other installations can then be "bu5.lt into11 the e.irplaM. For other tests th<:) plann :1ng; may start when the work order re.<:-.c.hea the Flie;h~ Test Toom .. 1. THE 'rYl~~ OF A IRPU. .HE '!.'he airplane on which the tes·bs o.re to be ,Jade will determine the available space for tho instrumentation. !f the airplane is_ a fi_ghter typo there will ver-1 prot-ably be very little spaoe and tht'l number of :tnstruments wh:toh :may be carried on any one fl isht will be 11.mi ted. The i nstrum.e:ntatioo will have to be flexible, capable of quiok oho.nges :from one test to another. Most of the re• cording of dl-1 t;a vd. ll have to be automatic because the pilot, busy performi.."lg a maneuver or holding stabilized oonditi,E,s,. vt.i U have 1:1 t tle time in whioh to 'be recordine; do.ta. For e:xanple, in a fir.,hter it was found nacessaT\J to insu-111 the autol'l'ntic observers on t i10 {~un mounts in the wings. If, however, the airplane is a large bcmbor or tra11sport, the problem is quite different. Plenty of' spa.oe is usually (.s. a.Ua.ble ru1d the :i.nstrum.entation oo.n be almost ns e:ktc.rnsi7e as desired. Fet,mr 1 - less strfr,gent restirotions a:re placed an space and weigjit _in the la:.rget" airplanes, but as a general rule the tests are more conplox and mo:re instrumentat:i.on '.ts usually required. l'lot¼'(H~n these two extremes lie the tests, of the intcrmedif;.te sizes of aircr0-ft which_ present a compromise bctrieon the roqui:renonts for 5.,:strur:\e.nte.bion ru1d t1-,e spaoe limitation. -10- 2. '.l.'YPE OF TES'f The limitations of' space and weir,ht are usually rather well defined nnd the fe.otor which must be compromised is 'the amount of i,, strumenta.tion. This is de-term1ned by the t:v-pe of test~ The engineel' must determine from the · wol"k o rd.er and from the conferenoes as e:xa.ctly as possible what da.ill. are to be :r:ieo.sm·ed arid from his own experience and k:-,owledg;o he must dotorm1ne tho best prn.cti oo.l means for nnking the measurements. One definite step in the ai.Tllpli£irot:i.~n of this problem is the preparation of a. _list of the vo.rious standard or common tests showi..l'lg the da. ta which a-re usually re-quired and the ins trumonts :rJ.ecessnry to obtam these data for each type of test. Any list of ·this sort must necessarily be subject to change ,vi th improvements whether in t:110 method of testing or i:n the :i.:nstrumentat\on. Also, a list of this sort.for almost any compe.:ny mnuf'aeturinr; airplanes for t ho nrmy, the navy end oonr.nercia.l use becomes extensive if &;'ly a.t!;empt is r:ade t :o . ooveI' all types of tests. At presr:r;t, it is possible to list only those tests which are C01nr.1m to o.11 threo 4',r;cneies ai,d which have become routi12e with a?,most every fl i[sht test orgo.niza:tion. However, such a list, which mie;ht propel"ly, be prepµ,rod by the Chief Instrmnentation Engir.eor; would be of groat assistt:ti10e to ·t;he various 0110 1.neers i_ , planning their instro,:10nm tion. Carryi.nc this idea :f'al-ther,_ it would then be possible to propo.re an installation mc.nue.l for the use ot--tho mechanics showh,g the :metho d of inata.lline; and the precautions to be usod in the '1 P.:Sta.lla tlon of the various types of histru:m0nte.t :i.on. This would be possible. in any complete ser.ae, t only after a :ra tho1· extonsi ve program of stan da.rdizat:i on of the testi1:e; required to prove the ai rpla.nos. 3. QUAL ITY OF Df1.'rl\.. It may SBem to the r •;'n .der,. as a first impression. that a die• eussion of quality is ur:n.eoessary in any c onsideration of i..'t'J.strum.enta.tion for flight testing-the instrumentation should be "as a.ccure.te a.a possible". TI0110ver,. probe.bly no otho:r sing le f'a.c·tor can cause tho instrumai. tat ion en1;:lneor so 1:nny "heada.ohes 11 as U...Yl accuracy rGquiroment •of "as good as possibl11/'. or course, care must be taken to a.void "throwing uway a ,~ouraO"/,. • but rec.pd ring that cor±rol positions be measured to the nearest oll.e-ten.th of' a degree, for e~mplo, unless it is really ne cessary ea.n oo.use the :l.nstrumenta tion enr;iu:,or many gray hairs v.rhl.ch r:iight well l1e avoi.ded. 'I'his re- quil'eme1,t is, of course, neoesso,ry in the ca~,e of tho principal a.irpla.:r1e cont rols but i s us1.nll y not v.arrurrl;ed for covrl flaps, and such 11 ux:iliary controls. In ordsr that r·:asonablo accu.mcy my be mairrta.111.ed i n the instruments use d, it is necessary that they be oo.li brr.d;ed at frequo:nt into rv-nls. The leneth of .tho inte rval htd:tv-i-een cal lbrntians "tTlll vo.ry for different :i.r:, s'l:;1"t..11:mnts, but n,, inst rument shov.ld be us£-)d while any doubt ox:tst s ooncernin[':'. its opm·a.t].on, 'I'he oa.libr-J.• tion of' some of .t he :i.rcstrurnents should be et routine functi on, per• formed in the instrur:ient shop or the stockroom• ·while other · i nstru- ments suoh as position ind:i.oo.to:rs cru; only be properly ca.librntod .after they are . installed. '1110 culibratio."l should be chocked, f'.G fu:r ns is pra.otioal, before ea.eh fH.ght . The instruments themselves muot be e:xn.mined o.nd oor:sidered with respect ·co t heir response to Yo.r:i.ablos other ·than th.a. t wh:i.oh they must measure. The most import:.tnt variables to whieh r;ood instruments must be insensitive a re t a.. AttitudEl and acoelero.tio:na - cyclic acceleration loa<ls up to •4g e.nd +9g. b. Vibrntions - which my include both hich frequency and· large amplitude unless the ins-1:;rument is care.fully mounted. o. Te:m~Jerat11re - vari!,.tio:n from 1s0c to ... a5oc. d. . Pressure and density - corrosp ondirg to e. pres sure range of from 2 lbs. per sq. in. to 15 lbs. per sq. in. e. Supply voltage (for elect~toal instruments) - vo.ria .. tions of 15;~ of the nol"'.!'00.l Yol tn{~e. Although the selection of the pa.rt:i.cular moons of or;to.ining the r cquir0d data is· strictly a. part of ir.strumento. tion ;1lannir:. 6 ., it is such a. 1:1€1.,jor rxirt of the function of the Instru.rnenta.-bion Im~· g:i.: eer that it deserves special attention. Much of the enr i r~eer's time a nc thought i~ directed tov1a.rd h :ls equlJ)If!EYnt.; the improvement of his present met).~ods., and the oonti nunl search for better ones. It is intended i :n this seotian ·-to discuss eome of t he methods and prc.cticos v,hich arc befog used b-J instrumentation en g;ineers as revealed to the o.uthors duri:r:.g their sur,,ey. The variety of the :instrumen ts a>:1d other equi[Jmont used in fl :i.ght tost fostru.'Tlonte. tion precludes a.ny poas ibHi ty of it COi7fJlote discuss:lon of all of them in e:ny tr•~;e.tise suoh as this. at the outse·I; we must limit our discussion. 'I'hore fore, The stand.a.rd n:i.rol"uft instruments such as ai.rspeed in di co.tors• al tirnetcrs, etc,. al t hough exteJ,s ively used i n flight testing; are rather u:dve rse.lly understood both in their operoi;ion and installa tiori and :i. t 1 a r ot feasible here to atte.r:pt to reproduce a discussion of these betrumonts as rrJJ.y bo found in books on e.iro:r-3.ft L ,strumants. It is sufficient ·co say that the particular L"1strunents must be selected for their sei1 si ti vi ty ar.d relia.bil:U..-y. A moi·e con pleto dis ci.rn~ ion is nttcnpted of thoso instruments wh loh a.ro, to a certs.in extent, pecuJ.iar to fl i f.,ht testi nir,. Even here the discussions mm;t be limited beoo.uao thorour,h e:x:pla:na.ti.or:s of oertail:- of the instruments would require special volumos for ro.oh. --74- TJ-ie application of strah ~ TeG to tho field of fli g)1t teat ·u ig is one of the recent developments of the a cienoe. At present, the nunbor of possible usas to -vkdch the se :i. struments may be put ia Al-t:;hou~h the t1irect fun -:-,.tio:n of tha stro.in incroos:1.n 6 ra,)idly. (!Jl. p;e is that of neasur:irg deforrrn ti 011s., i :ndireotly they om, be made to trrmsform suoh items e.s control forces., accelerntionrs, etc. into electriOf',1 qua.:..11titics. 'f'n e direct ariplioo.tJ.ons of tho r, ge s has been of f~reo.t benefit to atructuru.1 r e search both in fliz,ht a n d on the ground and their indirect use has a r~roo·t influet~ce en other aspects of f'li e;ht testing. 1'he primary va1ue of the stro.i.n gage is its speed of response. This is pnrticularly true of the wi:re- strip strain ga+c.Basioally, the1~e are two -types of stndn ga ;':ea, the .vire-Gtrip a nd. the 7'18.fp.e~io. Of oo~rso, strictly speaking thorrc aro numerous ·other t ypes of strctir gap:es; but thos e de_pend on mechanically Ftovinr; sys·t0ms for thoir indication. Thu.a tfu.o resp cnse of these f!J:\G0S is naturally slower and they have fow a pplioo ti m s ·co fli r;,ht tostint: • The mag;rietio ga. 0 e depends f'or its op11ration on varying the permeability of a ~19-wtio field. The field is o:ree ted by e. pair of . electromngnetic co Us placed so thnt thoir poles are 111 op~1osite directions. An a ~ ture of' soft iron · is ole.oed. a.cross one end of the pair of oons· with e. givcm air cap between t he arrw.ture and the poles. The poi.nts of a.t+vaohmant of the ooils and of the armature to the struct..1re to bo studi ( d are a given distance apart~ usu.ally one inch :iE the m ,strained oondi ticm. Any variation fa this distance. due to strafo., chs.::u-:es ·the size of t he air £:,"ap and thus oha:n 11·es the p~n--moo.:bHi ty nt,d the flow of mf,.g;netic curroot bch1-oen t he ccilH. The 02eration of the wire•st-rlp strain r~r:e depends on . the chanr: e in r nsis+.,;;u:ee of a wire due to a c.'hange i n its cross• seetior ul arco.. The o.otual physical a ·,poo.ro.n ce of these gages. may w.~ ~onsiderahly, but: their principle o.f o;:,oration is the SH-me. wire, usue.lly about .001 inches i n dia:metor, to a piece of th:1..n. paper with proper loo.d 1r.:tres attached. to be t:iea.surad. In t;his way several gw· ns_. Then any subsequent: chcir,re in the length of t he surfoce of th0 s.t rm!tur·o knerlia:te1y under tho cage r os , .J. -ts in a stretch:i.r![\ or contraction i n the wire e..r: d a ermsequent eh.a:n,::e in o:ross-section e.nd :i.n resistnnce. Tho pri1:cipal disadvan-ta.p;e of the wi r e-strip strain f:,'8. Fe is the d:Lfficulty in ea librr-.tion.. Onoe the r;a;:e has been p roperly ecr.wntod to e. member,. it is pmcrb5.ea.lly i mpossible to :rcmov6 it. T't1us t ho only •.n.r:ie.r:a of ca.1:ll.ir::" lting a gp.;:e of this sort is by calibrating; o.11e or -:nore reprcs0:nt.<l.tive ga,::e or ga v:,es a:·d assum:in g that elim.i.na.tes this difficulty but has other cHsadw.n.tages. Generally, the ?i!ng!'lctie gage does not have a "stmieht line calibration curve", that is, a variation in longt?1 does not oo.use a proport i.oDate cha.r.ge in our:rent. Wo satisfa.otory means of attncld.nr:: the magnetic r;aee has been found other than by moans of bolts. This, of oouroe • meo.ns drilling the struoturo, whioh is not usually pernissible. Also. because of its (',?'~, tar mass, the i.'lB.r netic r;age is smnowhat slower in response than the w:lre•st-rip streL, ca::0. For the:,e ·reaso:~s, the wire-strip gage is used ~ore r;ene1•al13r in fHght tost- b. A?PLI'C/1. TI Gl'iS • The aotunl appllca.t:i. 01_1a of the strain g;are to the field of fl ir;ht t0stirig a.re nearly e.s va. r-iecl as the number of 1ompa..11ies :inakirie~ use of ·them.. 'l'here is much opportur:ity for the cxcrciso of ingenuity both in the method of a.ctunlly a. :.1plyir:.g the f11se itsolf to the quantities to be mer-1.sured and b &.:age. the method of opera.tins the It is intended here only to g;ivu v..n i:n<l.i'-l:l.tion of o. few repro::;cntnt:lve ap'Jliro.t:1oris a:,d e. f'.'.enerri.l discuccion of the p1·ino5.ples -' of measuring tho strain_!ls i!'ltlioated by the ge.ges. T'~:e most obvious 1..,so of sl;;rnin f:1:l f'0~, is in the fiold of structural· resoarch. By the proper placin 0 of tJ1e ;:;nges it is possible o5.thor to :mer. . suro bendinr, and climine;t;e any tension or conprossi.an effects :i.:r a member or to !Jeasuro t···. ;~s:i.on o:r cornpros.s i on and eliminate a.-iy effects of bcnd:':ni_:;., H; vias 0::-ig:_1:ally considered nocessury to use a dwwa.v Gae;e, ·which viut> ca:-10::J.ted to a.n unstrained piece of metal a:lmi:!nr to tha.t u., .de1· test, to elindnate tompcrature -'l7• effects fror.1 the strain re1:1.d:i.r gs. Reoe:ntly. however, the ingenious use of Poisso.n's rat:i.o in the analysis of the strain do.ta has per• mitted tho applies.ti.on of 9.1J. four r~r~os to the strained nernbor so that; the sensitivity of' -!;ho circuit is .inorc::.1sed oo:nsidet't:1hly and ter:1pero:tur0 ef'fe-ot~ aro at the same tir;io elimir:r,ted. Jtrnin gages n:re al~o used in seta of three o ; ti. prmel whei-e no:i ther the direotim nnr the ma.gnitu6e of the strain are k11own so thn.t both of those factors may be cleterminad. Structwal :1.nvestiga.tions of this sort, a.s:lde from their roooo.rch value are also very useful in structure.1 integr:tty der:i.on• • strations or tests. In these tosts it is usu.t>.lly i:cd;fJl\ded -that the full loo.cl :f'a.otors shall he 0.ppl:1.ed to the id.rp,hne •1 n the fiHtl test. "iJhen the strueture to be t,;sted m tr-ta n1a::mer is ,ritnl, it is es .. peciR..lly reocssi~.ry tha.t the full loud conditions be e.;->proachocl ;1;radt1fJ,lly. H' ·strain rneasur1"?1:1<'nts of the pr:tno5.pa.i membors be 1rnde throu;··r..out the series of tests, the effects o:f the leads on tho ncmbcrs can be determl:n.cd an,J the fine.1 oondi tion Of.m be approached with ,•10:rq 12,telligenoe f)Yd grcnter con-fj.clercce. A.'Tlother vory im:portaid; application of strain r:a.r.,;es is in the Tneasun,rnmt of cortrol forces. iy moons of these f~ges it is poss:tblo to 1"east1re accurv.tf1ly o.ncl 9recisol:y ·b:ho force -which muat be applied by the pilot to perfon:i ary t1DV.cuver. Xt :is no loq;er recessD.ry to use n pilot's opinion e.s e, ori te ri. Y..1 i' or oetermininr; wh~n qontrols aro too stiff or too soft; the ac·btml forces can be One method for the measurement of oontrol forces is the moo.suromont of the otrain of a member in strain_ sample 1n a cable system. a ~sli-rod system or of' a. A more popular metl:od is that of measuring the f·oroos at the point of a:)plieatiorz. h special control wheel or Gtick is prepared with the struin gnp.:es on the spokes · of the wheel or on the hfi,ndle of the atiok so that the clew.tor and the ailoran forces a.re separately measured. Strain g;a.e:cs aro r,lso placed o:, tti.e carrier for the rudcl. er peduls to measure rud <l~r i'orces. The latter method is especially popular because t he specin.l c . .rntrcls i OEtn be prepared fl.lid ealibrate<l a..'!'J.d then. easily transfe rred unang di.f'foront airpl&n.es of' tlmt type . Strain i a..ces have also been used as position indicators. To do th is~ the r;ages are 'placed. en thfa 00.~}tilever strips, fixed o.,.., one e r:d and properly applied to the movable ?:Leraber o L the o·thor. The resul ta.l'J.t a train of the oau tilever strip in bending can then be calibrate d in t e nns of position or motion, By the use _of a. oa.ntilever beam i:n oanjw:i.ctian -with the pi·~fH3~· mass, strti.in r,30.dinr;s may also bo easily calibrated i n terms of aocel e rot :; on. a.ocelerometer i'he whole m1i.t is usually immersod in sorne non-oonduotive liquid for damping. Probably no a.speot of tho use of strain gages is so varying a nd is boi!.ig so ra pidly improved as the particulars of the circuits widch are uBod. to apply o. voltag;e to the Eages and to reeeivo and interpret tha sig;nnl from the r,a. r,e i n terms of stra :.n. 'l'he gages aro o.lnost 'lli,iversally use.d in (l. bridge circuit, but other tha.'1 t h is ha.roly a1,y similarity exists bet'11een the va.rio1is systems. 1.n the original method of usine; the vdre-str.ip strain gage it ~-s considered necessa:r-J to increase or decrease tho resiatanoe of one a.rm to equal that of the stra.ined am of the bridr.;e so tho.t no signal was retur ned. 'l'he change in resistance wrrn then ni:rbed a nd emulated in terms of strain. several p:roblans. 'fhis system presented First, it ,ms p;ervJra.lly rather tedious to make t.his a. djustm0nt ~.:rual ly ru,.d very comp li c:ated to perform i t a.uto:matice.lly. Secondly., ·bhe oonnectj ons to the stra1.ncd a.rm hn.d to be ,::arafully r:lB.de to avoid introducir,g a varyi.ng resistar,ce i r to the lino which vrould 1.nve.lic1.&t e the strain reRd:i.n?s . 'I'hirdly, it v.re.s very diff'icul t to make the "!leasurcment s t'direet reMin1r,". Hee.d- ' bes to:ke:ri 1:r: this manner were found to be capable of fu.ri ,:10re ac curacy th.an other cor sidera.tlo.ns would vJarrf:\nt. As an improvemant over t 1 ,i s system i t wns found that the si.~al c culd be i nto rnreted directly in t<.nr..s 'of str~.. h: if the bridp;e were initin.Uy bale.need. This method is e$sen tially acc.:urate within the limits of t.1-ie ftllowable strain of most 1nat~d.o.ls. It vro. s also found posslble as desoribec. previously to place a.11 four f?..!•ms of the bridGe at the po:i.nt of strairi.. i~! This elhn:l ne.te d much of the care "'nkillf!: the· cormect:i.ons to the e;ap;es; the 15.nes cc;uld thon bo ;jtJi:ned by oo.blo co:ri.noctors without fer:..r of a:f.'f'cotinr; th o stra in roe.di •r s. It has e.lso recently been fo1,m<1 th£-. t by the p,,opor sel ec·tion -ao- of the rasistru:ce .of the f~'l{~es and the s~sitivity of t...'le indicati ,ig irstruments,. it is possible to apply suf'fioient voltage to the · g:i. 0 as so that no am.plificatioo. of the returning si3:nal is necessary before it can be !~ea.sured in terms . of strain. These improvements ha.Ya co-n.sidorably simplified the strain mensuring equipment. In recording the strains frcr:, st:ructurnl integrity tests · or acceleration surveys it is almost ihpora.tive that . the qata be cont i1:u-'.)Usly recorder!. ·Toe frequency of reaponse of the recording elemen 1;s :must also be high because of the speed with m,ich tho strains may be o.ppliod and even rev.:,rsod especially in the case of high speed di-\res, flutter, etc. specify oscillogra ~)hie recordini;. 'fhes-e rcquirenmts practically The popular method of rocording is by mcc.ns of lig~ht beai-ns repected from gP.lvanometcrs onto sensitized film or pa.per because of the hi11L i'requency response nnd the low inertia of' this t-ype of r0co:rdi.ng. For recordinc stra.i~s froin other phenomena suc..1-i as control forces, position :L11dications, ~rte. ordinary vol'l~etera either on tho pilot's instrument panel and/or :i.n the autom£1.tic observer is the e-o,mn.only used. This is possible because these strains · are usue.lly present i::, a more or less stabilized condition e.nd c~ntin.uous ·recor<l.L'l.?; is ordina.:rily not necessary. d. STH,r-,r: rnDICATOTI A unique method oi' i:ndicati.--ig a.trains has been developed which is worthy of special r,ote. Although it is not an application of the 3trni11 r:;a p,es as discussed i i1 this seot:i.on, the sinplio-ity ail.d usefulness of the idea 1!6.ke it very in.t erosthig. In this pa.rt;i.. oular application it v1as not desh·ed to moo.sure the strrdns n.ccure. toly; the or:ly r Gqu ire,"lent wus thnt the pilo·I; be not:i.fied when a certain strain fa cmpression was r eached. It 'Wfl.s f'i)und thut a 1::dcro-switch \llould opm·i:.tte ,Ji th a cermin def'loeti.on or the buttor, and that the variat:i.ons iYJ the deflection. reqli:lred di d po·c exceed .five thouso.ndths of an inch. 'the :r.1:i.cro.-switch vm.s, the:r0foro, uocful for the hidica- ti.r:m of strabs if the f:,a / o length were lt:i.r;-se cnou r:~h to Eeke this error ner,liP;_;ible. The switch ·wns fastened solidly to the member at one spot o.:nd a rod of ai'\just&.ble len ;:th bee.r int; an the opera.ting button of' the svdt ch w:;1.s fast.:n-1ed to t}1e ,~wnbor Rt Etn.otlwr. S\Jot a f ·0.': inc::cs a.way . i)·, ,,. The le:i 1 ftch oi' the 1·od wa.3 then e.djustod so th& t r c,r,d.rod. c m:·1.pre ssion in the member befa•rn·<m the two po:b.ts of attnclmont 1.rou l d 0porate 'the switch. 'J.'ho strl.tch,. in turn,. opor- a:ted a trit,:r:0r ci 1:c<tJit ·which. eo~:::trollo d a. light i.11 the cock_oit. 'l'hc ci~c" i t was such that the l:ie;ht Y1onld rema. 5.u o,"'.l u.ntil the circuit was reset by the p:i.lo:t: . An ii."1sts.llc:t5.on of the switch and t:ti..e rod oo.11 bo soenJn Fig. ·.1. It is frequently neceson.r-y to meo.Gm·e temporatures duri.nc the progress of' f'l:i.ght tests. The moGt c o.~Nenie:nt means of' :,.;ef:.sc. r:i.;1g The operation of a thormocouplo depends on the fact that if tv.ro ,-;ires oi' dissimilar metals be joined at one encl to form a jun.otion, an electromotive force tr.rhioh is a function. of the tenpcrature of the jun,o tion will be pro~luoed... at tho other ends or tLe ,"'1ir-es. Thia electromotive force is ext:re!OOly small, a. f'cw millivolts; there- fore, the oo:nneotions :i.n the oireuits and the measuror.1ent of the elect_r.or.1otive .forco ?!lust be carefully rrade to prevent errors. In tho usual applicrd:;5-on of this principal, the vol-cage a.'1d thereby the tempera tm·e of' the ju:ncticm to be r,iot;.sur-ed, the 11 hot jur:.ctiun 11 , is oo::ipa:red w"ith tht,t of 8.J!othcr jun.ction which is at a ho1,m i:;c.eper~1.ture. The temperatt1re of the reft~renee junctioP is usua Uy obtained 1.1'J i.mnwrsing i t in melting_ ice~ thus i t is ca.lled the "cold junction". Diffe:rer1t oombina tio:ns of metals give diff'ercmt curves of vol ta~ vs t0!"1pera ture. For nost of the usual oombir1r,_ tions used, the electromotive force in millivolts is directly proportional to the temperature of. the hot junction if' the tenperature of the cold junction is held constant.. So-:ne of the m,eral combinations commonly used in therm.ooouples e.re; eoppe:r-consta.11-tan., iro.."Q.-eonsw.1-rtau, nlmool.-chromel., and plo.tinum-rhodiuw_. Tho selection of a proper 1>1eta.l to be used i11 e. then1oeouple depends primt\rily on. requirements for: (1) temporatu1·e range f'or which it ia suitable (2) a roo.ximum af elec'tromo·cive force 1 1 (3) a ro.tnimum thermocouple olect:rical rosisto. r ce (4) o. smooth, strai r_:ht calibration. curve (5) a high resista.u oe of tho netnls to corrosion, o.xidaticn, reauotion a!"d orysi:nllization. 'l 'he iron•cor1ste.:r..t8!1 thermocoupl0 is tho most co1nr:i.only used bec&use it satisfies most of the above requi:remen !~a and :i.n a dditim:1. it is strong,. r.ood:i.ly welded. and does :tot conduct 1100.t n ,adily. The electromotive f'orco r_: enerated by tho thermocom)le is usually in dieatred. by measuring t he amount of: rosistn:'. 0ce ~'hich is r":quired to reduce it to a. give:1 sta°'ldard value. This my bo dona ma11m1.lly by means of a. rsoo<l. oo.librrtted :;otent iom.etor or autonntica.lly by a Brown Recorder., The wic::spree.d use of the Brovm :Recorder in the field of f11.r;ht testing· necessitates at least a brief co~,sidere.- tion of its footuros. The rosie element of t he Brown \ ocorder is the self...:00.laneing potentiometer which automatically riea.oures the . thermocouple voltage and positions a 1119.rker. so that the tempr::?rature . 1 is recorded on n chF-.rt. 'l'he i.r1strum0nt is capable of record:,,1 g the tenpe:raturo of 1'14 thermocouples :in three mimrl:ics vd. th an accuracy of.!. 1/4:i of' full scale. The n easurine; cir eu1 t con sists of twelve a.utomnt:tc swi-cchos, each oo: trollinc .twelve tt'lermocouple circuits. Vnny companies r::nke ext ensive use of t h is instrumc::t, but few have been able to ~tk:e much improvement o:n its operation. 0:co t ypo of th0rr1oeouple ,miah ha.a nb1ost become s t andard is that; used i n t:1resuring cylinder hea.d· temperaturos. It consists of a thermocouple illibedded i n a ring which f'i 'ts under the srnrk plug-, . An oth~r type• for measurin g ey li,".lder base temperatures. ·are usually installed by the engi ne manufaoturers when ·fue en r;'me is built. Fi g. 2 shows a thil"d t y pe o:f thenioooo~le vm.ieh is e.n example of tha.t vrt, ich is widely .used in earta1.n installe.-t:ions such a.s fuel temperatures, oil ·t emperatures. eto. dsually. in the measurement of the temperatures of ~1lses suoh as tlie air in ,duots, exhaust gases., eta. it is usually · necassa:cy to prevent mdiation from a.f.feoting the temperature roo.dir1gs. This is espeoia..l ly true Vihen the t empe rature o.f . the duct j_.s very diff erent from that of the s0, s.. To reduce t he ai'fect of suoh radiation a shielded thormocouple such as -thn t sh own in Fi e • 3 is used. ' The thermoeouple9 whioh. have been developed . for the measure- ment or outside n.ir tomperaturf~S deserve special atte.ntion . It is necessary -thn.t, for this purpose, special s hi elds be desi gned to protect the thermocouple element fron the oooling; eff ect of the :f'ree air stream and from the hea tiq :; effeotn of the direct sun ts rays and t he impact of a ir on t.,'le movin;:t thermocouple. Several ,c tempera:!::ure "bulba'-' or "r,robes" have bee1.1 developed to perform this funet:ion. The most effective of t hes e t er•Tperature prolx~s ha.s been the t•Frar:z" t ype a n exi.1..rnple of Vi!W.ch is s hown -:in Fi g. ,1. This probe :ts desi gned to measure the adiabat:lc-001r1p ressio1: -OOM)Jerature of an airstrea.m. This ir..forma.tion t.oi-;ether with a. knowledge of the s~catiQ and total dynamie pressures of the air strear.1 00.1.1 •be to detf>rmine the temperature of t..1-i.e ~ree air strc.=R - .m. C,i.lculo. tio:ns used based on. the assumption ·chat the air i"'low does not separate from the divergent walls of the orifice at the front hav.e indicated the:t the effect of ·the fi11i te vel oci t ;r of a ir pa.st the thermocouple is negligible. In fact. in actual tests on a modified probe of t Lis °bJpe. i ,t was fou:n:d that 98 percc-nt to 09 percent of full adiabatic expansion was obtained at sea. level with on ly sH;r;htly l e ss perfeet expa..,."1sion e.t higher n.ltitudes. The simplest method for 1nos.suring prossures 41 is of course a. tube open to the air flow. This method is used i n pressure "rakes n or "Chrlstn'lts trees" • . Thes e are special names given to a.rra1cgements of the pressure heads to moo.sure certain patte rns of nro ~{ sures. The .sinple open tubes are praotieal for measuring t~ d c plus stetio of the airst:ream "."1-ith relc,tion to the tube ' ~nressures when the :meed is sufficiently great. If the dyiJ0;r,,ic pressure is not lar[-;e en ouf. !',h to ~ke this sort of hood praot foe.1; another design must be employed.. • A sket.ch of t he kiel type of pressure head wh ich i ncreases. tlrn vcloci ty of the air' e.t the entran ce of tho tube by meu.:ns of a sr•-e.11 venturi is shown b Fig;. 5. This t ype of pressure h oo.d is usually used in ducts., a.ir exits, etc. where the velocity of the air stroc...n is cor.1 - . paratively lo-w. The nost g en eral a pplioatlon of pressure r1easm·cmfmts on aircraft are those wh ich operate the rdrspoed. i n dic:>-. tor. pitot-stntie tube is widely used for t h is nurpose. The standard 'l'he · tot.al pressure o.s detected ~· the pitot tube is e:enerally rather n r; cum te; -bhe gr ua test error r es ulting from tho ~ngle botv,0e :n t h e a xis of t he tube and t he direction of t he r elnti vo' win d e.nd this e.ngle is usue.lly rather sn.all. ?h13 greatest er-l:'Qr :lr:c the rd.:r-sp0od systcJ!n :l.s i n t he measurement of the sta tio pt·essu re beoouse "bhe pres-sure at t ile s tv.tic holes around the outside of' the tube is increased or dec :·ease d appreciably by even a small angularity of t h e tube. i·;-e sh all >ere c onsider some alternate rne ·t h ods of detect i nc; t he sta. tic pressure. a. One method of measuring tho stn.tio '.) rossure accurately 0 • 1 1ng • b ombn vnnc • • h :ts • ess ential l y an a..1 ternnte v,y t;h e use or"' a • t ra1 i s 'hn sta:cic source towed by t..he airplan e a.t a distance grent 0;1ou r,h t-o i nsure its being outsi de ·the disturba11ees caused U'.f t he airplane. This method has been successfully used up to s peods of 2fi0-300 ?,r. P.H. Above these speeds t he cable or tubing wh ich supports t he 1>~b a.nd trar:smi ts ·the .pressure bo ;~ ins to 1~vhip11 a.r:. d be cones unr:taTP-gen.ble. Wind socks o.t inte rvRls along t h e cable :::ny retard such notion s -::w.iewha. t.. b. Another stat:i.c source is the uswiveling static" which has b ee!l used with some success if t h e 1.nstalle.t:l on is ce:.refully plru.12,e d. i The s vn.veli:nr; hood must be placed outside t li e air;)lane disturba.11.oes a n d if· the aata are to be veiy e.coureto. the hoo.d mustbe co.l i bra tea... o. It ms b0en found recently that a static orifice VJhich is essentially a pattern ~r smll holes properly plaood in the side of the fuselage, prqvides a very e.f'fective source of s-1:atio pressure which is pmctioally free .from error e,speoially that due to speod. The operation of t3'li& llfuselage .ate.tio orificatt is due to the pre- senee of tM boundary layer of still air immediately on the aur!a·oo of ·bhe a.irpla.'1e. It has been denonstre.ted by flight tests that the position error of a proporly desi?,ned fuselage s-tntio ayatsn is tme.ffeoted throughout the mn-g e of 7.~ oh :numbers normlly encountered. The airsp~d indioator is used to indicate the difference bet~en the total or pitGt pressure due to the airs-peed and tha ~ta.tic e..S.r pressure; however• ir.. other ir..stallations, airspeed in• dice.tors aro someti'!.les used to indicate various ot..!.ier pressure dif'fere:necs. Mo:t"'-e frequently, tM total pressures or the differe:nees petwean the total pressure and the static pressure'for various.test instnllation.s a.re indi cated on nnnomoters. photographed. Several -of these ffll.O- Quite a variety of liquids have bem and are used in -the mananoters. but WJ.ny eom~ies now use aoetyl~o tetra.bromide whieh has a speoific .~ra1rity of a.pproxinntoly three (3). • A liquid t of this density permits the use of .a size of t'lanometor wJ"iioh, for _the usual range of pressures, is a good oompror~ise 'between aecu1,acy of readmgs q.nd limitations or the allo-wable size. In special co?.1di- tions !:t is more o.dvwitagoous to u&e pressure gages, of. whid1 theta· are many t;rpes en the arket, rather than the IP.anometers. Genore.lly. the stondard fuel f'lov,r meters ~ro not surfidently i\'!ost commercial flow indicators accurate for use in flight tea.mg., have been found useful when the totalizer is used to indicate the total or.iount of" fuel used but the continuoudy indicating pointers · . do not accurat.e ly Jndieate the rate of fuel f'low. Same oth~..r means or moo.-suring fuel flow is, therefore, necessary. Most eom.pa.."1ios make use of the "oo.J.ibrated oo.n" ~ethod of measu.r:i.ng fuel flow. There are nuiy variations in the sp~cific equipment uood. but fundam.en't:3.lly ~he meth od eonsists o.f measuring the time 1:1;o oessa.ry to .consume a gi~1. amount of fuel. A known qua:nti ty of fuel is carried in. o. small tank and the time requ ired for th~ fµel to pass faro specif'ie points in the tank is :measured. The ta.11k is t1 necked dO\m" at these two poin t s to facilitate the time mmsurementa • .In the photoo-e~ph• F'i r,. 6, is shown cne of the more ele.bo.r:ate i.l'llilta.llatj_ons fGr the sinmltaneous or separate maaauremnt of fuel flow to two different engi.nes., In this illustration the cor.tah2e rs are 01Jlindrical and are r.:e.de of tra --.sparent plastic with the level indioo.tot's inside the tank. The hs..'1dlss f0:r f':illin g the ta:nks a n d t h ose for i ntrodueirig tho fool fr om tho tanks into the supply to the e11giries rm.y he seen in the lower part of the picture. A metallic floa.t with:?.n the tar.:k v.1as used in one fostallatj_on to vary a magnetic field and ope rate an electric circuit whioh e.utor..at ieally ti.med the fuel flow. However• this system has :not yet been perfected and was used with only limited success. One of the pitf'a.11s _ to be e.voide,d in the opeltltion. of this equipment is thnt of sticking of the v,,3.lves. This can be especially ·oongerQUS :i.n the case of the va.lve which shuts oft the flow of fuel fran the ree,; ular ~nka and draws the fuel su;:;piy for the engines from. the mea.surlne: tar.k. In one iJ'.lstance such a. stickirlg of this valve al?r.:0s·b caused the crash of the .tes~ airplane. 5. ACCELl\ POT-IBTYRS. The measurement of a eoelero tions is one of the r:1ost iraportan t requirenents of flight t.est instrumentation an.cl also o.ne of the most diff'ioult t-o perform. accurately. It appears that a good aceelero- me·bar has not yet be-en developed. A good acoale.rometcr must be essentially s5. ·ple. Aooelera• tio:n itseli' as a. quantity i~ essentially siniple and usually well isolated but it my '1-ary wi~ely in frequen cy nud amplitude. For this i-oo.son the frequenoy rosponso of' the a. cceloramet0r must be wide, but the motion of the 1110asur:i.ng system must also be co.re:fully damped to give the proper readin.1:,s and to avoid "over shootingtt. 'l'he visual a.ecelerometo:r is exter.~sively used as a cockpit instl'Ul!lent, but it is hardly us.-oo.ble where a ccu:racy is desired. '.l'he nww:ti..'Ylg of th:i.s instrumen:t; is very critical a.s vibrations nay make the instt-ument ineffeotive espooia.lly with regard to the poirrters ·w-hioh indi®te zre.:ldmum positive o.ncl ma.'ximmn 11egativo accelerations. The v.G recorder,. an acceloraticn inijtrument developed by the ·HA.CA., is frequently used to make aocelorat ian measurements during tost flights. 1'he record cf' acoelero.tions v ersus indioo.ted aiT,s peed is nndo on a ana.11 reotanele of smoked glass by a stylus. The stylus is moved vertioa.lly by o.ocelera.tions and alaig a horizontal:_ arc by a. differential betwee.1 the pitot a.rid static pressures. • '.l'he i nstru- ment is very simple, ecmi.pletely a.utons.tio .and cmi ~ very aooure.te. It is oo.libratad by aetually o.pplyiY.,g to it kno,m aceeleratione, on a rotat i ng table. a:nd simultaneously applying pressure differentials corresponding; to oerro.5.:n a.i rspeeda. If the :i.nstrumEm. t is used \tl thin a reasonable tLue or its oalibration,is properly lnstnlled, on a ~rt of the prirl.ia.ry structure~ and is. pro~l"ly damped it can be ver1 ~eeure.te in the mea.surem.ents ror wh:toh· it is intendeo. Hov18"'..rer, the scope of these measurements is limited• principally by tvro ~ 8 • First of these f"aetors 1s the absence of a time reference. Since airapeed is the other axis-, the ,correlation of any pe.rtioulo.r aooeler• a.tian 'With another functim or oe01:1rreneo 'BXcept airspeed is very diffioul t. Secondly., the :response to higher frequency aeceloratimis ,.. , is very en-atio. The trequenoies v.tiich are encountered even in le.nd1!1gs are high enough to rrake the ir1strunmrt "over shoot11 • In this oonneot:lan* the question has also a.risen as to the accuracy of the V-G record.gr in sudden applioations of acoel~rntion. such aa might conoeivably develop in quick "pull-outsn, shar?"Gdged f:.'l..tsts• ' ete. However. this instl'Ument has b~n e.xtensively used in structural , integrity demonstrations,. and in g;ust re~ea.roh and has well proven it~ merit for those applioo.tion~. Another type of e.oeelerometcr .mieh is now being developed ,'fls discussed in com1eotim with strn.b. gages. This · type shows much promise and it is possible that a cor.iplotely sat:isfaotory aooelerometer mny be developed al011g these lines. 6. AttI'l'UDt: r,.;sTRmm:wrs. It is necessary in nruiy t--ypes of fli t9'1 t tests to }:now t);:le a.tti• tude of the airplane in either pitch roll o:r yaw e.11 three. oooasionally The usual method of moo.surir1r,; the pitch, r:-oll,. and direc- ticn is by mea..."'.ls of the sta..".ldard gyro instrunents. The direotional ~ro e:r t,yro-oompass ind5.oo.t"s the direction of the airplane with respect to the earth but not with respect to the relati'Vl3 wind a.a is usually required. Cne very popular method of' measur1.ng the latter is by means of a yaw-meter. A photogt'fl,ph 1 1· • of the vane of a. yaw-meter is presented in Fig. 7. The movement of tho va..<ie moves the armature of a s elsyn tra:asmi ttor whi oh operates an indicator in the airplane. It ie neeesaary that the va,"".J.e be so plaoed e.s to be u.naffeoted by 1.ny disturbances which may be caused by the airplane. If required,this installation can also be made to indionte angles . or attack. A new 11 attitude indicator" is now unde:rg;ohig test by one of the i11struinent cotrtpa.niee. This indio~tor consists essentia.l ly of a gyroscopieo,lly contl"olled sphere vmioh is free to ro-tnte about any a:ds. The sphere is then oalibrated to show the position of the airplane. The details of this instrurne."l.t aro ~-.ot available a.a the instrument i.s still i n the developmental stage. The development of the torquemetor has probRb ly been the nost beneficial advar1oeme-.at in performanoe fl .:. gM; testixip; in the past decade. .It prov:ldes a method of measuring accurat ely the power being absofbed l'.Y'J the propeller whioh wa.a previously esti~.ted by a ca,1parisor, of t.he im.nif old pl"ess\,lre e.nd the en gine RPI,! wt th the . • en gine charts. ' This estir.no.tion 'base d on the assumption that the engine was opera.ting the so.me in the air as it had in ground tests was- usmlly 1..'18.oouro.te. The principal of opemtion of the torq uomete:r ie that of m.oosur-, ing the r 0aotion of the propeller torque on , the reduction gcr.r:i.n g • in ·the enr:;ine. This roo.otion is oonverted i :i'ito a pressure and trans.., mitted toe. @;,r;e. This gage 'f!JJ).y be lo~ted in the ooch.-pit. engineor•s station, or ir.1 a. photo-recorci.er. However, i.'1 tests of multi-engine airers.rt it is necessary to transmit thts pressure through the wing to the fusela ge. In high altitude testing; especially, the low temµel1i\.tures may oause the stationary oil iJ, these lines to co:r,gool e;iving false torque readings. 1'he usw:l r:1etho <l of rJneoyir-g t h is condition is -to pu.-np keroaerie into the U.11e un;l:;il t..'1-te oil is forced back i nto the ene;ine oomp;i..rtmoo.t where it is h eated. !!owevor • another solution to the problem is tQ use a s hort pressure line in the engi ne compai-tinon t,where the te,::poratur e is ab ove freez ing, to tran smit the pressur e to a selayn t:ra.:nStnittor 1,mich is located i E ·che rear oi' the engine oo-mp~'l.r ·bmen.tJ the elect:rio si gnal is then ti-a: ·s mit~.;ed to the selsyn i ndicator in the fuselage. a. AUTDYATIC m~co1rnrnc. Some diff ere2:oe of opin.i on exis ts co,·,oern:b 1g tho relative merits of manually an d automa t ically recorded de.ta. 'rhe ve.l ue of I!L'•lUally reoorded data lies in its avai~bility for immedia.te use. Host autoimtioe.lly ~oorded data require some sort of' processing and transcription. However. the oe.sa with which a. greater amomrb of data may be reoor;d ed e.utO!lll.tioo.lly, the redu-otion in flying time nnd the elimination of a certain amount of; 0 perso:ral error 0 t.r outweir)l t~e advantages of' I!Jlnue.l reeording. When data i~ recorded rnnually by either the pilot or the craw simul w.neously with autom0.-t i o reoorcl:tne; , it should never he interpreted as more a.ooura.te thtm thnt which. is recorded o.utom11tioo.lly. ·-· This, of course, assumes that the reliability or the instrumentation is the same at both stations. There are l!Nly wa:ys of automatically reoordil,g data, but essen• tially there ara two msthods in oommon use• ohart reoordine; and photographic recording. • Chart reoo:rding is vory useful where con- tinuous records are required and is otherwise used occasiopally in oon.."leotion with selective t"eoording. The Dro'111. Tempe rature Reeorder is a good example of seleotive or intenni tbent chart recording where the data are recorded en the chart as the various thermocouples :a ;re successively switched into the oiroui t. The priIIJQry value of' ohart recording i~ in its imm.ediate availability for useJ the true chart recordings require no procesaing. Exa.l"'lples of continuous cha.rt recording as used in flig,ht t ,,sting are the ·rught a.mly~er and the barograph. A recant advanoe:t1ent whioh has im:proved chart recordi:rig is the development of •11 teledeltoe" paper or: which the mark or tra.~e is ?Mde by a. hir.,h voltage arc from the pen or stylus to the foil be.ck:ing· of the pe.per itself', two advantages I The use of the teledeltos paper h.n.a pressure of the stylus on the paper is unneeessary, whioh reduces the friction in the indicating system end the opore.tim of the recording syotem is improved ra.ther than destroyed by altitude. The use of sensitized paper or film as a moans of recording is sort of a hybrid betwc,an cha.rt a.nd' photographic reoordinr,. Thia type or reeo~ding· is used in ma.ey osoillogra9hs and its a~)plication was disoussed h, oo?meotion vrith strain g;agos. True photographio recordint is tho :method moat vrldely used in flight test:tng at present to rooord data automatically. method the instrument roo..dings are photographed directly. In this The popu... larit-.r of this system is primv.rily due to its fle:dbili:'cy and the ease With which stv.ndard uircro.ft instruments may be utilized. The design 0£' the partioulc.r ::>hoto-rooorc.er raust be :ntlde to suit the speoifio conditions; the ~,pa and number of the in- struments to be photographed will of courso, depend on the typo of ·test. The physioo.l characteristics of the photo-reco_rder will be . . det~mi:nad by the looation f;..nd the Etir ;:>laLe in which it is to be installed. If the epa.oe and weight i'estricti cr: s a.re 1 ibcrul, size df the photO-l"'eCorder may be a minor problem. Howcvor, if t i·1e se restricti ons E).i-e _o onsidernble, such as is the case in a fightor airplan e, the proble,:, of' t;he design of the photo-recorder is more complex. One common method of reduoing the size is that of using . a :i'.lirror ·co reflect ·the i.-rmago of the :i.nstrmae:nts into the lens of the ' ca.'"n.e:ra. This serves, to L~,cr-oase tho field of the came1"8. without incroasing the length of' the recorder. recorders a.re presented., Several pictures of photo- The photograph, 'l-'ir;. 8 shows a photo- recorder in ·whieh the mirror is inclined to the plane of t}).e lens. This photograph is eapeoie..lly interesting_ beoo.uae i t shows a.n inste.llo.tion whioh was pe.rtioulArly difficult. Due to space limitations. it was i1ooossa,....,,. to mount the :rocorder on the f.".lln mou.,,rts in the wi..'1.e:, .)At J l'_.. • Figs. 9. and. 10 show exterior a.nd interior views of a photo-recorder wh:i.ch makos use of a mirror parallel to the pla..."1e o:f the camera lens. seen. In Fi[!. 10 the curved instrument panel can be 'fhis is an effar{; to roduoe the ~ra.lla..,--c in the roudin.i; o:f the instrtunc11ts o.lo:-,g boi:21 edges arJd to i.-rnprove the foous on these :1.nstru:monts. '.i'he arru.n.ge:men t o:£' the instru'!l1ents en the instrument panel is a.n.other foatu:ce of the otw.struot:i.on or the ;Jhoto-record<;;r whioh should be eivon oonsidore. tL,n. A convenient a.rr1~r,r:or.1ent of the instruments :i..n group~ co..n i.:;r.:iF.t:ly reduce ·tho effort required to analyze .t he recorded date.. Two photo r;rnphs of iY.1stru,,1e;;-,t pr,.nols aro presontcd to i,J.lus-t:;rotc the gfoupir1~ of -the L1st:rur,na11.ts. white lir,es, in geneml show the tro1.ips of .instruments. The J.n the photocro.ph, ?ig. 11, _t;1;e b.strurJ.cnts in the upper lef'b a re oil and ' fuel flow ar;.d tempernturc i::st:nU"lents, below theso are oil a.'ld fuel pressure :bstrum.02:ts, tho lower row a.re boost vressures., and to the rlr;ht a.re- mii:;cellffrtooun fl 5. 611.t and engine instruments. In Fi/s• 12. i;he irs-f:;rmJC:Tts to the loft of t 11e whito • li:r.c are nrJi.fae tachometers m the first rc,.v 11 :imnifold pressures in t..½.e second row and position irnliootors i11 the next two rows J t.lie instrun.ents on the bottom row are torque meters J and those to the rie;ht of' ~he line are miacellan• eous instruments. b. LI GHTINO. '.t'he lig:)':lting of the instrument panol of the recorder is critioal a..."l.d must be arffint;ed carefully. Ref'1'eoti ons of the li(",ht1ng •of the 1.nstrttme!'t panel my ensily ri.ti:n an otherw3.se good i ns-ro lla.• tio:n . One of' the aimnloat mea...'l'ls of lir,htin p,; the pw..el is by overall li [';hting whioh is usual.ly done O'J the use of fluorescent lights., 1-Ioir:ever, this is also one of the ,easiest \.-m..:,rs to i ntr0,Ji~oe r;lnre. Fig. 13 sh ◊v•rs a. m.:tl<l case of. glare trr,uble ')Tl. fot1r of the :ins tru::101':ts. . The ' • photor,:raph Ftg. 14 s 1.10\o11s e.11 e:xn::::ple of L"rtd.ividual light• fo g for oo.ch i nstriwnent.. Al th6uzh very cff'c'ctive. ~tis sy ste!!l is also shcwr the op~n ty;,?e of oonstruoti on . This ope'!l co~1struct i.o:::i is !!luoh ,c()re conven ient a::Jd may be used ,1hen •lir:;ht from othe r sources is not liable to a.ff.eot either the 1sle.re o~ the e:x1'>osu:r-e of the film. This· ~.rpo of photo-observer is ve~~y prae'bi<k'll 1. f it cnn be 'IS ed.J the i n struments, 1i r;hts. tUH~ o·l:;h.er 001rpon0nt r.:>n:rts arc much ~or':> ree.dily available for servS.e:lnr.; than ln the close d ty:) e o:f' c01istruct:ton. 1'he camera. is a very important f'eo.tu:re of'. the photo- ,·1Jserver. Some coT,pnniNl have been able to secure sniw.ble 'standHr-d electrtoa.llydriven motion picture ()am.eras and adapt them for use in the recorders. Two photographs 0f onEl of these oamoras in different installations are presented ~n Figs. 16 an d 17. ually in ·the movement. The principal al teratian is us- It is necessary that the speed of the camera be controllable through a groo:ter range than that usually available. The common speeds for the camera.a in the photo-recorders range fron one picture every thirt-3 . seconds to normal arunera. speed.· Some cameras also need an inor oo.se in a:vaile.ble filtn fotta.ge. This factor will be deterr:rl.ned by th~ nature of the a:i.rpla.ne and the t;osts. • The e.otun.l. length of film required 1a largely a matter of judf;emmt and should be estinia.ted on th~ re.sis of the duration of a single flig-J1t o.nd the number of tests normally oonduct ed on e. s inele flight. In this conn.eotion,. i t has been found advisable to run the photorecorder a.t a slow speed co-ntinuously throur,hout the test fli (!..ht allowi nr; the operator to i.nerease the oo:mera. speed '°"1e..'1 a test is behg run. This policy ~ill tend genera lly to improve the data by ~ivinr.; a. continuous record of the functioning of th~ airplane before u:n.d afte r e.s well as durinr: the test. An ordinary lens apera.ture is usually sa t1s:f'actory beoauee the intensity. of t he 1 i v;ht and the t;r11e of fihn. oan be a.djo.stod to suit the conditions. '.l'he focus "'!':'EJ.Y be erl-tical if the s~oe r e quirements a,:re very stringent, but this is not usually the case • • d. c r)NTRat MID COHEF•! LAT ION. The ocntrols for a photo--reoorder will "8.ry con siderably with co~"l d.i tions. Hov1ever, s te.ndard control boxes have bee:1 dovelo~d . by sone cm~i.es to fit tJ10ir usual needs a.nd if e.ddi tlonal emtrols -98- are neoessa?"'J they aro added aepar!l.te frcim the control boxes. The photograph;, F'ig. 18, shows one suoh box for the control of one recorder. '£he controls shown on the box are self explan&.toI"IJ. In another organization where larger alrplanes o.re usually tested and more tha.'rl. one recorder are usually LY\Sta.lled, a mul t7.ple oontr0l box 1.s required., Fig. 19 illuetre.tes a :riultiple control box whioh e.lso contains controls for a. Brown potmitiometer. The correlation a.'1:d _iden:tifice.tion of any single picture_ is a particularly important problem imien more tb,.n one recorder is used. This was fir-s t attGr.1pted. ~/ the us~ of very accurate clocks, but even the bost clocks did not p~rfonn this function satisfactorily especially when the flights were of long duro.tian ·o r if the pictures were .taken in quick succession. To provide the :neceasar:' oor:relatian. betvreen the different records the vttrlous photoGraphs a.ro usua.lly numbered conseeutivoly, This is aocoi•rpllahed by mef:ms of e. counter ,-m.ioh :i.s advanced oo.oh ti:me a picture is ta.kon by any or all cam.eras. This number is also reproduced on the oontrol box for the .Correla.• tion of any notes which may ho ~nken by the engineer or the pilot. L--i oonnC:iction with ·t..'1.o controls of the !)hoto-recorder, we m.i.cht also corsider briefly the mora general aspect of the cor.i-plete fli'ght test engineer's ' sta.tio11. 'rhls _avlJjaot -is of ;)0.rtioularly importa.:.<1oe in the large airrplancs n.lthour..,h i t my be considered to a much l,ess e~tent in the arra.ne;omon:t of the flir)lt test controls a.:nd instruroontatiop for the pilot iD a sir>..f.le.asoat airplane. For ..99-.. . purposes of this discussion, ~mly the larger, multiplaoe airplanes· will bo considered. The primary consideration in tho arrangetr.le:it of' the eng hiaer's station is the convenient loca.-t~on of' tho controls, instruments a.."ld indioe.tors. 'I'wo photor:;raph.e a.re pres anted as ex- amples of t"llo wry good instaUa.tion.s. Fig;. 20 is a.n enginee~t s station for the tests of a medi1,.-mi bomber where only one_engineer is used. 'l'he strip a.arose the upper rir)lt•l'i.and oo:mer is a writing table which folds do-wn for the convenience of the engineer. '.i."he photor;rn ?h, Fie;. 20, il}ustrates an engil'leor' s station in a larger o.irpla.110. tion. Positions fo-r two engineers we re prov-lded in t he installa.• 1~ legend for the · idontifioo. tion of the various · oornporter1ts is proYided. o. P'dO'l'OG:Rt\PHING '!'Ir.8 AE?L;\.Nli• - - • In so:n e tests it is impossible to secure sufficient in• forma tion ao::-1ce~.1ir.g the f'u.."1.0tioning of the airplane by c onventional bstru.,,e1~cte.tion • . Occa~iorally, photog:ra.ph:in g vari ous. po.rts of the airplan e is the solution to this problem. Ca.'norns are mounted on the airplane and such i tams as wings. stabilizers, elevators, oto. a.re photographed i n tlight so that such phenomena as flutter or air flow (by tufts) oan be titudied. 1':i.~. 22 illustra t;,~,e one in- -stalla.tion of a camern for the n tudy of the empennu r e of an airplane. The camera is mounted inside the fuselage,, out of the nirs ·(;r0£>2:1 and the emponr..a r;e is photographed by means of a mirror. _______ f. . Hf-. DI-0 TEL.Ct':l:T: Jl.r!'W. _ , A recent line of imp:ro··renient on the art of flight testing has b een the transnission of' test data to the ground by radio. Three reasons can be assigned for the necessity for thi.s type of equipnent. 1. On flights of long durs:tim! it ·ts ooxivordant to l'a ve tha date, ·on the ground. as soon as possible,espeoially on 1~porte.nt tests, so tho.t the date. can be ar.i,;.lyeed partially, at loo.st,. and the remAinder of the test schedule be ple.nne.d or considered with the lea.et a.mount of delay. 2. On especially ha.ze.rdous tests the loss of the airplane would not mean the complete loss of data ~1 ich, booo.use of the failure vmich ca.used ·t.ti.e crash, mit",ht well be invaluable. With other means of recording,. tho loss of the test a.irp1e.:ne, aside from the cost :ln time, personnel, and money, o:f'ten means the loss of data which ai.t:ht show . the :ree.son for the brash and O.."ly other data ,,hich ·my have been eol.leoted on that flir,ht. 3. The pro~ress of the tost !$.Y be Qho.rted and ealcu- la tio::..s nit de on the ground so thlll.t the pilot T!fl.Y be informed of the pror,ress of the test. This might pre11ent a.coiden'to a11d should acoelerate a teat prof;ram beoouse it would not then be neoesse.ry for the pilot to land to see how the teat ia g.o'ing. <ne of the m_ o st frequent methods of measuri ng take-o:f:f and la.ndJ.nrs runs is ~r means of. nn adapted motion picture carnere.. The -101-- oo.mern is s.dn:p~ed to pho·togrc~ph a stop-watch o..:1c~ the a:i.rr lane si:mul taneously. ln this method fla.t:s or DD.rkers are usun.lly spaced alone the runway to 1:nrk off units of did:e.1,co. A vn.d.a tim of this pnrt:i.culo.r method is the use of a recorcH g; theodolite. 0 A thoodol ite v.rhich has bcc.n ri ct:od with a moa:n. s of reco1·di :-1r; its axir:iuth a.:1d deflection is used to follow th1c: a.irplano. A conbina- tion of both of' these methods a n d un imp:rov·Ennerrt over both is tho use of the photo•thooclolite. pros(v te c: in Fir.;. 23. A pliotor::raph of th:1.s instrum():r-, t is It cor, sists essentially, of o. oruaoru which photor;rt'I.Jhs the airplane a.t oa.rei'tl1ly con-trolled i nt e rvn.ls. As ooch nLotogrn:c>h is taken, a grid whioh'is oalibrattcd both in horizontal ar:,d vertical <31.srer:.ce., i .s supori ·posed on tho picture. The grid is actually stn tionary vd thin the ins-trunent and the phototravhs a.re taken th:roush it. In any of these r1easurements the loc-1.1tian of tho :i.nstrument with r espect to the rurrway 1,mst be lo:ovm and ttl lm·v0.Dces must be made in the anr,;.lys:i.s of the do.ta f or the varit\tion b fro,.'11 thi; camera. to the airplane. distance For the !\rnzy- the i1".lportn.r:.t re"" qu:h-enents for ta.1:e-off tests o nncern the distn.nce to cl er:.r a 50... ft. obstacie ,,Jhile tJmt for t h e 'fe.-;-y C ( ) cema the ;)o b t r:..t which the 0 a.irple.:,1€ lel',vos the p;rou."!.d. Tho distance to clear e. 50-ft. obstacle is relatively easily ?neo.sured by noo.r:B of' t,,,e 0t1YH: ro, hut it is so:,owhat !'.1 ore diffionlt to dete·rn:i.ne ct!1e actual point where the a.ir- pla.no loo.ves the ground . Therefo::-e obsorv01·s PlUSt be s ret :' oned -102- a.lor.r; the runway to n ote a.r d r:n.rk t h is po .-Lnt. One method which has been used successfully on a large o.irplo.ne to nerform this ftmcticm is that of us ing a small ,vheel, rolling on tho 0;round ·t;o :i.n,liei.l.te t h e point at vtlich the wheels l e ave the ground. 'l'he hr i;e airplar-;e happened to have duul re:1n wheels and the small wheel was locat~d between these. Tho oo.ntilever boe,m ,irl:tioh oo.rried the wheel was hin ged to move iri the 'Vertical plane. As the o.irpla.ne left the ground -the vrheel dropped slig:htly brooking an electrical contact. Thts wheel 1'll.s used further to drive a tachometer ('.,enerc.tor to i.-vidi~cte the gro1.m.d speed and a. revolutions counter which ms oulibra.ted :i..i1 f'eet to measure the take-off run. 'I'he instru..,;ienta.tion :installation will be different fo:r every typo of i nercrument and mu ~; t be civen separate o.ttorrcion. This l'il-ty be greatly simplified by the preparation of an i :,;s~~llatio::i r;1£u,.ual as previously discussod. 'l'his is especially v-aluable ir, the trn.ining of new mecha'rlics e.nd even for the -cuiclt.:-.noe of expcirienced mon. The installation of the instrumentation accesso1•ies oa,-; best be per:"ormed durir..p; the construction of the airplane. Such items as pressure lin es, wiring, etc. can be easily placed in the a.irpln r:e during its cor., struction if the irrntnu:nc::-.d ;ation has b00n pliumed far enouf1! in advance. problem. This will r;rently si,,plify the i:nstt'Ul'nenta.tfon The instrunenta tion should be checked before cver~r fli eht J this is usually performed by tho l:t ne crow in accord.a.nee with a:n fo.st:rurnenta.tian check•off list as discussed i:n Part I. Some ccr;1.:. panies require that the photo-recorder and any oth0r recorders which may be iria$tv.1 1 ed, be oper£l. ted dui-inr; the ground run up. This length of film is then quickly devel oped and exmilined before the checkoff list is tt sir;ned ofrr'. If the data a.nal?sts find any data which is questimi.able, this fact should im!:ledia tely be brour,)1t to the a t-t;ention of the bstrumentation enrJ11e(ir. 'i'he r1anually recorded data w..a~r also serve o.s a check on the operntj_on of the instrumen ts i n the. autoroo.tio· observer. r ach :b,stru.r,ent which is ::-wt direct :rmdinr; ahould be plainly ma:rked and instrum.Emts v:hich are i>:::.opcru tive should also be plainly nn rked, usually b.:r a cross of white tape on the diRl. -104- In co11cl us:i.on of thi.s discuss:i or1 it is obvious the.t the problems of the instrmr.wntation enf).riec r a:re mny and varied. thorOl.lt;h Ic•ovtled[(e of the instr1i.r:ieT, ts witr. wl':i ch l1c YJOrks; he n:ust ::100.sm·e. !-le r.iust be faniliar with the 1:t'.rious tod1.; ·icul sul) jocts such a.s a crody:.ar;-,ics,. menhs.:.-tlcs,electro::·dcs, struetur·al analysis, otc. a: ,d he aust be able throuc,h p e rs onal ezpel"ie;·:ce to evaluate the i.,-n.:r:i.ous 5.dens a n d to select the n oGt prnctical for !lis pc.rticula.r pur:,oses. ::a n y ot110r personal a.tt :ributcs n r o :required to l:'..a1::o these is ingenuity. ;Jf.my probl1:-;,11s v:hio1:1 m'?-Y be confronted c.;r..:Uy • oa.n be soJ.~rnd by the irw enoous e.p1?lication of elemm.tar;/ prhiciples. -105- r,, .w. ILLUST:'A'l'IONS. ---~- Pig. Ho. TitlE1 1 Strain Indicator 2 Thermocouple 3 Q.uadriyJl e-shiel. ded 'rll0nn.ocouple 4 •re::1pern ture Probe 5 ' Kiel Pressure Uea.d 6 Fuel Flow Meter 7 Yaw Heter, ·mne 8 P}:oto-Lrccorder, Wi n g Insta.llo.tion 9 Photo-recorder e.xter ior 10 Photo-recorder, interior 11 12 Jrstrument P{,..,~01., ~fo. 2 lS Ins tru..-rnen t Pun cl, :,Yo. 3 1,1: Photo-recorder, Individoc,.1 Lir,,½ting 15 Photo-recorder, Cpen 'I'ype 16 Photo-recorder ca.mere. 17 Photo-recorder xm.nomcters 18 19 Eultiple Photo-recorder control box 20 fa:gi neor's Station., siq;le 21 22 Ce.rnera f'or photographing Frn-pennage 2~-S Photo Theodolite 24 0: 25 '," later Bal la.st Te.m::s 1. Fuel Co~1sumption '1'est Uni t 2. Counter 5. h ;struma!:i.tation Powor an d Bro,·,m Rec. Power 7. Brovr.c. He co~·dcr Vol ta.ge Control 8. Ix,te:rphcm.e 11 Ji'.ike11 Looo.ti o:n 9. Ce.mbridr:,e (H.A.C.A.) Fuel An,.lyser 10. Alumelf::: romol Py:romotc :r Pote:r:t •omot0r 11. Loce..t:l.on for Fuel Co:,su.m.ption Unit Fire ·'3 ott•l e Cmtrol 12. r,1m1enpolis•1 'oneyvroll Ilrown '.i.' e!'lr,era ture ~iecorder 13. frd.1'-ridual "t;,;p-_in e Turbo Tachometer I,- di cators 15. Individual Ex·;~:1.ne 11£'. ck Pressure I :: ciica t ors 16. 'fer:mer o.ture Indico.tors - l U. La:"'.lcltne Gcn r 19. Oil Cool e r f la p Positi oL h.dieo.tors 20. Cowl 1~10.p Position Indicators 11 Oil "out" of l:,n!I-\ r e Up 11 an<l 11 Dawn" L:i.ne Pressu1·e I:r.d:i.cutors 24. Pilot's lnstrumcnt Pe.nel 25. Pilot,'s and Co-pilot's Iristrur:1ent a ;1d Control Penel. 26. ;~t'!.r-faca Co'.".',trol .Positi,:-;n Indicctors 27. J1'a.r~omotcr Board and Photo Rox Li@1t:'.ne; Co.n trol 28. Cs.n0ru (4) Seloctlon· and Coxltrol 29. " Recordinr, Data" Co!,trol ?witch to ,·; ilot 30. l\e.. rn:i.r.g to Cl-e.t in Aft Cabin, 11 ?ictnres Bein r; Trk en" 31. Instrume:n.w.tion F;ng:i.neor-'s 'fable wit.11 1'hcrnooouple LisJGing 32. I 1: strumenta.tion Spo.ro Parts Dra:wcr. 33. lnstrumer,tntion I'.ng5. ne,Jr's S-1:;ation 34. Alumol/Cromel Tl)e1-moooup le CoJ1.t rol Switch 35. bdividual Fuel Tank Booster Pur,p Pr;,ssm·e I!1.dicator. 36. Iron/Constanta.'1 Thc~ rmocouple Control Switc-,hes., r o. 2 hn£:• 37. Iron/Constantan Pyrometer Potent:1. ameter 38. Iron/Consta.n¼n 'l'hermocouplo Control Switc:h \ o. 1, 3 and 4 r:11c, s. 39. Mai n Entran ce to FHf.;ht -Deok 40. TurbosuiJorchargel:" Waste Ga.to ?ositio:n Indicators 41. flight Test E'nginee r's (Power Plafrt Observer) Station 42. Ao:rod!rna.rnic Engineers Stfl.tion 43. 11 4•1. Pm:,rcr Sett:i.ng Ch.a.rt Ee cor-dt qi; Do. ta. 11 Wa.rninc: Light for i:'ilot -106- III. FWt' F8 THE~ms The dev eloy.>r1<mt of the a.rt of flight testing_ a pf.8A.rn to be mot ivated by the following pri•,,ary factors: · 1. The importan oo of rruinc fli r;ht test:in g r:1ore sate. 2. The desif,rl en r;:i.ne er 1 s n eed for reliable " full-scale da:ta on air loads and gro1.md loads. 3. The necessit'J of reducing the ti1D.o required a n d the a.mount of fli ght test i n g :-1eeded to approve a n aircraft after the prototype is constructed. 4. Post--vmr financial con side:rn.t i ons wh ich -r:rill probably de,P· ma;:-i d e. oonsidern ble redu<rtio:n 1n t h e cost of flig-)1t tostin r;. These fac i;ors are obvi ously i nterrelated i n softl.r a.a their effects on tho art of fli rJit testing e.ro con cerned. a ppears 'co be oaus:inr, tvro signi ficant t'I.D d Hov10ver,· t heir inf luence important trends. -107- The :ins'Cl'ument:-.:1.tion of' fli[~ht test aircr·aft is r.apidly becoming more cosp l ote and no!"e cmprehe:nsiva. Ins t rumcn tati-:m is now o.vail- able for wn.m:int; the pilot when noor-cd tioel loo.c~s a.re being e.n ooun -oored i ri ;rarious structural oor:1ponent0 of an t1:i.rcrn:ft. Develop• · ments in the use and application of theso and similar h:.strur:ients t will undoubtedl:;r rmke possible reliable fl:i ; _ht te$·t:; oheoks of theore-t,;ical calculations of air and g rou.nd lmds. Sor-iEl work is being done on the dev0L,p:r.10nt of instr1.rrnor:ts .-'ilich will ir.dicate "reduced" d&tR. For exanple • a torquem.etc r pressure ,,';lm.ge a n d a. ta.chomoter might be 001:ibined bto a sine;le l3. ?: . P. In- dicator. Any trend in this directior1 will r;rol~tly roduce data ro- ductim; time a21d will be ii1orth. while if it does not oonplieate the Lstrumentati on problcn too muoh. The development of radio telern.etorin F: and reliable radio co::, trol of tho t<:.; at airplane shmild be of g;r"-:"- t value i n flight tests for structural integr5:cy. Rn d:io tol~~etoring alone will prooobly 'be "fJ'ery useful in reduojng the size of t110 crow roqd l·ed for i'li :.;}1t tents and :'l.n 1YJak:il1g t h e data avu.:\.lable on t he r;rou::,d whilo t he t ost flirrht is still 5.n progress. 1-ladioo.l chan ges in t he rn.turo oi' aircn, f t ill prooobly require f dif'ferer'tt forms of il!,stru:monto. i: i on to evaluate r.tew desif!rl features and to measure hi p;her ran 1-r,es of por cox,rar.'. ce. -108- Flig;!1t i::;estin 6 is ro'.1:lcUy beccsn.ing ar lr11port;a1·t tool i:n. the ha.:nci.s o.f fo'.} design 021 g i:::.0or. J1any n.:-r,7 desie71s ::1equlr0 vc,ry little flight test:ing because new foc.tu:res arc :i.;1[;b,llcd :);1 o1de:::- aJ.rc,-.r,, ft; and provan in the air before the prototype is cor:lpl teu.. Do.sign (~if'ficul tieo are thus elii:rd.; , d;ed vm: 1e tho prototype is uwler desiai a:n.d constrnctir..m, rather thim after it is coi:-rplotod. -109- 0m:,0 of t h e na.-c:Tial ·wh ich tm s used i;; the pr 0parntioa of th:i. ~ t hosis i s conta. ·lI!e d :i.ci reports &.1·1d pape rs wh ich a.re . cl o.s s:i. f :l od, n ot been.us(➔ of the meth ods or . (':Rtn Ui.emselves, but because of t h e pro,:ject s vli.th which t hey we re associat ed. l'or t h is roe.s on tl1e biblj_ogra plw v,i:i ich is proseritc<l below is n ecessa rily inco10-pl c t.0. • Onl y that nato rial -r:11:i.ch -r..JO.s use d a nd wh ich h o.s act ual l y been rubl i s hed is listed boleiw. 'l'he detnils of son e of th e r ep orts exn.rr.. i :r,e d reprc seJ:t r:uch effort e.n d r e sof:rch on t h e pa:r-t of oertn.i:r; co••1pan i 0 s or i:r,dividuo. ls. Tl1e nu·chors ha:v o b eon c·u r o fu l to p r es er1.t suc!'.1 ma t or fo.l o::2 l y in t he f o:rrr1 'l'h:i s has be en do:::e v,h orever th o t cch :r:l.qu os i :nvoJ. ved. u re of i clGas. peculiar to OT: l y 01: 0 or;:Jv, iza t io:".• thus, t:,e p r epr·.r a t :i on a.nil c:'i str.i.but ion of' th i s t h es i s wi ll :1ot :;n any i:0.,U vi dual. 1. Allen , L . T., - 11 1'l:L)1t 'J?o r t:i.nr: :Ls t\. Sou:d A,."It~ TLll , April., :':a y, c., d June HP·3. 2. Reed, A, C• ., a.:,·d ";'i11 1. kon • .• . F., "Flit ht 'l'e st Or r:;ew"'l iznti on , ?rocedures, a:d Gr ew Train i nr~ , n :3oo i: r~ !d.rcrn.f i; Co., Ss.11 . 26, 1941. 3. Kendric~, . J. B,, " Ph:i.losoph:,r o::· Fli cllt Tost::.n;:", paper pr·esen-tod t,tt r10ot inf; : ortl:o r n C;;_J_ :i.for n ii:.t Soct io::. , SA F: , ~:e:)t . 1-:~ , 1943. ~us ·L1ess", -110- II. 4. Ken drick, J . :3., 11Ae ro- Eco:n orucs/ 1 pape r pro s en t ed at !"'100t:i.1,.f~ of t Le Vi.s , ,Janoo.ry 29, 1944 . 5. L:u1 sburrj1, R. ? . a :,:i d Sprio gel, w. ,John ,~Hey a:1d ~~ om, 1940. 6. Su~Jp l e:·)0:1 tal h.oa.c.H : ,1:; , i:'robler:, s , a T,d Case '·.nterial i:!1 I ndustrin.1 ·:\a.2:e. s Gl',o!~t, compiled by I ndustrial 1-'. cb . t i o ,, s fi od/.D,' , Co.lif'o:rnia Lsti tute of Teehnolo 1zy , 1943. • -1. n., ll Ix:dustrial '. 'b.JL .,:,'. Sn 0 n t", r :;[)TrLf- F;~··:.t'J\ Ti i':!J I n., 11 li:l e:r·:ren , Steph0n Flir.,ht Hosee.roh l ~1$trum.011-cution of t he t! :i.:.,.f le Soot 1' ighter", po.per pro scnted a t mec ti ~lf, of I.A. s., ,Jan . 2G, 194.4. 3. Bulleti1~ ,fo . 109/91., 11 i3rov{".1 En gi n eer:i nr; Pyro.r.1otry Systei.n ll1c1s cripti on 11 , 3:row:n I n strument Company, ;3e pt. 9 , l '.H3 . 1. Grif fin, Ha~ey D., nvul teo Hndio H0corder 11 , paper pr e s ented at r:ieet:i. rif~ of the I.A.£1'., Jun. 25, 1944 . 5. FLi. g:h t l'Jng i ,-x3 c,r bg Henort No. 4, rte. A . A. ''.<luipr.'!.ent f o:r necordin g Airplane Take•ofi' and I.a:i,din{!'. Che. rttct c riid;icsil f' li r)1.t T1:r;in e0ring a nd Factory I n spection Sect:i.on , C. A.A., ;··opt. of Co;:;,.r:icrc0, fiashin &:ton , D. c.