Development of a Portable Celestial Navigation Instrument for the Direct-Reading of Terrestrial Position Citation Hiltner, Walter Frederick (1945) Development of a Portable Celestial Navigation Instrument for the Direct-Reading of Terrestrial Position. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/mhz6-py61. https://resolver.caltech.edu/CaltechTHESIS:05192025-202602237 Abstract No abstract. Item Type: Thesis (Dissertation (Ph.D.)) Subject Keywords: (Civil Engineering) Degree Grantor: California Institute of Technology Division: Engineering and Applied Science Major Option: Civil Engineering Thesis Availability: Public (worldwide access) Research Advisor(s): Thomas, Franklin Thesis Committee: Unknown, Unknown Defense Date: 1 January 1945 Record Number: CaltechTHESIS:05192025-202602237 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:05192025-202602237 DOI: 10.7907/mhz6-py61 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 17246 Collection: CaltechTHESIS Deposited By: Benjamin Perez Deposited On: 19 May 2025 21:53 Last Modified: 19 May 2025 22:01 Thesis Files PDF - Final Version See Usage Policy. 28MB Repository Staff Only: item control page

• ASTRO - NAVIGATOR DEVELOPMENT OF A PORTABLE CELESTIAL ~AVIGATION INSTRUMENT FOR THE DIRECT-READING OF TERBESTRIAL FOSITION Thesis by Walter Frederick Hiltner In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy california Institute of Technology Pasadena, caliform.a 1945 ACElifOWLEDGMENTS In carrying out this investigation the author wishes to acknowledge a deep indebtedness to Dean Franklin Thomas for his supervision and sustaining interest, to Dr. John A. Anderson for his searching criticism, invaluable suggestions and assistance, a.nd to Professor Robert L• Daugherty for his generous cooperation. For assistance in the preparation of the manuscript, the author appreoia~es the assistance of Mrs. Doris Dumler and Miss Mary Stockly, TABLE OF CO1'1TENTS PAGE ACKNOWLEDGl.ilENTS • • • • • , • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • OBJECTIVE• • • • • II• III• HISTORY OF NAVIGATION BY INSTRUMENTS • • • • • • • • • • 2 A. Piloting • • • • • • • • • • • ·• • • • • • • • • • • 2 B. Dead Reckoning • • • • • • • • • • • • • • • • • • • 2 c. Celestial. Navigation • ••••••••• • • • • • • 3 • • • • • • 9 purpose • • • • • • • • • • • • • • • • • • • • , " , 9 B. Description• • • • • • • • • • • • • • • • • • • • • 9 c. Operation, • • • • • • • • • • • • • • • • • • • • • 16 D• Peculiar Problems • • • • • • • • • • • • • • • • • • 21 SUmmary and Criticism • • • • • • • • • • • • • • • • 23 PRELIMINARY INSTRUM!i!NT : A. NAVI GATOR-SPHERE • • • Ee IV• V• l .. . .. . . . . . ~---~ ~ 28 A• purpose • • • • • • • • • • • • • • • • • • • • • , • 28 B. Basic Principles ••••• • ••••••••••• • 28 o. Description • • • • • • • • • • • • • • • • • • • • • 32 D• Adjustment ••• • • • • • • • • • • • • • • • • • • 41 E• Use • , • • • • • • • • • • •• • • • • • • • • • • • 44 SUMMARY • • • • • • • • • • • • • • • • • • • • • • • • • 46 FINAL INSTRUMENT: ASTRO-NA. VI GATOR ' CHAPTER PAGE APPEND IX • • • • • • • • • • • • • • • • • • • • • • • • • • • 47 A. BibliogTaphy and References. • • . • • • • • • • • • • 48 B. Navigator-Sphere Correspondence ••• • • • • • • • • • 50 c. Evaluation of Navigator-Sphere by Army Air Force Materiel Command • • • • • • • • • .•• • • • • D• Astro-Naviga.tor Correspondence E. Patent AgTeement 58 • • • • • • • • • • • • 63 • • • • • • • • • • • • • • . . . . . 74 LIST OF FIGURES PAGE NUMBER Frontespiece Astro-:navigator Photograph . . . • • . . . •, . "Aerial Navigation by the Stars", hl:f.! Magazine, September 28, 1942 • • • . • • • 5 "Sphereogra.phical Navigation. 11 , Skyways, May t 1943 • • • • • • • • • • • • • • • • • 7 Navigator-Sphere Photograph •••••••. • 10 4 Index to Essential Parts of Navigator-Sphere. 11 5 Star Index for Navigatoi-Sphere ••••••• 15 6 Arrang-ement of Vernier Graduation for Navigator-Sphere • • • • • • • • • • • • • • 24 7 - Astro-Naviga.tor Assembly • • • • • • • • • • • 33 8 Trial Multiple Reflector • • • • • • • • • • • 35 9 Multiple Reflector Details • . . • • • • • • • 10 Telescope 11 Micrometer Drives •••• • ••••••• • • 39 12 Artificial Horizon, ••• • • • • • ••• • • 40 13 Essential Elements of Astro-navigator • • • • • 53 14 Celestial Position Finder 73 1 2 3 ' .• 37 • • • • • • • • • • • • • • • • • • •••• • •.••• DEVELOPMENT OF PORTABLE NAVIGATION INSTRU?imNT FOR DIRECTREADING OF TERRESTRIAL POSITION I• Objective Today with the remarkable developments in speed and range of aerial transportation, its precise control is essential. Navigation-- the determination of a moving position on the earth--is receiving careful attention from many investigators with widely various points ot view. As a result, useful improvements are a.ppeal"ing with growing frequency. The radio beam and the new air position indicator have contributed much to the ease of aerial Daviga.tien. But there is still need tor a method of determining latitude and longitude independent of dead reckoning. This need was nicely expressed by representatives . of the Army Air Force Materiel Command At Wright Field. • "Give us," they said, a.s if asking the impossible, "an automatic device which, held in the hands and directed toward the ,~ars, will read the observer's latitude ~d longitude. This thesis was undertaken to develop a portable celestial navigation instrument for direct-reading of terrestrial position. II. HISTORY OF NAVIGATION BY INSTRUM.E!.~TS The progress of navigation has been an interdependent development in its three fields: piloting, dead reckoning and celestial navigation. Starting from primitive observation with crude tools or none at all, each has increased in accuracy with the addition of new concepts and more caretully worked-out instruments. A. PILOTING Piloting-tracing a ccurse from land mark to land mark-was the system used by the first small vessels of the Egyptians in 3,000 B, o., by the early Chinese, and by the Phoenicians. This method using the sounding pole and the weighted line led to the development of maps and charts of the coast line and then of the entire world. 1 :mxcept in their crudest form, maps and the whole science of oartogTapby depend upon accurate measurement of distance and direction, and finally upon the geographic coordinate system for our round/ earth. Developments in piloting follow quickly upon improvements in ct:her fields. Witness especially the u~e of radio, radio beams, and radar to extend the range and accuracy of our piloting method. B. D]}AJ) RECKONmG Dead reckoning-by independent measurement of direction and distanee--was fathered by the lode stone, l See Appendix A for all footnotes. The Chinese, Arabs and -3 ancient Greeks knew of the magnet, but the earliest genuine record of a marine compass in use 1s A.D. 1297. 2 The chip log was first used to inqicate speed for sailing vessels, and developed into various patent logs for modern vessels, 3 Given the map obtained by the piloting method, the time and the distance travelled, position may be determined from any starting point. The direction is obtained from the earth's magnetic field with the magnetio compass or from the motion of the observer in space with the gyro-compas,. In each case, fund.a.mental technical difficulties limit the possible accuracy. time and speed. Distance ia, usually determined from the The most troublesome problem is to correct for drift, the motion of the sea or air itself, mentation on its own account. This requires special instru- The correlation of dead reckoning with ,;c,cJ.. geographic :position is further complication by the oonverg'8noe of the meridians. Most of these difficulties have been nicely solved by a~new instrument, the Air Position Indicator, now used on our B-29 Super-fortress, It is a quart,..sized device whieh fits on the instrument panel and fig'llrea latitude, longitude, nautical miles flown and correct , compass bearing automatically from dead reck:oning data. 4 c. CELESTIAL NA VIGil.TION Celestial Navigation-by observation of heavenly bodiesprogressed with astronomy and mathematics, especially as the need appeared in the limitations of the other two methods. The primitive Polynesians, in their remarlvlble expansion in the south Sea islands, had no tools at all--only their knowledge of the stars. 5 The EUropeans began their use of star sight measurements only after their ships pushed beyong the Mediterranean. In the fifteenth century, the Portugese, under Prince Henry the Navigator, took the lead in compiling tables and inventing nautical instruments. Columbus had only a cross-staff and a.n astrolabe, 6 in addition to his compass. 7 Then came Copernicus, Galileo and Newton, opening vast new areas in our knowledge of the universe. 8 In 1620, trigonometry was applied to navigation, follo-wed closely by logarithmic tables. Columbus• s cross-staff and astrolabe developed into the foresta.f'f, backstaff, double quadrant, and, finally, in 1731, the sextant. 9 Then, in quick succession, came three developments which led to • the foundation of modern celestial ~vigation: In 1837 Captain Thomas :g. Sumner of the United Sta. tes Navy made his unique voyage on 1ihich he discovered the "SUinner line of' position11 • 10 In 1865, Har:rison, the • • Englishman, brought forth the chronometer. 11 In 1875, Saint-Hilaire, the Frenchman, published his method of calcuiated al ti tude. 12 Figure 1, illustrates basic ideas involved. Because this fundamental principle of SUnmer and Saint-Hilaire is unchanged, the labor and ingenuity for each improvement smce has been focused on devising shortcuts, on simplifying tabulations, and on pre--oomputing the elements of the astronomieal triangle. Within the last twenty years, five successive methods of celestial navigation SEXTANr SIGHT measures angle of star above horizon, plnccs nuvi1:,1ntor on circle of position, on which height is constant. The center ol circle is substellar point. The distance to subO stellar point o m be rcn<l from sextant: I = 60 nauticnl miles. B·Y THE STARS ., L-cause he knows his ,viiy umong the stars, the aerial navigator can find his way to any point Oil curth. In the night sky, out hcyoud the sight of pilotagc points and the hearing of radio heacons, beyond his fuith in his instrument-reading and log-keeping,, the navigator can tukc up his sextant and fix his position within·a radius of 13 miles. This feat can he pcrform.,,l by anyone who has had a high-school "'lucution. The navigator travels in the symmetrical universe of Ptolemy, in which the earth is the exact center (.,ee "JIP''"ile). The sky is a starstuddt-d sphere . .Except for the sun and its satellites, which mq,•e along the line of the ,,clip tic, all the stars arc fixed in t.1 ... ir positions rdati,·c to the celestial coon.linates, just tL"' J>0inti; on (•arth are fixed on the tcrn,.,.trial coonlinates of latitude and longitt;dc. As the earth roti,tc•, thw:..lestial sphere, its ~xis through the ~ north star, a1;pcurs to rcrnh·drom cast to west around the earth-with the earth npparentlyremaining'fixed. Once this ancient concept of the universe is comprehended, the trick of celestial navigation resolves itself from complication to simplicity, Bm1cath every star at any given moment is a point on earth, the substellar point, at which the star is directly overhead. These points move as the stars move, parallel to .the lines or latitude around the earth, The positions of the s1111, 1nooi1 and planets, and of 30 navigation stars and hence of their substellar points arc listed in the almanacs relati,·e to Greenwich, England, for every instant of the day. By measuring the height above his horizon of two or more stars, the navigator loc,tcs their suhstellar points relative to his dead-rt-ckoning position. He locates these points in turn hr consulting his almanac and his chronontctcr, an accurate watch 3Ct on Greenwich thuc; He cau uow locale 1limsclf relative t~G rccnwich and plot his position on his chart. POSITION IS FIXID by nwnsurir,g the altitude of second star. Sin<-'t: he has now JocntNI himsdf on two circles., the naviga- tor m,ust he at one of their points or inkrscction. Sim.-e one point is absurdly rt.'mote, he knows he must be ut the other. B 6 have been taught our officer candidates at the Naval Institute in Annapolis. Of these, Ageton's method, and the new Altitude-Azimuth 13 • Tables seem outstanding today. These Hydrographic Office publications have reduced the intricacies of spherical trigonometry to simple interpolation in the tables. Attacking the problem of celestial navigation from a different point of view, captain p. v. H. Weems prepared charts14 covering the earth showing lines of constant altitude for several selected stare in each region. Given the actual observed altitudes of these stars, the lines of position may be plotted directly by graphical interpolation on these charts. this same end. The newest tabular methods accomplish much The Astro-Graph which has been used for navigating our Flying Fortre~ses projects these star altitude curves from photographic film directly onto the navigator's .table, to the scale of his chart. This device also provides m~chanical adjustment between the star altitude curves and the longitude coordinates of the chart, corresponding to the sidereal motion of the stars and of their respe.c ti ve curves of equal altitude relative to the earth. Recently, Drary A. McMillan, the Brazilian engineer, raised a minor tempest when he introduced his Sphero-graphical Navigation in sensational and provocative statements to the press. 15 He returned to the fundamental sphere, and by the use of precise instruments shown in n.gure 2 was able to obtain results by simple and clear graphical construction approaching in accuracy the requirements of SPHEROGRAPHICAL navigation needs these tools which were offered the Government at $5,000.00 a set. Across the globe moves a meridian hoop, used to draw lines of latitude and longitude. A spherical protractor, great-circle ruler and a spherical compass rest on the indispensable soi American •Nautical Almanac. Any slight warping or damage to these in• struments would put the navigator many miles off his course • Plotting by the Spherographical System ) • The navl9ator uses a meridian hoop to draw the Greenwich meridian llne an any convenient section af the 9lobe. This line and the equator, ,ermanently martied, become the base lines since latitude is measured north and south of the equator and longitude east and west of the Green• wlch meridl11n, A slip of one-ei9hth inch in drawin9 these lines would mean the difference of over sixty miles . 2. Aft.e r consultln9 the Almanac, to find the substellar point of a star at the Instant when he observed it, the navigator marks its position on the 9lobe. Two or three stars can be observed and their positions plotted on the 9lobe . Intersection of three circles is the fix. in daytime, there is only the sun. Between sl9hh of the sun, dead reckoning would have to be fi9ured, which wauld be diflicult on the 9lobe because strai9ht compass courses wauld have to be plotted as a curve with a chan9e of direction at every meridian makln9 the advanta9es of the system doubtful in the daytime. :I. After the navl9ator has a fix-the Intersection of the distances from the substellar points of two or more stars-he must measure latitude and lon9ltude In order to transfer the airplane's position to a re9ular 9eo• 9raphlcal flyln9 map. This operation offers opportunity for error. If the 9labe were held an the knees of a tire.d, shaken avigator, a sli9ht slip of a pencil ml9ht mean mlssin9 an island in the broad ocean. ••• Finally, the navi9ator must find his lon9itude by measurin9 with a 9reat•clrcle ruler alon9 the equator from the Greenwich meridian to the meridian of the fix. In this, he must compute his time just as in all navi9atlon. The McMlllen System does nat cut down the necessary operations such as shoatln9 the sun , cansultln9 the Almanac, consulting the chronom• eter and the major preliminaries to determinin9 a position. Notice the \ i J, 8 the navigator. The advantages in the pictorial representation of tbe relations in the ·problems of spherical trigonometry have long been recognized, both for the clear appreciation of the factors, and for teaching, However, precise graphics on a sphere require a skilled and steady hand, and ideal circumstances, oondi tions which do not always obtain in military aircraft. Difficulties in accuracy and manipulatiQn prevented the enthusiastic adoption of this graphical method, Mechanical instruments have been designed and some put on the market to simplify celestial navigation. 16 Nathaniel Bowditchputs the situation nicely: "Such. instruments are costly and subject to instru- mental errors, but they are very useful for checking computations and may some day be devised in a form useful to the navigator 11 • 17 It was the Bowdi tell prediction which the author had in mind when he designed and built the Navigator-SJ>here, described in Chapter III, which led to the conception of the direct-reading device described in Chapter IV. III. THE NA VIGA TOR-SPEERE A. PURPOSE The Navigator-Sphere is a calculating machine for the problems of celestial navigation. It is designed specifically to give the latitude and longitude directly f10m simultaneous star altitude sights. Given two star sights, and Greenwich sidereal time, these three values are set on scales of the instrument, the sel~cted stars plugged in, and latitude and longitude read off their scales. Th.at is all. The position is determined in the time it takes to tell it. Using the development madel, hand-made by the author, results for any given data are repeated consistently with a standard deviation of two minutes. The position so determined is absolutely independent of any dead reckoning or plotting on the chart. • Thus it gives the ideal check on the dead reckoning. The instrument may also be used with similar speed and accuracy to determine the oonventioml lines of position, to calculate great circle sailing data, and to establish fix from long distance radio compass bearings, B. DESCRIPTION The Navigator-Sphere, shown in Figure 3, looks like an intricate maze of bright steel rings surrounding a black sphere. Essentially it is a scale model incorporating the relations and relative motions involved in the simplified astrononzy- of celestial navigation. The ZENITH STAND/ SCREW DRIVER- ZERO LONGITUDE L LONGITUDE X a VERNIER instrument provides the three customary systems of spherical coordinates-siderial, geographic, and horizon--in the star sphere, the geographic scales, and thed>server's scales, respectively. It is mounted in a blued steel stand on a vertical a.xis with the zenith upright. The relationship of these parts in shown in Figure 4. Pivoted on the vertical axis are two star altitude soales. Perpendicular to this axis and mounted on the circle for the local meridian is the a~.imuth circle. Together the three provide two in- dependent sets of coordinates for observations in the horizon system. All three circles are graduated in degrees. The two star altitude circles read from zero at the horizon to 90 degrees at the zenith. verniers and tangent screws are attached to the star bushings so that each may be set to the observed altitude to a minute of arc. The azimuth circle is also graduated in deg:re,s from zero at the north limb of the meridian, east to south to west. A simple index is pro- vided on one of the altitude circles te read the azimuth to its position. In addition to the two star altitude scales and the azimuth circle are two other circles, one to measure latitude and one for longitude. In their basic construction, the latitude, longitude and one of ' the star circles are made like ball-bearings with an imier and outer member. The balls in the race between previde rotation between the two members in the plane of the ring. The other member of the latitude circle is pivoted on the vertical axis of the sphere. The inner member of the circle carries the pivot bearings for the polar axis. Thus the latitude circle, containing both the zenith and the polar axes, determines the plane of local meridian. It provides for the angular motion between the zenith and the pole which gives the latitude for the zenith. Tlla inner circle is gradu- ated from zero at the equator to 90 degrees at both poles, while the outer carries a vernier at the zenith with which the angle of the latitude there may be read to a minute of aro. Fastened to the inner latitude circle perpendioular to the polar axis and circling the sphere near the equator 1s the circle which determines the longita.d.e of the plane of the local meridian. The outer member of the circle is fixed perpendicular to the inner member of the latitude circle. It carries the vernier by which the local longitude, tha.t of the zenith, is determined. The inner member of the longitude ~ircle is graduated clear around in degrees from zero to 360 from east • to west, and thus gives readings of west longitude from Greenwich. Inside all these rings is the star sphere, made from a blaek, five-· inch, bowling ball. It is freely pivoted at the poles and fits snugly within the longitude circle. Its position relative to the longitude is determined by the sidereal time for .the observation. A brake and tangent ~Brew between the sphere and the circle permit the ~ccura.te setting of the sidere.a.l time vernier against the longi tu.de saale, thus placing the Greenwich meridian in its proper position rel~tive to the stars for the given instant. The sphere itself is a ba.k$- lite ball in which have been drilled small radial holes with the center of each at the exact right ascension of declination for the sixty-one principal navigation stars. A number stamped in the sphere surface near the hole, and a printed table, shown in Figure 5, provide a positive index for ml.familiar s·tars. Two inlaid steel bushings provide a ball-bearing set for the polar pivots. Because, for purposes of navigation, the appreeiable chaI1oo-es of stars' positions in right ascension and declination are due to precession only, these changes are made on the star sphere by moving the polar axis the approximate 50 seconds of arc per year tov,ard the vernal equinox, and by setting the sider eal time vernier ahead. On the development instrument this adjustment is accomplished by applying progTessively more eccentric polar bushings as the years pass. Thus the pole is moved and the stars are fixed. To correlate the observed altitudes with the definite position for the stars on the star sphere, cylindrical star pins are passed • ~adially through bushings in the star altitude circles into the holes in the star sphere. .~~ For a particular altitude for a certain star, the setting is mad~ on the star altitude circle and the star pin plugged into its proper hole. The arc of the altitude circle will then maintain the appropriate zenith distance between the star and the zenith. The several degrees of freedom for the star sphere are reduced to one, and the sphere may only move so the zenith traces a oirole of position over the sphere. Coordinates for points on this circle may be read off as desired on the latitude and longitude scales, and the corresponding azimuth to the star on its scale. With aey other star, one can do the same thing with the second _.~ r.; .. v Figure 5 NAVIGATOR - SPHERE - Wf. .)/Jt;;ev, - Development Model STAR # Star Name Mag. Alpheratz 2.2 1 o( Androm. 2.4 2 , Cassiop. Caph 2.4 3 c( Cassiop. Sohedir Deneb Kaitos 2.2 4 pceti 2.0 5 ,Y-Cassiop. 2.8 6 oCassiop. Ruchbah 7 .,,_Eridani o.6 Achernar 8 o<Arietis Hamal 2.2 3.4 9 9Eridani Aoamar 1.9 Marfak 10 o(Persei Aldebaran 1.1 11 o<Tauri 0.3 Rigel 12 ,orionis Capella 0.2 13 G(Aurigae Bellatrix 1.7 14 "C'Orionis El Nath 1.8 15 . (ITauri Betelguex o.5 £.6 ol.0rionis .17 otArgus Canopus -0.9 18 «Can.Maj. Sirius -1.6 1.6 19 f;Can.Maj. Adhara 20 e( Geminorum Castor 1.6 o.5 21 o(Can.Min. Procyon 1.2 22 ,Geminorum Pollux 1.7 23 £Argus 24 7\Argus Al Suhail 2.2 Miaplacidus 1.8 25 ,Argus Alphard 2.2 26 eo< Hydrae Regulus 1.3 27 o<Leonis 2.4 28 ~u'Flit Maj. Merak 2.0 29 0( Ursa Maj. Dubhe DenelJola 2.2 30 (/Leonie 2.5 31 ,.uraa Maj. Pheoda Acrux 1.1 32 otCrucis 33 l'Crucis 34 ,crtcis 35 £ Ursa Maj. Alioth 36 tursa Maj. Mizar 37 Cl( Virginis Spica 38 't'l Ursa Maj. Alkaid 39 , Centauri 40 I Centauri Arcturus 41 o<Bootis 42 atcentauri Rigil Kent. 43 /9Ursa Min. Kochab 44 o(Cor.Bor. Alphecca Dsohubba 4-6 oScorpii Antares 46 otSoorpii 47 et Tri. Aust. 48 1\,0phiuchi Sabik Shaula 49 ~ Scorpii 60 « Ophiuohi Rasalague 51 "C'Draoonis Etamin Kaus Austr. 52 (Se.git. 53 -'Lyrae Vega 54 O" Sagit. Nunki 55 otAquilae Altair 56 o<Pavoni s Peacock Deneb 57 oit Cygni Enif 58 EPegasi 69 otGruis Al Nair 60 «Pis.Aust. Fomalhaut 61 oCpegasi Markab 106 1.5 1.7 2.4 1. 2 1.9 o.9 2.3 0.2 0.1 2.2 2.3 2.5 1.2 1.9 2.6 1. 7 2.1 2.4 2.0 0.1 2.1 o.9 2.1 1.3 2.6 2.2 1.3 2.6 INDEX R.A. • Deel. • 1 23 +28 47 1 34 +58 51 9 21 +56 14 10 13 -18 17 13 21 +60 25 20 33 +59 57 23 55 -57 31 31 01 +23 12 44 03 -40 31 50 06 +49 40 68 11 +16 24 77 59 - 8 16 78 09 +45 57 80 33 + 6 18 80 42 +28 34 88 03 + 7 24 95 41 -52 40 100 41 -16 38 104 07 -28 54 112 47 +32 01 114 06 + 5 22 115 29 +28 10 125 21 -- .. 59 20 136 30 -43 13 138 09 .:.59 29 141 13 - 8 25 151 22 +12 15 164 38 +56 41 165 65 +62 03 176 34 +14 53 177 44 +54 oo. 186 53 -62 48 187 02 -56 48 191 08 -59 23 192 54 +56 15 200 26 +55 13 200 34 -10 53 206 21 +49 35 209 59 -60 07 210 52 -36 06 213 17 +19 28 218 68 -60 37 222 43 +74 23 233 06 +26 54 239 16 -22 28 246 31 -26 19 250 42 -68 56 256 48 -15 40 262 28 -37 04 263 06 +12 36 268 50 +61 30 275 08 -34 25 278 46 +38 44 282 68 -26 22 297 02 + 8 43 305 20 -56 56 309 53 +45 05 325 22 + 9 37 331 12 -47 14 343 39 '-29 55 345 30 +14 56 Star # Aoamar Achernar Acrux Adhara Aldebaran Alioth Alkaid Al Na'ir Alphard 9 7 32 19 11 35 38 59 26 44 1 Alphecca Alpheratz Al Suhail Altair Antares Arcturus ! Argus Bellatrix Betelguex Canopus Capella Caph 'l'Cassiopia Z4 55 46 41 23 14 16 17 13 2 5 20 39 40 Castor ,centauri ICentauri ,cruois 34 'f'cruois 33 Deneb 57 Deneb Kaitos 4 30 Denebola Dschubba 45 Dubhe 29 16 El Nath 58 Enif 5],,, Etaain 60 Fomalhaut 8 Hamal Kaus Austr . 52 43 Kochab 10 Marfak Markab 61 28 Merak Miaplacidus 25 36 Mizar 54 Nunki Peacock 56 31 Phecda 22 Pollux Procyon 21 Rasalague 60 27 Regulus 12 Rigel Rigil Kent. 42 6 Ruchbah 48 Sabik Sohedir 3 Shaula 49 Sirius 18 Spica 37 ol Tr i . Aust . 47 Vega 53 .i ,. sta.r--altitu.de circle. setting both circles loolcs the sphere, so tbat the zenith is located correctly relative to the stars. The latitude of tbe observer is then already indicated on the latitude scale. To find the longitude, it is further necessary to set the inner member of the longitude circle at the correct sidereal time. Then the long.l- tude index shows the observer's longitUde. The local latitude and longitude :provide a fix. This fix is at the intersection of the two circles of position described by the zenith tor each of the two stars separately. On the Navigatoi-Sphere, this intersection is automatically established in the hing-e at the zenith axis. 0 411 OPERATION The Navigator-Sphere -wa.s designed primar~lf to solve th• problem • of simultaneous star altitude sights; it is also adapted to solution of other problems involving :positions on a sphere, or measurement s> on a spherical surface. cribed herewith. Those with which the autho:r is acquainted are des- With reflection, and some ingenuity, the reader may very well oolve other such problems as he meets them. 1, Position from Simultaneous Star Altitude Sights Given: Corr~cted altitude observed for two stars, and Greenwich sidereal time. ~: Latitude and long.ltude of position. Set Greenwioh sidereal time in degrees and minutes of arc on the inner scale of the longitude circle, using the vernier on the sphere. Clamp and adjust precisely with the brake am tangent screw. Set the given star altitudes on eaoh circle with its vernier, using the olatrll> and tangent screw. Insert star pins through bushings in the star altitude circles into the holes for the given stars. The zenith axis is now mechanically looked in the required position at the co-altitude or zenith distanee from the substellar point for both stars. Latitude, and longitude west of Greenwich, fo~ the fix are read directly fmm their sea.lea. This position corresponds to the point of interesection of the circles of position around the two stars. Theoretically there are two suoh points of intersection, but this second point offers no confusion in practice. Usually the spurious point is thousands of miles away :from the known vicinity of the observer. However, if the approximate azinm.th of ea.oh star is noted, say within 30 degrees, or tle sphere ori ented so that the stars are more or less in their obvious relation to the zenith, the correct fix is established without question. The best intersection of the circles or lines of position is ob-- , tained when the azimu.ths of the two bodies differ by 90 degrees. For a difference of O, or l80 1degrees the circles are tangent and thus do not intersect at a definite point. on the instrument, These relations are easily demonstrated They should be oo:nsidered in choosing the stars for observation. Checks of the fix are readily obtained with additional sights. Sights of three stars will give three independent fixes, four sights, six fixes, and so on. The instrument gives each fix for every pair of stars, by readings of latitude and longitude without the intermediate plotting of lines of position. However, these lines of position may be 'drawn, by comieoting the several plotted fixes, or as in the following problem. 2. Line of Position Data for a Single Star Given: Observed altitude of star, dead reckOning latitude and longitude, and time. Find: Line of position. Set sidereal time, star pin and star altitude. Turn sphere to nearest degree in latitude and read corresponding longitude (and azimuth). Plot this point on chart. Turn sphere to nearest degree of longitude and read corresponding latitude. Plot this point en oh.a.rt. These two points determine the line of position. For check, this line should be perpendicular to azimuth noted above. Also, any number of other points on the line of position may be had by selecting awropriate values of latitude or longitude. Alterna.te method: Given: De R• Latitude and longitude and time. ~: Altitude and azimuth of any visible star. Set sidereal time on inner scale of longitude circle with brake and vernier on sphere. to latitude. star. Turn sphere to given longitude, tilt polar a.xia Loosen star altitude circle, and set bushing over chosen Insert star pin through bushing into hole for star position, clamp star altitude circle and adjust star altitude tangent screw and azimuth to exact given latitude and longitude. azinm.th for star, for this given position. the usual way: Read altitude and Draw line of position in Azimuth line through D• R. position, line of position perpendicular to azimuth line at a distance toward star equal to difference between observed and calculated altitude of star. 3. Rumling Fix The running fix is available by the usual methods of plotting on the chart, by advancing a previous line of position for run. Generally the run between sights is not sufficient to introduce serious error from the Clll'Vature of the surface. Though the instrment was designed primarily for fixes from simaltaneous star altitudes, it may also be used to reduce observation on the sun and planets, and for problems of great circle sailing• • Auxiliary fittings are provided for the solution of these problems. 4. Observations on the su.n Line of position from the sun may be determined just as for any star except that the position of the sun, in right ascension and declination nm.st be established on the star sphere, for the instant of observa~ tion. A movable locating pad is provided which ie set in position under the zenith axis, meas'Ul'ing declination and right ascension on the latitude and longitude oiroles respectively. In this development model, the posi- tion of the longitude circle may require the use of a bridge attachment for the eight degree band nea+ the equator. Line of position from sun sight may be found more directly using solar time. The position pad for the sun is set at the declination for the instant, along the index meridian on the sphere. (This corresponds to the equinoctial colure for stars and sidereal time.) Greenwich Apparent Time in degrees and minutes of arc, instead of Greenwich Sidereal Time, for the instant of observation is set on the inner longitude scale with the vernier on the sphere. angle for every longi tu.de. This places the sun at the correct hour The line of position is then determined .just as described above for the stars. Considering the importance of sun sights in actual navigation, an additional scale, inlaid in the sphere on the index meridian, may well be provided on which to set off the variable declimtion of the sun. 5. Observations on Planets Line of position may be found from sights on planets or moon using adaptions of the methods described for the sun• • If position by simultaneous altitudes is desired, the first method employing sidereal t:ime and position wou.ld be chosen. After locating the movable pad for the planet, it serves just as a star. 6. Great Circle Sailing Given: Origin and destination. n.nd: Course and run for each heading, plot of route. Clamp longitude circle relative to Sphere in any arbitrary position. Set pads at origin and destination, using zenith axis to locate g-eographic latitude and longitude coordinates. set each star altitude circle at O degrees. the pole for the desired great circle. Insert star pins, and The zenith axis is now at Set another pad to mark this spot. Shift one of the star pins to the pole for the great circle, keeping its star altitude circle locked at O degrees. The other star altitude circle now lies in the plane of the desired great circle. By releasing the clamp, the zenith may be set at any desired point on the great circle route, reading the distance from the fixed point, origin, or desti:na.tion, from the graduations on the great circle sea.le, reading the bearing of the course from the azimuth circle, and the latitude and longitude frcm their usual scales. Any desired number of points may be taken, and a flight table prepared. From these data., using the Navigator- Sphere, the relative motion plot for the flight may be traced through the heavens. Also, stars near the horizon may be chosen to steer by. D. PECULIAR PROBL:EMS In the construction and the development of the first model of • the Navigator-Sphere, several peculiar problems were encountered. Be- cause of the war, no skilled machinist~ oould be found in Seatfie, where the author was then living, to help with this project, Hovvever, he was allowed to use the equipnent and faoili ties of the Colleg-e of Engineering of the University of washl.ngton. Materials were also hard to get with the priority red tape and depended in part upon the size of the projected instrument. Considering the precision desired--to one minute of arc, one mile--and the probable ~kill and aocuracy of the author and the available maohines (a thirteeninch latba and a new mill), a five-inch bowling ball was seleoted for the star sphere. These balls bad not been manufactured for months and were completely out of stock. several cached. One of the local bowling a:tley proprietors had caught off guard in a sober moment, he parted with one, "for the advancement of science," and a.t twice the list price. Scraps of mild steel plate were begged from a sheet metal fabricator. It remained only to machine the steel into a precise instrunent. The ball bearing arrangement of the rings was selected for accuracy and ease of manufacture. This design turned out well, Two rings acting tog'8ther greatly improved their strength and stiffness. Some difficulty was encountered in attaching fittings to these rings without warping them, but these difficulties were mostly due to the restricted materials and restricted facilities at hand.. Dovetailed rings were used for one of the star altitude circles but the ball bearing device proved much the better. One member of each pair of rings was graduated all around the circle in full degrees. The other member carried the corresponding vernier, reading to two minutes of arc. Because the rings were offset from the axis of their pivots, they were right or left landed, depending on which semicircle was used, Thus, though only 180 degrees is needed to cover the whOle range of lati tu.de and only 90 degrees for altitude, the graduations are carried on around so the rings may be used on either hand if any ring interferes with another. All the scales were graduated in the lathe, scribing the lines with the horizontal motion of the lathe tool. The 360 degree circles were marked off using a 360-tooth gear attached ·to the outboard end of the lathe spindle by inserting a dog into the successive teeth. The trick used for graduating the verniers with this same equipment may have practical value to the reader in the construction of some similar device. Thirty equal divisions were required in the space for twenty-nine degrees of arc. To accomplish this end, the ring for the vernier scale -.yas set eccentric in the lathe so that tmse thirty divisions could be marked with the thirty teeth on the gear in the space for twentrnine degrees on the ring. phown exaggerated in Figure 6. This g-eometric relation is Thus by simple trigonometry the exact amount of the eccentricity may be oaloulated and the work set accordingly off-center in the lathe. On the six verniers graduated thus by the author, no error could be detected when the thirty s:r;:aoes on the vernier were matched with the twenty-nine on the corresponding graduated circle. Strictly speaking, the thirty divisions made thus are not exactly equal • • However, a rough calculation showed the maximum cumulative error to be about one hundredth of a minute of arc, hardly significant in :.'t his instrument. E. SUMMARY AND CRITICISM The Navigator-Sphere incorporates in one simple instrument adaptions of the valuable features of previous ·celestial navigation computers and has several new features of its own which add to its own which add to its eonveni ence and usefulness. First, a two-star fix is produced mechanically, with all the essential elements in their true relations. ,... ~ (D ! "'ii ~~, _ly RING CENTER • ◄o!u9; 'Y(i ~ f,9,~ • LATHE CENTER ' y 30° ' • 15° y .. p OL. ECCENTRICITY • 0.0354 R ~ ~ • R {0259)(3.867- 3.732) • R sin 14.5°(cot 14.5°-cot 15°) OL• (PQ) (cot 14.5°- cot 15°) LP= (PQ) cot 15° OP= {PQ) cot 14.5° PQ • R sin 14.5° Second, the position of the principal stars is plotted on the sphere. Tbus their position is always available without reference to the almanac or to any other tables. Also, this arrangement provides an ideal star finder, since there will be no projection distortion and the stars, in their true relation, stand out before the observer. Literally, one holds the heavens in his band. Third, mechanical adjustment is provided for the precessional movement of the poles, With this single adjustment all the stars are continuously preserved in their correct relation to the axis of rotatiou. This feature also eliminates the use of tables of star positions from year to year. Fourth, the convenience with which the Greenwich meridian may be used as the origin or reference eliminates entirely the use or computation of the hour angle for the .heavenly bodies • • Fifth, the mechanical arra~ement of the scales and parts combine to provide a sturdy, simple instrument, strong and accu.~t e, and easily made. For navigational purposes where an error of one minute of arc might be tolerated, this instrument can be produced by ordinacy mass p~oductton standards to give imperceptible error. This it could be made cheaply and in quantity so that every navigator in our air forces, Navy and Merchant Marine could have his own navigator-Sphere. Finally, celestial navigation by the use of this instrument is so sim-ple and obvious that it can be taught to almost anyone. Jmt like the riding of a bicycle, once the basic physical relations of time and space are impr essed on the manipulative and visual senses, they are simply not forgotten. Also, as in the case of the bicycle, it is difficult to learn from the printed pages without the machine, but understa?Kl.ing CCIIles quickly f·rom experience with the device in hand. In December, 1943, the Navigator-Sphere was exam.ined by Dr. s. M. Burka, Captain J. Ge P. Callaha.n,and Lt. Dion Hoy, under direction of Colonel G. v. Holloman of the Engineering D:ision of the Army Air Forces Materiel Command at Wright Field. They made the following criticism of the Navigator-Sphere: 1., "The device as constructed uses angular scales ~nd verniers. These are definitely difficult to use in the air". 2. "The device is limited to use at night and then only for selected star sights. The sun, the moon, and the planets cannot be used except with diffioul ty and special plotting"• 3., "The device is inherently fragile if kept to minimum weight. ~osed areuate members are subject to bending and misaligmnent in handling". 4. t.Accuracy is directly a function of the precision of manu- 1 facture and, for usuable size, extreme precision and careful choice of materials is required0 • 5. "The device solves for simultaneous sights on two stars and no provision is made in the instrument for allovnng for time difference or run between sights 11 • 6. ttThe use of the device does not af'ford as mu.oh time and effort-saving as might appear at first sight since the instrument replaces only one part (H.o. 218) of the equipment and operations required in celestial navigation. The taking of sextant observations and tbe plotting of the data require most of the labor and time, and the computation with the proposed device or with H. o. 218 are simple and rapid in any case". "Give us'', said Dr. Burka, "an instrument which will read latitude and longitude directly". In response to this request, work was begun on the AstroNavigator, which, it is hoped, will be to celestial navigation what the radio beam is to piloting and the Air Position Indicator is to dead reckoning. IV. FINAL INSTRUMENT: ASTRO-NAVIGATOR A. PURPOSE The Astro-Navigator is an optical instrument whioh, by observations on the stars, directly and continuously gives the local position in latitude and longitude. No addr tienal instruments, no tables, spherical trigonometry mor graphical methods are needed. Latitude is measured simply as the altitude of the elevated pole. Longitude is determined by direct comparison in the instrument . of local sidereal time and Greenwich sidereal time. The Astro-Naviga.tor differs from the preliminary instrument in that the position of the stare is taken directly fmm the heavens instead of mechanically located on the on the sphere. In answer to an oft-expressed need it provides an independent, self contained, portable celestial navigation instrument. B. BASIC PRINCIPLES Fundamentally, the problem of navigation from the stars is tba.t of correlating the horizon coordinate system with the celestial coordinate system. Therefore, we need to establish in the instrument the orientation of the celestial coordinate system and the origin for the horizon system, a~ measure the angles between them. For spherical coordinates only two reference planes are necessary. In the celestial sphere, these are determined by the pola~ axis and the direction of the vernal equinox; in the ecliptic system by the pole of the ecliptic and the vernal equinox. In the terrestrial system, these are the plane of the equator and of the Greenwich meridian. On the other band each star optically marks a particular axis which is related to the coordinate axes by angular differences; for example, in the celestial sphere the right ascension and declination of the stars. Given the stars in the sky, using their known positions, the instrument determines the orientation of the celestial coordinate system. With a clock drive in the instrument, these are related to the terrestrial system. By means of the micrometer drives, the coordi- nates of the zenith are measured in this terrestrial system. Consider the conventional equatorially mounted telescope where by rotation around the polar axis following a star at a given declina- tion, one can keep track of the passage of time with the rotation of the earth. suppose the equatorial mounting, with the declination • clamped, were reversed and the axis of rotation provided about the line to the stars. At some point in the rotation of the syste~ about the star axis, the polar axis would be parallel to the earth a.xis. One star restricts the rotation to a single axis but does not uniquely determine the orientation of the polar axis. for any individual star. Of course the same is true · Hov.ever, two stars taken together would limit the direction ot the polar axis to only two possible positions, one ot which is correct and the other completely wild. These separate jOlutions correspond to the two peints of intersections of circles of positions in the conventional navigation teehnique. The use of three stars will, however, uniquely determine the direction of the polar axis without any possibility for error. In order to measure the position of a number of stars at once, it is most convenient to see the images in coincidence. Therefore a multiple reflector is incorporated as the first step in the optical train. We use nineteen reflectors carefully adjusted at the start so that the light from each selected star will be reflected into a parallel bundle along any desired axis in the celestial coordinate system. The multiple reflector device is key to the operation of the instrunent and provides a number of basic simplifications to the technique of celestial navigation. The right ascension and declination for each star is incorporated in the orientation of the mirrors and is independent of any tabular values. Besides, all the bright stars wherever they appear in the heavens will contribute their share to the,determination of the position with a single sight, instead of the. repeated observations now required. The orientation so determined is completely unique, The immediate objections that w:1:uld be raised at this place are that the stars change their position in right ascension and declination, and that refraction errors will not be accounted for by any fixed arrange- ment of the mirrors. To take care of the precessional chang-e of position of tbe stars, we use the a.xis of the ecliptic as the main reference axis for these mirrors, Relative to the ecliptic coordinates, adjustment for precession is readily provided by a simple rotation about the ecliptic a.xis of approximately 50 seconds of arc per year. This is possible because the stars do not change their relative positions except for proper motion. The largest proper motion for stars used will be for Arcturus, in the neighborhood of two seconds per year. Considering the desired pre- cision of tbe instrument this is negligible. The effe~t of refraction, however, is more serious. Its elimina- tion depends upon the desired degree of precision of the instrument. If one minute of arc is satisfactory 1n the result, the stars can be used as low as 30° above the horizon and a mask can be used to prevent light £rem any of the stars lower than 30° elevation from entering instrument. In any event, the stars near the zenith will produce an ex.act ooinoidence and the stars near the horizon will be deflected from this exact coincidence depending up~n their altitude arxl their corresponding refraction. Other items in high precision position determination which are neglected in this instrument include t~e effect of nutation, parallax, and aberration. Experienced navigators will immediately notice that all reference so far has been to fixed stars. This excludes two classes of observa- tions, on the sun and on the planets. In the ease of the planets, it is more convenient in a simple instrument to neglect tJ:iem than to try to take account of the variations of their position in the mechanism of the device. This restriction is not as serious as might be presumed from the prominence of the planets, because the observed coincidence of a number of stars will be as bright as any of the planets. A usetu.l by-product from the use of the ecliptic axis is the simplicity with which the motion of the sun may be traced. The reflector for the sun is set at 45 degrees to the ecliptic axis and is rotated about the a.xis relative to all the other stars at a rate of about one degree per day. The orientation of the sun mirror for acy particular time of the year may be obtained from the almanac. In review, the simplifications in the Astro-Navigator involves the assumption of negligible proper motion and negligible refraction, bu.t provision is made for precession and for the sun's motion. C. DESCRIPTION The instrument has three essential parts: The multiple reflector, the micrometer drives, and the artificial horizon. The relative arrangements of these parts in the development model of the Astro-Naviga.tor is shown in the assembly d;awing, Figure 7. 1. Mtlltiple Reflector There are several possibilities for the design of the multiple reflector: a. A single prism might be cut so the light would be refracted at the entry wind.ow for a given star, and internally reflected from the entry windows for each succeeding star, coincident with the refracted beam there. Then the images for all the stars would appear superimposed. The use of such a. prism, besides its mechanical simplicity, might have had an added advantage derived from the dispersion caused by the glass, producing, in effect, chromatic astigmatizers to aid in the setting of coi~cidence. However, the difficulty of cutting the prism and probable excessive loss of light makes it necessary to rule it out. ' b. A series of plane-parallel glass plates may be arranged along the polar axis, each to reflect the light for its particular star and transmit the light already directed along the axis. A multiple :reflector unit for four stars was built using this method. Tbe use of the plane parallel plates was tboul#J.t to be simpler for preliminary construction. Figure 8. The arrangement of this reflecting system 1s eh.own in It was installed upon the objective end of a 3Q--power Berger surveyor's transit in place of the sun sh.a.de. When the transit was pointed toward the north pole, rotation of the reflector around this polar a.xis took care of the time, This preliminary instrument demon- strated conclusively in practice that a unique orientation was determined by au.ch a reflector and that the coincidences of the star images so formed was a very sensitive indicator of tne direction of the desired axes. The angles of the glass plate.a for this preliminary reflector were set by hand, using the stars themselves as the basis of measurment. This preliminary device was not satisfactory because the plane parallel plates scattered much too mu.oh light in passing through only four plates, The light from Dubhe was so greatly diminished as to be barely visible in the telescope with 1-.3/a inch objective. For the pr-·oposed instrument wtth nineteen reflectors, the use of plane parallel plates in series was shown to be completely out of the question. O• The arrangement ultimately obosen uses nineteen total reflect- ing mirrors laterally distributed across the field of view. of their oonstruotion is sh_?V,n in Figure 9. The details They produce a number of ALL DIMENSIONS IN INCHES LIMIT ON DIMENSIONS - - l UNLESS OTHERWISE NOTED NAME +½ ± /n DECIMAL ± .010 ANGULAR 0 FRACTIONAL 1 CALI FORNIAI NSTIT UTE TECHNOLOGY OF NUIIBERS ARE suR,ACE ROUGHNESS IN MICROINCH!S \"I V 'v ~•1 ROUGH MACHINE FINISH 11100TH MACHIN! FINISH ~ ROUGH GRIND V ,INISH GRIND 'v Vf;/ ,INE GRIN1>. u, P'OLISH 7-RJ/-.' '" c:- - R r..·::.:-1 f'/1!.\ .... ·•·,1 ~- - ,,, .. , , 1( ~A .:_, 1- .i -- ,,.. '-';~,., , 1 , \. _,,,, - .... _, ,. v ' l.-1 ..... ', # . _,' • ,-~ • • _ ,,.,·, .-. , • parallel rays which must be concentrated by the conventional optical system of a telescope so as to enter the pupil of the eye. Figure 10 shows details of the short 8-power telescope. The light from eighteen stars or the sun is reflected fran the small multiple reflectors, to a 23-1/2 degree mirror, to the 45 degree mirror, through the artificial horizon and the telescope to the eye. When the polar a.xis is correctly oriented, all the stare will appear fused into a single point at the east horizon, and the index for the vernal~inox will be in its correct position to give local siderial time. In addition to the small mirrors of the lllllltiple reflector, a large mirror is mounted at the intersection of the ecliptic axis and the polar axis so that the .light reneoted along the ecliptic axis is again ~eflected, changed in direction by 23-1/2° so that the light proceeding along the polar axis is directed toward the a:ruth pole. • This whole assembly, the multiple renector am the ecliptic reflector, is mounted together as a. unit and is arranged to rotate about the polar a:iis. 2. Micrometer Drives The micrometer drives provide rotation of the :riiultiple reflector around the polar axis and rotation of the polar axis about tbe east-west axis. The arrangement is shown in Figure 11. The rotation about the polar axis and the rotation about the horizontal east-west axis relative to the zenith is measured to determine the latitude and the local hour angle of the vernal equinox, From this local hour angle and siderial time, the longitude is obtained. These two drives a.re perpendicular to each other and provision is made to adjust the angle to exactly 90°. Approximate Eclipti£ Coordinates for the 18 Selected Bright Stars Distributed Throughout the Sky above Latitude 40° South Index No. - Name Mag. Celestis.1 Latitude Celestial Longitude 0 0 I 0 5 Gamma Cassiopia 2.0 48 46 47 11 Aldebaran 1.1 - 5 40 21 20 12 Rigel 0.3 -31 30 14 13 Capella 0.2 22 35 9 10 16 Betelguex o.5 -16 50 1 50 18 Sirius -1.6 -40 21 Procyon o.5 -16 22 Pollux 27 0 347 30 0 335 20 1.2 6 28 337 40 Regulus 1.3 0 16 301 29 Bulahe 2.0 49 29 315 40 37 Spica 1.2 - 2 02 247 38 Alkaid 1.9 54 14 273 50 41 Arcturus 0.2 30 46 246 40 46 Antares 1.2 - 4 24 201 '53 Vega 0.1 61 52 165 50 55 Altair 0.9 29 24 149 20 57 Deneb 1.3 60 0 115 40 60 Famalhout 1.3 -21 20 117 30 0 0 0 ALL DIMENSIONS IN INCHES LIMIT ON DIMENSIONS - - l UNLESS OTHEIIWISE NOTED ANGULAR DECIMAL FINISH + 1/1° l'RACTIONAL DRAWN BY CA LI FORNIAINSTIT UTE TECHNOLO6Y ± /u 1 of ± .010 DIEP'O I000H CLltARP'RINT IIOU<.H MACHINE FINISH SMOOTH MACHINE FINISH IIOU!iH GRIND ~ FINISH lolllND 'v Vf;/ HEAT TREAT ... ,.,,, Tc-'-ZECC'OL'?C_ .. __ ""·- .,.'~....:~-~~ TRACED IIY CHECKED BY e,,._;..;. ~ APPROVED BY c_,.., r .' # NUMBERS All[ SURFACE IIOU<.HNESS IN MICROINCHES 'v 'v '7 -;} DAT!! . .:'•24 - -#::, SCALE FINE GRIND. LAP COURSE NO. POLISH SECTION NO. z DWG.1 NO. I( r \ l.._,.,1 P'ORM 301 ' ALL DIMENSIONS IN INCHES Ll ■ IT ON Dlll[N!IIONS - UNL£9S OTHUIWIS[ NOTED l ANGULAII +½ 0 FIIACTIONAL DECIMAL ± 1/ u ± . 010 CAL IFORN IAINST ITU TE EC HNOLO 6Y OFT I ALL DIMENSIONS IN INCHES LIMIT ON DIMENSIONS - - UNLESS OTHERWISE NOTED l ANGULAR ± 1/11' FRACTIONAL OECIM"L ', + 1/3a ± .010 COURSE NO. Sl:CTION NO. ,.LL DIMENSIONS IN INCHES Ll ■ IT ON DIMENSIONS - - - l UNLESS OTHEIIWISE NOTED + YJ ± /sa Dl!CIMAL ± .010 ANGULAR 0 FRACTIONAL 1 NUMBERS ,_RE SURFACE ROUGHNESS IN MICROINCHES \''I 1/ ROUGH MACHINE FINISH \ 11/ 1/ FINISH GRIND \ / SMOOTH MACHINE FINISH ' \ I FINE GRIND, UI' '7 V!;/ POLISH ROUtiH GRIND Both motions are ball bearing mounted and ~rm driven. Ea.oh worm is connected to a s:i:;ecially designed counter so that the angles are read in the sexigesima.l system in degrees and mi:rmtes without scales or verniers. Along the worm shaft for the longi tu.de motion is a differ- ential drive, one of whose elements records longitude and the other sidereal time. Clock work mechanism is also incorporated so that the sidereal t:ime. can be maintained during the use of the instrument. 3. Artificial Horizon The artificial horizon mu.st provide the zenith, the origin from which to measure the altitude of the pole and the local sidereal time, and show in the field of view when this origin is true. As in the Army Air Force sextant, the Astro-Ifaviga.tor has a bubble under a spherical surface with lenses and reflectors to bring it into focus in the field of view. Its construction details are shown in • Figure 12, A reticule is also required to show when the instrument is D. ADJUSTMENT The details in the construction of the instrument must also provide for adjustment of the optical elements. The specific devices for this purpose are shown in detail in the working drawings of the parts. The problem is mu.ch the same as that of planning the adjustment of precise surveying instruments. and easily checlmd. The adjustments must be s:imple, strong, The specific steps in the adjustment are outlined below: l. Bubble. ment. Set up a remote target at the same elevation as the instru- This is most easily done with an engineer's level• It may also be clone wi'th the instru.ment itself by using the bubble, even though out of adjustment, to set two targets at the same elevation, if they are the same horizontal distance from the instrument. Adjust the three set screws which press on the 45o glass plate until the bubble is centered on the target. field of view. This centering should be checked for the whole The bubble sbould appear to remain at the same elevation for small inclination of the instrument. 2. Reticule. Support the instrument by the micrometer drive assembly. Rotate the telescope and artificial horizon using the latitude micrometer. The cross hairs should appear to rotate about their intersection as seen against any distant field. the large 45° mirror. 3. Polar Mirror. The line of sight passes through the hole in Move the reticule with jacldng screws until correct. support the instrument at the artificial horizon. two targets on a straight line through the instrument. Set Rotate the mirror, (and the whole micrometer drive) through 180°, using the latitude micrometer. Adjust mirror with three leveling screws until cross hairs bise9t the target for each direction. The line of sight will pass through the hole in the 23-1/2° mirror. 4. Polar .AXis. SUppo~t the instrument by the polar axis tube. Rotate the rest of the instrument around the polar axis using the longitudetime drive. The reticule should apJ?9ar to rotate about its center on the distant field. The line of sight will emerge through the hole in the 23-1/2° mirror. Adjust angle with the three push-pull screws. This adjustment depends upon the accuracy of step 3, and may affect its adjustment slightly. Repeat steps 3 and 4 until both are satisfactory. s. Support micrometer drive and artificial horizon Ecliptic Mirror. with polar axis horizontal. 54'. Set two target with included angle of 46° Using longitude-time micrometer rotate the polar axis tube 180°. Adjust ecliptic mirror until cross hairs bisect the target in each position. The line of sight emerges through the bearing for the sun mirror's shaft. 6. Axis of M.Ultiple Reflector. Affix the special adjustment mirror perpendicular to the sun reflector s ba.ft. Determine that it is per- pendicular to the sbaft by rotating the shaft with the sun micrometer. The distant field seen through the hole in the ecliptic mirror sbould appear stationary. Rock the special adjustment mirror on its ~herica.l seat until it is true, and then clamp in position. This aq.justment is independent of all the others and may be made first, in preparation for step a. 7. Ecliptic Axis. Same as step 5 except light is now reflected back on itself, and the line of sight emerges along the ecliptic axis throu~ the hole in the ecliptic mirror. steps 5 and 7 are also interdependent, and must be repeated until both are satisfactory. a. Multiple Reflector Mirrors. support the instrument with the polar a.xis exactly parallel with the axis of rotation of the earth and rotate about the polar axis to track the stars. This is most easily done by attaching the instrument to an equatorially mounted telescope with a tracking drive, in which case this adjustment depends only upon step 6. If such a mounting is not available, all the other steps must be taken, ana. the orientation of the polar ax.is is found approximately from the latitude and longitude of the adjustment station, and precisely by trial. Once the polar axis is oriented, set the mirror for each star by rocking and rotating its mirror pedestal until the star image appears at the cross hairs. 9. Latitude Counter. For an adjustment station of known latitude, turn the counter knob on the micrometer drive shaft until it reads correctly. Tighten set screw. 10. Sidereal clock. Adjust rate so that instrument traclrs accurately. 11. Longitude-Time Counters Start Tracking Clock. on its counter. Set sidereal time Turn longitUde counter knob to known longitude of ad- justment station and tighten set screw. This initial adjustment is quite distinct fran the use, in which the dials are set for a P3-rticular observation. E. USE The whole purpose of the instrwnent is to make its use as simple as possible. The Astro-Navigator is held in the hand, the telescope pointed toward the east, the polar axis toward the pole, and the vernal equinox toward its position in the sky. The traoking olock is started and the sidereal time set on the clock's counter. By rocking the instrument gently, the images for the visible stars are brought to coincidence. Then the latitude and longitude micrometer drives are adjusted until the bubble shows the vertical axis of the instrument is correct. Latitude and longitua.e of the observer is read off the appropriate counters. In the course of routine observations, the presumed position may be set into the instrument first, and quickly checked as above. For very precise use in the air it will still be necessary to correct the position as obtained by development model of the AstroNavigator for the effect of slow continuous turns, and for Coriolus acceleration. These corrections are tabulated and explained in detail in the Air Almanac. V. SUMMARY A portable celestial navigation instrument for the direct-reading of terrestrial position has been designed and reduced to practice. Its primary purpose is for use in aircraft navigation, where the need is urgent today. It may also find application in t he field of surveying. Latitude is measured by the altitude of the elevated pole. Longitude is given by the difference bet.ween the local sideral time as shown by the hour angle to the vernal equinox, and Greenwich sidereal time. The direction of the polar axis and the vernal equinox. are obtained by manipulation of the instrument. The device has three essential elements: the multiple reflector, the micrometer drives, and the artificial horizon. The multiple reflector is a fixed array of small mirror which reflect light from every one of the visib~ bright stars to produce for a particular orientation in space a parallel bundle of rays. This orientation is determined by observing the coincidence of all the star images with a telescope. The micrometer drives provide the necessary angular motion and its measurement, directly in terms of latitude and longitude. The artificial horizon provides the zenith, as the origin for the measurements of local latitude and longitude. In use, the observer will orient the instrument to obtain coincidence for all the star images, adjust the latitude and longitude micrometers until the bu.ble shows true, and read off the position. APPENDIX A. :BIBLIOGRAPHY AND REFERENCES :S. NAVIGATOR-SPHERE CORRESPONDENCE C. EVALUATION OF NA VI GATOR-SPHERE BY 4RMY Am FORCES MATERIEL COMMAND D. ASTRO-NA VI GATOR CORRESPONDENCE E. PATENT AGREEMENTS APPENDIX A BIBLIOGRAPHY AND REFERENCES 1 New International Enoyolopedia., Volume 16. New Yor~, 1923. Pages 659-660. Dodd, Mead and Company. 2 Montgomery, D. L., Simplified Navigation for the Amateur. Mirror Press. Los Angeles, 1932. Pages 11, 12. 3 Muir, w. C, p., Navigation and Nautical As.tronom.y, Institute, Annapolis, 1918. Pages 6-8, 4 Times- U, s. Na.val Francis, Devon, "Automatic Avigator", Popular Science, Volume 146, Number 4, .Pages 90 plus. April, 1945. 5 New International Encyclopedia., Volume 19. Page 19. 6 Ibid, Volume 16. Pages 659, 660. 7 Weems, p. v. H, and Eberle, William c, Learning to Navigate. Publishing Oorp:>ration. New York, 1943. Page 2, 8 Favill, John. Primer of Celestial Navigation. New York, 1940. Page 2. Pitman Cornell.Maritime Presa. 9 New International Encyclopedia, op,oit. 10 Favill, op.cit. Pag-e 111. ll New International Encyclopedia, op.cit. 12 Favill, op.cit. Pag-e 116. 13 United States BYdrographic Office :/J:211, Dead Reckoning Altitude and Azinm.th Table, A• A, Ageton, 1938. #214, Tables of Computed Altitude and Azinm.th, 1942. #219, {Altitude and Azimu.th for Selected Stars, Restricted). 14 Weems, p, V, H., "·S tar-Altitude Curves'', Weems System of Navigation, 1928. 15 °Air Navigation _for Global war"; D, A. MaMillen' s spherographioal system, Fortune Ma@ine, 27:741-7, Janus.ry,1943. ·I.J9 ..k,_ 16 Brouwer, Dirk; Keator, F. w., "McMillen' s Spherographical System of Celestial Navigation", Aero .Digest, 42:116 plus, April, 1943. Jones, v. c., t1Na.viga.tion Simplified: New Device Provides the Navigator with a ~uick Means of Obtaining a Fix on His Position", Flyi~, 33:156 plus, August, 1943. "Automatic Navigator", Science NewsLetter, 45:371, June 10, 1944, also, Science Digest, 16:96, August, 1944. Aatralida.de ••• For Fast Position Finding'', Aviation, 43:173 plus, September, 1944. 11 Brouwer, Dirk; Keator, F. w.: MoMillen, D. A., Spherographical Navigation, Macmillan, New York, 1944. Forward by Captain P, v. H, Weem1:1. Warrick, F" p. and Klemm, w. F,, 11S_pherogra.phical Navigation", Flying, 36:64 plus, March, 1945. • 17 Bowditch, Nathaniel, American Practical Navi&:3:tor, United States Hydrographic Office :ft9, Revised Edition, 1938. Page 118. lf -so APPENDIX B NAVIGATOR-SPHERE OORRESPOIIDENCE w. F. Hiltner to Drury A• McMillan March 2, 1943 D• A. McMillan to W• F. Hiltner April 20, 1943 w. F. Hiltner to National Inventors Council March 3, 1943 Natio:cal Inventors council tow. F. Hiltner March 30, 1943 (Sketch of "Celestial Position Finder") UNIVE.RSITY OF WASHINGTON Department of GENERAL ENGINEERING SEATTLE March 2, 1943 Mr. Drury A, Mc~illen Sao :eaulo :i,raz.i l Dear Mr. McMillan: FORTUNE tor January 1945 carried an interesting article describing your Sphe:rograpbical System for celestial navigation and yolll' efforts to introduce it to use in Olll' armed forces. Evidently you have progressed tar in its development to be aet~lly contracting for the production of the instruments. Two important difficulties were not brought out clearly in the FORTUNE ~ticle. l)Qubtless you are aware of these. The first difficulty is physical. The accuracy of results by yolll' method is limited by the • oa.re and skill in the gra-phical construction. The best accuracy claimed fQr the size of sphere and scales you use is a minimum error of three minutes. The "Da.Vigators" think they can do better than that, neglecting perhaps the question of the possible acclll'acy in the initial observation of the star's altitude. . From this first limitation arises a psychological impasse. Graphic~l methods always irk tho.se with an accounting apti tUde and an analytical bent. They are the ones who become the "navigation authorities", De gustibus non disputandum est, :Perhaps both of these difficulties might be reduced by .using the sphere as a map, a map on which are permanently located all the stars convement for navigation. Using two great-circle scales, hinged at their intersection, one could lay off on each scale from the center of the hinge, the observed zenith distance for a star. With these points on the scales placed simultaneously on the corresponding stars on the sphere, the a.xis of the hinge would indicate the zenith. (Same exception is found here as in the case of the~ intersections of the circles of position as mentioned in the above article. ) The location of the zenith is thus ~ndependent of clocks and of dean reckoning. To come down to earth, if the hinge is mounted to slide freely on a meridian hoop, the latitude of the position may be read directly on the meridian scale. The right ascension may be converted directly into longitude by arithmetic, or by setting the zero (Greenwich meridian) of a gradua.ted equatorial circle at the appropriate hour angle from the vernal equinox and reading the longltUde vernier. -2- Mr. Drury A. McMillen - March 2, 1943 The suggested instrument has several advantages. All the required measurements and settings are adapted to the use of the vernier and tangent screw--the accuracy may be as fine as warranted, easily within one minute of arc. The star points are permanently and aoourately located beforehand by the instrument maker. Since they do not change their relative positions in the celestial sphere (choosing stars with negligible proper motion) the use of tables of right ascension and declination is obviated. • T~ese points could be marked with circular holes, and the iero end of the two great circle scales fitted with mating conical pins to insure accurate measurement to the centers. :Provision can be made for the small correction to the position of the pole to allow for the precession of the equinoxes. The time required for obtaining the fix is reduced even from the graphical method, With simple instructions and a little p~ctice the navigator should be able to find his position imnediately after taking the star sights. Perhaps the greatest advantage is the compactness and ruggedness that could be built into such an instrument for any required degree of precision. A s;J.x inoh sphere would ;-e~dily provide an accuracy to one minute of arc. I am sending copies of this letter to FORTUNE Ma.~ine a.hd the Inventor's council in Washington. I wciuld be .very glad to work with you on this extension of your ideas. Very truly yours, /s/ Walter F, Hiltner Walt~r F. Hiltnsr I,~tru.ctor WFH:b ~ ... a, i I-'" "-.I C~LEf TIAL Ca :)ell& POSETI(]H FEWER -z..__-LC: eux ::-i1he1·.1.•.. :-_- i.,, 1· u ~· 'a)llllt.t / ~ ci. ;• ~ ,f.'(UDPe,/1· ~~~ ....-r-✓• ~.,-z _:..;:~- :o/-~' f /----=z.-..., V, l tnes.sed: ::,1rch ;_, lJ4.3 Dev .L~ uu _ Jl.,served zenith dlst~1ce for l..Ldel:, c.~1·~:.n Observed zenith eridian Hoop U'i ~ Oia DOS .Al-J"NUJ.~CIOS EM BONDS Rua Do Carmo 41 Sao :I>aulo April the 20th. 1943. Walter F. Hiltner, Instructor, Department of Engineering University of Washington, Seattle, Dear Mr. Hiltner, I have your letter and sketch of the 2nd. of March, and wish to thank you tor your suggestion. I have worked from the beginning on a sphere which has the 31 most prominent stars engraved thereon, thus saving the duplicate work of setting them out for eaeh problem. I thus get the Latitude by the intersection of two circles of position and do not even set out the Greenwich Meridian, but get the Longitude by measuring the I.HA and reading the GHA out of the Almanac and adding the two, or rather applying the tw9 algebraically. What might be described as the New Haven Method is that describeq in Fortune Magazine. At Yale they prefer to use a half globe plot the entire track, then ol;ltain each position and set it off on the Traek being made good, and rub out the .fix. I suppose in the end it is a question of each operator choosing the method he likes best. ..·~ We have worked on and thought of a good many substitutes for a simpl~ plotting surface the sphere, necessary tools but no more, and a man's hand. But as the problem spreads out, simplicity must also be given its place. We are not only concermd in obtaining a fix, although that is primary, but we are also under the necessity of making polar flights with the same instruments, the Meridian aoop being detachable, of plotting radio beams and intersection which go half around the world, obtaining sun, moon, star and planet risings and settings. We even have in mind two spheres, one inside the other set to sidereal time and with holes punched through at the loeations on the translucient outer sphere. There is not limi ta• tion to what can be done once the inherent idea is understood. But the deciding factor in the whole matter is use by navigators under difficult conditions, so we have laid down the principle that we do not wish to obtain an accuracy of one mile. No navigator ever docked a ship. That is done by a pilot who takes the ship in from its 2 to 4 mile posi t1on outside the port. Navigation never landed a plane. That is a pilots job. On the other hand it I can take a plane 20/4/43 2 WFH straight over the pole from New York to Chung King and get within 20 miles of Chung King air port I would teel that_I had accomplished the desideratum of the spherographical system • .And allowing 10' for sextant errors, and 10' tor bad plotting, that is an error of half a m~llimeter which a man ean see standing on his head or drunk, we feel we have averaged the possibilities of the system with universal application and ease ot operation, although each point could be developed to a more accurate degree. Be assured on the other hand that I have no wish or intent to disparage your suggestion. I wish there were more people like you who thought about and talked .about and tried to improve on the original idea. Later on when instrument makers and manufacturers in the States come to . their senses, and have not such a burden of war work, som.,ething like you suggest may be manufactured. I shall be in the states in May, and at the Yale Club of New York where .I would be glad to hear from you again. Sincerely yours, ls/D. A. McMillan D. A. ¥cMil~en March 3, 1943 National Inventors' Council Washington, D• c. . Dear Sir: You a.re probably acquainted with Drury A, MoMillen' s Spherogra.phical Method for celestial navigation as described 1n the January 1943 ~ORTUNE. Enclosed is a copy of a letter describing an instrument to further facilitate navigation, as based on his suggestions. It should be of considerable aid to the aircraft navigators if it were made available to them. I oall this to your attention too, to speed the suooessf'ul prosecution of our war. Vecy tru!y yours, Walter F. Hiltner Instructor WFH:b DEPARTMENT OF COMMERCE The National Inventors Council Washington March 30, 1943 Mr. Walter F, Hiltner University of Washington Seattle, Washington Dear Mr. Hiltner: The disclosure of a variation of the McMillen system of navigation which you have submitted to this office has been examined with interest. However, we do not believe that it overcomes the basio objections to McMillan's system whioh have been disoussed at some length in the issues of Fortune Magazine and elsewhere. Since the Navy Department is not intere~ted in the MoMillen system, it does not appear that any furtber consideration of your variation is justified. Accordingly, I am placing the eorresp~ndence carefully classified in our files where it will be immediately available should some future interest in this category develop. Very truly yours, J, o. Green Assistant Ohiet Engineer APPENDIX C EVALUATION OF NAVIGATOR-SPHERE BY ARMY AIR FORCES MATERIEL COMMAND ARMY AIR FORCES Materiel Command Office of the Connnanding General Wright Field, Dayton, Ohio 11 Jan 1944 Mr. Walter F. Hiltner, University of Washington, Seattle, Washington. Dear Sir: Attached for your infonnation is one ozalid copy of Engineering Division Memorandum Report No. ENG-54-655-886 dated 8 December 1943, subject: Proposed Navigation Devices. Very truly yours, G, V. HOLLOMAN, • Oolone.l , A;r Corps, Chief, Equipment Laboratory, Engineerfng Division. l Incl. Copy M.R. ENCr-54--655-886. ARMY Am FORCES Materiel Command Engineering Division SMB:dh:54-2 MEMORANDUM REPORT ON Date: a December 1943. SUBJECT: Proposed Navigation Devices. Equip:nent Laboratory Expenditure Order No. 655 SERIAL No. ENG-54-65&,,886 A• Pllrpose. 1. To report on visit of Mr. Walter F. Hiltner from the University of Washington on 26 and 27 October, 1943. :a. Factual Data.• l. Mr. Hiltner exhibited at Instrument and Navigation Branch office a model of a navisational computer of his design and described a propoijed sextant. Those present were: Captain J.G.P. Callahan, Equipnent Laboratory Dr• s. Me Burl~, Equipment Laboratory Lte Dion Hoy, Equi:pment Laboratory Mr. Walter F. Hiltnef, University of Wa$ll.i:r~.gton Mre G• Wrigt..t Arnold, Attorney 2. This visit was reported previously in the Daily Activity R~o" covering the above dates. ~. The device ~oposed by Mr. Hiltner was gone over in great detail with him. The l;>a.sic principle of the instrament is sound but 11:3 not :qew. It is ba.sed on a mechanical repfo~uction of the celestial sphere with the hour angle, ~ltitude, ~~mu.th and other arcs fl,uplic~ted PY mQvable metal arcs carrying angular divisions. Two LHA arcs are provided for simultaneous solution of two sights. Among others, Mr, Aylesworth of Los Angeles submitted au almost identical devioe to Materiel OOJDDBnd about 1930. Mr. Hiltner's soll,eme has one new feature, that of locating the navigational eta.rs by holes drilled into the cEmtral sphere. 4. The device has the advantages of such mechanical computers of simplicity in ope:ration and the possibility of making the reduction with minimum mistakes. It is not of military value due to the foll011.i:rlg disadvantages: Equipment Laboratory, Engineering Division Memorandum Report EN'G--54-655-886 dated a December 1943. verniers. Page 2 a. The device as eonstructed uses angular scales and These are definitely difficult to use in the air. b. The device is limited to use at ni~t and then only for selected star sights• The sun, the moon, and the planets cannot be used except with difficulty and special plotting. o. The device is inherently fragile 1£ kept to minimum weight. EXposed arouate members are subJect to bending and misalignment in handling. de Accuracy is directly a function of the pfecision of ~nuracture and, for usable aize, extreme precision and careful choice of materials is required. • 8• The device solves for siDillltaneous ste,its 0+1 two stars and no provision is made in the instrument for allowing for time difference or run between sights. 5. It was pointed out that the use of the device does not afford as much time... and effort-saving as might appear at first st.~t since the instrument replaces only one part (H.O. 218) of the equipnent and operat1ontt required in oelestial navigation. The taking of sextant ob~ervations a.p.d the plotting of the data »equire most of the labor and time, and the compu.tations with the proposed device or with H.O. 218 are simple and rapid i n ~ oase. 6. Mr• Hiltner also described a proposed sextant using a reflector floating on a mercury pool for altitUde measurements, and a vertical minor moved by a magnetic needle for bearing measurements. It was pointed out to him that even if the equipnent functioned (which is higbl,y ~robable} the operatious required, namely simult~eoue settings and orientation to obtain coincidence of two reflected images and a cross hair for altitude, and at the same time coincidence of two other reflected imagei, for azimuth, are impossible of perf~~ce in the air. 7. Mr. Hiltner and Mr. Arnold were given the original of the ab~tr~ct of the discussion attached as Appendix l for their records. o. Conclusions. l. The devices proposed are of no military value. Eq~ipment Laboratory, EngimeringD1v1sion Memora.ndum_Report ENGr-54-655-886 dated 8 December 194~. D• Page 3 Recommendation l. That no further consideration be given to the devices. Prepared by: s. M. Burk.a Approved by: G. v. HOLLOMAN, Colonel, A,o. Chief, Equtpment Laboratory. Approved by: F. o. CARROLL,Brig,General,u.s.A. Chief, Engineering Division. Distribution: Major General Branshaw; Mr. Walter F. Hiltner, University of Washington. " .. APPENDIX D 4STRO-NAVIGATOR CORRESPONDENCE Correspondenc~ with Office of Scientific Re~earch and Development w. F, Hiltner to Dr, vannevar Bush December 18, 1943 Carroll L. Wilson to w. F. Hiltner December 23, 1943 Theodore Du~, Jr., tow. F, Hiltner January 14, 1944 W, F• Hiltner to Dr. Dunham January 26, 1944 w. F. Hiltner to Dr. Dunham April 27, 1944 Proposed Thesis Program at Califomia Institute of Technology (Sketch of Essential Elements of Astro-Navigator) December 18, 1~4Z Dr. v~evar Buah Office of Scientific Research & Development 1630 P • street wa1:1hington, D. c• Dear Dr. vannevar Bus:ti: One summer evening a few years ago, I called at yo'Ul" New Hampshire farm with Professor F. Alexander Magoun. We helped you make a spliced rope halter for a new calf. • I am still making things with a nautical slant. The most recent if! the Navigato~Sphere, built last summer and briefly described in the enclosure. It was examined at Wright Field at the direction of General Giles, Gene Branehaw, and Colonel Holloman. There it was pronOUllCed scientifically correct, a definite improvement in instrumental navigation ea.loulators, but, in its present form, probably not acceptable to the service· branehes because of their difficulty in reading the five verniers. However, the authorities at the Al"lll'3 Air Base, Ephrata, Washington, a:-e still considering adopting the device for use by the crew should the navige.tor become a casualty. With the service requirements in mind, I have worked out a new celestial navigation instrument which might help O'Ul" Air Force over EUrope this winter. The instrument reads geographic latitude and longitude directly from sights on the stars. It ineerporates a new type of artificial horizon. Hanel held, this device should show the actual position contimously, and even mor~ accurately than ·the present octants determine the star altitudes. Gyroscopically stabilized, the .system migb.t well give position to a fraction Qf ~ mile, perhaps even close enough for accurate bombing through the cl0uds. My associate here, Dr. Donald H, Lougheridge, with whom I have discussed the physics aspects of the . problem, suggested that I write to you about this proJect. To develop this device rapidly JW;1t now, I need priority standing, financial support, and relief from more than a full schedule of classes. Can you advise me how to proceed in this matter? Very truly yours, W• F. HILTNER, Instructor OFFICE FOR EMERGENCY MANAGEMENT • OFFICE OF .SCIENTIFIC RESEARCH AND DEVELOPMENT 1530 _J:> Street NW. Washing1;on, D, o. December 23, 1943 Dr. w. F. Hiltner Depa;rtmQnt of General Engineering university ot Washington Seattle, Washington Dear Dr. Hiltner: Dre :Bush has asked me to thank you for your letter of December 18th in which you describe the :navigation instruments on which you are working. These sound interesting, and at Dr. Bush's suggestion, I am writing to Dr. Theodore Dunham of Division 16 ot NDRC e,nd asking him to get in touch with you t o d>tain more complete 1llformation concerning these devices and to as.certain whether this is a matter on which the OSRD oa.n help. I might say that a considerable amount of research effort .has been devoted to devices for the purposes yea. outline, and Dr. ])QD.bam is fully acquainted with the several projects on this subject. I am sending your letter and a copy of this letter to you to Dr. DUnbam at Mount Wilson Observatory, Pas~ena, California, and you may expect to hear from him at an early date. Very sincerely yours, Carroll L. Wilson Executive A~sistant to the D;rector CC Dr. Theodore Danham .... ,~ • b;o OFFIOE FOR EMERGENCY MAN.AG~ NATIOllAL DEFENSE :RESEARCH COMMITTlilE _ Of The OFFICE OF SCIENTIFIC .Rl'!JSEA.RCH AND DEVl!lLOPMENT 1530 P Street :NW. _ Washington, D, q. 6-105 Massachusetts Institute of Technology Oainbridge, 39, Massachusetts January 14, 1944 Drew. F. Hiltner Department ot General Enguie,ring University of washington Seattle, washi~gt;on - ' Dear Dre Hiltner: At I>:r• Bush's request, Dre Carroll Le Wilson has forwarded ·to me a copy of your lette~ to him dated Decembe~ 18, 1943, descriping the work which you have been doing on a :navigating device., I woo.ld be very glad indeed to have details regarding this instrument, so that our Section of NDRO can assess its possible usetu.lness for military use. would it be convenient for you to send sketches ant photographs of any model Which you may already have madt? :poe, this device inelu~e a talescepic system for sighting on the stars, or is it intended only to expedite calculation of geogr;aphical position from sextant observation? ::-~ I expect to be at the Mount Wilson Observatory, Pasadena, California for about ten days begimiing on January 24th. After January .. 18th, would you therefore be so kind as to address me in Pasadena? Very truly yours, Theedore Da:nbam, Jr. Ohiet, Section 16.l Optical _Instruments TI> s co: Dr. Wilson January 26, 1944 D.o otor Theodore Dunham, Jr. Ohief, seotion 16.l Optical Instruments National Defense Research. Committee :Mount Wilson Observatory • Pasadena, California Dear Dr, l)Unh.am: In my letter to Dr• Bush, DQo~mber 18, 1943, I mention two ~isti?l()t instruments, The navigator-Sphere ii:1 designed to determine the geographical position mechanically, from simu.ltaneous star altitude sights with sextant and cloek. It is a computing device. A photograph of the wo~king model I built myself is enclosed. Original features include: precise location of relative position of the navigation stars by acC11rate holes in star sphere, correction for precession by moving location of polar axis, automatic mechanical interseotion of lines ot position at zenith, ·(the vertical a.xis in the photograph). A patent for this instrument has not ye~ seemed justified and no formal action has been instituted. Therefore, I must require that you consider the photograph and these comments as confidential. Th• design and construction of the Navigator-Sphere and my subsequent contact with military se~vice requirements is backgt-ound for my continuing work in celestial navigation instrumentation. J!3" other celestial navigation instrument is e?Itirely difterent from the Navigator-Sphere~ It includes an optical system for sighting on the eta.r s {or on any body), a new type of artificial horizon, and appropriate means to measure .the necessary angles, including the geographic latitude and longitude of the observer. The deviee gives the actual position directly, and continu.ously. It may be hand held, or gyrosoopically stabilized li~ the bomb sights. Sketches or photographs of this new instrument are not yet available. However, my work is beyond the "good idea" stag-a. The theo:ry, principles, and essential details have been discussed with, and critically examined by several of my associates here, including Dr. Donald w, Loughridg-e, director of our OSRD project and Theodor s. Jacobsen, Professor of Astrononw-• I am pre-, pared now to build the development model, given the necessary priority standing, financial support, and relief from Tl19 teaching load. Dr, Wilson, of OSRD, tells me that you are well acquainted with other projects 1~ this field • . I would welcome your comments and suggestions. My pu,;-po se 1n writing to Dr. Bush was to discover how I could most effectively and rapidly perfect this new celestial navigation instrument for our war effort. I presume tbat you are in some position to cooperate in the development of such devices. On what basis is such cooperation arranged? Should I come to work in your laboratories? Do you have :f'und.s available for such projects? How are an individual's interests considered and protected? I would appreciate your advice. In ma.king similar arrangements, I have fo1llld the long distance telephone a great economy in time and an aid to mutual underf:ltanding. I can be reached at the University, MElrose 0630, Extension 44.0 or 296, or at my home, EE:nwood 8062. Very truly yours, Walter F. Hiltner w.int:b .. , 9 b April 27, 1944 Doctor Theodore DUnham, Jr. Ohief, Section 16,l Optical Instruments National Defense Research Committee 6-105 Mas13&chusetts Institute of Technology Cam.bridge, 39, Massachusetts Dear Dr. ])Un.ham: As you ean see, I've moved down to the California Institute of Technology in Pasadena ~d have not been able to give any attention to the matter of navigation devices. I had written to you on January 26 about thia devioe and since I have had no reply, I write now to bring this matter to your attention again. In my letter to Dr. Bush, Decenber 18, l94Z, I mention two distinct instruments. The navigator-sphere is designed to determine the geographical position mechanically, fran simultaneous star altitude sights with sextant and. clock. It is a eomputing device. A photograph of the working model I built myself 1a enclosed. Original features include: precise loeation of relative position of the navigation stars by accurate holes in star sphere, correction for precession by moving location of polar axis, automatic mechanical intersection of l\nes of position at zenith, (the vertical axis in the photograph). A patent for this instrument has not yet seemed Justified and no formal action has been instituted. Therefore, I mu.st require that you consider the photograph and these ~emments as confidential. The design and construction of the Navigator-Sphere and my subsequellt contact with military service requirements is background for my continuing work in celestial navigation instrumentation. My other celestial navigation instrument is entirely different from the Navigatoi-Sphere. It includes an optical system for si~ting on ~he st~rs (or on any body), a new ty:pe of artificial horizon, and appropriate means to measure the necessary angles, including the geographic latitude and longitude of the observer. The device gives the actual position directly, and contiwously. It may be hand held, or gyrosoopically ptabilized like the bomb sights. Sketches or photographs of this new instrument are not yet available. However, my work is beyond the "good ideatt stage. The theory, principles, and essential details have _been discussed with, and critically examined by several of my associates at the University of Washington, including Dr. Donald w. Loughridge, direc- · tor of our OSRD project and Theodor s. Jacobsen, Pr~fessor of Astronomy. I am prepared now to build the development model, g1 ven the necessary April 27, 1944 Page 2 priority standing, financial support, and relief fran my teaching load. Df• Wilson, of 0SBD, tells me you are well acquainted with other projeots in this field. I would welcome your comments and suggestions. My purpose in writing to Dr~ Bush was to discover how I could most effectively alld rapidly perfect this new celestial navigation instrument for our war effort. I presume that yQu are in some position to cooperate in the development of such devices. On what basis is such cooperation arranged? Shou.ld I come to work in your laboratories? Do you have t1mds available tor suchproJects? How are an individual's interests considered and protected? I would appreciate your ad.vice. Very truly yours, Walter Fe Hiltner WFH:Jc Prosra:!D: of Stud.y ~ Research For Degree 9!_ Doctor !! Philoso;eh.y & the Oalifo rnia. Institute of Technology Proposed by: Thesis: Walter F, Hiltmr December 29, 1944 Development of Portable Celestial Navigation Instrwnent for Direct-Rea.ding of Terrestrial Position. This thesis on the development of a portable celestial navigation instrument for direct-reading of terrestrial position requires the applioation of principles of astronomy, optics, and instrument design to the practical problem of quickly determining local position on the earth, Its primary purpose is for use in aircraft where the need is urgent today, but it may also find application in the field of surveying. Th• proposed instrument will be composed of three essential parts: Opttcal head to gather and direct the light. 2. Mechanism providing variation .and measurement of latitude and longitude. 3. Artificial horizon as origin for measurements. 1. The optical head will gather the light from the visible bright stars and direct the rays from every star into a parallel bundle. It is made with a fixed ar~ngement of mirrors or prisms, so that a particular orientation is required to produce the parallel bundle of rays. This orientation is determined by observing the coincidence of all the star images 1n a telesoope. • The bundle may bave any predetermined orientation in the celestial system whatsoever, but for convenience we will direct the ba.ndle .. parallel to the polar axis. • The altitude to the polar axis as tlm.s defined by the bundle of rays determines the latitude of the place. The local hour angle of Aries compared with Greenwich hour angle of Aries (Greenwich Sidereal Time) gives the longitude. The mechanism of the instrument permits the required angular motions and their measurements. The optical head is mounted Qn the pol~r axis of the inst:rument so it may be rotated 360 degrees about this axis, and its position measured from the horizontal east-west line along which the bundle of rays is further bent through 90 degrees from the polar axis. To facilitate the use of the inst:rwnent, a eleckwork 1•foll~ing" mechanism may be provided to continue rota.ting the optical head.. about the _polar axis in time with the apparent motion of the stars. The polar axis is in turn mounted on the east-west axis so 1 t may be turned 90 degrees up and down from the horizontal to provide for the variation in latitude and its measurement. B9th of the angular measurements dep:md upon the artificial horizon: the longitude fof the horizont~lity of the east~west axis, and the lat1tude for the origin of its soale. A simple bubble under a spherical surface will provide the hori~on for both coordinates. Its arrangement is nicely perfected in the new Army Air Foree sextant which also uses a horizontal sight direction as in this instrument. The observer will then orient the instrument to obtain coincidence :f'or all the star images, adJust the latitude and longitude micrometer .. until the bubble shows true, and read o:f'f the position. Avera.gtng dials are required for use in the aire Corrections for oourse-Q.rift and Ooriolus ~ooeleration mu.st be made a.a at present. Satisfactory for Thesis in Civ1l Engineering for Doctor of Philosophy at Cs.lifornia Institute of Technology. ~ i n Th.oms.a .APPENDIX E PATEi'\JT AGREEMEJ.{TS w. F, Hiltner to J. Paul Youtz March 5, 1945 Assignment to California Institute Research Foundation May 5, 1945 J, P, Youtz tow. F. Hiltner May 14, 1945 Inter-Department Communication CALH"'ORNI .A I NS'rI TUT:C: OF I'BCfaiO LOGY ?.ASADitNA Date March 5, 1945 To J. :Paul Youtz From Walter F. Hiltner Subje ct Inventions As you suggested in our informal conversations, t :O.is note is to call to the attention of the California Institute Research Foundation the work which I have be gun unde:r the supervision of Dr. John A• .Anderson, the de velopment of a port able celestial navigati on instrument for the direct-reading of terrestrial position. Aris i ng f rom t his research may be several patentable features wh:i.ch tile Foundation mi ght find profitable to exploit. I am agreeable to assi gnment to t he California Institute Research Foundation , in return for 15o/o of the gross returns to t he Foundation as a result of the exploitation t hey choose to give the idea. California Institute Research Founaation California Institute. of Technol,ogy Pasadena. 4, 0alifornia Celestial NavigationAppa.ratus as disclosed in the Doctor's Thesis, Oalifornia Institute of .Technology, by Walte~ Hiltner. Gentlemen: I hereby agree to assign to the California Institute Research Foundation, my entire right, title~ interest in and to the above-ident:tfied invention and any u. s. or Foreign Patent which the Foundation may elect, at its expense, to file thereon, in consideration of ~ent quai-terly to me by the Foundation of 16% of its gross income acc:ruing from said invention for such period as the Founaation desires to hold the patents~ I hereby agree to execute any and all papers and inatrwnents deemed necessary by the Foundatton to seci:ire patent protection for s-µ,ch invention in this and foreign countries and to )~ assign the applications and the patents on the same to said Foundation. This agreement is binding on myself, my heirs and assigns without restriction as to license or sale of the interest which may result. Walter Fe Hiltner Leonard s. L:yon Accepted for the Foundation Dated May 5, 1945 CALIFORNIA INSTITUTE :BESEARCH FOUNDATION 1201 East Oaliforni,a. Street P.ASADEMA May 14, 1945 2890 :Mr. Walter F. Hiltner Division of _Meohanical and Civil Engineering Oalitornia Institute ot Technology Pasadena 4, . califomia, Deat." Mr. Hiltner: Subject: Celestial Naviga.tion.Apparatas as disclosed in the Doctor's Thesis, California Ins~ttute of Technology, 'by Walter Hiltner It gives us great pleasure to return herewith a copy of your letter of agreement covering your invention ae, above de~cribei and upon which has been placed the signature of the President of the oalifornia Institute Research Foundation accepting your offer for the Found.a ti on. _ • • We appreciate this cpportuni ty to cooperate with you in ~ng tllis invention available to science and the public and trust you will keep us advised of any suggestions you may have to this end. Yours very sincerely, J, ?. Youtz Business Manager jpy:Jb encl..