Automatic Astro Compass Type MD-1

© Brooke Clarke, N6GCE 2001 - 2006

 

Astrotracker fits in 16x16x16" box	Display Panel, Star Data	Display, Azmith & Ground Range	1280-506-3827 s/n AF57 132 33 600 31502	Deutsch screw on shell 30 male pins 1  1/8" ID
J101 30 male pins cap 1 5/16-6 Acme	J102 30 male pins	J103 30 male pins	J104 900 Volts 3 each photo multiplier?
33 in Hg Plug?	Bubble level vial Prisim	Labels
Back of Display Panel, Star Data	Automatic Astro Comapss Type MD-1 Stock No. 6605-658-2565 Serial No. AF61-2136 Mfrs Part No. A21570 ?004 Contract No. AF33(600)-42020 Kollsman Instrument Corporation US
	Internal Photos
Side	Top	Raster

Background information

The Manual Astro Compass was replaced by the periscopic sextant which was replaced by the automatic astro-compass.  This may have been the first in a series of star tracking instruments used in aircraft, missiles and space craft.

There are two very similar astro trackers, the C2150 00 003 and the D21550 00 001, what the difference is is unknown.
I have been tokd this is a part number A2157000004 with NSN 6605-00-658-2565.
The part number D2155000001 version has a NSN of 6605-00-776-3234.

3 Sep 03 Phone call from R. S. who maintained the MD-1

R. S. maintained the MD-1 from 1967 through 1970, which includes the Viet Nam era.  18 Dec. 1972 bombing of N. Viet Nam was allowed.  The Arc Light missions were flown from Thailand, Okinawa and Guam using B-52s with MD-1 capability.  Nixon was a football fan and he named a later mission "Linebacker".

The MD-1 was used on the B-52 C & D as well as in the E and F variants.  Many of the boxes that made up the MD-1 system were located in the right forward wheel well.  Subjecting them to problems from slush from wet runways.  One of the problems was the tuning fork that drives the clock would die.  Being an analog system you could not just replace the tuning fork box, but also needed to adjust a number of pots.

Another problem in the states was when a chew chief would scrape ice off the B-52 they would sometimes also scrape off the dome of the MD-1 and ask to have the dome replaced.  Well you can't do that, the whole MD-1 needs to be replaced and properly leveled.

The Hound Dog missile that was carried on the B-52 also used a smaller version of the astro tracker.  Sometimes when the about 2 foot diameter MD-1 astro tracker was ordered, the one foot diameter astro tracker for the Hound Dog would be delivered.

There was a star simulator that had 3 "stars" in known locations that could be used for testing the MD-1 system.  When testing at night mag 1 stars were used since they were easier to lock onto.

Lighting bugs were not a problem.  Most of the time when a problem ticket on the MD-1 showed up it was do to lack of training, rather than equipment failure.

There are B-52s on static display, that should have MD-1 systems at: Travis, Castle, March and Edwards fields in CA.

Hisory, AF Plant Representative, Boeing Airplane Co. July - Dec. 1958 by Col. Robert E. Lee
Unclassified CMS 0476305
This report contains sections for:
Quality Control -

The MD-1 Astro Compass continued to be a source of trouble.  It was discovered that several of the small plug-in amplifiers had bent pins and socket damage due to misalignment of the sockets in the unit.  However, this problem appears to have been cleared up by the vendor at this time.

Another problem of the MD-1 System was the inaccuracy of the clock used with this equipment and the fact that there was no flight test tolerance for the clock.  this condiditon was alleviated with the issuance of a flight tolerance and the installation of a new Tuning Fork and Time Standard Amplifier.

Production - B-52G engineering was moved from Seattle to Wichita completed by 31 Dec. 1958.
Industrial Property
Security
Flight Operations and Acceptance - 143 B-52 flight tests for 459:10 hours.
Finance and Accounting
Contracts - B-47 Project: Milk Bottle, B-52 Projects: Wheat State, Harvest Moon
Photoss - refuling During Maiden Flight of B-52G Stratofortress, zB-47 Stratojet in Water Injection Take-off.

Control Panels

ion, the capabilities of the system were classified.  That's why the displays and some of the controls in the following images have been sanitized.
 

Display Present Position	Display Star Data for 3 stars	Display Aries GHA & UTC Lower instrument is a clock
Choose how to set assumed Lat Lon	Display True Heading Heading Correction	Display True Azmith Altitude Intercept
Master Control Must allow setting 3 star positions & present position

In addition to the above control panels there are 10 other ATR type boxes with the analog computer and other electronics boxes that make up this system.

In this version an automated Star tracker looks out a clear astrodome on the top of a B-52E/F and tracks either a star or the Sun. There were a number of star trackers built for many programs both for aircraft, missile and space craft navigation.

Manuals

AF manual 51-40 Volume 3 Air Navigation (15 Apr 60) has  a couple of pages on the MD-1: Cover,  Part 1,    Part 2,   mentions "minutes of arc" accuracy. Done using an analog computer.  Photographs of the instruments are not sanitized, so you can see more than on the photos above.  This is just 2 years after the classified paper above and the capabilities are no longer classified.

Operation

WANTED - Manual with schematic and/or theory of operation diagram for the star tracker

By inspection of the parts manual T.O. 5N15-2-2-4 some things can be learned.  All of the parts listed below need some type of electrical connection.  There is a minimal amount of electronic content inside the star tracker.

• a single photomultiplier (fig 5-27) is used that looks like an octal based vacuum tube, maybe a 931 photomultiplier (Burle).
• the telescope assembly sits on a roll-pitch correction assembly that has maybe +/- 8 degrees range (T.O. 5N15-2-2-505)
• the telescope assembly includes parts to aim in azimuth(rotation) and elevation (tipping the prism) but what are the rest of the items are for?

T.O. 5N15-2-2-507 contains a modification that improved the operation of the MD-1.  It is applied to the 3 kHz raster assembly p/n 85 21552 0370.  This implies that there is an X-Y scanner in the system and would explain some of the active components above and the use of audio transformers.

Astro Trracker Major Assemblies Fig 2

• 2-9 Vertical gyro - is external to the astro tracker (available from C&H Sales )
  
• 2-47 Telescope Fig 3 - contains the optical tower, prisim and underneath the tracker and photomultiplier
• Telescope sub-assembly Fig 4 - just the optical tube
• Tracker sub-assembly, photoelectric cell Fig 5 - metal casting that holds the photomultiplier, 2 ea transformers, cover that allows light into the center of the tube along the long axis.
• Gear Box Tracker sub-assembly Fig 6 - larger in diameter than the telescope with many electrical feedthrough terminals around the outside. has the "raster".
• 6-17 synchro control transformer B106
• 6-18 induction generator Fig 7 MG102
• 6-28 synchro control transformer B104
• 6-35 synchro resolver B105
• 6-48 synchro control transformer B103
• 6-49 induction generator Fig 7 MG101
• 6-60 potentiometer, secant
• 6-67 synchro control transformer B102
• 6-71 synchronous motor Fig 9  B101
• 6-78 permanent magnet generator Fig 10 G101
• 6-135 Differential Assembly Fig 11 (no electrical parts)
• 6-173 solenoid L101
• 2-62 Blower, minicube  B111, B112, B113, B114
• 2-94 Roll Drive gear Box
• 12-12  induction generator (induction motor?) Fig 14  B109
• 12-13  induction generator Fig 15 G103
• 12-17 magnetic brake assembly Fig 16 L102
• 12-3 (2 each) switching circuits that contain an audio transformer Fig 13
• 2-98 Roll Synchro Gear Box Fig 17
• 17-20 synchro control transformer  B110
• 2-102 Pitch Synchro Gear Box Fig 18
• 18-21 synchro control transformer  B108
• 2-105 Pitch Drive Gear Box Fig 19
• 19-1 magnetic brake assembly L105
• 19-5  induction motor B107
• 19-9  induction generator G102
• 2-133 Pitch Gimball assembly  Fig 20
• 2-134 Roll Gimball assembly  Fig 21
• 2-136 Platform assembly Fig 22 

Patents

many with class 250/203.6
The original idea was to just track a single star when it was dark out.  Then a problem surfaced at dawn and dusk there is an East West gradient in the sky background that causes an error in the early type star trackers.  A number of solutions were found.  The next step was to have a star tracker that would track a star in daylight.  This requires optimizing the signal to noise ratio in the complete system.

Three of the patents below are assigned to Kollsman, but which of any apply to the MD-1 remains to be seen.

6236939 May 22, 2001 Method and apparatus for controlling spacecraft attitude with rotational star trackers
6047226 April 4, 2000  Enhanced stellar attitude determination system
5525793 June 11, 1996 Optical head having an imaging sensor for imaging an object in a field of view and a tracking sensor for tracking a star off axis to the field of view of the imaging sensor - Santa Barbara Instrument Group
4159419 June 26, 1979 Three axis stellar sensor
3936632 February 3, 1976 Position determining system - star tracking for satellites 250/237R; 250/203.5; 250/203.6
3578975 May 18, 1971  Apparatus for Monitoring the Guidance and Focus of Telescope
3295010 Image Dissector with Field Mesh near Photocathode, ITT
3165632 Jan 12, 1965 Star-Tracking System using a Frequency Modulated Carrier Wave, defective USPTO pages
3131249 April 28, 1964 Stellar Compass, Karolus Kunze,
3127516 March 31, 1964 Star Tracker having adjustable scan dependent upon radiation intensity, bad USPTO pages missile?
3122644 Feb 25, 1964 Binocular Star Sensing System, North American Aviation, star position in the presence of gradient background illumination
3117231 Jan 7, 1964 Optical Tracking System, U.S. Navy, sidewinder IR tracker?
3100264 Aug 6, 1963 Star Energy Identification System for Space Navigation, Polarad Corp, amplitude frequency absorption spectrum used to identify objects in space for satellite navigation.
3088033 April 30, 1963 Automatic Multiple Grid Scanning Tracker, Northrop day & night star tracker
3080485 March 5, 1963 Stellar Orientation Monitoring System, HRB-Singer, a motor scans a photo multiplier and the star pattern is recorded and compared in future scans, for missile navigation
3080484 Mar 5, 1963 Electrooptical Light-Detecting Apparatus, Hughes, day or night star tracking, uses narrow band filtering requires constant frequency, not frequency modulation like in nutating systems, this is a switched system aimed at missile navigation
3072794 Jan 8, 1962, Northrop, Rotating Wheel Scanner for star tracking
3053984 Sept 11, 1962 Star Tracking System, defective USPTO pages
3037289 June 5, 1962  Directional Reference Correction System, Sperry Rand, math for making star tracking corrections
3015249 Jan 2, 1962 Tracking Telescope, Northrop, automatic star tracker
3014133 Dec 19, 1961 Star Tracker, United Aircraft, submarine periscope
3002097 Sept 26, 1961 Dispersion Scanner, Northrop, star tracker with acceleration correction
3002096 Sept 26, 1961 Light Tracking Device, Kollsman, removes background illumination even when a gradient
2998529 Automatic Astrocompass (Kollsamn) (Sun in daytime, Star at night) 250/206.3 ; 250/203.1; 250/203.4; 250/207; 356/139.02
    calls :
    2421012 Homing System (Navy) cylindrical lens and chopper 250/206.3 ; 102/213; 244/3.16; 250/203.1; 250/214.1; 250/215; 250/233; 318/480
      2713134  Radient Energy Controller Followup System (Kollsman) reticle and PMT 318/575 ; 250/203.3; 250/203.7; 318/16; 318/489; 318/625; 318/640; 74/5.34

2981843 April 25, 1961 Star-Tracking System, Hughes Aircraft, works with a bright background
2948813 Aug 9, 1960 Tracking System, Aerojet-General, missile
2947872 Aug 2, 1960, Star Tracking System, Kollsman, (filed 23 Jan, 1956)
2943204 June 28, 1960 Star Sensing System, North American Aviation, daytime and multiple stars, rotating reticule
2942118 June 21, 1960 Radiant Energy Angular Tracking Device, Westinghouse, off center reticule is rotated
2941082  PhotoElectric Automatic Sextant (Kollsman) 356/139.01 ; 244/3.18; 33/268; 356/148
    calls:
    2444933 Automatic Navigational Director (Navy star tracker) 318/581 ; 244/3.18; 250/203.1; 250/348; 318/480; 318/640; 33/1SC; 701/222; 73/178R
    2462925  Radiant Energy Directional Apparatus  (R. Varian sextant that works in daylight) 318/640 ; 250/236; 318/480; 318/625; 33/268; 73/178R
    2492148 Automatic Navigating Instrument for Craft Guidance (Sun or star) 318/582 ; 244/3.18; 313/531; 318/480; 318/577; 318/656; 33/1SC; 33/268; 33/320
    2513367 Radiant Energy Tracking Device (Sperry) 250/203.6 ; 244/177; 244/3.18; 250/204; 250/233; 250/236; 318/582; 318/640; 33/1CC
    2532402 Navigation Instrument for Craft and Pilot Guidance 318/581 ; 114/144E; 114/144R; 235/61NV; 318/577; 318/632; 318/675; 33/264; 33/268; 89/1.51
    2533686 Gyroscopic Sextant (gyro replaces visible horizon) 33/275G ; 33/282; 33/318
    2762123 Navigation System (Sperry) (celestial nav) 33/1SA ; 235/61NV; 244/3.18; 250/203.6; 318/582; 33/268; 356/248; 701/221; 701/222; 74/5R; 74/5.34
3263944 Aug., 1966 Space Craft Navigation System
2931910  April 5, 1960 Automatic Star Tracker, Northrop, rotating wedge with a 10 deg clear field (application 14 March 1949)
2930545 March 29, 1960 Automatic Celestial Navigation Control System, General Scientific Projects, objective prism, track 2 stars
2922224 Jan 26, 1960 Navigation System Employing Star Heading Reference, General Precision Labs, "star tracker" a rotating wedge causes a sin wave output of the spot of light is off center and a DC output when centered.
2921757 June 26, 1948 Long Range Automatic Navigator Device General Scientific Projects "Stellar Compass" 4 photo cells
2906916  Sep 29, 1959 Position Sensing Detector Du Mount Labs photo multiplier for missile homing
2894396 7/1959 a gyroscopic unit
2762123 May 26, 1948 Navigation System - Spery Rand Corp - 3D gyro system with star tracker using photo multiplier tubes
2734269 Aug 11, 1952 Angular Position Data Apparatus - Ionoscope arc seconds accuracy
2713134 July 12, 1955, Radiant Energy Controlled Follow-up System, Kollsman, photo multiplier and 400 Hz rotating mask, automatic star follower This appears to be the patent used for the MD1.
318/575; 74/5.34; 250/203.3; 250/203.7; 318/16; 318/489; 318/625; 318/640
It calls the indented patents below:

2462081 Feb 22, 1949, Servomotor System assigned to Sperry Corp (auto pilot for flying wing)
2462925 March 1, 1949 Radiant Energy Directional Device, Russell H. Varian, Palo Alto assigned to Sperry Corp
Can track stars during both night AND day!  Automatic star tracking.  The construction is based on a sextant.

2369622 Orientation System, Feb 13, 1945, Toulon, automatic pointing to a source of energy (IR) on a ship
2246884 Potentiometer, June 24, 1941, balanced control system for temperature indication
2155402 Sun Compass, April 25, 1939, Joseph C. Clark, true meridian indicator using motors and light sensitive sensors

1963692 Light Sensitive Cell (Clark Cell), June 19, 1934, Joseph C. Clark, Selenium photo cell process for making

2102587 Solar Navigator, Dec 21 1937, Leon T. Eliel, use the Sun to fly an airplane in a straight line for map making.
1999646 Light or Ray Controlled Follow-up System, April 30, 1935, B. A.  Wittkuhns assigned to Spery Corp. uses photo cells and motors
1976648 Remote control System, Oct. 9, 1934, B. A.  Wittkuhns, to Spery Gyroscope, dual cathode photocell

2513367 May 25, 1948 Radiant Energy Tracking Apparatus, star tracking telescope

2369622 Orientation System, Feb 13, 1945, Toulon, automatic pointing to a source of energy (IR) on a ship
2397933  Line Tracker Control, Aprio 9, 1946, milling machine controled by drawing

Control by PC

If the schematic of the star tracker can be located or reverse engineered, then it may be possilbe to use the star tracker without all the other boxes in the system directly from a PC and using a custom made interface.

Synchro Systems  -
Control Sciences Inc. -
Analog Devices - Synchro to Digital Converters -
ILC Data Device Corporation -
Natel Engineering/Muirhead - hybrid contract manufacturer, but has Synchro history
Pentland Systems - VME synchro converters
Computer Conversions Corp. - amplifiers -
VMIC - synchro converters - Tutorial -
Poly-Scientific -Resolvers & Synchros - Synchro Application Data -
Hotek - North Atlantic Angle Position Indicator, API Model 8810 -
Micro-Precision Technologies - Synchro- and Resolver-to-Digital, Digital-to-Synchro and -Resolver -
BBG Inc. - serial converter -
ICPE S.A - Synchros & Resolvers
Integrated Publishing- Gunners Mate Training  Chapt 5 -Synchro Circuits -
North Atlantic Industries -
FT Technologies Ltd - Synchro/Resolver Converters -
Science Engineering Associates, Inc. - Synchro Digital Converter for INS Interfaces -
KineticSystems Company, LLC - 3-channel, Digital-to-synchro Converter -
ACTIS Computer - RDC-20 Dual-channel Resolver / Synchro Converter -
Eagle Technology - PC-40 4 Channel Digital to Synchro Converter ISA Board -
 - Multi Mission Military Aircraft Simulator -
North Atlantic Instruments - angle position indicators and realted equipment for synchro/resolvers, S/R simulator with 3VA output. 76CS1 will measure 8 chan & drive 6 chan with 1.2VA.

Test Equipment

Test Set Synchro Type TTU-23/E -

Palm Pilot Software

There is also a program for the Palm Pilot called "astro compass".  This uses the time and location of an observer to calculate some astronomical data.

Links

Kollsman later provided an Astro-Compass System (a combination mechanical, electro-mechanical and electronic analog computer system).

This Astro-Compass System solved the celestial navigation problem by locking unto light from the sun in daylight hours, and to the intensity of light from stars in the darkness of night. Its gyro system was so sensitive, bench systems had to be installed on concrete pedestals several feet deep into the ground, to minimize disturbance from earth vibrations by the roll of 18-wheeler trucks riding highways ten miles away.

This Astro-Compass System was installed only in E and F model B-52s, and later removed. (I have no proof, but, from experience, one of the reasons for removal could have come from this system's ability to lock-on to the glow from lightning bugs impacted on the glass dome during B-52 take-off rolls, later blocking points of view, rendering the system inoperative in-flight.)

Atop the stabilization unit, and protruding slightly above the skin of the fuselage, is the rounded cupola of the star tracker unit. By setting on his astro control panel the Greenwich Hour Angle, the sidereal hour angle, and the declination of the sun or star to be used for navigational purposes, the navigator can cause the astro tracker to lock onto the heavenly body, after which it will provide continuous heading information to the computer.

The N5G Hound dog missle also used the astro tracker.

Yankee Air Museum - has restored B-52D but no MD-1 info
Kollsman - still in business making similar products
B-52 Stratofortress Association -
Air University at Maxwell AFB -

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