MIL-S-5807A Sextant, Aircraft, Periscopic
Kollsman Instrument Corporation
MS part no. MS 28011-1

Brooke Clarke, 2001 - 2014

MIL-S-5807A Sextant, Aircraft, Periscopic
MIL-S-5807A Sextant, Aircraft, Periscopic

D-1 Mount (Types: 1708-01 & 1869-01)


2894330 Astrocompass
Astrocompass Patent Drawing MIL-S-5807A Sextant,
                Aircraft, Periscopic
Periscopic Sextant
                  Sextant, Kollsman 2579903 MIL-S-5807A Sextant,
                  Aircraft, Periscopic

Mount 2554010
                Sextant Mount Patent Drawing MIL-S-5807A Sextant,
                Aircraft, Periscopic
3207025 Optical System for Periscopic Sextant
                  System for Periscopic Sextant, Kollsman

MIL-S-5807A Sextant, Aircraft, Periscopic
                    Sextant, Aircraft, Periscopic
                    Sextant, Aircraft, Periscopic
                    Sextant, Aircraft, Periscopic
MIL-S-5807A Sextant, Aircraft, Periscopic
Fig 1 Periscope in case

                    Sextant, Aircraft, Periscopic

                    Sextant, Aircraft, Periscopic

Fig 2 Label side
                    Sextant, Aircraft, Periscopic

Fig 3 Elevation knob side
                    Sextant, Aircraft, Periscopic

Fig 4 eyepiece side, upper left knob is bubble control
                    Sextant, Aircraft, Periscopic
Fig 5 Close up of label and filter wheel & white knob cross hair lamp brightness
                    Sextant, Aircraft, Periscopic

With Russian Chronometer
                  Sextant, Aircraft, Periscopic

MIL-S-5807A Sextant, Aircraft, Periscopic
                    Sextant, Aircraft, Periscopic
MIL-S-5807A Sextant, Aircraft, Periscopic
MIL-S-5807A Sextant, Aircraft, Periscopic
MIL-S-5807A Sextant, Aircraft,
Fig 6 Warning label, clock winder & pat # 2516187
Fig 7 Elevation readout & clockwork dial
Fig 8 Cover page of Pat 2516167 Calculating Instrument
MS 28011 Sheet 1 with part names
Fair Radio has a different one and the seal appears to be broken (see Fig 5 above for good seal)


This aircraft sextant was used for celestial navigation.  I think it has been replaced by GPS and/or inertial navigation systems.
The patent is dated 1945 and the sticker on the sextant is June 1986.  This instrument is a masterpiece of mechanical and optical engineering.

The bubble is there and can be controlled by the knob.

I think the idea is that the person sighting a star or the Sun, keeps it in the cross hair and at the same time keeps the bubble centered.
As the elevation control is moved up and/or down the clockwork mechanism is averaging the elevation over a period of time.

When the elevation dial is at 90 you are looking straight up and with it set for 0 you are looking at the horizon.  The smallest division on the elevation counter is 1 arc minute ( 1/60 of a degree).
Note you can only see out the periscope after the clock lever is pressed, winding the clock AND pushing the button to start the averaging.
How you get the averaged answer is a mystery.

I have not wanted to break the seal, but if you did I expect that the clockwork inside would be very interesting.
There are two GE 327 lamps easily accessed behind metal covers. One illuminates the bubble and the other the azimuth scale on the mount.

The Filter Wheel (Fig 5)  has 8 positions:  1= no filter,  2 = green, 3 = red, 4 = green+ND1, 5 = ND1+red, 6 = ND2+green, 7 = ND3+red, 8 = ND3+green.  The Neutral Density filters starting at no. 4 are strong enough that you can look at the Sun.  It's image is about the same size as the bubble. 

To hold the sextant some type of support would be helpful, like a 2x4 with a hole to clear the 1.375" diameter periscope tube and a way to keep it from falling out (maybe use the pin on the side of the tube?).  Unlike the sextants used on ships that are hand held, this one needs an external support.

I've heard that the MA-2 sextant was the precursor to the periscopic sextant.  The MA-2 required a glass dome which required good optical properties and the dome was not supposed to break or blow out, but that did happen, so the periscopic solved those two problems.  See anon. external web page Air Navigation Sextants based on AFM 51-40 (U.S. Air Force manual "Air Navigation") section pertaining to bubble sextants, from the 1955 and 1960 editions.

US Patent 2516187 -Calculating Instrument application Feb. 24, 1945 covers some of the operation of this sextant. (see Fig 6 above)
The key feature is the "averager" that mechanically averages the elevation setting over time.

MIL-S-5897C(ASG) contains operational specifications such as:

3.3.1  Sextant.  Hereinafter, the term "sextant" shall be construed to mean the sextant proper, Periscopic tube, connecting cable, and watch clip.  The sextant shall be a bubble-type sextant built in the form of a periscopic telescope with the periscope projecting above the skin of the aircraft.  Provision shall be made for 360 degree rotation of the instrument around the vertical axis and tilt of the sextant up to 14-1/2 degrees minimum from the vertical axis.  The sextant shall conform essentially to Standard MS28011.
MS28011(AS) consists of three drawings: A.F. Manual 51-40 Air Navigation has a little information on this sextant.  Vol 1 has descriptive info and Vol 3 operational info

ID Plate

The ID plate reads:
Sextant, Aircraft, Periscopic
MS Part No. MS 28011-1
28 Volts A.C. or D.C.
Specification MIL-S-5807A
Mfr's Part No. 1471B-01
Mfr's Serial No. 3870
Order No. NOas 52-535
Stock No. R88S0400-050-000
Kollsman Instrument Corporation
U.S. Property  35050-1

And the paper sticker says:
Aerospace Guidance and Metrology Center (AGMC)
Repair Date JUN 16 1986
Newark Air Force Station
Newark, Ohio   43057

The label on the periscope tube says:

D-1 Mount (Types: 1708-01 & 1869-01)

May 2014 - When combining the mount and sextant the crank on the mount does turn the Veeder-root counter but does not rotate the sextant in azimuth.  There is a ring that's the lowest part of the mount that says "LOCK --->" but I can not rotate the ring any more to the right.  There's an open threaded hole, maybe there's supposed to be some sort of bolt there to lock the azimuth?  

Answer:  When a sight is to be made the sextant is removed from the carry case in installed into the mount (while the door is closed) and the ring at the bottom of the mount is turned.  The sextant is now "locked" into the mount and you can let go without it falling (I'd rotate it to be sure the ring has really locked it).  At this point when the outer door is opened there will only be a very small air not a large one like would happen of the outer door was opened without the sextant being installed.

Prior to making a sighting you set the azimuth using the crank and Veeder Root counter ( dd_dd_m) which turns the azimuth scale that's visible in the eyepiece relative to the aircraft centerline and you preset the sextant elevation angle using the Elevation knob and the Veeder Root counter that's adjacent (ddm).

When it's time to make the sighting the outer door is opened and the periscope lifted.  There are two pins that hold the periscope in the up position and these are missing from my unit.  You can see the two pins clearly in the photo below of a mount installed in a C-133.  They are 180 degrees apart.  There's a ramp on the protrusion on the sextant body that indicates that these are spring loaded and all that's required is to raise the sextant and it snaps into place.  The pin is pulled out to allow lowering the sextant when the sighting is complete.Perisocpic Sextant D-1 Mount in C-133

The sextant not only has an optical path that looks at the star but also a path that reads the azimuth from the D-1 mount.  The azimuth path includes provision to light the numbers on the mount.

The D-1 mount in the photo at left is in a C-133.
There appears to be a dummy periscope connected to a hinged arm. Not sure why.
There are two connectors on the mount.  One is cabled to the aircraft and the other (not used in photo of C-133) is for the cable to the sextant.
It looks like the type 1708-01 in this photo and so is mounted on or close to the aircraft center line.

The mount photos below show the mount disassembled into the part that attached to the aircraft body and contains the trap door and the part that holds the periscope.
The two parts that mount the main assembly to the aircraft differ in that type 1708-01 has the two faces parallel to each other so would be used on the center line of the airplane whereas type 1869-01 has an angle between the two faces so would be used to one side of the aircraft center line.  Note the bottom flange (4 mounting holes) needs to be level  so that when the periscope if plumb it's tube is plumb.  That way the swash plate will have equal travel in all directions.

Perisocpic Sextant
                D-1 Mount 1869-01
The 2 contact socket is marked 12S-3S.
The other connector has 3 pins and a smaller shell size.
Perisocpic Sextant D-1 Mount Type 1869-01
Perisocpic Sextant
                D-1 Mount Type 1869-01Mount, Periscopic Sextant
28 Volts A.C. or D.C.
Type: 1869-01
Kolsman Instrument Corporation

Top plate is on aircraft skin.
Perisocpic Sextant D-1 Mount Type 1708-01
Perisocpic Sextant
                D-1 Mount Type 1708-01

Perisocpic Sextant
                D-1 Mount 1869-01
Each turn of the crank rotates the periscope
5 degrees in azimuth.  The Veeder root counter is in
0.1 degree increments.  000.0 to 359.9 deg range but
there is not stop so you can just keep going in a circle.

The knurled device next to the switch is an aircraft
lamp holder.

Swash plate with 4 mounting hole bracket on top side.

Perisocpic Sextant
                D-1 Mount 1869-01When the knurled knob is
unscrewed it allows the
air pressure to be equalized.

Bottom plate has the
 4 screws.
The bottom plate (4 screws) is level in the aircraft.
Perisocpic Sextant
                D-1 Mount Types 1708-01 & 1869-01
The ramp with hole for spring loaded pin that I do not have.
                Sextant, Aircraft, Periscopic

On the opposite side from the ramp there's no hole for the second
spring loaded pin in the mount. You can see vertical marks from pin.
Maybe there's a second hole on newer sextant models?
Note up arrow that matches arrow on mount (see to right).
Pin on sextant tube fits bayonet LOCK in mount.
                Sextant, Aircraft, Periscopic
Allignment arrow on LOCK ring.
Bayonet path for pin on sextant.
Azimuth scale inside (o deg), reference mark on outside.
The Veeder Root counter is off by about 4 degrees,
probably an assembly error?

                Sextant, Aircraft, Periscopic


GB704644 Astrocompass and Adapter for Periscopic Sextant, Kollsman
2894330 Astrocompass, V.E. Carbonara (Kollsman Inst Co),Jul 14, 1959,  356/143 ; 356/147 - This looks like the S5807 Periscopic Astrocompass
2239790 Remote Indicator, P. Kollsman & V.E. Carbonara (Square D Co), Apr 29, 1941 - synchro?
2306684 Conductively Heated Pitot Static Tube, V.E. Carbonara (Square D Co), Dec 29 1942,
D114362 Design for a Shell of a Pitot Static Tube V.E. Carbonara (Square D Co), Apr 18, 1939
2225032 Thermionic Relay, V.E. Carbonara (Paul Kolsman), Dec 17, 1940
2262920 Illuminating Means for Instruments, V.E. Carbonara (Square D Co), Nov 14 19341 - lamp installs from panel side
2554010 Mount for Periscopic Sextants, V.E. Carbonara & E.D. McDonnald (Kolsman Inst Corp), May 22, 1951, -
3042296 Celestial Data Computer, V.E. Carbonara & E.D. MacDonald (Kolsman Inst Corp), Jul 3, 1962, 235/61NV - looks like the MD-1
583518  Solar Attachment for Telescopes, P Stoller, Jun 1 1897,
1346412 Astronomical Instrument, E. Meitner, Jly 13 1920,
2077398 Navigating Instrument, J.C. Clark (Ludington Corp), Apr 20 1937,
2444933 Automatic Navigational Director, R.E. Jasperson, Jly 13 1948,
2508027 Celestial Position Indicator and Compass, P.E. Hoffmeister, May 16 1950,
2599381 Axis Converter, I.H. Gerks (Collins Radio), - parabolic dish
2724895 Navigating Device, P.E. Young, Nov 29 1955
2748485 Navigation Course Computer, W.H. Newell (Sperry Rand) Jun 5 1956,
2758277 Linear Phase Detector, J.I. Daspit (Gilfillan Bros), Aug 7 1956,
2762123 Navigation System, O.T. Schultz (Sperry Rand), Sep 11 1956, - uses photo multiplier tubes & 3-axis gyro stablization
2857672 Navigation System, D.O. McCoy (Collins Radio),  Oct 28 1958,
2458654 System and Method of Utalizing Microwave Radiation from the Sun, G.C. Southworth (Bell Labs), Jan 11 1949 - Sun location through clouds for navigation
2672608 Automatic Tracking Mechanism, R.M. Ringoen (Collins Radio), Mar 16, 1954, - cloud tracking?
2599381 Axis Converter, I.H. Gerks (Collins Radio), - parabolic dish
1845860 Navigating Instrument, E.J. Willis, Feb 16 1932,
2077398 Navigating Instrument, J.C. Clark (Ludington Corp), Apr 20 1937,
2444933 Automatic Navigational Director, R.E. Jasperson, Jly 13 1948,
2762123 Navigation System, O.T. Schultz (Sperry Rand), Sep 11 1956, - uses photo multiplier tubes

2998529 Automatic Astrocompass, D.B. Nichinson & J.J. Connors (Kolsman Inst Corp), Aug 29 1961, 250/206.3 ; 250/203.1; 250/203.4; 250/207; 356/139.02
2421012 Homing System, T.W. Chew (Navy), May 27 1947,
2541060 Tone and Density Compensating Device (Faximile Inc), F.A. Hester, Feb 13 1951, - photomultiplier tube
2713134 Radiant Energy Controlled Follow-Up System, H.J. Eckweiler (Kolsman Inst Corp), Jly 12 1955 318/575 ; 250/203.3; 250/203.7; 318/16; 318/489; 318/625; 318/640; 74/5.34 -
Photo multiplier El/Az mount
2941082 Photoelectric Automatic Sextant, V.E. Carbonara, J.E. Manhasset, L.E. Sharpe (Kollsman Inst Corp), Jun 14 1960, 356/139.01 ; 244/3.18; 33/268; 356/148
2444933 Automatic Navigational Director, R.E. Jasperson (Navy), Jly 13 1948,
2462925 Radiant Energy Directional Apparatus, R.H. Varian, Mar 1 1949,
2492148 Automatic Navigating Instrument, R.J. Herbold, Dec 27 1949,
2513367 Radiant Energy Tracking Apparatus, L.B. Scott (Sperry), Jly 4 1950,
2532402 Navigating Instrument for Craft and Pilot Guidance, R.J. Herbold, Dec 5 1950,
2533686 Gyroscopic Sextant, J.B. Peterson, Dec 12 1950,
2762123 Navigarion System, O.T. Schultz (Sperry Rand Corp), Sep 11 1956,
 Bendix A-15 Aircraft Sextant, probably made using the same patent

1674550 Liquid Level, F.L. Hunt & K.H. Beij, Jun 19 1928, 33/380; 33/390  - A-8 sextant (A-10, A-12?)
1703705 Means for Determining Altitude, K.H. Beij, Feb 26 1929  356/148; 362/ - A-8 sextant (A-10, A-12?)
2306874 Liquid Level, E.F. Flint (B&L Optical Co), Dec 29 1942, 33/380; 33/390 - A-8 sextant (A-10, A-12?)

1531615 Aircraft Sextant, F.L. Hunt & K.H. Beij, Mar 31 1925, 356/148; 362/23 -
3181812 Aircraft Sextant Mounting, B.E. Dixose (Northrop Corp), May 4 1965, 244/3.18; 356/139.01; 356/147 -
2316466 Instrument for the Simultaneous Direct Determination of Lattitude and Local Sedereal Time from a Single Setting on the Night Sky, N.W. Storer, Apr 13 1943,
  356/145; 33/268; 244/3.18; 356/148 -
2357390 Optical Instrument, E.F. Flint (B&L Optical Co), Sep 5 1944, 356/146; 356/148  -
2384507 Observation Instrument, T.L. Thurlow, Sep 11 1945, 356/148; 74/810.1 -
2385978 Optical Instrument, E.F. Flint (B&L Optical Co), Oct 2 1945,  356/148  -

Zenith Cameras

2384666 Astronomical Camera, D.L. Wood (Kodak Co), Sep 11 1945,  356/148; 356/249; 396/322; 396/332; 396/429 -
2995992 Zenith Camera System, E.L. Merritt (Photogrammetry Inc), Aug 15 1961, 396/50; 356/148; 356/249; 359/557; 359/665; 396/12 -
2968228 Zenith and Level Recording Camera and Level, E.L. Merritt (Photogrammetry Inc),Jan 17 1961, 
396/50; 33/292; 352/140; 352/170; 356/148; 356/249; 359/555; 359/664; 396/12 -
3164073 Zenith Camera, E.L. Merritt (Raytheon) , Jan 5 1965, 396/432; 33/1.00R; 396/351; 396/428; 396/463 -
2210090 Gyro-stabilized Reference Point for Cameras, F.W. Lutz & J.D. Peace (Fairchild Aerial Camera Corp), Aub 6 1940,
2273876 Apparatus for Indicating Tilt of Cameras, F.W. Lutz & J.D. Peace, Feb 24 1942, -
2384666 Astronomical Camera, D.L. Wood (Kodak Co), Sep 11 1945,  356/148; 356/249; 396/322; 396/332; 396/429 -
2393575 Means for Operating Aerial Cameras for Making Flashlight Aerial Photographs, (Graflex Inc) -
2460836 Level Device Employing a Light Reflecting Liquid Surface as a Horizontal Reference Surface, G.H. Lovins (American Inst Co),
  356/249; 33/290; 33/348; 33/377 -
2468781 Camera control for Bombardment Aircraft, H.P. Roganti,
2792767 Pulse Modified Camera, V.H. Schmidt, May 21 1957, 396/8; 396/387; 396/401 - for high speed cameras
2922346 Photographic Recording Devices, A.L. Smith, Jan 26 1960, 396/332; 396/180; 396/535 - take photo of panel meter
3002278 Method for Space Navigation, P.V.H. Weems, Oct 3 1961, 33/1.0SA; 33/228; 33/268 -
3080801 Zenith Camera System, E.L. Merritt (Photogrammetry Inc), Mar 12 1963, 396/13; 33/331; 359/431; 359/641; 396/315 -

2986966 Stabilized optical system, Braddon Frederick D, Mccartney Earl J (Sperry Rand), Jun 6, 1961, 356/149, 359/556, 359/557 - Celestial navigation from submarine periscope - cold war nuke prior to Transit satellite

Periscope sextant, Tno, Aug 30, 1966, 356/144, 356/143 - for submarines, but has good list of reference patents.
Cited Patent Filing date Publication date Applicant Title
US1006230 * Oct 28, 1909 Oct 17, 1911 F.L.G. Kollmorgen
Keuffel & Esser Co
Periscope.  Classical.  Had prism to keep bottom of image down,
by rotating prism 1/2 angle of objective.
Relay lens system to allow extending retracting.
US1937378 * May 2, 1933 Nov 28, 1933 Gen Electric Sound-motion picture producer
US2384209 * Jul 13, 1940 Sep 4, 1945 Sukumlyn Thomas W Method of producing optical wedges
US2408495 * Jun 19, 1945 Oct 1, 1946 Hudson Wager Robert Smoke inspection device
US2505819 * Jul 26, 1945 May 2, 1950 Sperry Corp Panoramic sextant having gyro stabilized reticle
US2534543 * Jul 21, 1947 Dec 19, 1950 Andrew J Bramlette Light concentrating reflector camera
US2579903 * Jun 16, 1948 Dec 25, 1951 Kollsman Instr Corp Periscopic sextant (see above)
US2758500 * Jul 28, 1952 Aug 14, 1956 Kollsman Instr Corp Optical artificial horizon
US2819404 * May 20, 1952 Jan 7, 1958 Gunther Herrnring Optical image-forming mirror systems having aspherical reflecting surfaces
FR338386A *

Title not available


Mk II Astro Compass
MD-1 Automatic Astro Compass
Periscopic Sextant (used on the P-3, see Hickory Aviation Museum virtual tour below)


A New Periscopic Sextant - Navigation, Volume 1, Issue 11, Virginia Withington - "A transparent astrodome in the top of an airplane permits the use of a hand-held sextant of modified periscopic design, but when installed in a pressurized aircraft its use involves a risk which has sometimes proved fatal to the observer."

History of the Sextant - page 2 with various aircraft sextants
Celestaire - Navy Mark V without AveragerNavy Mark V with Averager -
Garcia Avation - pricey
Deutsche Optik
Helmut Singer Elektronik - stock varies
JANS of London -InstrumentsSignificant events in the evolution of marine navigational instruments
Kollsman -has licensed Carp Industries. (CAGE 0D9X5) to mfg these systems.
CAGE CODE: 0D9X5, Status: A - Active
DUNS Number: 194909032
Voice Telephone: 321-952-1303
SICs: 3728 Current List of SIC Codes
Date CAGE Code Established: 09/26/1988
Last Updated: 01/04/2001
NavList: A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
Carp Industries - Kollsman out-of-production spare parts - Installation & Operation Instructions, Pub #S332C-300-961 dated 09/61 - Government type high prices

Celestial navigation aloft: Aeronautical sextants in the US by Deborah Warner

Hickory Aviation Museum - P3-C interactive tour - Grab circle behind pilot's seat and look up to see this periscope sextant mounted in ceiling of P-3.

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page created 6 Aug 2001.