- Links to overviews of WWII German aircraft compasses. (The WWI compass list is momentarily not available)
- The Royal Airforce Museum's own website also displays many items with their data (via Navigator / search : "compass").
Specialized books : go to Miscellaneous / History and Bibliography.

Aéronautique Militaire
AIRPATH (go to "Standby compass")
Aperiodic Compass
Arcaute (see Navigation)
Armee-Kompass I, II & III

B, B-3A (Type B)
     TURENNE (B.B.T.)
Bearing Compass
CAMPBELL (Bennett)
Centesimal compass
Compass Spirit
Compensation (books)
Consolidated Instruments
COOK Cobb-Slater

Damping Liquid (Spirit)
Dead Beat
Dordilly (see DALOZ)
DR - Distant Reading Compass
Driftmeter (see DALOZ)
Earth Inductor Compass
Emil (German compass type)

FK 5 (P), FK 6 , FK 10, FK 15
Flux Gate or Valve (gyro compass)
Franz / Fränzchen (German compass type)
Functional Test Device (VION System)

Gyrocompass / gyrosyn

HUSON (Smith's ~)

Induction compass

Japanese Manufacturers (WWII)
K.B.B. (see Kelvin, B. & B.)
KELVIN & partners: Bottomley & Baird (K.B.B.), K. & J. White, K. & Hughes
KG-1B (КГ-1Б in cyrill. letters)
KI-12 / KI-13 (КИ-12 / КИ-13 in cyrill. letters)

Le Prieur (see Navigation)
Letecke Pristroje Praha
Lke 11 E, Lkf 5/6, Lkp 4, Lp5

Mark II (s. Air Ministry)

Navigation (Navigraph)
NISTRI (go to OMI)
Northerly Turning Error

OMI (Ottica Mecc. Italiana)
Pattern 200, 223, 259 etc.
PDK / ПДК in cyrill. letters
Pfadfinder für Aviatik
Pinedo's Compass
Projektionskompass (PLATH  PH 10)
PZO Polskie Zaklady Optyczne

Q - R
Radiation, Radium Paint
Radio Compass
R.A.E. / R.A.F. (Royal Aircraft Establishment / Factory)
Repeater Compass
SALZGEBER (s. Star Compass Co.)
SHERRILL (land vehicle compass)
SMITH's Aircraft Instruments
Stand-by Compass
Star Compass Co.
Star Pathfinder (s. Consolidated Insr.)

Tanks and Armoured Vehicles

UGR-4 (YГP-4 in cyrillic letters)

VION (including compasses for land vehicles)
W.D. 32
X - Y - Z
Z9, Z10, Z4h (Plath)
Unknown aircraft compasses

- A -


The Société Anonyme d'Exploitation et de Représentation Aéronautique (A.E.R.A.) was a French company located 29, av. de la Grande Armée, Paris 16e. Addresses in Anvers/Antwerp are also known. It supplied many flight instruments in the 1920s. Its logo featured a bird (woodpecker). The compass type A.M. 1 has been designed by Louis Dominique Joseph Armand DUNOYER (source: L'Aéronautique, Ausg. 16, Sept. 1920) who had filed before WWI several patent fpr ship compasses (btw. 1906 and 1909). AERA is also the designer of a famous drift calculator (link to picture and descr.: dérivomètre, patent no. 451.080, 1913) which could be adapted on top of a compass or a map holder.

Type A.M.1 as described in L'Aéronautique (ed. Febr. and Sept. 1920)

Click on the images for enlarged views.
Technical Data
The compass types A.M.1 & A.M.2 (AM stands probably for Aéronautique militaire) were described 1933 catalogue and in the monthly magazine L'Aéronautique (1920 and ...)

Linkto a three-side-view (excerpt of "1914-1918 L'aéronautique pendant la guerre mondiale" by Maurice de Brunoff, 1919, 735 p.)

Click on the images for exhaustive full descriptions (in French).

NOTE: Not to be mixed up with VION's models AM1 and AM2.
Type Orientation A.M. 2 - 1925

Pics courtesy Jan Valášek

Type A.M. 2 - 1930

Pictures posted by member 'Guynemer'
on the web site
Two models called A.M.2 have been built.
Click on images for enlarged views.

Picture courtesy ailesyport

Ad for model CT (Tourism Compass), type DV10

Picture courtesy ailesyport
Link to description of mod. C in Traité pratique de navigation aérienne by Duval & Hébrard, 1934
- Center and r.: Ad for models B (navigator) and C (pilot)

Figure published in the book Cours élémentaire de compensation et d'emploi by Capitaine Robert Gaujour (1936) giving instructions for compensation (copies available). Below:
View of mod. B 1930 (compl. descr. available in French)

Type E 10 
Fig. at r.: patent 788.079 (1935)
Technical Data
- Dim.: ?
A type E.11 appears in the cockpit of an a/c type AMD 315 (manual dated 1954). This compass is also listed as a type Bianchetti 201.
Type 6 NB - Click on the image to read the relevant descr. published in L'Aéronautique in Aug. 1931

Ad. in 3 languages (Dec. 1932)

Type Ch
Click on the images at left and right to read the relevant descriptions published in the review L'Aérophile in 1936.
Type CT /  DV 10 - Fig. at r.: Patent no. 729.684, 1932


Aero-Compass was the designation of the very first compasses made by Hughes and used aboard aircraft. They had been designed by Captain Creagh-Osborne —hence the engraving C-O. AERO COMPASS (see pic at right - courtesy auction website ViL— and also called the Pattern 255-259 depending on the size and use. Later models were specific for PILOT and OBSERVER (see entry Creagh-Osborne below)

Aéronautique Militaire

The very first compasses used aboard French balloons and aircraft during WWI and in the 1920s featured in addition to the makers name the words AÉRONAUTIQUE MILITAIRE. We know of such compasses made by MAUVE and by VION. The authority called Aéronautique Militaire was a department of the War Ministry. These compasses are also part of the U.S. study called Report No. 128 dated 1923.

Click on the image at left to see a full description of both compass types.


The Air Ministry was formerly a department of the British government with the responsibility of managing the affairs of the Royal Air Force. It existed from 1.4.1914 to 1964. Different types of aircraft compasses were built for the A.M.: the P Series compasses were pilot’s compasses, the O Series being observer's compasses.
During WWII, they were built by several makers. After the serial number on the bezel, a suffix (letter or sign) denotes the manufacturer or another characteristic. They are explained in the Air Publication 1234. Henry Hughes and Sons (later Kelvin Hughes) also made compasses under the trade name HUSUN.

We display here just a few examples: The model 06A, a landing compass was a hand bearing compass for use on the ground (for modern instruments see SESTREL, SAURA). Other compasses installed on-board of aircraft were based on a same design like the P series. Some were equiped with a mirror and the O2 had an azimuth circle.
The compasses used by the RAF were aperiodic compasses, i.e. they settled onto a true course after a turn without overcompensation, this being achieved by means of sophisticated features like strong magnetic moment, small inertia and heavy damping. For further information concerning navigation on RAF aircraft with these compass types and more technical details concerning the aperiodic compasses, please go to cairdpublications.

The following information concerning the various P models' chronology was sent by a friendly visitor. Any complementary data will be welcome:

Picture at right courtesy M. Goosey: A P12 compass (click on the image for an enlarged view).

- P1: Apparently no compass was ever designated this way. This abbrev. stands for a former WW1 compass.
- P2 (see table below)
- The P.3 was a vertical card compass dated about 1930. I suspect (but have no hard evidence) that the designation P.1 was assigned to WW1 RFC (Royal Flying Corps, predecessor of the RAF) compasses that remained in service after the Air Ministry was formed.
- The P4 was a mid-1930s compass and was used in “large” aeroplanes, including the Hawker Hart, Sunderland and early four-engined bombers. It was replaced by the P10, which was identical in size but had four cross hairs rather than two. Some P4's were modified with four cross hairs as P4A. It was the P10 that would have been fitted to the Lancaster rather than the earlier P4, but I have no doubt that P4's were also used when the need arose.
- I have no information about the P5.
- The P6 was fitted to “small” aeroplanes. It was replaced by the P8, which had a slightly larger bezel.
- The P7 was an inverted version of the P6 and was replaced by the P9, which was an inverted P8.
- The P8 was in common use from about 1937 and was used in the Spitfire, Hurricane, Tiger Moth, etc. and was replaced by the P11. There was also a version marked as the P8M (M for 'Modified with four cross hairs').
- The P9 was an inverted version of the P8 and looked similar to the P7.
- The P10 was an improved version of the P4 with four cross hairs.
- The P11 was an improved version of the P8 with four cross hairs.
- The P12 (s. pic. at right) was an inverted version of the P11 viewed via a mirror which hung below the bezel (see picture). It probably was the last magnetic compass in the P Series.


The cardinals (N-E-S-W) and the 10-deg. markings on the compasses were made of a radioactive compound (radium and zinc sulfide/copper) which is still "hot" although the paint is no longer visible in the dark. In 50 cm (1 1/2 ft) distance, the gamma radiation measured is 0.35 µSv/hr (microsieverts/hour). The natural background radiation is about 0.10 µSv/h. The threshold for hazardous radiation is 0.30, this means that this instrument is not dangerous if always kept at this safe distance from the body (10 ft).
Click on picture for an enlarged view

The application of Radium compound paint for letters and figures instruments was described in a patent no. 110,203 (follow link for pic.) filed in Oct. 1916 by F. O. Creagh-Osborne, F. H. Glew, A. J. Hughes and Henry Hughes & Son Ltd.

Read the news about contaminated beaches because of the dumping of decommissioned equipement after WWII.

Pict. Notes on Aero Compasses and their Adjustment (Air Pub. 191, 1918)

(For a drawing of a sectional view with the parts list ask the museum's curator via the CONTACT button)

(Click on images for enlarged views)

Pic. Magnetic Compass in Aircraft (Air Pub. 802, 1920).
Model name: R.A.F.*  Mark II (note: for type Mk III go to HUSUN)
Technical Data

- Dim.:  9½ x 5½ x 5½ in. (240 x 140 x 140mm)
- Weight: 4 lb. 10 oz. (2.3 kg)
- Spherical bowl in a cubic case, inside face of inclined glass window also spherical (same radius as bowl), the correction magnets were located in the "grip"
- Designer and maker: Royal Aircraft Establishment, Farnborough.
Description (in a not quite flawless French ☺) published in La boussole magnétique pour la navigation aérienne. by Capt. Creagh-Osborne, 1916.

This system was especially developed by Dr. Keith Lukas to overcome the phenomenon called Northerly Turning Error (description in Air Publ. 802 - ask for copies).

* Royal Aircraft Factory, Farnborough

Pic. Magnetic Compass in Aircraft (Air Pub. 802, 1920). Comprehensive description available: ask for copies

Details: see at right

(Click on images for enlarged views)
Type 6/18 - Aperiodic Compass - Mark III
Technical Data:
Inventors: Campbell & Bennett, England from 1918 onwards until superseded by the models described below.
- Dim. (height x dia.): 4½ x 6½ in. (115 x 166 mm)
Printed onto crew members training poster (see enlarged view):
Printed below border: "16604 W.977/13657 4/25 R. & L. E.2858"

Original photograph by courtesy of powerhousemuseum post-edited by Jaypee for COMPASSIPEDIA
MARK IIIA Aperiodic Compass
version 1924, HUSUN

Pic. courtesy History of Air Navigation by A.J. Hughes, 1946

Most compasses correspond to a defined "Pattern". See overview HERE.

(see definition and procedure HERE )

1 - HAND-HELD TYPE 04 and 06
Stores* Ref. 6A / I.248
* see menue Miscell./Terminlology, successor of Pattern 254


General description and section view


(Photocopies of AM compass manuals can be ordered)

* A landing compass is used to "swing" the compass installed in the fully equipped aircraft i.e. to write a table with the deviation values (description in the Air Pub. 802, photocopies available). See also BOES below.

(Click on the pictures for enlarged views)
Technical Data
- Diam.: 3.8 in. (95 mm)
- Overall length: 9 in. (190 mm)
- Weight: 2 lb. 4 oz. (approx. 1 kg)
- Serial no.: 38899H (H = Hughes)
The Air Ministry logo (see pic. below) was not engraved on all items. Some featured only the Army's broad arrow ("crow foot").

The compass card's winged North symbol (mirrored view):

Certain characteristics like the divisions ring and N-S arrow are maybe evolutions compared to the Type P.1.


(Click on the images for enlarged views)
The system was apparently gimballed like ships compasses.

Pictures courtesy G. Rooney

The casing without the divisions ring.
The aircraft's axis (direction of flight) was represented by means of a long pin located on the casing's side wall opposite to the word AFT. The card's south-north axis was enhanced by means of an arrow featuring a letter S at one end and a letter N in a red triangle at the northern end. The arrowhead features two bird wings with feathers like on the TYPE 06A's card above (click on link for pic).
Technical Data  
- Height: 3 18  (80mm)
- Dia. (top rim): 6 ½ in.  (165mm)
- Dia. (base): 5 ½ in.  (140mm)
- Dia. of compass disc: 2 38 in (60mm)
Markings: Type . P. 2 . (with the three dots!), AFT, No. 195 D.

The card already featured the spider leg-shaped damping wires (see also the exploded view of Type P.6).

The card supplier's name in the north symbol (stylized fleur de lys) is HUSUN (click on link for pic). The center letters are masked by the S-N arrow. This is the abbreviated trade name of H. Hughes & Son Ltd.

Front view (compass)

(Click on the images for enlarged views)
LH and RH views:


Pictures courtesy aspentree123
Technical Data
Compass type: vertical type, free rotating sphere
- Height: 10 in. / 250mm
- Dia. of compass window: 2.25 in. / 55mm
Weight: 3 lb 11 0z. (1.66 kgs.)
Type P3, S/No. 734 H* and a large letter M in white paint; Stores Ref. 6A/O.224
- Compass casing: brass; mouting frame: aluminum, grip: wood
Type P4, P6, P8 compasses
Stores Ref. 6A/O.227, .367 and .726
These compasses had apparently the same shape. Only internal technical details vary.

P4 top view and exploded view of P6
(Click on the images for enlarged views)

Side view:

A P4 in situ in a Lancaster bomber's cockpit
(Cockpit picture by courtesy of

For a FOOTAGE (part 1 of 2) about low-level navigation and compass use click on the image below:

Youtube footage about low level navigation
Technical Data

P4 - Built in (Lancaster?) bombers
- Diameter: 7 ¼ in. (184 mm)
- Weight: 5 lb. 14 oz (approx. 2.5 kg)
- 4 magnets

P6 - Built in ...?
- Diameter: 5 38 in. (136 mm)
- Weight: 2 lb. 4 oz (approx. 1.2 kg)
- 2 magnets

P8 - Built in Spitfire
- Diameter: 5 38 in. (136 mm)
- Height: 3 in (77 mm)
- Weight: ... oz (approx. 0,821  kg)

Side view of the casing which is shallower than the other models of the P-Type series
Pictures courtesy T. Kent
Click on the images for enlarged views
Technical Data  
- Height: ... mm
- Dia. (top rim): .. mm
- Dia. of compass disc: 4 in. (100mm)
- Markings: Type P4A 

General description and section view (above)

Photocopies of AM compass manuals
can be ordered

Click on the images for enlarged views
The P4 compass was also available in an inverted overhead panel version (click on the image for a view of the aircraft cockpit)

A compass stowed in its transit container
Type P7
Stores Ref. 6A/O.430

Pictures courtesy G. Rooney
(Click on the images for enlarged views)
General description and section view

(Photocopies of AM compass manuals can be ordered)
Technical Data
Type P7 aircraft course-setting compass with illuminated grid and a mirror in the base to reflect the compass reading.

- Diameter: 5 ½ in.
- Height: 8 in.
- Weight: 4 lbs. 8 ozs. (approx. 2.3 kg)


Side view, simplified crown

Pictures by courtesy Cl. Waldteufel
Technical Data
- Dia.: 161 mm
- Height: 120 mm
- Weight: 1.021 kg

At r.: A P8 in RAF blue-grey on its container


Pictureby  courtesy M. Goosey
Click on the images for enlarged views

Picture by courtesy D. Broughall
Type P.11
"Designed in conjunction with the Admiralty Compass Department and manufactured by Kelvin & Hughes Ltd."

Description: slightly smaller than the P10.

Type P.12
See list of compasses above and picture of blue compass at r.
(full text available for P. 11 and P.12)

Fig. 14 - Exploded view
Type O.2 and O.3  with azimuth circle
Stores Ref. 6A/O.380

Picture at left courtesy J. Richardson
Pic. at right: O.3 (centesimal system)

General description and section view
(Photocopies of AM compass manuals can be ordered)

Link to a description of O.2 & O.3 in
The Aircraft Engineer's Handbook
Technical Data
- Dia.: 6 ¼ in.
- Weight: 6 lb. 2 oz. (approx. 3 kg)

Azimuth circle
(stores Ref. 6A/O.411)

Click here for a FOOTAGE about a compass in perfect condition.
Type SO2 - Stores Ref. 6A/1078

Picture courtesy 28peche
(Click on the images for enlarged views)
Side view of prism and lamp fitting

Technical Data
- Diameter: 16.5 mm
- Weight: ?

Bomb Sight Type D
Stores Ref. 6E/O.276

This instrument is primarily designed for use in the course-setting bomb sights Mk VII A, B and C.

(Click on the images for enlarged views)
General description and section view

(Photocopies of AM compass manuals can be ordered)
Technical Data
- Diameter: 4 in.
- Weight: 1lb. 11 oz. (approx. 750 gr)


ALBATROS, Tell-tale Compass

This WWI German Aircraft (see Wikipedia) featured a tell-tale compass (read description on enlarged view of picture at right courtesy FLIGHTGLOBAL/Archive online, 1915-0954).


A system called ANDREWS Inverted Compass is cited in the U.S. document Serial Report no. 1720 - Experimentation (s. a. R.A.E. / R.A.F.).
We have no picture of it. It can be similar to the Air Ministry Type P.4 with mirror.

Aperiodic Compass

Literally, a compass without a period, that is, a compass that, after being deflected, returns by one direct movement to its proper reading, without oscillation. Also known as Dead Beat (link to a pic of a HUSUN nautical compass). This type of compass was invented by G. R. C. CAMPBELL and his technical solution implemented in most Air Ministry compasses (see above).
Description published in Aircraft and Flying by F.V. Monk and H.T. Winter, Gresham Publishing Company, London, 1934):
"The "dead-beat" action is attained by making the magnet system very light (no card is attached to it) and including in it eight radial filaments. The whole of the remaining space under the glass lid is filled with spirit and it is the resistance which this liquid offers to the motion of the filaments which quickly brings the system to a standstill."

The cardinal points references are placed on four of the filaments. The azimuth degree marks are shown on a rotatable verge-ring that carries a set of parallel grid-lines running in the north and south direction, and the pilot steers his course by keeping the lines parallel to the long north and south pointers of the needle system. The verge-ring is previously set for the desired course by pressing down the ring, turning it till the degree mark of the course comes against the forward lubber line, and then releasing (source: History of Air Navigation, by A. J. Hughes, 1946).


Inventor of a drift assessing instrument called "estimateur" - see NAVIGATION

Armee-Kompass I, II & III

German WWI compass models built by LUDOLPH and by PLATH. Go to the relevant entries to these makers.


German manufacturer (more information HERE). The confidential three-letter-code during WWII was bxx (click on link for pic.).
Pic. at right: Manufacturer's flyer for gliders compasses.
Click on image for view of the glider compass types Fränzchen and Kleiner Emil ** 

See also Wrist, Marching and Nautical compasses.

Orterkompass (Observer compass) type Lkf 5b Franz* and Lkf 7 Fränzchen** (Little Franz)
Supply no. Fl.23203-1,
predecessor model of OK 38
This instrument was also produced by C. Plath and W. Ludolph.

Enlarged view of the compass card:
click on picture at r.

Technical data
- Dia.: 120 mm
- Height: 80 mm (case) + 50 mm (glass dome)
- Weight: ca. 750 g (w/o attachment parts)
- Techn. Data in the ASKANIA catalogue***.

Photographs and description in the book Luftfahrtnavigation (Sönnichsen, 1940, see menue Miscell. / History and Bibliography)
Type Lke 6/7 kleiner Emil** (little Emil) and Lke11 Emil*

Note * : During WWI the nickname for pilots was Emil and for observers Franz. Source: souvenirs of the WWI ace Ernst Udet in Mein Fliegerleben, 1935, and in French translation Ma vie et mes vols, 1955 (no Engl. translation known).

Pics from  ASKANIA BORDGERÄTE***, Sonderdruck AERO 510, 1937/38 (flight deck instruments, Special issue)
Technical Data
Note ** :  The light-weight smaller versions (1/3) of these Instruments (made for gliders and tourism aircraft) bore diminutive designations like kleiner (little) Emil and Fränzchen = little Franz.

Photographs and description in the book Luftfahrtnavigation (Sönnichsen, 1940, see menue Miscell. / History and Bibliography)
Großer Peil-/Orterkompass Lkp 4
(large bearing/observer compass)

Technical Data

- See ASKANIA BORDGERÄTE (Sonderdruck AERO 510, 1937/38)

Fernkompass (pneumatic tele compass)

Ad. published in 1941
Technical Data
The assembly comprises the following parts (table: picture of the catalogue)

At right: functional drawing
See also patent no. 711,582 - 1938/1941
Kompensier-Peilscheibe Lp 5
(compensation bearing disc)

Pictures courtesy Jan Hessels
Technical Data
Link to Description in the book Luftfahrt-Navigation (Sönnichsen, 1940)
Description in catalogue (click on image below left)


An astrocompass is not a real (magnetic) compass but an instrument used in aircraft like a sextant on ships to determine the direction of true north and read one's true heading by taking aim at a celestial body with reference to the data of an almanach. See the tutorial "Use of an astrocompass" on Youtube:
( )

A Facebook entry also describes an inverted astrocompass.


Joachim Richter was a German watchmaker located Am Wald 2, Ende Erzbergerstr. 75 Karlsruhe 31. Miscellaneous aeronautical equipment. Automatic watch Model 08/15 Military (pic. Maistero/Watch Lounge). He also built at least until 1945 pilots' goggles (pic., mod. 1935).

Model FK.16
(Führerkompass = pilot's compass)

Pictures Henri Note (click for enlarged views)

Technical Data
- Weight: 206 gr
- Depth: 60 mm
- Diam 57 mm
The FK16 is a LUDOLPH development and product. It is also integrated in their navigation equipment for divers.


- B -


This instrument made by SPERRY-BADIN is a simple compass gyro activated by air flow. Inscription: "L'appareillage aéronautique" (APA). This company was created in 1923 and was the successor of the Laboratoire Badin (shop for aircraft instruments) created in 1911 by the famous inventor Raoul Badin.
Description and Technical Data: click on picture at right.


In its 1910 catalogue, the French compass maker and retailer VION displayed two pocket compasses with transparent glass bottom, stating that this design was specially conceived for ballooning. The other compass (on the enlarged image of the catalogue) was probably made by S-L. See also BORDÉ.

Special compass for ballooning as shown in the VION catalogue
 (c. 1910)

Click on picture above for full descr.
Technical Data
- Diameter: 45 mm
- Depth: 12 mm
- Weight: 40 gr
- Manufacturer: Houlliot
- Serial no.: 56 (punched on the side)

It was carried in a leather pouch with snap lock and a large round window. Early 20th c.

Printing plate for catalogues of Houlliot compass retailers
(s. F S & C)


Carl Bamberg was a German compass manufacturer located 87-88 Kaiser Allee in Friedenau near Berlin. The compasses were installed in aircraft and airships. For more information click HERE. See also Nautical and Pocket Compasses.
At right: Ad published in the book Der Flugzeugkompass (Gansberg, 1917)
C. Bamberg developped the first remote indicating compass called tele-compass. "Its liquid magnetic compass (period of 25 secs.) is mounted in gimbals. A free magnetic element in the form of a float carries a metal disc cut in shape so as to act as a shutter in regulating the passage of light projected upwards from the base of the bowl by two electric lamps diametrically opposite each other. The light rays from each lamp are focussed by a lens upon a corresponding photo-electric cell. [...] The cell forms two arms of a Wheatstone bridge, which includes a galvanometer used as a course indicator. D.C. is supplied to the bridge. A small deviation from the set course unbalances the bridge and is indicated to the pilot by the deflection of the course indicator hand to the right or left as the plane deviates therefrom"  (source: A. J. Hughes, History of Air Navigation, p. 105). Link to Pictures (courtesy K. Kracheel, Flugführungssysteme, 1993).
NOTE: Read full description in English in the relevant British patents no. 147,194 and 147,215 (1920). The original German patents have not been discovered so far. They were applied for before and during WWI in 1913 and 1917. See also the modern system developed by Messrs. Huhn and Kistenich for model U-Boats.
The book Navigation und Seemannschaft im Seeflugzeug (Navigation and seamanship for flying boats) by Theo E. Sönnichsen, 1918, describes the three versions produced, i.e. the compass as installed in the pilot's or observer's seat, the overhead (tell-tale) compass installed in the upper wing and the one installed in the lower wing.

Picture courtesy Horst Kahnt

Technical Data

- Diameter: 115mm
- Height: 84mm
- Weight: ... g ?

Above right: The compass of the  Zeppelin L-31

Picture at r. courtesy Jan Hessels
(click on the images for enlarged views)
Plain version in only two colours with black course pointer

Technical Data
- Diameter: 150mm

Picture courtesy G. Schlumbrecht
The compass installed in the pilot's or observer's seat with its battery, lamp and rod for compensating magnets

Section view  

NOTE: The tell-tale (overhead) version (see pic. at r.) didn't necessitate compensating magnets.

Two views of the overhead version

Patent no. 491,359 filed in 1930 by Bamberg & Askania

Compass rose with manual setting of the flying route angle.

Barbier, Bénard & Turenne  (B.B.T.)

The French company Etablissements Barbier, Bénard et Turenne (B.B.T.) was created in 1862 and closed in 1982). It was located 82, rue Curial, Paris 19 and was successors of KRAUSS. It produced in the 1930's / 1940's compass types called Type 120, 700 and 900, the models designed by MOREL and also ships compasses together with Doignon (read also the French Wikipedia). Compass type CR12 Mengden tracker: s. MOREL.

Type 700 - Technical Data
Dim. (ext. dia. x ht.): ... x ... mm
Photograph of the compass as published in Colonel Gaujour's instructions for the compensation of compasses (1946)

Type 120 - Technical Data
Dim.: ... x ... mm - Patent: see MOREL's  "Small compass" type E10. Photograph of the compass as published in Colonel Gaujour's instructions for the compensation of compasses (1946), compare to VION's Type 150

Type 900 - Technical Data
- Dim. (ext. dia. x ht.): 135 x 170 mm

Pictures courtesy pseudo17dom

Photograph of the compass in Colonel Gaujour's book on compensation of compasses (1946)


David Barker of Greenacres, WA (US) was granted a patent (no. 104,224) in Aug. 2002 for a head-up display compass featuring a mirror-imaged compass rose (see pic at right). Read a short description HERE.

Bearing Compass (Pelorus)

A bearing compass or pelorus is used to measure the angle between an object the position of which is knwon (church tower) and one's own position or more specifically the axis of one's vehicle (read PELORUS in the Nautical Compasses section). It used to be an important tool to calculate the compensation of aircraft compasses with and without bombs.

Bearing compasses made by ASKANIA and PLATH
Excert : Les compas d'aviation du Capitaine Gaujour, 1936

NOTE: French designation TAXIMÈTRE, German designation PEILSCHEIBE

Procedure and fig.


BENDIX Aviation Corporation is a U.S. company created in 1928 that merged with PIONEER. Inventors like Adolf URFER, G.V. RYLSKY (see table below) and Ch. H. COLVIN filed patents for Pioneer and Bendix. For more information go to "Rockwell  Collins" in Wikipedia.

Copies of the patents listed on the label are available
Technical data
Dia. (dial): 100mm (5 in)
Manufactured approx. in 1940

Picture courtesy Ames Swartsfager - Click on the images for enlarged views

The upper plate masks a lamp.

Pictures courtesy Tony KING
(Click for enlarged view)

Rear face (connectors)

Technical Data
- Breadth: 87mm
- Height: 80mm
- Weight: 883gr
Markings: BU. AERO. U.S. NAVY

F.S.S.C. No.: 33-C-800
MFR'S Part No.: 1822-1-B

Patent no. 2,188,821 for a new system allowing to uniformly illuminate a compass rose (1938). Rylsky also filed in 1940 a patent (no. 2.227.368) about the internal electrical illumination.

 (Click on image at left for view of full page - Photocopy available)

"The novel means of the present invention comprise a transparent ring of light-conducting material (40) [...] composed of glass, quartz, "Lucite" or any other suitable material. The light from a lamp (42) may be introduced in the ends (40c) of the ring and conducted thereby around the periphery of the compass. The ring-light is provided with a plurality of light-reflecting surfaces (fig. 2, 40a and 40b) extending around the circumference of the ring, the reflecting area of these surfaces gradually increasing in amount of the distance as the distance from the light source increases."

Model D-12
The patent above was implemented into the model D-12

Cut-away view (Installation instr.)
TYPE 1829

This compass was used in all sorts of land vehicles incl. tanks. It is said to have also been used in aircraft (Installation Instr. avlbl.) but we lack evidence.

Pictures courtesy priv. coll.
(Click on images for enlarged views)

The flight instrument below is a radio compass indicator. It is not a compass per se but an indicator that has a needle coupled to a synchro motor that is coupled (via a 5-wire cable, connector PL 118) to another device or mechanism that actually performs the compass function (e.g. flux valve). The knob labeled VAR allows the calibrated direction ring to be set (E-W) for variances in magnetic declination that is different at all localities over the world and varies over time (especially as the airplane proceeds in an East-West direction). Magnetic variation is noted on maps and aeronautical charts which allows the pilot or navigator to correct for this variation as the airplane proceeds from one location to another.
(This definition was kindly given by LLoyd Crawford.)

(Click on the pictures for enlarged views)
Radio compass / Signal indicator I-82-A
Signal Corps U. S. Army
S/N: 4771
Period: WW2

Technical Data
- Diameter: 13 cm
- Depth: 9 cm
- Weight: 600 gr

Picture courtesy worldconflictimages
The next step was the integration of the compass into a complex instrument called Air Position Indicator (ad published in 1944, Japan is burning...).
Picture courtesy worldconflictimages

BÉZU Maurice

M. Bézu was an inventor who was granted many patent among others for magnetic compasses and the related devices like flux gates and repeaters. He created in 1945 The company called 'établissements BÉZU', then in 1957 the company 'société d'études et de réalisations électroniques SERE-BÉZU' which became a subsidiary of SFIM in 1970, then of SAGEM later.

Picture at right: Patent no. 980.822 (1951)    


W. W. BOES Company was a U.S. company located 3801 Salem Ave. in Dayton, Ohio (created in...? existed until...?).
Products: astrocompass, compass swinging sight (table below).

Click on the image for an enlarged view in working position as shown in the original user instruction
Instrument used to perform the operation called SWINGING.
Read more details HERE.

Click here for viewing an ad dated Sept, 1943.
Technical Data
- Diameter: ?
- Depth: ?
- Weight: ?
- Supply designation and no. :
Sight, compass swinging, 42013536


Paul Alphonse Barthélémy BORDÉ (b. 4.4.1872; d. 12.12.1942) was a French engineer, airship pilot and optician. The company created by his father in 1856 was located 99, Bd. Haussmann in Paris.
The engraving on the compasses: Breveté SGDG (standard French patent mention = see Miscell. / Terminol. / Abbrev.) refers to the patent no. 427.490 filed in 1911 for a compass with a course and a drift pointer. The instruments displayed in the first row were probably prototypes specially manufactured for filing the patent. They were kept by the inventor's heirs together with several other compasses maybe made by wholesale makers. Several versions of the rotating card are known (s. below).

Pic. at right: Ad published in the list of participants in the 1910 world fair in Brussels (click on image for view of products scope)

Pictures courtesy of Chr. Bordé

Technical data
- Diam.: mm
- Thickness:  mm
- Usage: on-board airships

Pictures at r. courtesy E. Gosteli

Technical Data
- Dia.: 82mm
- Height: 58mm
- Usage: on-board airships

Pic. at r.: ad published in
L'Aérophile in 1912

- C


George Richard Colin CAMPBELL, Lieutenant-Commander Royal Navy filed together with Prof. Geoffrey Thomas Bennett, both members of the Admiralty Compass Observatory / Compass Department in 1918 a patent (no. 127,135 - copies available) the principle of which was applied in almost all compasses produced for the Royal Air Force (s. the Air Ministry models): a double cross of eight wires allowing an optimum damping of the magnet needle's oscillations in the fluid. These compasses were called aperiodic. He had also filed together with Geoffrey Brancker HARRISON (Commander, Royal Navy) another patent for a stabilized compass (no. 125,791) with a solution for the northerly turning error problem.

The aperiodical compass designed by Campbell & Bennett

Fig. and description
(excerpt of Report No. 128)

Click on images for full view and text

Fig. of the UK issue of the patent
(compare to the Fig. of the US issue no. 1.341.296)

Fig. published in the Campbell-Harrison patent no. 125.791


Centesimal Compass

Special compass developed by Hughes & Son. Several instruments featuring this very unusual (and short-lived) gradation (link to comprehensive description) are known: the types O.3 and Pattern 253 A.C. (Aperiodic Centesimal). They were described among others in the FLIGHT review, issue July 25, 1929. A WWII Japanese compass also features the four wires numbered 0-1-2-3 but the dial is a conventional one.

Picture courtesy T. Marett

Pic. published in The Aircraft Engineers' Handbook by R. W. Sloley, sixth ed. 1953)

Pic. published in Aerial Navigation by A. J. Hughes, 2nd ed., p.10 & 11, courtesy Muzeum Lotnictwa Polskiego (
Museum of Poland's Aviation)

Pic. published in Aerial Navigation by A. J. Hughes, 1st ed. 1923, p.15


Eric Hollocoombe CLIFT (51, Sinclair Road Kensington W., London - born 28.9.1874, d. 22.11.1922, read full data record HERE) was an engineer. He filed a patent (prov. spec. 13,203 / no. 3404/1911) for a compass system featuring a device allowing to mark a course and a transparent bottom to follow the drift while looking at the ground (compare to the French DALOZ system). Compasses designed by E. H. Clift and produced by H. Hughes & S.

Technical Data
Click on the thumbnail images at left to view large-size pictures and read full description on the National Maritime Museum's web site (Royal Museums Greenwich).

Drawings below courtesy Flightglobal / Archive (online).

Shock-mount described in the patent 

Figs. of the patent

Click on images at left for full view of the FLIGHT MAGAZINE articles


See Rockwell Collins in Wikipedia - Products: radiocompass, compass slave indicator


Charles H. Colvin filed in 1920 a first patent (no. 1,334,273) for a compass that could be simultaneously read from either side and the top so that pilot and observer could use the same instrument even if not seated at the same level. He was in 1922 assignor to PIONEER when he filed a second patent accepted in 1928. This compass is almost identical to Hughes' HUSUM model below.

Figures on patent (photocopy available)

Announcement published in a patents review

Click on images for full view and text
Figures on patent no. 1,679,764

Compensation (book)

Official Air Publications published by the british Air Ministry:  
Notes on Aero-compasses and their adjustment (Air publ. 157, London 1918)
Remarks on compasses in aircraft by F. Creagh-Osborne (Air Publication 802, London Nov. 1920)
Compass types dealt with: Patterns 253, 256, 259, 5/17, 6/18 and R.A.F. Mark II.
For similar books in French go to Creagh-Osborne (below) and via the menue point Miscell. / History & Bibliogr. / Early days of Aeronautics: Les compas d'aviation - Cours élémentaire de compensation et d'emploi by Capitaine Gaujour, 1936, dealing with the compass types AERA, MOREL and VION. BBT-compasses are dealt with in the 2nd issue published in 1946.
You will also find there a German publ.: Der Flugzeugkompass, Kompensieren und Handhabung (Ganzberg, 1917).


The U.S. manufacturer Consolidated Instruments Co. of America Inc. (located at two different addresses in N.Y. city in 1928 and 1929, see ads below) built in the late 1920's a spherical compass called Star Pathfinder Type F and P. The company's logo was a bird's wing.
Apparently this compass type is a further development of the instrument patented by Gustave A. Salzgeber and made by the Star Compass Company.

(Click on the images for enlarged views)
Technical Data
- Dimensions (ht. x br. x dp.): 6½ x 4¼ x 3¼ in. (163 x 106 x 80mm)
- Weight: 2 lbs 8 ozs (approx. 1.250 kg)
- The front plate was available with two different shapes: Type F and P

(Pics at left courtesy, ads in Popular Aviation magazine 1928 and AeroDigest 1929)
Ads (1928/1929)

(Click on images above for more ads)


WWII ace Flight Lt. Harry COOK designed a special compass for sailplanes and described it thouroughly in the December 1956 issue of Sailplane & Gliding (3 pages).

Click on images for enlarged views
Technical Data
This compass type was designed to avoid specific problems arousing when the fluid kept turning in the bowl after the plane circled in thermals. The first version was not gimballed. The indicator is a dart pointing to a divided circle on which E and W are swapped, indicating thus directly the heading.
Manufacturer: COBB-SLATER Instruments Co. Ltd (acquired in 2007 by BNL)


Captain Frank Osborne Creagh-Osborne (1867/1943) was Superintendent of Compasses at the Admiralty and a British inventor. He developed several compass systems which were manufactured by H. Hughes & Son Ltd, Dent & Co & Johnson Ltd and also by Sperry Gyroscopes and wrote several books about the development and use of aerocompasses (see also the sections Marching Compasses and Wrist Compasses).  In 1915, Henry A. Hughes took part in a meeting at the Admiralty and explained the advantages of this compass (source: minutes of meeting in 'Improvements in prismatic compasses with special reference to the Creagh-Osborne patent compass' - Ask for a copy). The application of Radium-compound paint for letters and figures instruments was described in a patent no. 110,203 (follow link for pic.) filed in Oct. 1916 by F. O. Creagh-Osborne, F. H. Glew, A. J. Hughes and Henry Hughes & Son Ltd.

Creagh-Osborne published in 1915 the booklet The magnetic Compass in Aircraft) . He described therein not only the Pattern 200 but also the compasses utilised by the observer, i.e. attached to his wrist (or leg) by a leather strap and in Kite balloons (see menue Miscell. / History & Bibliography - copies available). According to Ellis Island's immigration records, he landed in New York on June 8, 1918 on board a ship called Olympic arriving from Southampton.
The compass made by KELVIN (link to pic. of Pattern 200) was also designed by Cptn Creagh-Osborne.

Click here for a view of the manufacturer's label of H. HUGHES & Son Ltd. (see below).
Air Compass Type 5/17

Pictures courtesy mfc80

For the Type 6/18 compass check "Air Ministry".
Technical Data
- Dimensions: 6½ x 558 x 4 in.  (165 x 143 x 100 mm)
- Weight: 2.5 lb. (1.25 kg)
- Divisions: 360 deg. every 10
- "upright compass"

This extremely simplified compass was used in the famous WW1 Sopwith RFC/RAF aircraft. The figure 5/17 means design-appproved May 1917. More than 50,000 pcs were built. (Source: Steady as she goes, Fanning, 1986).

For the R.A.F.
- Others : check also the "Pattern" entry.
Early compasses were described in the document Aircraft Mechanics Handbook (1918, no pattern indicated)

Pattern 253

Description of Pattern 253 in the U.S. Report No. 128 dated 1923 (excerpt).

At right: view of a Pattern 253 signed HUSUN featuring SOUTH in Dutch language, Z for ZUID (Pic. courtesy P. Collis).
Description and user instructions for Air Compasses (French edition)

Below: The English issue (attention: the content is not identical with the French version!). A special protractor was included in a pocket.

Pictures courtesy S. Wiggins

(Click on the images for enlarged views)
Instrument panel compasses
Pattern 255 and 259

Pattern 255

Pictures courtesy Th. Wimmer

Marking on the front side of a PILOT's compass
Marking on an OBSERVER's compass (link to pic.)
The patent numbers indicated on the compasses (1148/15 and 17736/15) refer to the application documents and the year 1915 (copies available).

The compass type described in Pat. no. 17,736 is for the patterns family 255/259. The numbering started in 1913 with pattern 200 and the compasses were issued from 1915 on.

Patent no. 1148 describes several prismatic and liquid dampened compass types displayed in the Marching and the Wrist compass departments.

Observer's wrist compass Pattern 261 BLACKER-Type and wrist marching compass


Side/top view with the manufacturer's label of DENT & Co. & JOHNSON Ltd.
Air Compass Pattern 259

Technical Data
- Dimensions (height x breadth): 152 x 135 mm
- Depth (w. lugs): 108 mm
- Depth (w/o lugs): 89 mm
- Weight: c.1.7 lb.
- Divisions: 360 deg. every 10.
- Fluid damping

A marching compass Pattern 261 fixed on a tripod with micrometer reading is used as a landing compass.

Pictures courtesy N. Godrigde
In the ad published on the booklet's cover, this compass doesn't feature the rear (and fore?) sights.
The compass itself is described in the section Marching Compasses.


- D -


Gaston-Jules DALOZ (living in Ramerupt, Aube, France) filed in Aug. 1910 a patent (no. 419.682) for a system that permitted to follow the displacement of the landscape on ground through the transparent card of a compass (see detailed description and comment as published in FLIGHT no. 107, iss. Jan. 14, 1911). The parallel lines were introduced via an additional patent in Nov. 1910.
The device was then further developed by Abel-Louis DOIGNON* (patent no. 431.275, May 1911) who added a liquid damping and mechanical solutions permitting a rapid (re-)setting.
In spite of this, the compass was not to be used as such (no cardinals) and the pilot needed a navigation compass. The system was first applied in 1920 by Le Prieur (cinémo-dérivomètre S.T.Aé.) who invented later the Navigraphe (see Navigation) and also adapted as a drift assessing instrument and called dérivomètre Dordilly (L'Aéronautique no. 93, Feb. 1927, p. 53) and dérivomètre Salmoiraghi (L'Aérospatiale no. 215, April 1937, p. 51).
* See Doignon's marching compass.

The original Daloz-Patent
(Cover 9 2/4" x 1 ft)

Original drawing of DALOZ's system

Version with grid (in Les merveilles de la science, chap. Aérostation Aviation by Max de Nansouty,  Boivin ed., 1911)

The further development
(DOIGNON's patent)

Damping Liquid (Spirit)

The oscillations of a compass card are damped by a liquid, generally destilled water and a small percentage of pure alcohol to avoid freezing. During WWII the RAF maintenance shops were supplied with such bottles. They were and transported in a wooden container filled with damping wood chips. These box and bottles were supplied by Kelvin-Hughes (s. marking on label: Maker K-H) but with no Part No. (NIL).
Technical data - Bottle: Ø 95mm, 240mm long, content designation 6B/373 Compass Spirit, Qty 1 quart. Container size: 360 x 340 x 210mm; total weight: 15 pounds. Supply markings (labels on container) : 6B/373 Compass Spirit and 6/Stores/36356/CB.41B.
NOTE: This item is for sale. See more pics in the SHOP.


Jacques Jules-Marie DELSUC was a French engineer who is considered as the main inventor of the gyroscopic compass. He filed several patents between 1938 et 1947. His system was called Carpentier-Delsuc (in Col. Gaujour's book) because it was built in the plant Ateliers (Jules) Carpentier, 20, rue Delambre à Paris. List of French patents: 794.310, 810.985, 847.055, 921.822. US patent : 2.247.288 (copies available).


Deperdussin was a French aircraft manufacturer (see Wikipedia) located 19, rue des Entrepreneurs, Paris.
This instrument with a very unusual design was invented in 1912 by Gaston Emile Colombel who lived 50, rue de Moscou, Paris (Frebnch patent no. 427.928, 17 Aug. 1911, British pat. no. 26,282). It was installed in the following aircraft during the first crossings of the Channel, three of them in thick fog: Biélovucie flying a Hanriot machine, Moineau flying a Bréguet, Prévost a Deperdussin, Guillaux a Clément).
The brochure & catalogue (13 p., photocopy available on request) also contains exerpts of letters sent by pilots after winning races:
- Crossing of the Alpes by Biélovucie in 1913.
- Coupe Pommery (1,129 km) won by Guillaux in April 1913.
- Races Paris-Amiens-Paris and Circuit Forézien (400 km) won by Molla. The latter flew the best time on the 1st leg of the waterplane race from St. Malo to Jersey and return in thick fog (letter dated Feb.1913).
A. Védrines thanked the inventor Colombel in the name of Serbian Air Force pilots.

Model MONODEP 1912
Dampening of vibrations by means of springs.

The Monodep in the Report No. 128 dated 1923 (read descr. in the enlarged view)
Model MONODEP 1914
Gimballed item, scale with MILS divisions (1/4 of full circle = 1600)

(Click on images for enlargement)
Technical Data - (Functional description / patent's fig.)*
The compass magnets are concealed in the bowl. The visible card rotates in a vertical plane and is linked to the magnets via a right-angle gear. Only the cardinals are painted on the card (red star for North). The route to be flown is set on the external scale (graduated 90° or 1600 MILS for a full circle) by means of an arm linked through the cover glass via a 1:4 gear to a second arm terminated by a red star which indicates the position of the card's north red star. A full circle of the scale corresponds thus with only a 1/4 of the card's rotation. The heading measured on a map is set via a special protractor and the external arm on the scale. The pilot only has to make sure that the two red stars remain superimposed.
Model 1914 featured an integrated lighting with a battery which could be replaced in flight (6 hrs life time). The card was divided into four quarters of different colours and called Capitaine ROISIN after its designer.
The magnetic declination could be set during production.! This seems surprising now but in those days, the aircraft range was not big enough to make an in-flight adjustment necessary.
* The patent describes a flat instrument.


Jacques De Vries et Courbet, 17 rue des Pruniers, Paris, was a French manufacturer of photographical equipement.

Technical Data

Dia.: ... mm
Height: ... mm

Click on image at left to read the complete description (excerpt of the document Report N° 128, 1923)

Click on the image above for an enlarged view of the cover

D.R. - Distant Reading Compass

The DRC system consisted of a gyro magnetic master unit situated at the rear of the aircraft well away from magnetic disturbances. Repeater indicators were fitted for the navigator and pilot. Additionally, courses were fed to the Air and Ground Position Indicators (GPI), the H2S and Mk XIV bombsight. We used true courses, a Variation Setting Control (VSC) providing the necessary conversion. The DRC was a reliable, accurate and stable instrument. Available to the pilot, however, in case of a rare unserviceability, and a cross-check for the DRC was the P12 magnetic compass. - Picture: A.J. Hughes, History of Air Navigation, 1946)


Drift occurs when a lateral wind pushes an aircraft sideways off the desired track. To keep flying along the right course, the pilot must counteract this drift by steering his aircraft according to a computed corrective angle. A. J. Hughes writes (in his History of Air Navigation) 'one of the first books on air navigation was a little primer by Cdr Newton, givig tables of corection for drift'. Some early compasses and other devices featured a transparent bottom and a lens with parallel lines. A. J. Hughes writes in his History of Air Navigation (1946, p. 32) about one compass "pattern with a very big bowl [that had] a glass bottom through which the drift over land could be observed by a setting pointer on the compass float". He was probably mentioning DALOZ' invention or some improvement of it.


DURKEE Co. was a New Yorker ships compass maker. He is named as the manufacturer of a compass called Type A featuring a vertical card. It is described in the Air Service Information Circular dated June 15, 1920 'Aerial Navigation Instructions', Chapter II.6. (click on image at right for description)

- E -

Earth Inductor Compass

This navigation aid was invented in 1912 by Donald M. Bliss (read Wikipedia) and improved and patented in 1924 by Morris Titterington, founder of PIONEER Co. This compass type equipped the Spirit of St. Louis when Charles Lindbergh flew from New York to Paris in 1927. Short techn. descr. in Engl.: see Wikipedia. Exhaustive descr. in French HERE: Aviatechno. (Link : Views of components)

ELGIN Watch Company

Major U.S. watch maker. Incorporated August 1864, sold in 1968. During World War II, all civilian manufacturing was halted and the company moved into the defense industry, manufacturing military watches, chronometers, fuses for artillery shells, altimeters and other aircraft instruments and sapphire bearings used for aiming cannons. (Source Wikipedia)

The B-3A compass was a later version of the “Type B” compass introduced in World War I. Most of the production of this particular model occurred around 1929. Very few of these would still have been in use by the WWII timeframe. They were one of the most common forms of military aircraft instrumentation as they could be used in just about any aircraft type ranging from trainers to pursuit (i.e. fighters) and bombers.
(Source Smithsonian Institution)

Front side

Rear side

Compare with Creagh-Osborne's Pattern 259 and 5/17 design.

Markings: Air Compass A.C. U.S. Army, Type B-3A made by the Elgin National Watch Company. 

Pictures courtesy P. Grace

- F -


Louis Favé (1853-1922) was a French engineer laureate of the elite highschool Polytechnique. He invented many precision instruments.

Technical Data
Compass for balloons
Interior dia.: 178 mm
Height: 100 mm
Descr. excerpt of the document Report N° 128

Click on the images for enlarged views

Functional Test Device

This device was made by the French compass manufacturer VION to test their own compasses and used as early as in the 1920s. The wording of the maximum admissible error in the test procedure (see img. in table centre) was used in a booklet published in 1922 (Traité Pratique de Navigation Aérienne, link to image).
When a vessel or aircraft makes a turn, the compass bowl rotates and the liquid inside also. Although the compass disc inside tends to remain in the same position in space due to the magnets being attracted by Earth's magnetic North pole, it is partly dragged (in French ENTRAÎNEMENT) by the fluid's motion. With this test one measured how important the drag was. The angular difference from the original position after a full (360°) revolution effected in 30 sec. was not allowed to exceed a certain value depending on the type of compass shape (here "horizontal" display i.e. flat disc viewed  from above or "vertical" display like a sphere, band etc. viewed from a side window) or size (see below).
Note: The crank needs to be turned about 15-16 times at the rate of 2 sec/turn to make the large disc fulfill a complete rotation in 30 sec. For the same amount of crank turns, the small disc only rotates 180°, hence one needs to operate the crank about 35 times at the rate of 1 turn per sec. to reach 360° in 30 sec.
In the booklet, it also says that the compass rose should come back to its original position after 25 sec. and 3 to 4 oscillations.

Compass Testing Device

The large disc is rotated by the crank on the right. The small disc is moved by a belt
The zero references are the brass pointers to be observed either from above or from the side.

(Click on the images for enlarged views)
Technical Data
Ø large disc: 277 mm
Ø small disc: 80 mm
Interaxes distance: 250 mm.
Ground plate: 255 mm x 500 mm
Test procedure / max. values
(see translation at right):

Pictures by courtesy of D. Binon
Excerpt of the Traité de Navigation Aérienne (p. 8):


After a full revolution effected in 30 sec.
- Max. error 12° on horizontal* compass disc Ø 140 mm
- Max. error  8° on horizontal compass disc Ø 85-75 and 60 mm
- Max. error  7° on vertical* compass disc Ø 60 mm

* Examples of VION compasses with horizontal and vertical disc:


- G -


The French Société des Établissements GAUMONT, 12 rue Carducci, Paris, patented after WWI two compass-related systems.
One for an improved telecompass working with ring magnets (French patent no. 549188, British no. 180684, click on the fig. at right for full-view of the four figs) and another one for a gyrocompass.


The early U.S. aircraft compasses were quite often adaptions of the British Creagh-Osborne designs.
Read descr. (excerpt of Report no. 128) on enlarged view of picture at right.


Carl Paul GOERZ Optische Anstalt was a German maker located in Berlin-Friedenau. Read the company's history in the German WIKIPEDIA.
In the book Der Flugzeugkompass by captn. Fritz Gansberg, 1917 is a description and user instr. of the two versions below (copy available).
S. a. GOERZ pocket and survey compasses.

Technical Data
- Dim.: ?

Click on images for enlarged views

Technical Data
- Dim.: ?



Alexander Gross was a Hungarian immigrant who fournded the firm Geographia in London which produced maps. He designed an anti-drift aero-compass described in FLIGHT (Sept. 13, 1913) and in The Mastery of the Air by Wm J. Claxton (1930).


Udo Guerra was an Italian engineer (dom. 16, Via Stazione S., Pietro, Rome, Italy) who invented in 1933 a tele-compass (patent accepted in 1935, UK no. 435,437, US no. 2,038,787) title: Improvements in Variable Induction Compass with Potentiometric Control and Indicator. This system was the immediate forerunner, if indeed not the direct inspiration, of the first fixed magnetic element A.C. excited type compass. The latter was invented by Guerra's associate Ettore Caretta two years later (Brit. patent no. 451,850. In this radical invention the determination of the earth's field in the horizontal plane is obtained without any moving parts at all but by the action of the current induced as a result of the presence of the magnetic field. (source: A. J. Hughes, History of Air Navigation, 1946, p. 108). Check also the table showing the separate development of Tele- and Repeater compasses (source: ibid. p. 106).

Gyro-compass / Gyro syn

A gyroscopic compass is an electrically operated instrument, controlled and damped either by gravity of electrically so that the spin axis settles in the meridian. These instruments are not the object of this museum. The gyrosyn is a remote-indicating compass system employing a directional gyroscope which is monitored by and synchronized with signal from an element fixed in azimuth and designed to sense its angular displacement from the earth's magnetic meridian. This element, called flux valve or flux gate (link to descr. and diagramm), is located at some remote point, e.g. wing tips, away from extraneous magnetic influences.
(Source: Chambers Dictionary of Science and Technology, 1974).
The development of gyroscopic compasses is best described in A. J. Hughes' Book History of Air Navigation (1946), see ex. picture at right.
For pictures of a modern flux gate CLICK HERE.

- H -


Leslie Alfred HAMILTON (1919-2005) created this company in... to produce and sell his invention, a compass with vertical card. The designation HI-400 stands for Hamilton Instruments, 4th prototype (read more details HERE).

Note: This system and this company are not associated with Hamilton Standard, a U.S. Company created in the 1920's by Thomas Foster Hamilton (July 28, 1894 – August 12, 1969) who was a pioneering aviator and the founder of this company.

This compass type is still being made by Precision Aviation. The mechanism is explained in the patent figures.

Click on the picture for an enlarged view
Technical Data
- Dimensions: 70 x 60 x 50 mm
- Weight: 270 gr/0.6 lbs.

The deviation can be compensated in order to show a correct display by turning the screws at the lower front part:
the left-hand screw (green paint mark, upper one on pic. below) is for the North-South axis and the one on the right (painted yellow) is for the East-West axis.


HASLER A.G. successor of Telegraphen-Werkstätte von G. HASLER, Berne / Switzerland (only information available found in the International Guide, imprimerie Crété, 1931, page. VIII.35)


This company published an ad in the booklet The Magnetic Compass in Aircraft by Captain Creagh-Osborne (1915). Link: example of a Heath compass.


Edward Lowther Holmes (38, Woodville Gardens, Barkingside, County of Essex, USA) filed together with Hughes (read below) a patent accepted in 1942 (US no. 543,069, title Improvements in and relating to Magnetic Compasses) describing a system called tele-compass featuring an external trailer (link to system's description). He later developped improved systems called Mag-Gyro and Repeater Compass (source: A. J. Hughes, History of Air Navigation, 1946). Check also the table showing the separate development of Tele- and Repeater compasses (source: ibid. p. 106).


HUGHES (Henry H~ & Son Ltd.)

Henry Hughes was born in 1816. In 1838 Henry Hughes & Son was founded at 120 (later at 59), Fenchurch Street, London as a maker of chronographs and scientific instruments. Henry died in 1879 and his son Alexander J. succeeded him as chairman. The firm was incorporated as Henry Hughes & Son Ltd in 1903. Hughes & Son worked together with Captn. Creagh-Osborne among other inventors (see Type 5/17). In 1935, S. Smith & Son Ltd. acquired a controlling interest in the company. This resulted in the development of new marine and aircraft instruments.


(For HUSON go to SMITH) - HUSUN was the abbreviated trade name of H(enry) HUGHES & Son Ltd. This name appears on many aircraft compasses (see also Air Ministry above). The usual former pattern no. was sometimes replaced by another like Type Av. 744 (link to picture of an ad in Flight, 1929). Following the destruction of the Fenchurch street offices in the Blitz of 1941, discussions with Kelvin, Bottomley & Baird Ltd resulted in the establishing of the joint venture company Marine Instruments Ltd at 107, Fenchurch Street, London in 1942. Henry Hughes & Son Ltd was a founding company of KELVIN HUGHES (see Wikipedia and the company's own website). Check also the Air Ministry (A.M.) chapter for compasses made by Kelvin-Hughes like the type P.11.
In a pre-WWII booklet (Instruments for Aerial Navigation by A. J. Hughes, 1924? - pics courtesy Museum of Polish Aviation Archive) the various instruments patterns currently used are described (click on links for pics and descr.):
Campbell Bennett 6/18 Mk. II and Mk. III Aperiodic Compasses, P.2 Compass, Mk. IIIA, P.3 & P.4, O.2 & O.3, 253 A.C. (with flat glass) and 253 D.G. (with domed glass), S.O.2 Pilot and Observer, 5/27 A., 259A, 256 (seaplanes), 254 (Observation Compass), Pattern No. 2 Medium Landing compass and an Airship Compass. Almost all compasses depicted bear a HUSUN-Label featuring the inventor's initials "C. B. Patent" (ask for copies).

Picture courtesy xy
(Click on images for enlarged views)
Technical Data
- Dimensions: mm
- Weight: g
- Markings:
• on side: Manufacturer's label HUSUN and Table MAGNETIC COURSE COMPASS
• on dial rim: MK. III. A. - N° 10838
(For Type Mk II, go to Air Ministry)

Picture courtesy Lady-Sam
(Click on images for enlarged views)

This compass was selected by Pioneer in 1926 for the equipment of a highly integrated instruments panel. (click on pic at r. for viewing an article published in the French review L'Aéronautique, iss. no. 87, Aug. 1926)
Technical Data
- Dimensions: mm
- Weight: g
Markings on top and on front side:
HUSUN no. 662
I.B. COMPASS + Patent no. 127.135

The patent number refers to the invention of Lt-Cdr CAMPBELL but the same design appears on the patent no. 1,474,394 filed in 1919 by J.P. WARBURG.

Source FLIGHT avril 1951
(Click on the images for enlarged views)

Technical Data
- Dimensions: 2.25" x 2.06 x 1.81"
- Weight: 3 ozs / 100 g

Design: Admiralty Compass Observatory
Manufacture: Kelvin and Hughes (Aviation) Limited
Retailer: Smiths Aircraft Instruments Limited

- I - J -

Japanese Compasses (WWII)

We concentrate here various information to be found on the followings websites:
- Compass pictures: liveauctioneers, wehrmacht-awards, warrelics, collectair,

Manufacturers names:
Tokyo Aviation Indicator Company
Yokogawa Kenki Seisakusho

Picture courtesy G. Rooney

Main component of an  instrument with a mirror on top in which the mirrored figures 0-1-2-3 located at the end of wires could be read (see pic. at right).

Top view: the wire cross with the figures 0-1-2-3 at the ends and the deviation correction scale. View of a similar compass with a scale (0-10°) inside the bowl. The adjustment for deviation caused by metallic masses on-board was done by means of plugs stuck in the base stemm. (Pictures courtesy Liveauctioneers)

Technical data
Dimensions (ht. x dia.) : 70 x 50 mm
Compass with mirror 8'' ht. x 6 1/2'' dia. (230 x 162mm).
Mounted on spring-loaded gimbal. The tiny arrow on top indicates probably the flight direction.

No external markings here but a similar compass is known in its original container. It is marked completely in kanji with a plate indicating Noritake.

NOTE: Compare to the Air Ministry O.3 and Pattern 253 A.C. (Aperiodic Centesimal) design and description

The manufacturer's label

Pictures courtesy ebay member axialcompressor
Type 1 Model 1

Manufacturer: Tokyo Aviation Indicator Company

Picture and information courtesy ebay member messerschmitt*109
Type 2 Model 2 "Gou"
Manufacturer: Tokyo Aviation Indicator Company

Japanese Imperial Army Type 2 Model 2 "Gou" Magnetic Compass, as used in various early and mid-war Japanese Fighters and Bombers such as the Nakajima Ki-43 "Oscar", Kawasaki Ki-100 "Tony", Mitsubishi Ki-21 "Sally", Kawasaki Ki-48 "Lily", Mitsubishi Ki-67 "Peggy", and others.

Pictures courtesy ebay member 4corners54
Dimensions (dia.x ht.): 4 x 5in. (100 x 125mm)
Manufacturer: Tokyo Aviation Indicator Company

Picture courtesy ebay member messerschmitt*109
Type 92 Magnetic Compass
Manufacturer: Yokogawa Kenki Seisakusho

This instrument was mainly used in single engine navy aircraft like the Zero, Nakajima B5N2 Kate, and Aichi B7A2 Grace. It was also used in the Okha 11, the infamous "Baka Bomb".

(Picture far left and information courtesy Gunbunny / Wehrmacht-awards).

Original manual of the Type 98 "Kou" compass (1938) - pdf file available

- K -

KADLEC (Instrumentenfabrik Prag) / dxt

Ladislav Kadlec was an instruments manufacturer located in the former Czechoslovakia, now Czechia (see also Wrist Compasses). The former address was PRAG X, ŽIŽKOVA 10. Under the German occupation, the three-letter confidential code was dxt visible on a type OK42 (OK = Orterkompass i.e. navigator compass) produced for the German Airforce Luftwaffe (see picture at right).
Kadlec also built probably before WWII the aircraft compass type LK-14 (see table below).

Pictures courtesy M. B. Dumitru

Technical Data

Dia.: 150 mm, Height: 110 mm
Marking: LK-14 ; PR-159
Excerpt of a control protocole: LK = letecký kompas = aircraft compass
Picture courtesy Vojenský Historický Ústav Praha / Czech Military History Institute, Prag - For a picture of the entire document click HERE.

KEARFOTT - USAF N-1 Master Indicator

KEARFOTT is a North American manufacturer of flight instruments (more information HERE).
The instrument presented hereafter is an evolution of Kearfott's N-1 navigation system which was developed approximately in 1948.
The N-1 Compass System is a remote indicating magnetic slaved, directional gyro-stabilized compass system, specifically designed for airborne use in all latitudes. The Earth magnetism sensor is called here C-2 Remote Compass Transmitter. In addition to its use as a compass system, the N-1 also provides an azimuth reference signal for directional control of the automatic pilot and directional reference for other equipment. In magnetic slaved operation, the N-1 indicates the magnetic heading of aircraft during normal flight conditions. It is a highly accurate system that enables precise navigation on long range flights by taking into account both the Earth's rotation and curvature. This feature made it thus possible to perform grid navigation, i.e. to fly directly on 'great circle' routes and achieve the shortest possible distance between two points on the Earth.

Kearfott ultimately produced around ten thousand systems for USAF and commercial applications. There are still approximately 500 systems installed and active (e.g. in C-130 Hercules aircraft) within the USAF inventory and the AF has an ongoing repair depot activity (complete description in the original KEARFOTT document available).
Source: ASTRONAUTICS Corp. of America

The dial represents a motionless compass card. The long pointer indicates the actual aircraft's heading and the short one its present position between the Equator and one of the poles (LATITUDE scale: northern hemisphere is located left, southern hemisphere is right).
Example below: Actual position readings: Heading: 32° NE, Latitude: 38° N.

• Knob in upper right corner reads:
• Knob in lower right corner reads:

Click HERE for descriptive drawing of front face.

Rear face: with cover - click on image for enlarged view without cover

Click HERE for descriptive drawing of rear face.

The N-1 system components

Click HERE for functional drawing.

Operation instructions available (prov. iss. July 1952, 42 p.)

Master Indicator Technical Data
- Dim.: 120 x 120 x 220mm
- Weight: approx. 4.5 kg / 9 lbs.

(Click on images for enlarged views)

Description: Normally the small pointer on the latitude scale is set to "off" for magnetic slaved operation. When running in "free gyro", then the small pointer is adjusted to the approximate latitude that the aircraft is operating in and corrects the gyro for "earth rate" precession ('Free Gyro' operation is the normal operating mode in the arctic and antarctic regions near the Earth's magnetic poles).
The latitude pointer is set by the navigator and it does not give any position. Many times navigators operating in the antarctic (particularly in the Southern Latitudes) have set their latitude as N instead of S and suffered large induced corrections because of the wrong latitude.
The very small pointer on the L / R indicator, indicates input by the magnetic flux gate detector (C-2 Remote Compass Transmitter) which is remoted on the wing or other portion of the fuselage. It will continuously fluctuate back and forth as it receives the magnetic information.
(Explanations transmitted by Breckinridge S. Smith - Major, USAF ret.)


The name Kelvin is generally associated to nautical compasses (see the company's profile in this category) but Kelvin produced together with various partners aeronautical compasses. In the Oct. 5, 1912 issue of the review FLIGHT an article (The evolution of the Aero Compass) describes the first 'aero compass' designed by Cptn Chetwynd (see his profile in Wrist Compasses). Kelvin and J. White produced for Dyott's monoplane a special compass featuring a tiny mirror, (click here for description and picture in FLIGHT, April 26, 1913). . Kelvin, Bottomley & Baird (link to ad, 1929) produced in 1925 a compass for air-craft called 'Pattern America (see pic. below). Furthermore, Kelvin produced the first official service aeroplane compass (see Pattern 200). They later produced in 1932 two versions of an aperiodic compass designated KBB 3 and KBB 4.

Click on the images for the full description published in FLIGHT.
Read also HUGHES. Kollsman and K.B.B. published together an advertisement in FLIGHT in 1938.

The first Aero Compass (1905)

Technical Data
Dim.: 5 78 in. dia. by 3½ in. deep; weight: 3 lbs. 2 ozs.
Instruments designed by Cptn Chetwynd in 1912

The pattern AMERICA

The K.B.B. compasses type 4 and 3

KG-1B (КГ-1Б in cyrillic letters)

Descr.: Russian-made instrument. No manufacturer's name known. The designation is the abbrev. of the Russian word Курсогоризонт KoursoGorizont (Course / Horizont). Pic. at right courtesy Dave Reid

KI-13A (КИ-13A in cyrillic letters)

Russian stand-by compass, probably made in the 1960s by KATAV-IVANOVSK INSTRUMENT-MAKING PLANT, JSC (Катав-Ивановский приборостроительный завод) located in Katav-Ivanovsk, 456110 Chelyabinskaya oblast, Katav-Ivanovsk, ul. Karavaeva 45. Visit their web site (Russian/Engl.).


(Click for enlarged views)


Compass manufacturer, French address 73, rue Laugier, Paris (this is the only available information, it was published in the International Air Guide, imprimerie Crété, 1931, p. VIII.35)


Danish manufacturer (s. Bézard Marching compasses, Danmark).

Technical Data
- Dia.: mm


Pictures excerpt of Report No. 128 dated 1923.


US manufacturer, part of ELBIT. Paul Kollsman (February 22, 1900 in Germany – September 26, 1982 in Beverly Hills, California) was an inventor. He invented barometers and instruments for airplanes. Several patents for compasses are known. Kollsman and K.B.B. published together an advertisement in FLIGHT in 1938.

Pic. courtesy J. Turanin


Eugène Adolphe KRAUSS, located 16 and 18 rue de Naples, Paris, was a compass manufacturer and predecessor of MOREL-B.B.T.. He filed several patents together with Morel (see also the International Air Guide, imprimerie Crété, 1931, p. VIII.35)