Aircraft Pilot's Standby Magnetic Compass

© Brooke Clarke 2012

Aircraft Pilot's Standby
          Magnetic Compass
Background
Markings
Details
Photographs
Deviation Adjustment
Patents
Related
Links

Background

Part of my interest in navigation is the magnetic compass.  This comapss is a liquid filled version designed to be mounted on the instrument panel of an aircraft.  Aircraft use brings with it a number of problems that are not present for compass use on the ground so this compass has a number of features that are special.

aka B-16 compass.

Markings

Front

MS17983-2
AIRPATH

Back

Compass, Magnetic, Pilot's, Standby
Type MS17983-2
70214-CB-2100-T4-M
28-Volt DC Lighting System
6605-51-8187
DAAJ01-74-D-0046(PTB)
Serial No. 5152

Right Side

AP
 1
IMP

Details

Airpath model CB-2100-T4-Ait has florescent markings, not sure what color filter, but think it's clear.
The lamp can be a OL-300 or 327 or 328.
The compensation adjustments are made so that the error is split between North and South and between East and West.
Mating Connector to make cable for lamp power p/n: ______?______
Spare Parts diagram at the Airpath web site.

Photographs

Fig 1
Aircraft Pilot's
                Standby Magnetic Compass
Fig 2
Aircraft Pilot's
                Standby Magnetic Compass
Fig 3
Aircraft Pilot's
                Standby Magnetic Compass
Fig 4
Aircraft Pilot's
                Standby Magnetic Compass
Fig 5 top cover for replacing lamp
Aircraft Pilot's
                Standby Magnetic Compass
Fig 6 bottom cover for deviation adjustment
Aircraft Pilot's
                Standby Magnetic Compass
Fig 7 UV light
Aircraft
              Pilot's Standby Magnetic Compass
Fig 8 UV light
Aircraft
              Pilot's Standby Magnetic Compass
Fig 9

Deviation Adjustment for B-16

From The Navigator - Vol 12 No. 4 Summer 1965

The only equipment required is a brass screwdriver (which is non-magnetic). Naturally, a sextant or astro-compass is used to determine the heading.

First turn the aircraft to a heading of 000°, then read and record the deviation. By means of the N-S compensating screw, take out all of the error until this heading has 0° deviation.  Now turn the aircraft to a heading of 090°, record the deviation, and once again remove all deviation by means of the E-W screw on the compensating magnet.

The next aircraft heading is 180° and deviation is again recorded. On this heading, one-half of the deviation is removed by means of the N-S compensating screw.  This employs the coefficient system of deviation analysis.  Under this system, deviation is resolved into components, of which there are five. The effect of each component is represented by a coefficient.  For the purpose of this discussion, it will suffice to say that removing one-half of the deviation will compensate for these coefficients.

Now turn the aircraft to 270° and once again remove one-half of the deviation by means of the E-W compensating screw.

Having removed the deviation on the cardinal headings, now go ahead and swing each 15° around the compass rose.

You’ve completed an important job, but what do you do with the information. Provided for us is the Air Force Form 57 (Pilot’s Compass Correction Card); transpose your information to it and “the pilot’s friend" is ready because of the navigator’s preparedness."

There is also: Standardized Procedures for Performing Aircraft Magnetic Compass Calibration - includes image of Correction card and how to fill it out.

Patents

2458022 Altimeter, J.O. Phelps (Airpath Inst Co.), Jan 4 1949, 73/387; 73/178.00R; 116/271; 116/DIG.43 -

1873684 Compass,
                Urfer Adolf, PIONEER INSTR CO Inc, Filed: 1929-05-11,
                Pub: 1932-08-23 -? Standby Compass



1873684 Compass, Urfer Adolf, PIONEER INSTR CO Inc, Filed: 1929-05-11, Pub: 1932-08-23 - Standby Compass light

2041072 Magnetic compass, Kollsman Paul, 1936-05-19 - liquid damped
2078574 Compensating
                device for magnetic compasses, Kollsman Paul,
                1937-04-27



2078574 Compensating device for magnetic compasses, Kollsman Paul, 1937-04-27 - standby compass deviation adjustment

The compensation function is contained in a box (12) that can be attached to either the top or bottom.  Since the lamp housing
is attached to the top the compensation box is attached to the bottom.

Note that the centerline of the compensation magnets is in line with the pivot centerline (11).
 

Related

Navigation -

Links

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Page created June 29, 2012