First "True" Compass Guides Fliers to Target
January 1944 Popular Mechanics

May 1968 Popular Mechanics
May 1968 Popular Mechanics - RF Cafe[Table of Contents]

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First "True" Compass Guides Fliers to Target

Hailed as the greatest advancement in its field in 4,500 years, the Gyro Flux Gate compass is guiding U. S. bombers to remote enemy targets and home again. The new compass, developed by the Bendix Aviation Corporation, requires no "correction card" which is necessary with magnetic types because it gives the "true" reading. This eliminates the danger of error by pilot or navigator in the heat of combat. The flux gate compass uses the earth's magnetic field to develop minute electrical impulses which, when amplified, turn the compass indicator. The impulses are taken in through the "flux gate" which receives and rejects the magnetic flux from the earth. The flux gate is a triangular-shaped coil attached to the bottom of a gyroscope which keeps the unit on a horizontal plane. This compass will not go off its reading when a plane dives or climbs rapidly, according to W. A. Reichel, director of engineering for the Bendix company. The needle will not lag or overshoot during a turn, nor does it "hunt" back and forth in rough weather. It functions perfectly within 300 miles of either pole, regions where magnetic compasses are useless. This factor is expected to play an important part in postwar aviation along arctic routes. Because the transmitter of the compass can be located at a distance from the indicating dial, it can be installed. on a plane where it will not be affected by metal parts, such as armor plate, that impair the accuracy of the standard compass. As many compass dials as are needed for the crew can be mounted in a bomber. Development of the compass was made public only after one of the instruments fell into enemy hands. Bendix officials believe it will be impossible for the enemy to duplicate the performance of the compass during this war.

Compass transmitter is shown on the tail of the plane (top left) with master dial on the nose, amplifier in center. Above, testing new compass; left, "fins" used on the compass