Crace's Change of Bearing Instrument
Crace's Change of Bearing Instrument was a Torpedo Control instrument conceived by a Lt. Crace of Australia to determine the bearing rate of a target so that the deflection can be computed to set a Torpedo Director.[2]
Instrument
It used a special telescope atop a gyro compass receiver. The telescope had crosswires and a prism in it that permitted the operator to simultaneously observe the target beneath a 5 degree arc of the gyro compass card below. The operator worked a training gear to keep the crosshairs on target and call out the bearing to a second man. This second number was equipped with a circular slide rule and also received ranges by voicepipe.
Sliderule
The sliderule had two discs. The inner one had "S * sin(Bearing)" and the outer one "(pi * Range) / (100 * TimeIntervalBetweenBearings)". The result would be passed by Navyphone to the director position.[3]
Experience
By late 1914, it was determined that sufficient practice gave good results, but the amount of calculation required seemed worrisome.[4]
See Also
Footnotes
Bibliography
