GB581732A - Calculating apparatus - Google Patents

Abstract

581,732. Calculating - apparatus. MAHE, J. B. D. DE. July 8, 1942, No. 9451. [Class 106 (i)] Apparatus for the assessment of data obtained from photographic records taken by aiming cameras of an attack by torpedo or other weapon from aircraft and other moving platforms against a moving target, comprises a circular calculator of the slide rule type whereby linear and angular measurements obtained from the photographic records may be interpreted, and, for use in conjunction therewith, a velocity triangle calculator whereby the data derived from the slide rule can be utilised to determine the accuracy of aim and theoretical result of the attack. Speed tables of the travelling weapon and of the target are also provided. The camera negative is measured by a graticule to obtain the necessary data for setting the circular slide rule to determine the range of target, the height' of the aircraft and bearing. The slide rule, Fig. 1, comprises a base-plate A and a rotatable apertured disc B. On the baseplate are engraved a scale a 1 representing height, a scale a<2> for length of target, a scale a<3> for angle subtended by target length, and a scale a' representing height of target image. The disc is engraved with co-operating scales ; a scale b<1> for the " aim-off angle," two scales b<2>, b<3> for bearing angle and a scale b<4> for range. The velocity triangle calculator, Fig. 2, comprises a base C, a sector D, a weapon track arm T, a range pointer M, and a cursor U. The base C is engraved with a range scale R and carries an " aim-off angle pointer P. The sector D is provided with an angle scale S and is rotatable round a pivot Q representing the position of the attacker at the moment of discharge or release. The track arm T is pivoted to the sector at a point Q 1 in line with an arrow Y on the sector indicating the point at which a torpedo would enter the water when released from the aircraft operating at the normal dropping height and speed. The range pointer M is arranged to slide in a slot on the base and carries a vertical pivot X on which the cursor U is mounted. The cursor is engraved with ships' track scales S<1>, S<2> and S<3> and a bearing protractor V. The scale S<1> is for a ship on a straight course and the scales S<2> and S<3> for a ship's turn towards and away from the target in avoiding action. An additional scale G is formed on the sector to set the track arm T to-take into account the effect of gyro angling.