Patent GB-882733-A (GB)
Title: Improvements relating to bombing apparatus
Inventor: FAUTECK WALTER SCOTT
IPC: F41G3/24
Filed: 1959-04-07
Abstract: 882,733. Bomb-sighting apparatus. MERGENTHALER LINOTYPE CO. April 7, 1959, No. 11689/59. Class 92. Relates to apparatus for "toss" bombing from aircraft by which the bomb is automatically released on the correct trajectory towards a target during the pull-out after a dive, as distinct from normal dive bombing or level flight bombing. The theoretical basis of the invention is as follows: if an aircraft is at height Y o , Fig. 2, diving towards the target T at an angle B while travelling at a speed V o , the angle of divergence E is the angle that the bomb must be elevated above the dive path in order to hit the target. The target angle B can be measured with a gyroscope, altitude Y o  measured as a function of the static pressure at the aircraft and velocity measured as a function of the impact pressure (as indicated by a pitot tube) on the aircraft. A mathematical equation can be derived which enables E to be determined from these measurable quantities and which can be represented by a three-dimensional cam, the rotation of which is proportional to B and the longitudinal position of the cam follower with respect thereto is proportional to Y where Y = #(Y o , V o ). In practice difficulty would be encountered in elevating the bomb above the dive line and ejecting it at the proper angle. In "toss" bombing, the pilot dives the aircraft at the target T, Fig. 13. At some point P, the pilot begins to pull out and in order to hit the target the bomb must be released at that point on the pull-out arc where the tangent to the arc is elevated above the aircraft target line OT by the divergence angle plus an angle dependent on the elements of aim to be corrected for. If the divergence angle computed at P be E, then if the same divergence angle is applied after the plane proceeds to point O, in order that the initial velocity vector of the bomb makes the angle with the horizontal that was computed at P, it is necessary to increase the divergence computed there from E to E + D where D is the angle between the dive line PT and the line from aircraft to target OT. The angle D can be computed from an empirical equation and thus the bomb can be released at that point in the pull-out path where the target angle A 2  as measured by a gyro plus the angle of divergence E equals the target angle B plus the angle D. According to the invention the three dimensional cam 33, Figs. 3, 5, is set rotatably in accordance with the target angle at which the aircraft approaches the target and the cam follower 46 positioned longitudinally with respect to the cam axis in accordance with the altitude and speed of aircraft. The radius of the cam at the point where the follower contacts the cam surface is proportional to a theoretical angle of divergence as computed for vacuum ballistics, and electrical means are provided which in response to the position of the cam follower supply a voltage output proportional to this angle. Means are also provided which are automatically responsive to flight and atmospheric conditions and which actuate electric means to supply output voltages to a summation circuit as correction factors to the theoretical angle of divergence, and gyroscope controlled means are also provided in the summation circuit to supply a voltage representative of an angle which continually changes as the aircraft traverses its path of pull-out from the dive, so that when such angle coincides with the corrected angle of divergence, the bomb release mechanism is actuated to release the bomb. Various voltages are supplied to the summation circuit as corrections in respect of- (a) resistance of the air through which the bomb is falling-voltage F (b) wind conditions-voltage W (c) angle of attack-voltage G. As the aircraft traverses its pull-out path, a voltage is provided in the circuit of Fig. 26 which represents the angle of departure A 2 , Fig. 13, of the aircraft at each instance as determined by the gyroscope. The position of the brush 223 on potentiometer 223 is fixed since the rotation of the cam was stopped at the point P to fix the target angle B. The gyro actuated brush 221, however, continues to sweep potentiometer 160 as the angle A 2  changes during pull out. The unbalanced bridge provides a voltage output R. The voltage, together with those in respect of the corrections referred to above are fed to a summation circuit, Fig. 27 (not shown), which controls the point of release of the bomb during pull-out. The signal for bomb release is given when the voltage output R equals E-D+F+GŒW.