Patent GB-600502-A (GB)
Title: Improvements in or relating to radio apparatus for object location
IPC: F41G9/02
Filed: 1943-01-28
Abstract: 600,502. Bomb-aiming from aircraft. SPERRY GYROSCOPE CO., Inc. Jan. 28, 1943, No. 1505. Convention date, May 19, 1942. [Class 92 (ii)] [Also in Groups XXXIII, XXXVIII and XL (c)] Bomb-aiming from aircraft is directed during bad visibility by a computer in conjunction with radio-location apparatus (see Group XL (c)) comprising a " scanner " comprising an assemblage of radiators spun about an axis and directing pulsed beams repeatedly passing through the angle between bounding lines 20, 30. Signals reflected from a target within the cross-hatched area swept over by the beam cause an image 111, Fig. 6, of the target to be formed on the screen of a cathode-ray tube " navigation " indicator, the vertical and horizontal positions of which image correspond respectively to the " slant-range," or direct distance from the aircraft to the target, and to the angular direction to the target relatively to the sighting line 10 which bisects the angle between the lines 20, 30 and is represented by a vertical trace 108 on the indicator. A " vernier " indicator is also provided, which gives an enlarged indication of the small part of the field of the navigational indicator enclosed by the lines 105 and containing the target image. The axis about which the scanner is spun may be angularly adjusted in elevation, to vary the " sighting angle # of the radiated beam, and also in azimuth to shift the scanned area transversely of the line 119 in which the aircraft is heading. Remote control means are provided for effecting these adjustments, and also for eliminating the effects on the indications given by the system of pitch, yaw, and roll movements of the aircraft and of the drift angle α of the aircraft and " cross-trail " of the bomb in falling (see Group XXXVIII). The computer 75, Fig. 8, which may be of the type described in U.S.A. Specification 2,162,698 determines the value #<SP>1</SP> of the sighting angle # at which the bomb should be released. This angle is a function of the altitude time of fall, " trail," and ground speed, for which factors the computer is manually adjusted. The ground speed shaft 97 of the computer assumes an angle proportional to tan. #, or to R/h where R is the horizontal range to the target and h is the altitude. In order that the computer may co-operate with the radio-location system, which indicates slant-range, and not horizontal range, a threedimensional cam 98 is provided on the shaft 97 and is longitudinally adjusted on it according to the altitude setting of the computer, angular adjustment of the shaft then giving a movement to the cam-follower 101 proportional to R/sin.#, that is to the slant-range. This adjusts through a selsyn transmitter 103 a phaseshifter controlling the timing of pulses producing a horizontal " slant-range " reference trace 107 on the indicator screen (see Group XL (c)) so that the vertical position of this trace is controlled by the computer. The computer also causes, through remote control means (see Group XXXVIII), corresponding adjustment of the sighting angle # by adjusting the angle of elevation of the spin axis of the scanner. The aircraft being so headed that the image of the target is split by the vertical-trace 108, so that its course will carry it over the target, the angular speed of the shaft 97 of the computer is adjusted to cause the reference trace 107 to remain superposed on the target image as both travel down the screen. The ground speed may then be read from the computer and the sighting angle #<SP>1</SP> at which the bomb is to be released determined by the formula