Patent GB-1205625-A (GB)
Title: Aircraft computing bombing instrument
Inventor: FAXEN PER TORSTEN
IPC: G06G7/80
Filed: 1967-11-15
Abstract: 1,205,625. Bombsights. SAAB A.B. 15 Nov., 1967 [16 Nov., 1966], No. 51994/67. Heading F3C. [Also in Division C4] In an automatic dive bomber sight fitted to an aircraft (Figs. 3, 4, not shown) a computer of the kind described in U.S.A. Specification 2,609,729 continuously calculates from various physical and aerodynamic constants and parameters the angles of divergence and attitude of the aircraft at which bombs must be released to hit a target on which the diving aircraft is optically aligned, and also compares the calculated and assumed attitude angles of the aircraft to initiate a bomb release signal at coincidence; while a switch (Fig. 3, not shown) operated by the pilot at pull-out initiates a one-shot pulsed energy (e.g. laser) transmitter to measure accurately the slant range of the target, which is fed to the computer to correct the computation of the angle of divergence by comparison of horizontal distance signals calculated from barometric height input and slant range measurement; the corrected value being stored for calculation of required pull-out attitude angle. For correction of errors arising from false reflections of the slant ranging energy beam, the barometric height h, dive angle # and measured slant range # are fed into resolvers 33, 34 (Fig. 5, not shown, and Fig. 6) to produce signals representing h cot # = x<SP>1</SP>h and # cos # = x r<SP>1</SP> respectively; representing height based horizontal range and slant range based horizontal range, which are applied over diodes 42 and interconnected adding resistors 43 to 48 for combination with a signal representing an increment or decrement of target horizontal range #x<SP>1</SP> allowing for inherent error to energize diode feedback differential amplifiers 39, 40 of which the former energizes relay 50 when x<SP>1</SP> + #x<SP>1</SP> # h<SP>1</SP>, which operates contact 51 to allow the latter amplifier to energize relay 52 when xh<SP>1</SP> + #x<SP>1</SP> # x<SP>1</SP>r, which relay controls contact 53 to select horizontal range signal xh<SP>1</SP> when inoperative and x<SP>1</SP>r when operative. Thus when the horizontal range from the reflection measured slant range lies between the horizontal range derived from barometric height and dive angle and positive or negative present increments, and is therefore accurate it is used for the computation while if it lies outside such incremental limits due to inaccuracy from spurious reflections, the barometric calculated horizontal range is substituted. The apparatus is also applicable to horizontal bombing with homing on target and pull-up at release; the slant range measuring device being vertically oriented and sighted on target by the bombardier. The attitude angle is then derived from the alignment of the ranging device and the required angle of divergence referred to the line of sight from aircraft to target is calculated therefrom. At switch and laser operation, the slant range is measured and angle of divergence calculated and stored for calculation of the required attitude angle during pullout, while bombs are released at equality of calculated and physical altitude angles.