Patent GB-972486-A (GB)
Title: Simulated on-ground aircraft pitching moment system
IPC: G09B9/20
Filed: 1962-07-30
Abstract: 972,486. Flight trainers. CURTISS-WRIGHT CORPORATION. July 30, 1962 [July 31, 1961], No. 29215/62. Heading B7W. [Also in Division G4] An aircraft simulating apparatus having computer produced signals representing flight factors and forces acting on an aircraft and means for simulating pitching moments during the take-off and landing of an aircraft with main and nose wheel landing gear, comprises a rate of pitch computer 10 having input network 13 energized by signals at a, b, c, d, e representing different pitching moments including nose wheel pitching moment signal produced by computer 27, this signal being applied according to simulated " on " or " off " position of the nose wheel with respect to the runway. Signals at a, b, c, d, e represent respectively, a feed-back signal from amplifier 12 applied via switch 14; nose wheel pitching moment applied via switch 26 from computer 27 and pot 28; main gear pitching moment from computer 40 via pots 43, 42, 41; pitching moments due to brake application via pots 46, 45; and pitching due to aerodynamic forces from amplifier 48 via pots 50, 49. The sliders of pots 42, 46, 43 are moved by acceleration servo 32 controlled from accelerometer 21, 22; the sliders of pots 34, 43, 28, 49 are controlled from a servo 39 representing the reciprocal of the aircraft gross weight; and pot 50 is controlled by aircraft pitching computer 51. The summing of signals at terminals a, b, c, d, e gives the pitching moment when the aircraft is on the runway and is applied via integrator 35 to pitch attitude servo 36; integration of signals at c, d, e gives the pitching when the nose wheel leaves the ground. With aircraft at rest, a height-above-runway servo 17 closes switch 19, energizes H-relay to close switch 16 and energize NW-ON relay through switch 15 thereby closing switches 14, 26. Since acceleration n is zero and angle of attack negative the output of computer blocks diode D 2  but provides a feed-back through diode D 1 . As all aerodynamic factors are zero the only signals are at a, b, c so the attitude gyro indicates the static angle of attack. When aircraft moves on runway, the accelerator n increases and angle becomes less negative until at lift-off, the polarity of signal from computer 27 reverses and diodes D 1 , D 2  become non-conducting and conducting respectively, to energize NW-off relay which opens switch 15 to cut-out NW-ON relay. This converts computer 10 to an integrator. The main gear signal at c is effective until the aircraft leaves the ground when H-servo 17 opens switches 19, 20 to remove the voltage from pot 41 thereby reducing the main gear signal at c to zero. If during take-off the brakes are applied then signals applied to terminals d, e reverse the signal from computer 10 to simulate bringing the aircraft nose down. During simulated landing, the acceleration decreases and angle of attack is negative causing reversal of the output polarity from computer 27 to block diode D 2  so that when H-servo closes switch 19 on touch-down to close switch 16 the NW-ON relay is energized through switch 15 so that the apparatus functions as previously with computer 10 acting as a summer. Specification 792,676 and U.S.A. Specifications 2,731,737 and 2,842,866 are referred to.