GB910231A - - Google Patents

Abstract

910,231. Aircraft instruments. KOLLSMAN INSTRUMENT CORPORATION. Oct. 31, 1958 [Jan. 24, 1958], No. 34992/58. Class 4. An aircraft take-off indicator comprises means for indicating the instantaneous airspeed required for the aircraft subsequently to reach a predetermined take-off speed in a predetermined time, means for driving the indicating means as a function of time, and further means for indicating the measured instantaneous airspeed. In Fig. 7, a spring driven clocktype mechanism 80 with a starting solenoid 81, drives a shaft 82 on which is a rate controlling means 84, and which operates a synchro 94. Therotor of a further synchro 76 is driven by a motor 72 energized by amplifier 74. The motor also rotates the stator of a synchro 78, the rotor of which is driven by a pitot-static diaphragm 60 through linkage 62, 64 and gears 66, 68. An indicated airspeed pointer 38 is driven over a fixed scale 37 by gear 68, and a ring gear 42 is driven by motor 72 through gear 70. Ring gear 42 has an inwardly projecting marker 48. The output signals of an angle of attack responsive device 98, and the synchro 78, are connected in series to one fixed contact 92 of a switch 95, and the output signals of synchros 94 and 76 are connected in series to the other fixed contact 90. The movable contact 97 is connected to amplifier 74. Before take-off, the pilot rotates an arm 88 to the position T.O., abutting stop 91. This winds the spring of mechanism 80 and closes contact 97 on contact 90. Further, he adjusts the rate mechanism 84 by a knob 50 until a pointer indicates on scale 56, the known acceleration required if take-off speed is to be reached in the distance available. The clock mechanism 80 is released by solenoid 81 by closure of a number of switches such as 81a, these being closed under the conditions: pilot's manual start control operated, wheel brakes off, and engine throttles open. The marker 48 is then driven in corresponence with the rotation of shaft 82 by motor 72, lack of correspondence being detected by comparing the signals from synchros 94 and 76, and feeding the resultant over contacts 90, 97, to amplifier 74. By comparing the positions of marker 48 and pointer 38, the pilot can see whether his actual indicated air speed is above or below that required at any time during the take-off run. Non-linear transmission means, such as cams, may be utilized when the aircraft does not normally accelerate uniformly during take-off. After take-off, arm 88 is rotated manually or automatically to the position A/A abutting stop 93, closing contact 97 on contact 92. Ring gear 42 is now driven relatively to pointer 38 in accordance with the angle of attack, by comparing the signal from device 98 with that from synchro 78, and feeding the difference to amplifier 74. Ring gear 42 has other markers, not shown, representing approach and stalling angles of attack. Preferably, a further pointer, not shown, coaxial with pointer 38, indicates the maximum permissible airspeed at any time on scale 37. Knob 50, scale 56, and means for operating arm 88 are all mounted on one escutcheon.