Simulation of aircraft icing and de-icing effects

摘要

790,463. Simulating icing in grounded aircraft trainers. COMMUNICATIONS PATENTS, Ltd. Aug. 3,1956,No. 24004/56. Class 4. Apparatus for the simulation of aircraft icing and de-icing comprises an electrical circuit providing an electrical quantity representing a non-linear growth of ice on an aircraft, and manually operable means for modifying the circuit to produce an electrical quantity representing a non-linear decay of ice. In Fig. 1, closure of an instructor's icing switch 19 energizes a relay RL1 from a current source 14, closing contacts RLIa and RL1b. if the trainee's de-icing switch 17 is open, relay RL2 is deenergized, and contacts RL2a and RL2b are also closed. Current is thus supplied to a heating coil 13, which heats a thermistor 15. Relay RL3 is also de-energized, contacts RL3a and RL3b being closed, so that the voltage of source 14 is applied across thermistor 15 and a resistor 16. As the thermistor 15 heats up, the voltage on line 20 fed to a flight computer 8 varies non-linearly with time, and represents the build up of ice on a part of the aircraft, e.g., the elevators. This input to computer 8 is used to used to modify the press, lift and drag computations made, and also actuates a control loading device 12 which makes the trainee's control progressively heavier as simulated ice formation increases. The control may be locked solid when a predetermined simulated ice level is reached. A modulator 22 may be activated by an instructor's switch 23, whereupon the simulated cockpit is vibrated by a cam 25 driven by a motor 24 to simulate the vibration due to successive extinction and re-ignition of jet propulsion engines which may occur in icing conditions. If the trainee closes the de-icing switch 17, contacts RL2a and RL2b open, and the heating coil 13 is de-energized. The thermistor cools and a non-linear decay of ice is represented by the fall in voltage on line 20. Relay RL3 is energized after a time delay due to a thermistor 21, which heats up to a predetermined temperature before it passes enough current to energize relay RL3. When this happens, contacts RL3a and RL3b open, and the voltage on line 20 falls to zero, simulating the shedding of ice in bulk. Means similar to the above are provided for each area of the aircraft for which icing is to be simulated, e.g., ailerons, flaps, or rudder trim tabs. The characteristics of each circuit may be varied by mounting each thermistor 15 so as to be axially slidable in coil 13, thus varying the thermal coupling. An attached scale and pointer device (not shown) indicates a time constant for the heating of thermistor 15 for any axial position thereof. An output from the computer may energize relay RL1 when ambient conditions, e.g., altitude indicate that icing would occur in a real aircraft.