Patent GB-780510-A (GB)
Title: Improvements in and relating to ground aviation trainers
IPC: G09B9/46
Filed: 1955-01-17
Abstract: 780,510. Flight training apparatus. LINK AVIATION, Inc. Jan. 17, 1955 [March 31, 1954], No. 1372/55. Class 4. Apparatus for training pilots of helicopter aircraft comprises a cockpit 100, with a windscreen 133, enclosing a seat 101, a collective pitch control lever 102 carrying a throttle control 103, a control column 111 having two degrees of freedom about shafts 112 and 117 respectively a rudder bar 123, a loud speaker 134 for reproducing engine noise and an instrument panel 130. The throttle control 103 is mounted on a shaft 109 within the lever 102, rotation of the control causing rotation of the wiper arm of a potention meter R-110 and the lever 102, when rotated on a shaft 104 drives through gears 105, 106, the common shaft 107 of axially-mounted potentiometers R-108 and R-505 (Fig. 5) and R-601 (Fig. 6). Fore and aft movement of the column 111 operates, through gears 114, and 115, a potentiometer R-116 and sideways movement operates, through gears 119 and 120, a potentiometer R-121. Movement of the rudder bar 123 operates, through gears 126 and 127, a potentiometer R-125. A translucent screen 137 is mounted in front of the windscreen 133 and a housing 200 encloses computer mechanism 201 which carries a support 204 for a shaft 205 upon which a bracket 206 is rotatably mounted under the control of a servomotor M-400 operating through a pinion and sector 208 and 207. The bracket 206 carries a mounting 213 for a servomotor M-500 which, through a pinion and sector 215 and 214, rotates a platform 216 carried by a shaft 211 in the bracket 206. The platform has a pivotal mounting 218 for a further platform 225 and this is rotated about its pivot 218 by a servomotor M-600 operating through pinion and sector 222 and 220. The platform 225 therefore, has three degrees of freedom and it carries the following elements for projecting a light image onto the screen 137. A lamp 227, having a reflector 228 and a mirror 229 illuminates the screen 137 to represent a runway, the limits of which are provided by opaque screens 245, 246 and 255. A further light source 258, fronted by a tinted screen 259 which may carry cloud effects, provides a representation of the sky. The screens 245 and 246 are mounted on concentric shafts and they are driven respectively through gear and sector drives 237, 238 and 240 and 242 by servomotors M-800 and M-700. Each sector has a cutout and these overlap to provide an opening such as AOB in Fig. 4b. The screen 255 is moved vertically by screw and nut mechanism 252, 253 operated by servomotor M-900 and this provides a representation of the distant end of a runway as shown by the line CD in Fig. 4b. Engine speed simulation (Fig. 5). A negative D.C. voltage is applied to potentiometer R-108 and an equal voltage of opposite polarity is applied to potentiometer R-505, the wiper arms of which are both operated by the collective pitch control 102 and the voltage applied to R-108 is applied also, through resistor R 502, to a further potentiometer R-503, the wiper arm of which, operated by an engine speed servomotor M-1500 supplies a voltage through a feed back amplifier U-501 to an integrator U-503. The potentiometer R-110 operated by the throttle control 103 has equal voltages of opposite polarity applied to it and the output is fed through an amplifier U-502 to a manifold pressure indicator I-501 on the instrument panel. The output from amplifier U-502 is fed also to a potentiometer R-511 which supplies a voltage to the integrator U-503, output from which passes through a vibrator X-501 which supplies an A.C. servo-amplifier U-504 to energise an A.C. induction motor M-1500. This operates a " follow-up " potentiometer R-526 so that the position of the motor M-1500 will be a measure of the simulated engine speed. The motor operates the wiper arm of a potentiometer R-528 which controls a small D.C. motor mounted on the control column 111 and the motor drives an eccentrically mounted weight 511 which simulates the vibrations transmitted to the control column from the engine in a normal aircraft. Altitude simulation (Fig. 6). When simulated engine speed reaches a predetermined value motor M-1500 closes a relay K-102 energized by a D.C. voltage. At a higher engine speed a second relay K-103 is closed to energize the potentiometer R-601 operated by collective pitch control 102. This feeds an amplifier U-601 which supplies a voltage to a potentiometer R-604 controlled by motor M-1500, the output of R-604 being applied to a conductor 602, and a potentiometer R-606 positioned by an altitude servomotor M-1600, to apply a voltage to conductor 620 which takes account of the variation in rotor lift caused by " ground effect." The aforementioned voltages applied to conductor 620 to represent rotor lift are negative and to represent the effect of gravity on the aircraft a negative voltage is applied at terminal 603 and fed to the conductor 602 through a potentiometer R-609 which may be adjusted according to the weight of the aircraft being simulated. Allowance is made for variation in lift resulting from fore and aft or sideways translational movement of the aircraft, and two networks are shown in Fig. 6 for supplying a voltage to conductor 602 through resistor 610 (fore and aft) and resistor 611 (sideways) respectively. The voltages on conductor 602 are summed algebraically and applied through conductor 609 to an integrator U-604 which operates a simulated altimeter I-601. The integrator U-604 supplies also a voltage to a terminal 620 for operating the servomotor M-900 for the shutter 255 and a voltage to a servo-amplifier U-605 to operate the altitude servo M-1600 (not shown). Heading simulation (Fig. 7). The potentiometer R-125 operated by the rudder pedals has equal D.C. voltages of opposite polarity applied to its ends to supply a potentiometer R-702 operated by the engine speed motor M-1500. The output from this potentiometer, with a voltage from a terminal 702 fed by amplifier U-501 (Fig. 5) to give a signal representative of rotor torque and a further voltage from a terminal 705 to simulate " weathercocking " is fed to an integrator U-701 which produces a voltage proportional to rate of turning which is applied to a further integrator U-702 which energises the heading servomotor M-500 which is positioned by a follow-up potentiometer R-717. Circuits are given Figs. 8 and 9 (not shown) for operating the rolling and pitching servos M-600, M-700 and M-800..