Patent GB-880320-A (GB)
Title: Improvements in or relating to flight simulators
IPC: G09B9/24
Filed: 1957-10-28
Abstract: 880,320. Grounded aircraft trainers. GENERAL PRECISION Inc. Oct. 28, 1957 [Oct. 26, 1956], No. 33566/57. Class 4. Grounded aircraft training apparatus comprises means for multiplying an electrical potential representing the cosine of simulated flight path elevation angle by a simulated airspeed input to obtain an electrical potential representing the product, means for multiplying an electrical potential varying with simulated sideslip angle by a, quantity proportional to the airspeed input to obtain an electrical potential representing the product, means for obtaining two signals representing the sine and cosine of simulated heading angle, means for multiplying one product potential by one signal, and the other product potential by the other signal, and for adding the two products so obtained as electrical potentials, to obtain a potential representing one of the northerly and easterly components of simulated velocity relative to the ground. In the embodiment of Figs. 1-4, the northerly component VNG of simulated velocity relative to the ground, the easterly component VEG and the rate of climb h are computed from where Vp = air speed, #= flight path heading, γ = flight path elevation angle, and # = angle of sideslip. The functions of γ are computed as sin γ = cos α sin #-cos # (# sin Ï+α cos Ï) (4) cos γ=cos α cos #+sin # (# sin Ï+α cos Ï) (5) where α is the angle of attack, # the angle of pitch, and 0 the angle of roll. V NG  and V EG  are integrated to provide simulated ground coordinates, and the effect of simulated wind is included. In Fig. 3, signals of opposite polarity representing Œ α are applied at terminals 301, 302 from the output of a conventional flight computer, and energize a cosine potentiometer R301 the slider of which is driven by the computer Ï servo, Reference to a potentiometer as a sine or cosine potentiometer implies that the potentiometer is suitably contoured and its slider driven linearly by the appropriate servo, or that the potentiometer is linearly wound and its slider driven in an appropriate non-linear fashion. The slider derives a signal -α cos Ï  fed through an amplifier U301 (all amplifiers effect polarity reversal) to energize a cosine potentiometer R303 the slider of which is driven by the computer # servo. The output α cos Ï cos # is applied over terminal 307 to terminal 202, Fig. 2. Again in Fig. 3, a signal representing # from the flight computer is applied over terminal 304 to a summing amplifier U304. The slider of a constantly energized potentiometer R309 is driven by the # servo, and derives a signal - # + sin # also fed to amplifier U304 which thus has an output - sin #, energizing cosine potentiometer R312, the slider of which is driven by the flight computer α servo. The resulting signal - sin # cos α is fed over terminal 310 to terminal 201, Fig. 2. In Fig. 4, signals of opposite polarity representing Œ #, from the flight computer, are applied over terminals 401, 402 to energize sine potentiometer R401 driven by the computer Ï servo. The resulting signal is fed through amplifiers U401 and U402 to a cosine potentiometer R405 the slider of which is driven by the # servo, deriving a signal # sin Ï cos # fed over terminal 404 to terminal 203, Fig. 2. The input to amplifier U201, Fig. 2, is thus - sin # cos α + α cos Ï cos # + # sin Ï cos #, and its output is taken as sin γ, as in equation (4), and applied to a potentiometer R204, the slider of which is driven by the flight computer V p  servo. The resulting signal - V p  sin γ is taken as h, as in equation (3) and fed to an h servo 11 through amplifier U-202. In Fig. 3, the α cos Ï output of amplifier U301 is fed to one end of a sine potentiometer R305, and is fed to the other end through a (polarity reversal) amplifier U302. The slider of potentiometer R305 is driven by the computer # servo, and derives a signal -α cos Ï sin # fed over terminal 308 to terminal 205, Fig. 2. Also in Fig. 3, the slider of a constantly energized potentiometer R306 is driven by the # servo, and the cos # output energizes through amplifier U303 potentiometer R308, the slider of which is driven by the α servo, deriving a signal - cos # cos α fed over terminal 309 to terminal 204, Fig. 2. In Fig. 4, the - # sin Ï output of amplifier U401 is fed directly, and through amplifier U402, to energize sine potentiometer R403, the slider of which is driven by the # servo; deriving an output - # sin Ï sin 9 fed over terminal 403 to terminal 206, Fig. 2. The input to amplifier U203 is thus - cos # cos α-α cos Ï sin #-#<SP> </SP>sin Ï sin # and its output is taken as cos γ, as in equation (5), and energizes potentiometer R209, the slider of which is driven by the V p  servo. The output V p  cos γ is fed through amplifiers U204 and U205, and terminal 209, to terminal 101, Fig. 1. The output - Vp cos γ of amplifier U204 energizes potentiometer R212, the slider of which is driven by the # servo, deriving a signal - V p  # cos γ fed through amplifier U206 and terminal 211 to give a V p  # cos γ input at terminal 102, Fig. 1. In Fig. 1, a resolver R103 is energized by the V p  cos γ signal on terminal 101, through amplifier U101, and through amplifiers U101 and U102. The resolver sliders are driven by the flight computer # servo, and derive signals V p  cos γ cos # and V p  cos γ sin # fed to amplifiers U103 and U106 respectively. A resolver R107 is energized by the V p  # cos γ signal on terminal 102, through amplifier U104 and through amplifiers U104 and U105. The resolver sliders are driven by the # servo, and derive signals V p  # cos γ sin # and V p  # cos γ cos #, fed to amplifiers U103 and U105 respectively. The output of amplifier U103 is thus in magnitude V NG  as in equation (1), and that of amplifier U106 is V EG  as in equation (2). To simulate the effect of wind on groundspeed, the slider of a constantly energized potentiometer R111 is driven by an instructor's control W1 to derive a signal representing the desired wind strength. This energizes a resolver R114 through amplifier U107 and through amplifiers U107 and U108. The resolver sliders are driven by an instructor's wind bearing control W2, and derive signals representing the northerly and easterly wind components, which are fed with negative .polarity to amplifiers U103 and U106 respectively. Alternatively, resolver R114 may be constantly energized, the sliders deriving cosine and sine functions of the wind bearing, these then being multiplied by the desired wind strength. Amplifiers U103 and U106 feed integrators 1101 and 1102, which derive the coordinates of the simulated aircraft relative to the ground. In the embodiment of Figs. 5 and 6, the northerly component X E  of velocity relative to the ground, and the easterly component Y E  are computed from In Fig. 6, signals of opposite polarity representing Œ # are applied at terminals 601, 602 from the flight computer, and energize cosine potentiometer R601, the slider of which is driven by the computer Ï servo to derive a signal - # cos Ï fed to amplifier U601. Signals of opposite polarity representing Œ  α are applied at terminals 603, 604 from the flight computer, and energize sine potentiometer R609, the slider of which is driven by the Ï servo to derive a signal α sin Ï fed to amplifier U601, which thus has an output # cos Ï - α sin Ï. This output energizes potentiometer R604, the slider of which is driven by the V p  servo, and derives a signal which is fed to one end of each of potentiometers R607 and R608 through amplifier U602 and is fed to the other ends of the potentiometers through amplifiers U602 and U603. Potentiometer R607 has a cosine function, and potentiometer R608 a sine function, and both sliders are driven by the # servo, deriving signals - Vp cos # (α sin Ï-# cos Ï) and Vp sin # (α sin Ï -#cos Ï), fed over terminals 605, 606 to terminals 503, 502, Fig. 5, respectively. In Fig 5, a cos γ signal derived for example as in Fig. 2, is applied to terminal 501 to energize a potentiometer R501 the slider of which is driven by the Vp servo. The resulting signal Vp cos γ energizes both ends of sine potentiometer R503, through amplifier U 501 and amplifiers U 501 and U502. The slider of potentiometer R503 is driven by the # servo, deriving a signal V p  cos γ sin # fed to amplifier U504 which also has an input from terminal 503. The amplifier input is thus V p  cos γ sin #- Vp cos # (α sin Ï - # cos Ï) and its output, by equation (7) represents Y E , and is fed to an integrator 1502 deriving Y E . Amplifiers U501 and U502 also energize a cosine potentiometer R505 the slider of which is driven by the # servo to derive a signal V p  cos γ cos # fed to amplifier U503 which also has an input from terminal 502. The amplifier input is thus V p  cos # cos γ+ V p  sin # (α sin Ï -#cos Ï), and its output by equation (6) represents X E , and is fed to an integrator 1501 deriving X E . Wind components are fed to amplifiers U503 and U504 as in Fig. 1.