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Aviation History
1961
1961 - 1016.PDF
116 FLIGHT, 27 July 1961 Missiles and Spaceflight. lateral-acceleration system (Fig 3). Here a movement of the stickproduces a proportional change in curvature of a circular path. This appears to the operator as an acceleration across his field ofview. Four stick-movements are required to produce the required displacement. Considerable skill and anticipation are required ofthe operator, because (a) he must judge when sufficient lateral velocity has been accumulated and must then null the accelerationdemand; and (b) he must next judge the magnitude of the decel- eration (i.e., curvature of path) to apply and also the exact time,so that the lateral velocity is reduced to zero when the missile just reaches the target sight-line. Clearly, this type of control requires a high order of skill. Par-ticularly in the case of the shorter-range targets, when the cor- rection has to be accomplished in a short distance, the requisiteskill can only be acquired by selected operators after considerable training. Mention has been made of cars and aeroplanes. While these areacceleration controlled, to the driver or pilot they appear as velocity systems. With the steering wheel or control column held in a fixedposition, the outside world moves across the field of view at a constant rate. Imagine now a system in which movement of thesteering wheel is required to put the car into a bend, but in which the movement then has to be taken off to hold the car in the turn.To straighten out of the corner would require movement of the steering wheel, first the other way and then back to centre. Such asystem would appear to the driver as an acceleration system, and it is easy to see that it would be much more difficult to use. The Vigilant control system is the nearest practical approach tothe idealized velocity-control system of Fig 4. In practice, any system which depends on aerodynamic lift forlateral movement achieves the required displacement by moving in a circular path. To achieve a velocity control system two principalchanges are necessary:— (a) The missile must be "advised" when it has acquired thedemanded heading, and then constrained to fly a straight course thereafter. This is done with the aid of theautopilot gyros, which provide space references. The missile obtains a measure of the angle turned-throughby means of a signal generated by the gyro in opposition to the command signal. When the two signals balance,the fin deflection is zero, and the missile flies on a straight course on the commanded heading; LEFT RIGHT DOWN h.e RANGE ACROSS RAI STICK POSITION MISSILE COURSE Fig 2. Idealized displacement system VIGILANT... AC WING! ROCKET MOTOR FORWARD LAUNCHING SHOE FAIRINGS GYRO UNIT WARHEAD PROTECTION / CAP DOCKET * PLUG No.5 FORWARD CONNECT-' TO FAIRINGS OUTER CONTACT INNER CONTACT RF SCREEN GYRO CHARGE TERMINAL BLOCK GYRO CHARGE FUZE MONITOR BLOCK SUB-BOOSTER PELLET MAIN BOOSTER PELLET RUBBER STRIP RETAINING GUIDANCE WIRE TO MISSILE WHEN IN CARRY BOX MAIN CHARGE . NOSE PROBE IN RETRACTED POSITION 'FLEXIBLE GUIDE ^CONNECTION TO CARRY BOX Vickers-Armstrongs (Aircraft) have prepared this drawing to indicatt tl\i compact and logical layout of their one-man anti-tank missile. In tfa accompanying article they explain the fact that this relatively sophisti- cated weapon, which carries its autopilot with it, is more expensive -Mi its immediate competitors; but its unique ease of control more ha compensates for this, in that operators can become proficient vi simulator training, and that very few rounds need be fired per yet r retain proficiency. Results already obtained by the British Army corirn all the company's claims, and actual figures will provide ample eviti .'"<'
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