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Aviation History
1957
1957 - 1392.PDF
482 SCIMITAR "Flight" photograph A Revealing Description, and Notes on Deck Landing RARELY is it possible to publish such a detailed description of a newBritish military aircraft as that of the Scimitar given below. It has been reprinted by permission of the Admiralty, and is followed bynotes on deck-landing and catapulting trials provided by Vickers- Armstrongs, whose Supermarine Division is, of course, the manufacturerof this remarkable new fighter/bomber, soon to enter F.A.A. service. THE Scimitar is one of the two fastest and most powerfulsingle-seat aircraft coming off the production line in thiscountry, and will be the first of the new generation. Service intensive flying will start shortly and the first squadron will form later. Compared with current single-seat Naval strike/fighter aircraft the Scimitar is large. This larger size has, broadly, three causes; nearly twice the weight of useful load is carried; there is a higher thrust/weight ratio giving a very high initial rate of climb, and greater range and endurance is provided. Further, the aircraft has plenty of development potential. A wide variety of equipment is already planned for the different roles, and design studies for con- tinued improvements are under way. These are possible because recent tests with the blown flap have been very satisfactory, and the aircraft is well within the limits of the ships' gear. Cockpit Layout Starting at the port side aft, mere are two long levers operating the L.P. fuel cocks, with relighting circuit breakers on their right. Forward along the console we have the emergency flap/undercarriage/hook levers, and the I.F.F. and V.H.F. control boxes. Immediately aft of the throttle quadrant are the rudder and standby tailplane trimmers. The throttles also incorporate the H.P. cocks. The relighting switches are on the rear face of each throttle lever and the starboard throttle grip houses the airbrake and "press-to-speak" switches. The airbrakes are at present infinitely variable but are being modified to two positions—in or out. Forward of the throttle quadrant are grouped the engine starting switches, and above it is the sliding hood control switch. To the left of the main instrument panel, from top to bottom, are the arrester hook lever, cockpit emergency lights, flap and undercarriage controls, undercarriage warning lights and brake gauge. Alongside the flap lever is a desynn indicator showing trailing edge flap angle, and next to it a similar type of indicator for the airbrakes. (This will later be changed to a doll's eye" showing white when airbrakes are out.) The engine instruments and fuel presentation are on the right of the main panel. Each fuel tank is individually gauged on the long bank of vertical-scale indicators. The pointers for each tank are all in line when the fuel balancing system is functioning correctly. In the event of it not doing so the fuel can be manually balanced by means of the three-position switch underneath the gauges. To the right of this switch can be seen the cabin altimeter and three "doll's eye" indicators for engine fuel pressures. A flowmeter showing rate of flow and pounds of fuel gone will also be fined here. Above the main fuel indicators is a "totalising" fuel gauge which reads the last 2,000 1b. Alongside are two J.P.T. gauges. The two instruments next above are the r.p.m. indicators which are now calibrated in per cent r.p.m. Coming down to the starboard console forward there is the centralized warning system, comprising a total of ten potentially "vital" failures—cabin pressure, wing fold, two generators, two hydraulic pressures, compressor port and starboard, and fire warn- ing port and starboard. In the event of a failure of any of the above items the main attention-getter lights flash red—these are in the front top corner each side of the-cockpit. The pilot then refers to the panel to determine the exact nature of the failure, cancels the flashing lights and takes appropriate action. Aft of the C.W.P. are bomb and R/P selector switches, audio approach, stores jettison, pressure cabin switch, cabin temperature control (which is fully automatic) and oxygen panel—the latter also has a remote indicator in the centre above the main instru- ment panel—wing fold lever, g-suit control, etc. The transverse panel above the main instrument panel is being extensively rehashed to incorporate radar navigation and sighting devices. Below the main panel are the trim indicators, pitot heat switch, instrument early-start switch and over-ride switch for use with drop tanks. Longitudinal and lateral trim is obtained by the four-way switch on the control column, and there is also a standby tail trim switch on the port console. The trim indicators are "doll's eyes" and are trimmed white for take-off, but all go black when the weight comes off the undercarriage legs. The brakes are toe-operated, and may be parked by pulling out the T-lever. The hood is force-jettisoned by pulling the lever on the inner side of the port console. Pulling down the ejection seat blind automatically fires the hood before the seat. Control Systems. The control system has remained basically unchanged since the first flight, and consists of rod/cable runs operating the valves of hydraulic actuators. Feel is provided artificially. It is a straightforward system, with a minimum of tricks and gimmicks. Pitching control is obtained from a tailplane operated directly by a tandem actuator. There are no elevators or tailplane flaps. The two cylinders of the actuator are fed by entirely separate hydraulic systems. Full operation on either system alone is possible except at supersonic speed, when there is a small reduc- tion in the available g. Since each hydraulic system is provided with two pumps, one on each engine, the failure of one system will not occur due to an engine or drive shaft failure. Coming for- ward from the actuator, one passes the flap-operating link—f non-linear gearing—to arrive at the artificial feel system, which is under the cockpit floor. Duplication of artificial feel is arranged so that failure of one system will not be felt by the pilot. Twin hydraulic jacks provide the feel forces, which are varied by E.A-S. and Mach number pressure capsules. At low air speed a constant jack "base pressure" gives effectively a plain spring feel. At speeds above 300 knots E.A.S. the pressure increases with speed to remain proportional to q. Above M = 0.9 this pressure is biased by the Mach meter capsule to prevent the gradual "sti k heavying" which would otherwise occur. The ailerons are also operated directly by tandem actuators
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