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Aviation History
1963
1963 - 0954.PDF
FLIGHT International, 13 June 1963 The only instrumentation required in the cockpit for RB.I62 lift jets might be a row of parallel gauges recording jetpipe pressure, to show immediately any loss of thrust by one unit. At far right is a schematic diagram of a cockpit power lever. Both arrange ments may be incorporated in the GAMD Mirage IIIV TAKE-OFF JET LIFT LIFT JETS POWER INDICATOR / /^ CRUISE l)25 TYPICAL THROTTLE TRAVEL FOR ROLLING TAKE-OFF automatic or left to the pilot's discretion. In most installations the total lift and trim of the aircraft would be maintained by shutting down another RB.162 on the opposite side of the aircraft while allowing some of the remaining engines to operate at an emergency rating with their governors reset to give 107 per cent of the normal thrust. This emergency rating is available primarily to enable the remaining units to serve the fixed-area aircraft control nozzles without being overbled and thus suffering excessive turbine tem perature. An accompanying illustration suggests some of the ways in which lift units may be installed. In the hypothetical transports the RB.162 is seen installed vertically, obliquely (to give both lift and thrust) and horizontally (to increase acceleration on a conventional take-off). In practically all cases it is possible to achieve almost perfect intake efficiency, since the lift intake(s) may be designed specifically for peak efficiency under take-off conditions. In supersonic aircraft the lift-unit bay is normally shut off above and below by upper and lower doors except when the lift jets are actually in use. Where ram-air starting is a requirement it is logical to increase the pressure ratio across the lift jets by employing some form of ram intake and exhaust scuttle. In the case of transport aircraft, one of the most attractive lift pods employs the lift jets installed horizontally across the pod, with an intake on one side and rotating cascade nozzle on the other. This arrangement mini mizes pod size, weight and drag; it also enables lift jets to be in stalled immediately beneath the wing and allows the lift-jet thrust vector to be rotated. In other installations, the RB.162s themselves may be tilted about a limited angle, and Rolls-Royce have also prepared a simple hinged nozzle capable of being tilted through ±15° by any suitable actuator. At first sight it might appear that the use of multiple lift jets would pose problems in the sphere of inspection, maintenance and repair. In fact, the daily inspection involves merely checking the oil level and visually inspecting the two open ends of the unit and its external plumbing, which takes one man about lOmin. Faulty units may be unplugged and removed in approximately the same time, and installation of a fresh jet takes about a quarter of an hour. All the electric, air, fuel, oil and instruments couplings are self-aligning and self-sealing, and the throttle control is a push/pull rod with two bearing pads which mate with corresponding pads on the end of the airframe linkage. The only connection which has to be effected manually is the main engine mounting, which is locked with the aid of a socket brace. In Rolls-Royce's view, "Overhaul life is of paramount importance with regard to costs, maintenance in the field and supply problems. The lift jet will, of course, operate for only very short periods of one or two minutes per sortie and its running time at maximum r.p.m. will be measured in seconds. At its present stage of develop ment the lift jet has an installed life between overhauls at least equal to that of the propulsion engine, estimated conservatively at 2,000 operations, equivalent to 1,000 sorties. With normal life develop ment it is expected that this capability will be doubled. When over haul is required, the simplicity of the RB.162 is again a virtue. Accessibility of installation, automatic coupling and absence of engine-mounted accessories make engine change a relatively minor operation. The engine can be lifted by two men and be carried in a light helicopter. Strip and rebuild time is a mere fraction of that required for a conventional engine. Turbine replacement, should it ever become necessary for inspection or replacement of damaged blades, is a simple field operation which should often be possible without removing the engine from the aircraft." The RB.162 should form a fruitful basis for the development of other powerplants Already it has been scaled both up and down; while the RB.181 has been planned for installation in slender pods barely 3ft deep, it may well be that the first lift jet to go into produc tion will have a thrust of at least 5,0001b. At present, the RB.162 is specified as the lift source in some 20 projects by manufacturers in many countries. Some of these pro jects have been the result of detailed discussions between the engine and airframe manufacturers, while others are merely ideas which a company would like to implement if it could find a sponsor. In some cases the RB.162 is employed as a lightweight source of bleed air or shaft power, especially driving an auxiliary compressor for blowing the flaps and control surfaces (and possibly leading edges) of STOL aircraft. Rolls-Royce have also investigated fan conver sions of the RB.162. For lift purposes the RB.175 lift fan would give about twice the thrust of the straight jet, with a considerably lower specific consumption and noise level, with a slight penalty in thrust/weight ratio. The RB.175 would seem to be a candidate for the eventual VTOL version of the Hawker Siddeley 681. Some Rolls-Royce sketches of hypo thetical types of aircraft equipped with the RB.162. In each case the 162 is employed for booster propulsion, not necessarily with a vertical thrust vector. The aircraft in the upper part of the diagram are suggested super sonic strike fighters, and those in the lower part are military and civil transports. Most of these configura tions are actually the subject of studies by airframe manufacturers in- several countries
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