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Aviation History
1958
1958 - 0228.PDF
VEHICLE RECOVERY EJECTION GEAR •CAPSULE- ALTERNATIVE 4TH STAGE I4OLB PAYLOAD) 238 FLIGHT, 21 February 1958 SATELLITE LANDING GEAR MANNED VERSION 3OOLB PAYLOAD SPACE PROBE FUEL OXIDANT FUEL AERODYNAMIC (VEHICLE GUIDANCE & AUXILIARIES BAY TEST x DETACHABLE^PROTECTIVE CONE 1ST STAGE (SOLID ROCKETS) 2ND STAGE 3RD STAGE 4TH STAGE n TOWARDS ASTRONAUTICS frequently referred to as the corridor of continuous flight intoouter space. Fig. 2 shows this and compares the performance of 1943 and 1958 aircraft with the new regime which must soon beopened up. In order to illustrate some of the performance possibilities invery high-speed, high-altitude flight in the flight corridor, I have selected a hypothetical aerodynamic experimental test vehiclewhich could be air-launched from a Vulcan (see heading picture on page 236). Air-launching of experimental high-altitude vehicles is a well-known technique. The photograph (bottom of page 236) shows a recent N.A.C.A. test vehicle which is launched from a MartinB57A (American Canberra) at 45,000ft. It is a two-stage rocket which reaches a maximum Mach number of 10.5. Another appli-cation of the same concept was proposed by Robotti, a consultant of Fiat in 1956. A Convair F-102A carried a winged two-stagerocket built from V.2 components and a WAC Corporal. By flight refuelling and launching at 46,000ft, this test vehicle was estimatedto attain a height of nearly 2,000,000ft. For some experiments the attainment of high Mach number isthe primary objective: for others, Mach number associated with a particular altitude is desired; and for physical experimentsaltitude, irrespective of speed, is the aim. Air-launching is also suitable for investigating an important class of re-entry flightpaths from satellite orbits. These are characterized by flight-path angles less than, say, five degrees (rather than the 20-40 dcg ofballistic rockets) and are associated with devices able to apply aerodynamic lift as well as drag in the control of their flight path. fig. 3. Four-stage flight corridor research vehicle. Three stages are propelled by solid, liquid and liquid rockets respectively. After launch at about 35,000ft in a gentle climb, the solid boosters accelerate the vehicle to about Mach 2 and are jetti- soned, possibly with some wing structure. The next stage, which contains the guidance and control equipment accelerates to about Mach 10 near 200,000ft. After a long coast to increase altitude the hit propulsion stage is fired. The test vehicle is, of course, separated from the third propulsion stage tor the sake of the experiment. This seems to be essential if recovery of men or equipment isdesired at some predetermined part of the globe. For this reason the primary objective of the study I now proposeis to project a 300 lb aerodynamic vehicle containing instruments and telemetry equipment to Mach numbers exceeding 15 ataltitudes of the order of 400,000ft and at small flight-path angles to the horizontal. In any particular case, speed and altitude canbe varied by choice of the initial climb path, and performance and payload weight can be exchanged] In the example (Fig. 3) a four-stage rocket-propelled vehicleis used. Three of these stages are propelled by solid, liquid and liquid rockets respectively. After launch at about 35,OOOft in agentle climb, the solid boosters accelerate the vehicle to a Mach number of about 2 and are jettisoned^ possibly with some wingstructure. The next stage, which contains the guidance and control equipment, accelerates to a Mach number of about 10near 200,000ft. After a long coast to increase altitude the last propulsion stage is fired. The test vehicle must obviously beseparated from the third propulsion stage for the sake of the experiment. This arrangement is not necessarily the optimum; advantagemight be taken, for instance, of air-breathing accelerators for the first part of the trajectory, below about 90,000ft.A vehicle of this type could fly other trajectories of current interest with alternative payloads. Farside (3 lb) and Vanguard(5 lb and 20 lb) suggest that the physicist can be satisfied with far smaller payloads than the aerodynamicist, and in such cases near-satellite performance should be possible. Alternatively, with a different wing, the vehicle could be flown more nearly verticallyto place a payload of 300 lb near 400 miles altitude (with three stages) and 1,000 miles (with four stages). A smaller but stillhighly useful payload of 40 lb would, of course, go substantially higher. A manned version could assist aviation medicine experi-ments with a reduced performance. No special merit is claimed for the air-launching technique.There are very many ways of going about this kind of experiment; some are cheaper than others, and some offer more flexibility.As an indication of the immense possibilities for the immediate future, over 250 projects have been submitted to the U.S. authori-ties for vehicles to operate beyond the atmosphere. This country, however, need not produce a rash of such projects, but I really dothink we should be getting on with one or perhaps two of them. P. 181 and 182 (continued from page 235) accessory box drives the pressure and scavenge oil pumps, fuelpump and percentage gas-generator tachometer, and also transmits the drive from the starter motor (electric, i.p.n. or pneumatic)which is mounted on the starboard side. From the rear of the accessory gearbox a drive shaft can be extended to a remote boxmounted on the airframe. Single-lever control is provided for the all-speed-governed fuelsystem, which has been designed to permit the use of any normal gas-turbine fuel (including, in emergency, petrol). Two engine-mounted levers are fitted to govern the speed of the gas generator and power section. The first operates the throttle and h-p. shut-off cock and the second combines the selection of propeller speed, feathering and application of the parking brake. The propeller r.p.m.can be varied quite widely without incurring a marked penalty in specific consumption, but Armstrong Siddeley suggest that thepower turbine be held at 85 per cent of maximum r.p.m. Air-bleed and electric anti-icing systems are incorporated, and the com-pressor is surrounded by an annulus incorporating air tapping points for all normal bleed purposes. It is worth laying special emphasis upon the efforts made byArmstrong Siddeley to increase the reliability and inbuilt safety of the engine. In any free-turbine engine, mechanical failure—such as stripping of the input gear to the propeller—can lead to sudden and catastrophic runaway of the power turbine, and inthe P. 182 a unique arrangement is incorporated to cut off the fuel should the r.p.m. of this section increase beyond a given limit.The basic layout of the engine places at least three layers of heat-resistant steel around the turbine section; moreover, the peripheral rings which preserve the outer profile of the gas patharound the turbine rotors are themselves strong enough to contain any blade failure which could occur. In the delivery volute fromthe centrifugal compressor the diffuser cascades have stainless- steel leading edges, and each vane overlaps its neighbours to cutoff any line-of-sight path which could be followed by foreign bodies entering the engine. Containment of the axial compressorrotors is ensured by steel bands inserted into the stator casing around each rotor stage. Virtually all the foregoing applies also to the P.181 helicopterengine. This unit will be available in either forward-drive or rear-drive versions, and is being designed for omni-angle installa-tion. In the front-drive version the reduction gear is mounted in the intake centre-body, and in the alternative arrangement thecomplete gearbox is suspended in the centre of the single or bifurcated exhaust duct by means of a lightweight structure. ARMSTRONG SIDDELEY P.181 Free-turbine turboprop for fixed-wing aircraft, with two-stage axial compressor followed by a centrifugal compressor mounted on the same shaft and driven by a two-stage turbine, the propeller being driven by an independent single-stage power turbine. Overall length from propeller-cone abuttment line to rear face of exhaust cone, 59.975in; approximate overall length including spinner, 89in; maximum overall diameter (over compressor stator casing and combustion-chamber joint flange), 27.3in; equipped dry weight, approximately 600 Ib; maximum compressor speed, 20,000 r.p.m.; maximum power-turbine speed, 14,600 r.p.m.; maximum mass flow, 12.5 Ib/sec. P.181 turboshaft engine for helicopters, generally similar except for the following particulars: overall length as shown in the photograph, 63.675in (including 6 kW generator); equipped dry weight, approximately 540 Ib.
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