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Aviation History
1964
1964 - 1018.PDF
FLIGHT International, 9 April 1964 573 wheels and brakes (incorporating axle-mounted Maxaret anti-skid units), brake-operating equipment and brake cooling. Each of the two split-type main wheels, for use with tubeless tyres, accommo- dates a plate brake and an air-cooling installation. The wheel rims incorporate fusible plugs which ensure controlled deflation of the tyre in the event of excessive heat build-up resulting from emergency braking. The air-cooling dissipates heat normally generated by the brake before it can soak into the rim and tyre beads. It consists of a fractional-horsepower electric motor driving a shrouded impeller, and the complete assembly is housed within the axle adjacent to the anti-skid unit. Each Maxaret anti-skid unit is driven through a flexible coupling from the wheel hub, thus ensuring immunity to the effects of weather and any damaging material flung up by the wheels. Maxaret allows the use of maximum braking power in all conditions of weather and runway without resulting in wheel lock and consequent skidding. Multi-piston brakes are used, incorporating jigsaw-type segmen- ' ted rotor assemblies, and stator assemblies carrying inorganic pads. Automatic adjusters ensure that, as the pads wear, the working clearance remains the same, so that the displacement of the operat- ing fluid is maintained at a constant figure throughout the service life of the unit. The principal brake structure can be of either steel or titanium. Problems arising from the high operating temperatures necessitated special test rigs at Dunlop's Aviation Division fac- tories in Coventry, so that components could be tested under all conditions likely to be encountered in service. Powerplant Principal among Category 1 subcontractors are Bristol Siddeley * Engines Ltd, responsible direct to the MoA for the supply of the Olympus 22R turbojet. This powerplant has a reheat thrust in the 30,00O-35,00Olb class, and two are installed in tunnels in the rear fuselage of the TSR.2. The company's Patchway division is well advanced in the development of this powerplant, which is developed from the earlier two-spool Olympus engines that have served so well in Vulcan bombers, and have earned a reputation for excep- tional reliability. The technical specification for the 22R, calling for a high maxi- mum thrust and a very low specific fuel consumption, was a tough one; but it has been successfully achieved, with ample potential for further "stretching." Froblems that have had to be overcome in the development include, on the one hand, those associated with operation at Mach numbers greater than 2: high-temperature lubrication and increased severity of vibration stresses. On the other hand there are problems of very-low-altitude operation: in- creased engine structural loads resulting from higher air density, and greater likelihood of damage from foreign-body ingestion. Bristol Siddeley's experience of low-altitude operation of the Orpheus turbojet in the Fiat G.91 has given them a good under- standing of the difficulties. Damage by birds and other foreign bodies is minimized by the inherently robust design of the Olympus. © Iliffe Transport Publications Ltd 1964 Basic strength requirements for a supersonic turbojet demand the use of guide vanes and compressor blading of steel. The use of specialized materials in some areas has demanded the evolution of new manufacturing techniques. Technical data on the Olympus 22R remain restricted. However, it is known that the Concord's Olympus 593 engines are derived from the 22R. It has been stated that, compared with the Olympus 301 engines already in service with the Vulcan B.2, the mass flow of the Olympus 593 has been increased, and the thrust has been raised still further by a new high-pressure turbine, undoubtedly with cooled blades, allowing an increased combustion temperature. In TSR.2 the Olympus 22R has a fully variable intake and vari- able-area nozzle, and a reheat system fully controllable over the entire range by a single lever. It is possible for both powerplants to operate under well-matched conditions in every phase of flight, and at low altitude the aircraft will cruise without reheat. The intake cone is moved by a Lucas jack with manual or automatic controls, and the intake lip has Dunlop anti-icing heater elements. Some eight years ago Bristol Aero-Engines entered a licensing agreement for developing and manufacturing the American Solar reheat sys- tem. The system now in use on the Olympus 22R differs widely, both thermodynamically and mechanically, from the original Solar system; materials, layout, construction and fuel-injection system are all very different. A Rotax 12-joule high-energy ignition unit is fitted, and the engine fuel system is by Lucas Gas Turbine Equipment. Except for the flow distributor and nozzles, all fuel-system components are mounted on a single chassis, with consequent reduction in pipe- work and simplified installation and removal. The system incor- porates two pumps, venturi meter and appropriate nozzles. Flight trials of the Olympus 22R engine, installed in a Vulcan test-bed, began in February 1962. This aircraft, it may be remem- bered, was destroyed by a fire on the ground in 1962. Subsequent development of the engine has been carried out both at Bristol Siddeley's own facilities at Patchway, and by a Bristol Siddeley team in the high-altitude, high-speed test chamber at the National Gas Turbine Establishment at Pyestock. The Patchway test-bed is pro- vided with an air intake heater for simulating conditions at speeds greater than Mach 2. As well as the propulsive engines, Bristol Siddeley also provide TSR.2's on-board auxiliary power unit. This comprises a Cumulus turbo-compressor with power take-off. It is capable of providing pneumatic power for main-engine starting and cockpit and elec- tronic air-conditioning, as well as shaft power for electrical and hydraulic services on the ground. The Cumulus is a 50 h.p. single- shaft gas turbine, with a single-stage oversize centrifugal compressor driven by a two-stage axial turbine. Compressed air bled from the outer casing of the annular combustion chamber provides a maxi- mum flow of 2.61b/sec for aircraft services. Integrated Subsystems Looking at the "brains" of the TSR.2: the Systems Division E (Electrics and Electronics), responsible for the whole of British Aircraft Corporation's activities in the fields of communications, radar, electric power generation, cockpit instrumentation, auto- matic flight control and flight instrumentation engineering, has the prime task of integrating the entire weapon system. The Division commands elaborate laboratories for carrying out rig tests, and comprehensive computing facilities. It includes a microwave divi- sion specializing in the design of suppressed aerials and the cutting of waveguides, for outside customers as well as for BAC'S own needs. The nav-attack system specified for TSR.2 has posed new prob- lems for the Corporation, and new solutions have been found. The high degree of accuracy necessary demands great complexity of equipment. This is accentuated in the case of TSR.2 by the versa- tility of the aeroplane and its exceptionally wide range of altitude and speed. When the specification was issued no existing electronic equip- ment was capable of meeting the expected range of performance and environment. When terrain-following at exceptionally low altitudes it is important that the pilot should be completely happy, and confident in the reliability of the indications presented to him. The aircraft itself must respond immediately to pilot demand. Obviously, the forward-looking nose radar must be of the highest possible standard; and here, it is claimed, Ferranti have set a
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