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The Project Y interceptor was expected to attain a maximum speed of about Mach 2.25 in level flight, with a service ceiling of 65,000ft (19,812m). Estimates of range are less clear, but 1,000 miles (1,609km) was considered realistic. Armament proposals included two or four cannons and/or spin-stabilised FFARs (Folding Fin Aircraft Rockets). It was also thought that British de Havilland Blue Jay air- to-air missiles might be fitted at some point in the future. No provision was made for an intercept radar and it’s hard to see how bulky electronic equipment of that era could have been accommodated in such a design. At that time airborne radar required a second crewmember and the RCAF may have believed that the CF-100 would fulfil the night/all-weather role, while Project Y would operate as a high-performance daylight inter- ceptor directed from the ground. A good deal of Project Y’s initial develop- ment was undertaken by Avro at Manchester, England: this included engine integration studies and wind tunnel testing. According to a previously secret USAF document from 1959, which outlines the background to the Avrocar, a small, unmanned Project Y demonstrator was test flown by Avro UK in 1953, although records of these trials (and many other important historical documents) were lost in a serious fire that took place in (4.88m). In its upright launch and landing 1959. During a meeting in Britain during position the P.724 would have been sup- March 1953, which was attended by Dr ported bya shock absorbing leg carried in the Ormond Solandt and Sir Roy Dobson, it was _ single tailfin and two other legs that retracted agreed that Project Y showed considerable _ into fairings along the wing roots. The flush promise. Dobson made it clear that Avro UK cockpit occupied a forward section of the and the RAE were still interested in Project Y, _ lower fuselage and the pilot would fly the air- but they were waiting to see further studies of _ craft in a prone position. However the Avro a similarly specified Avro (UK) proposal designers soon realised that it would be diffi- called P.724. cult if not impossible to achieve a satisfactory The initial P.724 proposal had been for a __ thrust/weight ratio with a single engine and VTOL tail-sitter powered by the newly _ they therefore progressed to a twin-engined designed high-performance Rolls-Royce __ configuration. RB.106 axial flow turbojet engine, which had The twin-engined P.724 used two RB.106 a quoted static thrust of 15,000 1b (66KN), ris- engines, which led to a new airframe with a ing to 21,800 lb (97kN) with reheat. This was a 60° delta wing that looked somewhat like a technically advanced design, using two sepa- _half-sized Avro Canada Arrow. The overall rate axial flow compressors driven separately length of the twin-engined P.724 was 37ft by single-stage turbines. Reheat was an inte- (11.28m) and the wingspan was 24ft (7.32m). gral feature of the RB.106 engine with an auto- Weight fully laden was expected to be matically controlled convergent-divergent 24,500 Ib (11,113kg), which included 8,000 Ib propelling nozzle. Although the RB.106 was —_(3,628kg) of fuel carried in the wings and cen- finally cancelled in 1957 as a consequence of tral tanks. Estimates suggest that the P.724 the UK’s ill-considered stance on fighter would have been capable of Mach 2.5, witha development, much of the technology found _ service ceiling of at least 60,000ft (18,288m). its way into the Orenda Iroquois turbine devel- Both afterburning RB.106 engines would oped for the Avro Canada CF-105 Arrow. have been supplied with air from forward P.724 was a semi-dart-shaped aircraft with _ intakes alongside the nose, which housed the a nose air intake. It had an overall length of _ pressurised cockpit and accommodated the 32ft 6in (9.91m) and a wingspan of 16ft pilot ina prone position. This version of P.724 60 A drawing of the proposed Project Y aircraft, showing the use of a single landing leg and glass panels below the cockpit. Avro Canada Avro UK P.724 VTOL interceptor Mk 1 design. via Bill Rose Secret Projects: Flying Saucer Aircraft