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Aviation History
1958
1958 - 0319.PDF
FLIGHT, 14 March 1958 333 installing later types of engine—an advantage which has paidhandsome dividends, for Canberras have done sterling work as flying test-beds for almost every new British jet engine (androcket motor). Removing the engine from the fuselage allowed Mr. Fetter'steam to give the aircraft a bomb bay of substantially increased overall dimensions which could carry many combinations of bombs,induding a single 8,000-pounder. The more efficient axial engines had a lower specific fuel consumption, and thus the tankage wasslightly reduced and the cells above the bomb bay somewhat simplified in design. The elimination of the fuselage jet-pipemade possible a simpler and lighter tailplane and also saved con- siderable weight aft. In turn, this led to a reduction in the lengthof the front fuselage, without any reduction in the available stowage space as the former engine bay became available for bomb loadand fuel (as the drawings show). Data about high-subsonic aerodynamics was obtained fromGermany, and an alternative layout for the twin-engined scheme was planned with a sweep-angle of 30 deg on the wings. Thiswould have raised the critical speed by about 35 m.pJi. at 40,000ft and, owing to the more forward position occupied by the enginesand heavy wing roots, a still more compact fuselage became pos- sible. But there were also disadvantages, and to this day the ideaof a swept-wing Canberra has never again been seriously con- sidered. It must be remembered that in 1945 tip stalling wascausing trouble on swept tailless designs (the D.H. 108 and A.W.52) and sweepback invariably increases wing structure weight. In anycase, the maximum speed envisaged was not seriously affected by compressibility, owing to the modest total thrust. Compared with the single-engined scheme, the gross weight ofthe twin-engined (straight-winged) aeroplane was reduced by more than ten per cent, to under 40,000 lb. This was due to the reduc-tion in aggregate powerplant weight, lower fuel consumption and the improvement in fuselage design and consequent structuralsavings. The wing area was reduced from 1,040 to 950 sq ft, without increasing the wing loading, and the aspect ratio wascorrespondingly reduced from 5.4 to 4.9. There were also some detail design changes in the pressure cabin. The navigator wasplaced behind the pilot, facing forward and connected with his colleague by a gangway on the starboard side. This gangway waslater extended to the nose to provide a stand-by prone visual bombing position when it was found that suitable blind-bombingradar was not immediately forthcoming. The proposed radar scanner was to be housed entirely within the lower half of thenose and the twin-wheel nose gear was moved back and arranged to retract vertically behind the pressure bulkhead. Finally, in the autumn of 1945 the first real Canberra designcame about. A brochure was submitted to the Ministry of Supply to meet the B.3/45 specification, and on January 7, 1946, a con-tract for four prototype English Electric A.I aircraft, as they were then known, were ordered (the name Canberra was applied afterthe prototype flew). At about this time Mr. Petter and his strengthened design and development team moved from their con-verted garage home in Corporation Street, Preston, to the R.A.F. aerodrome at Warton, eight miles west of Preston on the muddybanks of the River Ribble. During the war Warton had been occupied by the United States Army Air Force, and to some smallextent it was a suitable habitation for a design staff. There was, for instance, a central-heating system so efficient that it eventuallyhad to be taken out of service to provide more "British" working conditions. Details of new aircraft being designed and developed in Britainand the U.S.A. began to reach the outside world, but work at Warton managed to go steadily ahead in great secrecy. Neverthe-less, a year or two later, well before the first flight of die Canberra, it became an open secret—at least in the British industry—thatthe English Electric Co. were making the first aircraft of their own for more than twenty years. There have been many suggestions that the Canberra shouldbe turned into a civil aircraft, and in this context a study made in October 1946 is worth recalling. This described a 34-passengerairliner for stage-lengths of between 490 and 930 statute miles, depending on the operating altitude, with a maximum range of1,600 miles with 16 passengers. This interesting design was a straightforward development of the A.I project with an enlargedfuselage giving an interior diameter of 10ft. The cabin was pressurized and soundproofed and entirelyunbroken by structure. The seats were arranged in orthodox style in pairs on either side of the gangway. Baggage was to be storedunder the floor within the pressure hull—this for structural con- venience—in a space estimated at 320 cu ft. In order to take fulladvantage of this freight hold, it was proposed to load baggage and cargo on to a series of trays which were then to be pushedalong the length of the freight compartment on tracks. This allowed the size of the compartment door to be kept to a minimum,and it was suggested that baggage should be pre-loaded on to special trays immediately on arrival at the airport, so that embarka-tion time could be kept as short as possible (shades of the Electra!). This civil version was to have had two Rolls-Royce AJ.65s, eachof 6,500 lb-thrust, boosted by 1,000 lb for take off. Later develop- ment was envisaged by installing more powerful engines. Theoriginal AJ.65s would have given the aircraft a cruising speed of about 450 m,p.h., which would have put the aircraft in the sameperformance bracket as the early Comets, though over shorter ranges. This study was typical of the investigations which are alwaysmade by companies which have a good basic aircraft design to play with. That it was never proceeded with was due to severalfactors—not the least of which was that a great deal of English Electxic's energies were then being devoted to the development Below are projects dating from 1945 and 1946. Lett is the original, single-engined bomber design. On the right is the next stage, with twin axial engines, and below the latter is the 34-passenger transport, which was planned in the autumn of 1946.
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