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Aviation History
1951
1951 - 1525.PDF
i6o FLIGHT Since the 7076 appeared at the S.8.A.C. Display last year the dorsal in- take for the Rolls-Royce Derwent turbojet has been extensively modi- fied, as seen to advan- tage in this flying view, secured from a D.H. AVRO DELTA DEMONSTRATE^ A Wing Form of the Future: Convincing Indications of its Practicability SOMETHING of a milestone has been reached by theAvro Company in delta-wing development and, so thatit should not pass unnoticed, a way was sought, within the bounds of strict security, to review the success of the work to date and to exhibit the excellent results. A demon- stration was therefore arranged at Dunsfold airfield, near Guildford (recently taken over by the Hawker division of the Hawker Siddeley Group) in order that test pilot Roland J. Falk might show off his sleek and angular charge. The technicians principally concerned (Mr. S. D. Davies, B.Eng., F.R.Ae.S., chief designer, and Mr. J. R. Ewans, A.C.G.I., B.Sc., D.I.C., A.F.R.Ae.S., chief aerodynamicist) were also enabled to tell of their convictions and intentions regarding the delta configuration. An article by*lr. Ewans, incidentally, appears oh pages 172-174of this issue. In it, a very strong and convincing case is stated for the delta; and the flying demonstration at Dunsfold did muchto dispel any doubts which might have existed as to the practical application of such promising theory. A. V. Roe first set out to prove the case for the delta-wingaircraft as a practical type and not, as might have been supposed, merely to build an idealistic research machine with a delta wing.Thus, in the .case of the 707B, with which we are mainly concerned here, the simplest method of feeding air to a well-tried turbojet—the Rolls-Royce Derwent—was employed, namely, by provid- ing scoops above the unit itself. This is housed in the rear fuse-lage, with the turbine level with the wing trailing-edge. Athena main wheels and legs were quickly available, so they were em-ployed. Similarly, a Hawker P. 1052 nosewheel, with lengthened leg, saved time and money as compared with new equipment.Even the control surfaces of this so-called low-speed version of the 707 are surprisingly conventional and operate with normalgeared tabs and set-back hinges. Moreover, these controls are ailerons and elevators, operating in exactly the same manner ason a Chipmunk, for example. The 707B has no flaps, but dive brakes are positioned at aboutmid-chord, well inboard. These, it was learned, are very effective, producing drag roughly equal to twice that of the whole aircraft.Even so, they do not represent the latest ideas on the subject. The design of effective dive brakes which operate equally welland without undue trim-change over a wide speed range is pre- senting a problem to many designers. Because no mention may be made of speeds or other per-formance, W/C. Falk, the test pilot, was severely limited in the comments he could make. However, he was insistent that anyexperienced pilot would be able to handle the 707B with con- fidence in a matter of minutes and with the minimum of briefing.In addition, he stated that the extreme nose-up attitude assumed on take-off and (especially) for landing does not feel or appearout of place to the pilot. View from the cockpit remains good. Performance on the power of a single Derwent was noticeablylively for an aircraft which probably weighs about 10,000 lb. The take-off run was shorter than would be required by most currentj et fighters, and the climb was remarkably good. On coming in to The plan form of the 707 is displayed on a low run. W/C. Folk's aerobatics were a revelation, the rate of roll appearing especi- ally high. Below, the 7076 is landing without para- chute and the angle of attack is high in conse- quence. land, the pilot made his final approach with nose fairly high andspeed of about no m.p.h. On a demonstration slow fly-past, with everything down, observers guessed the speed to be lower.During the afternoon this "low-speed" machine did some relatively high-speed work, which included immaculate upwardrolls and inverted flying, including spot-on turn-unders of the Derry-introduced type. Manoeuvrability and rate of roll wereboth exceptionally good, and a rough timing showed the machine to be capable of a rate of roll in the region of 180 deg/sec. On one landing the tail parachute was streamed when themachine was being held off, less nose-up than usual, at about 20ft. The deceleration, when coupled with the effect of powerfulbrakes, resulted in the 707 pulling up within one-third of the run- way length (Dunsfold's main E-W runway measures 6,123ft).Having reached taxying speed, the pilot cut his tail parachute loose at almost the exact spot at which he had become airborne.
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