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Aviation History
1953
1953 - 1538.PDF
THE X-3 is white-painted, as are all N.A.C.A. research machines. Though all-up weight exceeds that of the DC-3, span is less than that of a DC-3 tailplane. The illustration below depicts the Douglas crew preparing the X-3 at Edwards A.F.B. boundary-layer slots are visible just forward of the main intakes; the air extracted probably passes out around the jet nozzles. The needle nose carries several pitotjstatic and yaw-sensing heads. DOUGLAS X-3I| -"•" Two Westinghouse J34 turbojet* of 4,500 lb thrust each. Span, 22ft 8in; length, 66ft 9in; height, 12ft 6in; all-up weight, over 27,000 lb; design speed, Mach 3 (representing from 1,960 to 2,280 m.p.h., depending on height); design altitude, 200,000 to 300,000ft. FROM ALL QUARTERS craft capable of Mach 3. Remembering how little was known of such speeds in those days it is doubtful if the contract speci fied anything else. Over 60 possible combinations of turbojet, ramjet and rocket power unit were studied. It is nothing short of extraordinary that the power of the X-3 is derived solely from a pair of after burning Westinghouse J34 turbojets of but 9,000 lb total thrust. Rockets, will, we hear, be added later. The X-3 has a small, con ventional fin and rudder; single movable horizontal tail surface; conventional ailerons; "droop-snoot" wing leading-edge; and split flaps. The wing is, of course, sharp-edged and stubby—and unswept, for there is little to be gained and much to be lost by introducing sweep-back for a Mach number of three. Altogether the control system of the X-3 is surprisingly con ventional—far more so than those of such aircraft as the F-100 and F-103, although the latter are much better-looking. As the X-3's wing loading at full load works out to at least 200 Ib/sq ft, the wing must be completely solid, apart from a small spanwise channel for control runs. All controls are clearly fully powered and irreversible. The leading edge and ailerons are hinged from external brackets which result in long under-wing fairings. Air frame materials consist almost exclusively of stainless steel, titanium alloys and K-Monel alloy, all of which retain their strength at the temperatures produced by skin friction—which we estimate to reach 1,500 deg F at sea level, falling to 500 deg F at 200,000ft. We know that an air-conditioning system of unusual capacity is fitted, although the pilot of the X-3 always wears a full-pressure suit. The pilot sits in a slightly reclining position on the port side of the small cockpit. Unless the entire nose is removable for the purpose, he enters via the nosewheel door. Under the intakes are what appear to be fan-type air brakes, of a design similar to those of the SAAB J 29. Directly under the wing, the flat-bottom of the fuselage is apparently formed by a huge air brake almost identical in shape to that of the F-100 (Flight, November 6th). Within the fuselage is housed 1,200 lb of experimental equipment, some of which is linked with the pressure-sensing holes scattered over the airframe, of which there are some 850. Nearly all the equipment carried was specially developed by the N.A.C.A. For over a year the X-3 has been operated from Edwards A.F.B., California. With a take-off run of 15,000ft the X-3 cannot take off from any other airfield. The X-3 has carried out some impressive flights but, without rockets, cannot have approached the limits given in the table above. With a razor-edge wing, even allowing for the drooping leading and trailing edges, the maximum lift coefficient cannot be high; assuming an empty weight of some 15,000 lb, the landing speed inevitably works out to over 200 m.p.h. Australian Firefly Trainer NOW undergoing final full-load, Ratog and armament trials by the Royal Australian Navy is the protoype of an interesting Firefly AS.5 conversion undertaken by Fairey Aviation of Australia. Outwardly distinguished by having two stepped cock pits, the new variant is suitable for dual instruction, tactical training, gunnery and rocket work, bombing, deck-landing and catapulting, and night flying. Very considerable re-working has been necessary, and this has been carried out by a design-team under L. C. Williams, engineer ing manager, R. A. Manuel, chief technician, and L. C. Pitt, experimental D.O. head. The Firefly T.5 is the first aircraft engineered by this branch of the company.
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