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Aviation History
1952
1952 - 0974.PDF
438 FLIGHT, II April 1952- ROLLING-OUT the BARREL A Swedish Pilot's Impressions of the Rotund Saab J-29 ONE of the first Swedish Air Force officers tony the 650-m.p.h. Saab J-29 was Lt. Percy Silfvenberg, who has since contri buted to the makers' house-journal some brief impressions of its characteristics. As the following extracts show, it appears that the J-29's designers have succeeded in marrying the high performance available from a 5,000 lb-thrust de Havilland Ghost turbojet with the moderate low-speed handling qualities required for military usage. "The cockpit," reports Lt. Silfvenberg, "is equipped and arranged in a most practical manner, so that one feels rapidly at home in it." Although the 30-deg backward inclination of the ejector seat felt unfamiliar at first, he found it comfortable, and the field of vision was excellent. The steerable nosewheel, con trolled by a short lever in the cockpit, also gave an unusual first impression (although the steering technique was quickly mastered), since the aircraft rolled on its narrow-track undercarriage during sharp taxying turns. For take-off, the Ghost gave rapid acceleration—". . . I held the stick neutral and the aircraft practically flew itself off when the speed reached 112 m.p.h. With undercarriage and flaps up, the speed rose very quickly and the climbing speed was as high as that a J-28 (Vampire) pilot is used to reading for cruising speed in level flight." In flight, Lt. Silfvenberg found the J-29 to give a normal response to the pilot's control movements. The hydraulically powered ailerons felt very light, but elevator control was rather heavy and the aircraft was stable in the looping plane. Tail trimming was effected by the variable-incidence tailplane (itself electrically actuated by a switch on the control column); the aircraft responded very quickly to changes in trim, so that "a little care is needed on the part of the pilot, particularly at high speeds." Ailerons were less effective at low speed, particularly during the final approach; large aileron-movements were necessary for small changes in direction or to counteract gusts. The pilot's first impression of this characteristic was unfavourable, but he stressed the need to avoid violent changes of direction at low speed with full flap—with this and most other modern high-speed aircraft. The landing "was not difficult, but because of the aircrafPs low-speed characteristics it demanded plenty of concentration to avoid losing too much speed. At the stall, which occurs at a sur prisingly low speed because of the effect of the slots . . . there is a marked raising of the nose . . . aerodynamic drag causes speed to drop rapidly if the aircraft is balanced on the main under carriage with the nose so high that it is almost on the point of overbalancing on to the tail." Summing up, the Swedish pilot describes the J-29 as "an exceptional fighter with the capacity to strike hard and quickly, and with the qualities to win the pilot's complete confidence." A lively impression of the Ghost-powered Saab J-29, the only Western European swept-wing fighter in service SHAKING THEM UP AN unusual structures rig has recently been introduced by the Bell Aircraft Corporation in order that studies may be made of the effects of large-amplitude vibrations on aircraft and guided- missile components. The rig takes the form of a 40-ft tower, within which a mounting chamber is suspended by multiple shock-cords. These in turn are anchored to nitrogen-driven pistons at the base and head of the tower. The tower is said to be capable of accommodating components weighing up to 3,000 lb, and to be able to "shake" them at frequencies up to 15 c.p.s. over amplitudes up to 5ft. The vibration is forced by the head and base pistons which can be regulated through a timing device actuating cycling valves to vary piston-frequency and stroke either in phase or in any ratio out of phase. Large-amplitude vibrations are per haps more usually produced by electric ally driven vibrators; on page 454 of this issue is illustrated a British low- frequency generator-set designed to supply current for such equipment. The new Bell vibration tower (see above) for subjecting components to low-frequency large- amplitude vibrations. Power is from nitrogen, compressed in the cylin ders seen on the truck. ANOTHER R.C.A.F. AIRFIELD THE war-time airfield at Langar—about ten miles E.S.E. of Nottingham—is to be occupied by the Royal Canadian Air Force. Since the war it has been used as a maintenance base by A. V. Roe and Co., Ltd., who will continue to have the use of it. Many of the R.C.A.F. personnel will be housed in Nottingham, but Bingham Rural Council, which has tenants in huts round the airfield, has been warned that some of them must leave. CANADIAN FIGHTER PROGRESS SPEAKING in Toronto last week, Mr; Crawford Gordon, Jr., president of Avro Canada, said that production of the Canuck two-seat all-weather fighter would reach a high rate next year but had been retarded by "large-scale changes in the armament requirements." Since the original armament is reported to have included four 30 mm cannon, there seems every justification for assuming that the revised armament will be based principally upon guided missiles. This assumption is underlined both by recent reports of Canadian missile development and by the fact that Mr. Gordon referred to the Canuck specifically as a bomber- destroyer. In the same address, Avro Canada's president announced that all Canadair-built Sabres would be of the F-86E type powered with the Avro Canada Orenda turbojet. Choice of this new power plant should provide a still higher performance for the Sabre; Mr. T. K. Finletter, U.S. Secretary of the Air Force, recently stated that Canadair had agreed to supply "a large number" of Sabres to the U.S.A.F. in addition to those now being built for the R.A.F. and R.C.A.F., all with the Orenda in place of the original J-47. In passing, it may be mentioned that a much-modified Sabre, armed with 20 mm cannon, is to be produced in Australia; this version will be powered with the Australian-built R-R. Avon.
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