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Aviation History
1952
1952 - 0870.PDF
384 FLIGHT North American F-86 Sabre (General Electric J-47), showing air brakes. should, however, be borne in mind that the R.A.F. sub-types are powered with the Goblin 2, of only 3,100 lb static thrust, whereas export variants of the Vampire (Swiss Mk 6, Swedish Mk 50, and Norwegian Mk 52) have the Goblin 2 of 3,300 lb. This confers a correspondingly better performance, the maximum speed being 548 m.p.h., and R.A.F. pilots have found that the superiority of the export Vampires has been almost embarrassingly apparent in Continental exercises. Rate of climb at 30,000ft is quoted as 75oft/min for the R.A.F. version, i,i75ft/min for the export model. All marks of Vampire retain their speed to an unusually high degree at altitude, title sea-level figure of 548 m.p.h. being reduced by only 5 m.p.h. at 20,000ft, 39 m.p.h. at 40,000ft, and 49 m.p.h. at 45,000ft. Certain comparable types of considerably higher speed—the Thunderjet, for example—are believed to experience a sharper fall-off in speed and rate of climb with altitude. As is well known, the Vampire scores further at height in having a low wing-loading (about 40 lb/sq ft with internal fuel only) and low span-loading. Handling and other aspects of performance will be more profitably discussed later, in relation to the N.F.10 two-seater. Figures having been quoted to show the improvement in per formance obtained with even a 200-lb thrust increase on the Vampire, without airframe modification, it is understandable that the Venom F.B.I now about to enter R.A.F. service should be greatly superior to all Vampire variants in speed, climb and ceiling, for the power plant is a de Havilland Ghost, nominally of 5,000 lb thrust, and capable of much greater outputs with water/ methanol injection (10 per cent increase) or tailpipe reheat. A Venom with reheat was demonstrated at Farnborough last year. The Vampire wing having been a limiting factor in high-speed flight, a new wing was developed for the Venom, having a reduced thickness/chord ratio, leading-edge sweepback (to compensate for the rearward movement of the e.g. brought about by the heavier Ghost), square tips, and—after initial trials—boundary-layer fences. Venom performance figures are withheld, but the speed must surely exceed 600 m.p.h., for the similarly powered Swedish J-29 attains at least 650 m.p.h., while the Nene-powered Argentine- built Pulqui II—now destroyed—was capable of a similar per formance. Even France's S.N.C.A.S.E. Mistral, which retains the old Vampire-type wing, but, like the Venom, has some 5,000 lb of thrust, is good for 578 m.p.h. In level-flight and diving speed, however, the Venom could hardly match the Mig-15. An official statement on performance confines itself to the "marked increase" in maximum speed, service ceiling and rate of climb as compared with the Vampire, and the "greatly increased operational ceiling," where, due to the comparatively low wing-loading and well-harmonized controls, manoeuvrability remains "positive and precise." Certainly, there is no reason to question the Venom's qualities as a high-altitude intercepter, and at extreme heights, by virtue of its small turning circle and generally superior handling qualities, it might do well against the Mig-15. Against bombers of types comparable with the Canberra, capable of flying at heights around 50,oof., the Venom should prove a powerful antidote. As for climb, it can only be remarked that the Mistral, with its Vampire-type wing, can reach 32,800ft in about 7£ min, and that the special Ghost-powered long-span Vampire, to which the Venom is closely related, ascended to 56,500ft in 23 min 50 sec, passing 40,000ft after 7! min and 50,000ft after 13^ min. At 59,446ft it was flown "hands-off" for a short time. Radar-equipped North American F-86D and, below it, the TF-93.A Republic F-84E Thunderjet, powered with a General Electric J-47,
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