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Aviation History
1950
1950 - 1995.PDF
PLIGHT, 23 November 1950 VAMPIRE TRAINER . . . a Gyrosyn, whilst the setting knob is employed only when the instrument is functioning as a normal directional gyro. Each gyro gun-sight can be used independently of the other, the master control is within the reach of each pilot, and each sight has its individual selector switch; the range control is conventionally embodied on each throttle. On the left-hand side of each mounting is a switch for raising or lowering the sight, and a red emergency knob at the lower right of each mounting is provided so that, if an electrical failure occurs with the sight extended, a wire is snapped and the sight automatically retracted. It is difficult to assess an aspect of fighter-pilot training which is more important than gunnery, in which term, of course, must .be included R.P. and/or bomb attacks, and in this regard, the side-by-side pupil/instructor relationship afforded by the Vampire Trainer is nothing less than ideal The use of standard Vampire 5 wings enables the Trainer to carry the eight rockets or two 1,000-lb bombs of the Mark 5, in addition to the fuselage armament of four 20 mm Hispano cannon, each with 150 rounds. Thus, not only does the aircraft provide training potential matched pre- cisely to the operational ability of the single-seat Vampire fighter-bomber but, if necessary, in an emergency, the Trainer can be immediately used in full-blooded opera- tional roles. At the present time there is a distressing lack of training aircraft in which gunnery instruction can be given to pilots at high speed and, even more important, at high altitude. The Vampire Trainer should fulfil this vital requirement admirably, for its stability limitations at its operational ceiling should be in no wise inferior to those of the Vampire 5. De HaviUands refer to the 115 as an "all-purpose" jet trainer, and they are not overstating the case. In addition to training in gun-, rocket-, and bomb-sighting, air combat and fighter navigation, which are implicit in the layout and equipment of the aircraft, the Trainer is also eminently suitable for employment as an advanced trainer, and for the ever increasingly important work of jet con- version. So straightforward and docile are the flying characteristics that it was seriously suggested to us that the trainee pilot might well go straight on to the Vampire Trainer from an ab initio type such as the Chipmunk or Prentice. Another and, we should think, extremely valu- able use for the new aircraft, will be deck-landing training —all that is needed is the fitting of catapult and arrester hooks and retention tongue. For the young pilot being initiated into the difficult art of deck-landing, we can visual- ize no more comforting and confidence-instilling arrange- ment than to be able to essay the venture with an old hand sitting by one's side. To some extent, the same thing applies to initiation into the forbidding realms of compressi- bility. The excellent control characteristics throughout its speed range for which the Vampire is world-famous means that the handling of the Trainer at high Mach num- bers well suits it to this employment. Curiously, despite the large flat area of the front screen, the Trainer has a greater maximum speed at the higher altitudes than has the 467 Detail of dual control articulation and cross-linkage. single-seat Vampire: these, of course, are estimated figures, but the design people concerned have a reputation for con- servative estimation, and justify the increased maximum on the grounds that the fuselage has a better fineness-ratio. In brief, the performance of the Vampire Trainer can be summarized as follows: The operational ceiling of 40,000ft can be reached in 16.3 minutes, and when the aircraft is fitted with two 100-gallon drop tanks, the opera- tional ceiling is reduced to 34,000ft, which can be reached in 17.5 min. The maximum level speed is 467 kt at sea- level, and 452 kt at 40,000ft. At a Mach number of 0.7, at 40,000ft (395 kt), the radius of steady turn is 1.95 nautical miles. At the same speed and altitude, the aircraft can achieve a minimum radius of turn of 0.95 njn. At lower altitudes, these figures will naturally be considerably improved. The endurance at altitude with allowances for take-off, climb and descent, is approximately two hours without drop tanks and three hours with. Without drop tanks, the air- craft has a still-air range of 730 n.m. at 30,000ft, and 345 njn. at sea-leveL With drop tanks, the corresponding figures are 1,080 n.m. and 540 n.m. For practice ground-attack duty with eight 25-lb R-P.s, a practical radius of action of 100 njn. at 5,000ft can be achieved, whilst leaving an ample fuel margin at the end of the flight. Without external equipment, the limiting Mach number at high altitudes is nearly 0.8 and, without drop tanks, 0.7. The maximum true level speed of which the Vampire Trainer is capable (without external equip- ment) is 477 kt at 20,000ft, this being equivalent to a Mach number of 0.775. C. B. B-W. TESTING SUPERSONIC AIRSCREWS THAT supersonic airscrews are receiving a good deal of con-sideration in the U.S.A. is implicit in the announcement that the world's first supersonic-airscrew spin-pit will be in operation early in 1951 at the Aeroproducts division of the General Motors Corporation, Dayton, Ohio. The pit takes the form of a steel cylinder of 12ft lOin diameter, 7ft 10in high, which is sunk below ground level with an airtight seal to a concrete base, and a steel-dome roof. By evacuating the chamber down to 0.01 atmosphere (i.e., 99 per cent vacuum) an engine of only 450 h.p. is sufficient to rotate test airscrews at relatively high r.p.m. The test specimen is rotated in a horizontal plane, by means of a vertical drive- shaft through the dome from a right-angled gearbox. It appears that tapered blades of very thin section form the basis of present Aeroproducts studies. Illustrations of com- parative sections at a 20in-radius show the supersonic blade to have a t/c ratio of about 4.83 per cent, by comparison with a t/c of 22.55 per cent for a conventional subsonic blade. EARLY WARNING OF ENGINE FAULTS A NEW-TYPE instrument known as an engine-performance *1. indicator has been developed by the Consolidated-Vultee Aircraft Corporation, its purpose being to give advance warning of impending engine failure. Comprising a compact detector unit, linkage, and an indicator dial for the cockpit, it is installed adjacent to the carburettor, where it performs a function described as " measuring the distances to right or left to which the engine is displaced when the airscrew is rotating." The cockpit unit is basically a voltmeter graduated in b.h.p., and the accuracy of the indication is said to be greater than that of any device of this kind previously developed. Should the engine show signs of rough running or power loss prior to a failure, the needle on the gauge immediately oscillates and a warning light glows on the panel, thus giving the engineer time to check operation and, if need be, feather before serious damage occurs. (It is often difficult at present to detect an incipient failure in time to save the engine from complete destruction with, in extreme cases, loss of the airscrew and reduction gear.)
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