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Aviation History
1948
1948 - 1927.PDF
NOVEMBER I8TH, 1948 American Choice FUG HT 593 highly manoeuvrable at high altitude. Spin recovery was "easy when pressure on the elevators was released." It appears that'the take-off angle is a little startling. "It seems, at first, ' Welch reports, "as if the nose is pointed too high and you might stall. You soon get used to it, ' though." -; Armament is said to include up to six 0.50-inch guns, rockets, or either light bombs or two 1,000-poiinders. Although official confirmation is lacking to date, it *. seems very probable that the F-86 has more than once been dived at a speed exceeding Mach 1. At least one * British pilot has flown the F-86 at high speed. Pending the release of full performance data it can be- stated that maximum speed ia service trim is at least 670 m p.h. ; service ceiling over 40,000ft; maximum range over 1,800 miles, and tactical radius 500 miles. NORTH AMERICAN f-86: Span, 37 ft I m; length, 37height, 14 ft; and all-up weight, 13,715 Ib. ft 6 in; The Gas Tor bine in Service Aviation Air Commodore Banks States His Opinions Before the R.U.S.I. AT the outset of his lecture, The Gas Turbine and its Placein Service Aviation, before the Royal United ServiceInstitution, on November 17th, A. Cdre. F K. Banks, C.B., O.B.E., notified his audience that he would take hiscourage in both hands; he would give his views on the in- fluence the gas turbine would exert upon the thinking of thosewho had to plan ahead for our military well-being in the next 10 or 15 years. Much of the lecture was, in fact, conjectural,and much explanatory. Of special value in the latter con- nection was A. Cdre. Banks's concise description of the variousforms of gas turbine. -.- It was supposed, he recalled, in the very early days of thegas turbine, that the engine would be tailored to fit a particu- lar aircraft. The thought behind this was that the turbojetin its original (Whittle) form was so simple to make that it would be a comparatively easy matter to build an engine foreach new aircraft. This idea has, however, been discarded for the simple reason that it is not practicable, being pro-hibitively expensive both in time and money. Military aircraft of the future would all be " bulk limited "because of their speed, so that both the engine and the fuel carried must offer the smallest possible bulk to make way formilitary equipment and the various means (radar and the like] for using that equipment to the best advantage. The axialcompressor helped in this direction, and although it was more sensitive to damage than the centrifugal type, and might dropslightly in efficiency during its working life (because of dirt and slight damage or erosion to its many blades),these disadvantages could not be overriding where maximum performance was demanded andwhere, after all, the life of a first-line military aircraft was relatively short. Certainly this wasthe case in war, where performance was every- thing. The lecturer did not think (and here he ad-mitted treading on thin ice) that the jet fighter would be of much use as an escort to the air-screw-driven bomber or the jet bomber, because of the difficulty of carrying the extra fuel load.It seemed that it would be more practical to resort to a " parasite " machine which would becarried in an escort aircraft accompanying the bombers. This parasite might be propelled by aturbojet or liquid rocket motor. It might have to be jettisoned, or considered expendable, thepilot escaping by parachute, because the escort, or mother aircraft, might be involved in actionand it would be impracticable to effect a " hook- on." The very fast jet bomber, flying at greataltitudes, might have a fair chance of escaping attack from piloted aircraft, if not from guided missiles with proximityfuses. In any case, once it arrived over its target and dis- charged its bombs, it probably had a better chance than theescort fighter, which might still be retaining a large propor- tion of, if not all, its military load. Further considering the turbojet fighter, A. Cdre. Bankssaid that it was still open to question whether or not a single- "i" twin-engined machine would be the final answer. This wasa very important decision to make because it influenced future A.Cdre. F. R. Banks. engine development. As he saw il, to get to a maximumoperating height of, say, 45,000 feet, and maintain the highest possible, speed, the ail-up weight, frontal area and wetted sur-face must all be at the minimum possible, other things being equal. If this were the case, then the aircraft would probablyhave a single engine of high specific output, i.e., high thrust per square foot of engine frontal area, and high power/weightratio. The Air Commodore agreed that this contradicted his previous thoughts and views ot about two years ago. The rate of increase in engine power would be largely deter-mined by the advances made in practical aerodynamics, and tile lecturer's guess was that there would be a steady upwardtrend from the present maximum of 5,000 1b thrust per engine to about 10,000 lb, in stages of approximately 2,000 1b, inthe next ten years or so The specific consumption should be reduced to about 0.9 lb per pound of thrust within two or threeyears and, say, to 0.85 lb in five or seven years. This mainly applied to turbojets for fighters or interceptors. For the jetbomber fuel economy was more important and some increase in engine weight and mechanical complication would bejustified if the bulk of fuel carried could be appreciably reduced. Because the ducted-fan unit had not yet been tried in theair, and no aircraft had been specifically designed for it, its value remained largely conjectural. Of the three practical methods of augmenting turbojetthrust (liquid injection, after-burning and rocket) A. Cdre. Banks preferred after-burning because it madeuse of the normal engine fuel and was more economical in fuel consumption than the othermethods. About 2| 1b of fuel (in addition to that consumed by the engine) were used in after-burning for every one pound increase in thrust, •vhereas at least double this quantity was re-juired for the same thrust increase in the case of other methods. Reverting to the subject of jet bomlwrs, thelecturer foresaw that, within the next 10 or 15 years, turbojets intended for these aircraft wouldbe giving cruising consumptions, at operating altitude, at least 20 per cent better than nowobtained. To achieve this, for cruising speeds of, say, 500 m.p.h., the ducted-fan unit might havesome practical application, but later, at speeds of some 100 m.p.h. higher, it would probably >e necessary to revert to a compounded jet engine of fairly high pressure ratio, i.e., withtwo compressors in series, on separate shafts. A compounded jet unit would eventually haveto be designed to give a specific fuel consumption of not more than 0.8 Ib per pound of thrust (static sea level) and, in itslater development, 0.75 lb. Future jet bombers would probably ^arry a crew of two and would be equipped with every possibledevice for blind-flying and for searching or scanning. Considering what he called "the really long-range bomber"and its power plant, A. Cdre. Banks said that at the moment there were two possible engines—the compounded pistonengine and the propjet. He favoured the propjet because he was sure that one could be built which would give an
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