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Aviation History
1949
1949 - 1291.PDF
JULY 14TH, 1949 FLIGHT 55 Wheel Brakes . . for this particular purpose, which would tend to introducefurther complications. Modern brakes are barely keeping abreast of require-ments. The prospect of ever-higher landing speeds and all-up weights indicate that some drastic changes or someform of retarding force additional to that obtained from wheel brakes -will become most desirable, if not essential,on some future aircraft. Already considerable thought has been given to the problem, though some of the suggestions. considered have bordered on the fantastic. Intensively developed over the past few years, for bothpiston- and turboprop-engined aircraft, is the reversible- pitch airscrew, which is proving remarkably efficient.For reducing the landing run, and for ground manoeuvring such as turning or backing, such an airscrew is extremelyvaluable on large civil airliners and military aircraft. It is particularly useful on ice-covered runways, where wheelbraking might be treacherous. . The introduction of tricycle undercarriages has enabledhigher wheel-braking forces to be used without fear of the aircraft nosing over, but it has aggravated the energy-absorption problem, since the aerodynamic drag is consider-, ably less than for the earlier type in the tail-down attitude.An idea of the loss is given by an approximate calculation which showed that, to provide a tricycle-undercarriagefighter with a drag equal to that for a tailwheel layout just after touchdown, required an addition of about 20 sqft of air-brake area, which was not a practicable proposi- tion. When calculating the size of brake required it isusual to assume that all the kinetic energy must be con- sumed by the brakes on a nosewheel type, but only 0.7for the tailwheel types. Aircraft fitted with double flaps could be given anincrease in drag by swivelling the subsidiary flap round, this movement simultaneously closing the slots andobstructing the flow over the top surface of the wing. This would however, further complicate the flap-operating gear. NEWS OF THE Of the more unconventional efforts, an emergency brakingmethod tested in the United States on light aircraft con- sisted of a type of gun fitted vertically in the fuselagewhich, at the moment of landing, shot into the ground a "harpoon" attached to a cable made from a materialsimilar to nylon which, when stretched, absorbed an appreciable amount of energy. Such a scheme obviouslycould not be used on concrete runways. An idea (put to the test by the Germans during the last war) whichappears to have interesting possibilities, particularly on snow-covered runways, is the tail parachute. One, ofribbon pattern to permit the maximum passage of air, is fitted to the Boeing XB-47 jet bomber, and has provedquite satisfactory in operation. . • . • Wires and Rockets Two schemes which would have the advantage of beingable to utilize experience already gained are, first, the use of arresting wires across runways and, secondly, forward-firing rockets. The first would require wires and retarding gear similar to that developed for aircraft carriers, butwould be considerably less fierce in operation, and the aircraft would probably only pick up the wire after touch-down in order to avoid, the possibility of bouncing pas- sengers through the cabin-roof. Such a scheme would bequite cheap to adopt. The forward-firing rockets suggestion would utilize aform of modified JATO rockets. They would have to be permanently housed within the structure, probablyinside the fuselage, and would be faired in during normal flight. Such a scheme would appear to be eminently suit-able for the supersonic aircraft of to-morrow which will probably touchdown at speeds that, even to-day, wouldseem quite impracticable. None of these ideas by itself is likely to make the wheel-brake redundant. It would be supplementary to them and, on first introduction at any rate, would probablybe used only in an emergency when it was desired to shorten the normal landing run for a particular reason. HUGHES HOWARD HUGHES recentlyannounced improved launching and hangarage facilties for the vast Hughesilying boat—sometimes known as the Hercules—at present docked at TerminalIsland, Los Angeles Harbour. A new metal hangar and a novel dry-dock cradlewill be constructed simultaneously while delivery of suitable airscrews is awaited. The eight-engined Hughes is theworld's largest aircraft; so far it has cost £7,000,000, of which Hughes has volun-tarily contributed ^2,500,000 in addition to the United States Government's £4,500,000. The boat was built at a lower costper pound weight than any other large prototype. Removal and replacement of the skin from elevators, ailerons and rudderhas been undertaken as a precautionary measure because of discovery of broken ribs and structure inside the tail assembly.The removal of the skin and the complete inspection of all the internal structure of these surfaces required detachment o£both elevators and ailerons in their entirety. These structures are enormous, each elevator being larger than the wing of aBoeing Fortress. The interior damage could have resulted in a serious accident had it not been discovered before flight.Damage did not exist when the aircraft was returned to dock after its initial water-taxying tests in the spring of 1948. Although the aircraft has made fast taxi runs in the handsof Howard Hughes himself and has even flown for about a mile at a height of 100ft over Los Angeles Harbour, flight trialsare still held up through lack of suitable airscrews. Hughes has been negotiating for the supply of a set of HamiltonStandard "high-activity" blades but is being forced to await delivery owing to other priority orders. It was originally planned to moor the flying boat in theharbour for the 21 days during the construction of the hangar B 29 The eight-engined Hughes flying boat will carry up to 700 troops. and cradle, and it would have been necessary to re-dock it forinstallation of the new airscrews. However, Hughes was con- cerned over the danger of high winds and ramming. The installation of the new cradle, while supporting thetremendous weight of the boat, presented a complex problem; it will be solved by carrying out the work section by section.The cradle will make use of the pivot principle, and will be easily adjustable to any angle determined by the flying boat'scentre of gravity during a particular launching or docking: the placing of tremendous pressures on the hull is eliminated andsafer and faster launching and docking are permitted. The Hercules is at present sheltered by a tubular steel canvas-covered frame. Metal sheets will be laid on top of this struc- ture to serve as "armour plate" protection from any fallingtools or beams while the new hangar of steel and corrugated aluminium is being constructed. In order to obtain full performance data for the boat, test-ing will be spread over a long period. The purpose of the entire test programme will be to provide information on thedesign, construction, and flight of very large aircraft. After the boat has launched for the second time in its longbut inactive career, it will be tested on the water, probably for manv months.
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