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Aviation History
1946
1946 - 0417.PDF
FEBRUARY 28TH, 1946 FLIGHT Star, with radial-flow compressor. Apart from the airscrewof the front unit, a certain amount of jet propulsion is obtained from the turbine exhaust pipe which projectsthrough the belly of the fuselage approximately amidships. First Tested with a Merlin Engine An interesting feature of the development work which has gone into the XP-81 is that before the TG-ioo unit vva J installed, the machine was tested in flight with a Merlin engine mounted in the nose. In that form, therefore, the Vultee was basically similar to the Fireball. The installa- tion of the two turbine units is indicated in one of our illustrations. The TG-ioo unit is much more powerful than the Merlin, but of lower specific weight, and so the weights of the two units may have been sufficiently alike to bring the e.g. into the correct position with either. The weight of the I-40 unit so far aft has obviously made it necessary to push the front unit farther forward than is usual in relation to the wing, hence the long nose of the XP-81. It would be interesting to know the effect of this on directional stability. The fin and rudder do not appear to be above normal size to counteract the forward '' fin effect'' of the long nose and the large four-bladed airscrew. The wing is of orthodox design so far as its plan form is concerned. Its aerofoil section is one of the N.A.C.A. laminar-flow types, and in order to get the wing surface as smooth as possible, the skin is of heavy gauge so that no dimpling occurs at the rivets, the heads of which are milled. In this way, it is claimed, no painting or other treatment is necessary to fill-in depressions. The heavy- gauge plating is applied to the forward 34.5 per cent, of thewing chord and forms, with spar and leading edge, a torsion box extending to the centre line of the fuselage. The trail-ing-edge portion of the wing is a somewhat lighter structure and carries equipment, ailerons and flaps. Thermal de-icing is used for the wing and tail leading edges, and is provided by the heat from the TG-ioo exhaust. Structurally the fuselage is of orthodox type, with semi-monoeoque construction and flush-riveted skin plating. A bubble-type canopy covers the pilot's cockpit and isarranged to slide back, either to the extreme of its travel or to intermediate stops. A device is under development forcatapulting the pilot from his cockpit in case of emergency. The pilot's cabin is pressurised by the air from the TG-ioocompressor, and refrigeration is also provided so that con- ditions can be kept comfortable regardless of altitude orclimate. An automatic pilot is installed, in view of the long ranges for which the machine might be used. The large air scoops in the sides of the fuselage supplythe I-40 jet unit in the tail. The TG-ioo obtains its air through an annular scoop around the airscrew reductiongear. The normal supply of fuel for the two power units is carried in internal tanks located just aft of the pilot'scompartment. For long-range operation provision has been made to carry external drop tanks. Design of the XP-81 began in September, 1943. Thefirst test flight with the Merlin installed in the nose was made on February nth, 1945, and the first flight with theTG-100 unit on December 21st, 1945. A British Meteor with Rolls-Royce Trent units driving airscrews flew before this. HAPPY LANDINGS AS part of a drive against accidents in the R.A.F., the Direc-torate of Accident Prevention has produced the first num- ber of a monthly publication called Happy Landings. In aforeword, the Chief of the Air Staff, Lord Tedder, says, that now the war is over the R.A.F. will have fewer aircraft, andmost certainly none to waste. The last ounce must be got out of what the R.A.F. has, and, therefore, the accident rate mustbe drastically cut down. The publication which, incidentally, introduced the R.A.F.'s" Safety Pin-up " Girl, Prudence, is handsomely produced with the use of colour and reflects much credit on its originator.Air Commodore A. C H. Sharp, D.S.O., who is the Director ol Accident Prevention. HELIUM-INFLATED TYRES IT is reported that the Goodyear Tyre and Rubber Companyhave, for the first time, successfully applied Helium to the inflation of aircraft tyres. The chief difficulty in the useof Helium for inflation is that it diffuses too rapidly through natural rubber, but this problem has been solved by usingButyl synthetic rubber inner tubes. Helium diffuses through this material only a- quarter as fast as through natural rubber.or 67 per cent, as fast as air through natural rubber. It is calculated that, on an average, approximately 92 lb.c! air is required to inflate a uoin. tyre, but that only 13 1b. 1 Helium is needed This shows a saving of 158 lb. for the:ain wheels of each aircraft, irrespective of any weight saved v using Helium for the nose or tail wheel. This new development would seem to have a considerableJ value, for it has been estimated that each pound of weight • >aved in commercial aviation is worth about ^25 over the yearin passenger and freight revenue. On this basis, a saving ol AIRSTRIP ... No. 3 approximately £4,000 would be effected in the case of eachlarge aircraft in a single year. S.M.A.E. ANNUAL DINNER '"THE Society of Model Aeronautical Engineers held theit-i- annual pnzegiving, dinner and dance at the Lysbeth Hall, London, W., on Saturday, February 16th, and it was attendedby over 200 members, the guest of the evening being Sit Frederick Handley Page Mr. A. F. Houlberg occupied the chair, and after the toastto the King Mr. M. R. Knight rose to propose " The Guests " and referred to Sir Frederick as an outstanding personalityin the aircraft industry. His interest in the tailless type ot aircraft was evinced by his sponsoring of an S.M.A.E. contestin 1945 for models of this type, and the Society was very grateful for his assistance and moral support. Another prominent guest was Mr. F. J. Camm, journalist,brother of Mr. S. Camm, the Hawker designer, and among the many well-known model aircraft enthusiasts were Mr. A. Judgewho went to America at the age of 19 and won the Wakefield International Trophy for Great Britain, and Mr. R. N. Bullock,another Wakefield Trophy winner, who obtained the cup in 1929 with a low-wing model. Sir Frederick Handley Page, who presented the prizes, ex-pressed the opinion that in model aircraft there were great possibilities for the future, and the adventurous spirit prevail-ing was the same as that which encouraged the early pioneers to surmount their difficulties He stressed the importance ofthe research side, which enabled flight characteristics to be judged and tests made with model aircraft from which couldbe obtained useful data for their full-scale counterparts. Sit Frederick added that he would like to see at some future date aspeed trophy for models on the lines of the famous Schneider Trophy.
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