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Aviation History
1936
1936 - 2002.PDF
^—WHMMi JULY 16, 1936. FLIGHT. Q7 duplicate photo there is considerable surface stalling at all the aileron strands except the two nearest the tip. An attempt will be made later to repeat all yaw tests at lower speed to find if the down-wind tip can be made to stall before the inboard part of the wing, but this may not be pos sible with the Swallow as built. It is also hoped to carry out tests on other machines, but for the moment that concludes the evidence. There appear to be some further peculiarities of flow as affected by sweeping the wing, according to model tests, but as the writer has only just found them and they need further study, it is hoped to give an account of them, if real, later. The films of the flow taken on the Swallow have not been processed and seen at the time of writing, but it is thought that the only other point that they will bring out is that it is extremely difficult to get " front separation " of the flow at the stall, which appears to make the machine very pleasant to handle at minimum speed. The flow direction within the stalled and semi-stalled regions does not yet seem to have received much attention in published work on this subject, and it is hoped that the present tests will help to fill that gap. The adoption of any great amount of sweepforward will prob ably require study with regard to tip loads in pulling out of dives and perhaps on flutter, but it does seem to be a way of improving lateral stability, as Mr. H. B. Irving has been at pains to point out. and as used in his new biplane arrange ment. If the trailing edge angle is important, as it seems to be, this knowledge will be useful in connection with tapered wings, and it would be very interesting if evidence could be collected about existing tapered machines with the T.E. .swept forward at a good angle. AIR-MAIL COMMENTARY More " Hindenburg " Souvenirs : The Lundy Service : Commemorating an Atlantic Flight By ALEC DAVIS AIR MAIL activity in many countries is recorded by new stamps and covers. Most interesting, probably, are i souvenirs of the Hindenburg's first crossing of the North Atlantic. The special stamps illustrated in Flight some weeks ago were used on the outward flight. Some letters were posted on board and have postmarks with the words '' Luft- schiff Hindenburg " instead of the usual town name. Leichtenstein, desiring to pay tribute and probably make a little money at the same time, issues two stamps, of i franc and 2 franc value, showing the Hindenburg in flight over land scapes. Both stamps are exceptionally good-looking, finely printed by Courvoisier. Atlantic Coast Air Services have issued a set of labels for use on letters and parcels flown between Lundy, in the Bristol Channel, and Barnstaple aerodrome on the mainland. They bear a sketch map of the route, with the name of the company and values ranging from |d. to is. They are not, strictly speaking, air-mail stamps; the Post Office does not deliver to the island, but letters and parcels are carried by air when marked with an accommodation address, care of the company. The inhabitants of Lundy pay air carriage either inward or The Hindenburg cover. The Lundy Island label, Leichtenstein stamp and Lithuanian stamp. outward, and the labels, as shown, represent the amount paid. The Lundy line was started in April, 1935, ran daily through out the summer, weekly in the winter, and went back to daily operation on April 1 this year. A Short Scion and a Monospar are used. As a change from machines, Lithuania chooses a man for her latest air-stamp designs. He is Felix Vaitkus, whose flight across the Atlantic on September 21-22 last year ended with a forced landing in Ireland that damaged the undercarriage of his Lockheed monoplane. A map of his route, with dates, appears alongside the head-and-shoulders portrait. It is stated that 210,000 of the 15 centu issue were printed, 200,000 of the 30c, and 100,000 of the 60c. An addition to British Empire flown covers is provided by the inauguration of the Tata service to Trivandrum, in the south-west corner of India. [Our contributor is always willing to answer queries con nected with air-mail matters. Letters should be addressed cjo the Editor.—ED.] OVERLOAD pOR some years it has been the policy of the Bristol Com- vh J?ny to base its engine development upon extended full- overload testing of production types. d 1™^ tne_ past twelve months the company's engine past s e 'pment department has completed more than 1,500 hours unions overload testing of Mercury and Pegasus engines 'inputs which average 5 per cent, in excess of the maxi- minnt r""ngs normally permissible for not more than five This sound policy has materially contributed to the development of the new series of Mercury and Pegasus engines, which are now in full production. - Such arduous overload testing very clearly demonstrates that these engines • are never dangerously stressed even at maximum permissible rated output; while at normal rated output they possess an exceptionally wide margin of speed, although the various series are always outstanding in respect of high outputs and low weights.
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