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Aviation History
1922
1922 - 0144.PDF
all but Australia declined the suggested arrangement for earning on experimental airship services to India and the Antipodes. But even if these schemes were found unworkable at the present time, there is another aspect of the question of which the Air Ministry appears to have failed to take account. If there is any lesson to be learned from the two acci dents to airships it is surely that research is wanted, not only on models in the wind tunnel, but also, and more so, on actual airships. Under the mantle of economy two of the older airships were prevented from participating in experimental and research work for which they were quite suitable. The necessary apparatus had already been installed in one, but only inconclusive results had been obtained when the ship was withdrawn. Now, if we are to benefit at all from the money, work and lives spent on airships, we have an oppor tunity to do so by recommissioning one or two of the present ships, keeping at any rate sufficient personnel to operate them and sufficient materiel to keep them in the air, and proceed with such experiments as are known to be required before the design of an improved ship can be laid down with the certainty that there will be no weak spots and no broken girders when manoeuvring the ship. The static safety of " R.38 " was admirable, but the strength against aerodynamic forces was too small. It is clearly indicated in the report of the Accidents Investigations Sub-Committee along which lines research is needed. Such research could be carried out with relatively little outlay, and the results would be of the very greatest value to future work on airships. Without it the road to further progress is barred, and we shall have to restrict ourselves to such ships as that outlined by Major Scott in his paper before the Air Conference, which, although capable of good work, do not represent the best that can be done. In his paper Major Scott was very moderate in his claims, and if there is any fault to find with his excellent paper it is mainly that he errs on the side of modesty, and as he himself pointed out, the Germans would probably undertake, and guarantee, to exceed by a considerable margin the performance and weight figures given by Major Scott. It therefore seems not a little unfortunate that, so far as can* be seen, nothing &t all is likely to be done with the existing airships. Even if they were only retained in commission for research purposes, we should at least get some results from the money expended on them up to the present time. Otherwise that money will have been entirely wasted. Not only so, but if the policy outlined by Captain Guest represents the Government view, we have no hesita tion in saying that it means the renunciation by this country of all future claim to a place in the world as airship constructors. That we can leave airships alone for ten years, and then start de novo as Captain Guest suggested, is simply absurd. It cannot be done. By that time other countries will have made enormous progress, will have the experience, and, moreover, will have established themselves as airship manufacturing nations in the <S> - <$> France's Great 1924 Competition. FROM France it is reported that the prize of one million francs offered by the French Society for Aeronautical Propaganda for the " best" aero engine will probably be augmented by another million affered by the French Air Minister. But few details are to hand at the time of going to press, but it appears that the competition will be for MARCH 9, 1922 world's estimate. Who will then dream of coming to England for airships ? No, if it is good-bye now, it is probably good-bye for all time. Let the Government well ponder the problem before too late. «• • * In our correspondence column will be Soaring found a most interesting account of a D m . rough-and-ready experiment carried out Air Currents on board one of the P. & O. boats to determine what sort of air currents seagulls make use of in gliding behind the stern of a steamer under way. The amazing result was that it was found that in the region in which the gulls were gliding there was actually a descending air current, and not, as generally supposed, an ascending current. If the observation is correct, and there is no reason to doubt it, it seems to indicate that the birds make use of the turbulence in the air and not of its general direction. This fact, if it be a fact, is of the greatest interest in connection with soaring flight problems, and we shall welcome communica tions relating to this subject. • • * Among the many problems with which Testing the aircraft designer is confronted, Aerofoils probably one of those which cause most Flight annoyance and uncertainty is the application of the results of model tests to full-size machines. In order to approach as close as possible to a _ correct solution, test runs in wind tunnels have to be run at very high velocities owing to the small size of the models tested. Even then there is frequently some disagreement between the model results and the full-size figures. This difference is known as the " scale effect." In America, and also to a certain extent in this country, work is progressing on methods of test which will establish the scale effect. In America, the problem is being attacked in several ways. First of all, at Langley Field a compressed air wind tunnel is being constructed in which the air is compressed to about 20 atmospheres, while the wind speed is as high as 25 metres per second. The Reynolds number will therefore be the same as that for a full-size machine. At McCook Field another tunnel is being constructed, in which the air speed is to be 200 m.p.h. This tunnel has a diameter of i-6 metres, and although the models will be small, indeed will have to be on account of the forces to be expected at 200 m.p.h., the product VL will be approximately the same as for an actual machine. In the meantime, experiments have been made with towing a model aerofoil underneath an aeroplane in flight, and the preliminary experiments, although of a fairly rough-and-ready nature, indicate that it should be possible to test aerofoils of consider able size at a flying speed of 100 m.p.h. or more with good accuracy. This should enable tests to be carried out, not only at the same Reynolds number, but at the same size and speed as the full-size machine, and thus provide further data on Scale Effect. A report of this free flight method of testing is published elsewhere in this issue. engines of 350-450 h.p., and weighing not more than 2 lbs. ,'h.p. It is understood that competing engines will have to pass a reliability run of 240 hours, in stretches of eight hours each, and that the total time taken in completing the 240 heurs must not exceed 100 days. The competition will start on March 1, 1924, and entries must be received before December 1, 1923. I44
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