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Aviation History
1922
1922 - 0130.PDF
a good speed and at a comparatively low altitude, variously given as i.ooo and 1,500 ft. As the airship itself is approximately 400 ft. long, it will be seen that its height above the ground was not more than four lengths at the most, and that consequently the momentum of the airship would carry it on, especially as there may have been some slight delay in stopping the engines. It is to be observed that the breaking of the R.38 also took place at a relatively low altitude, and that it is stated in the report that, as the forces are pro portionate to the air density, the latter ship was not strong enough to withstand the stresses set up at high speeds and low altitude. If the " Roma" had been at 2,000 to 3,000 ft. at the time the tail broke the ship might probably have been saved, as it now seems fairly well established that she did not catch fire until striking the electric wires. A further point of similarity between the two accidents is that both were, directly or indirectly, due to the forces on the tail. In the case of the " Roma " the tail gave way, while in R.38 the tail pressures resulted in breaking the longitudinal girders. In other words, both accidents were due to aerodynamic forces set up during manoeuvres and not to any weakness existing when regarded statically. One is forced to the opinion that both accidents point to an urgent need for further research, both in the wind tunnels, on models, and on full-size airships in flight. It is known that all streamline shapes are unstable to a greater or smaller extent, and that an airship requires a good deal of control in order to keep her on any given course. While model experi ments can, and do, give a great deal of information, full-scale research is also required, and it seems to us that, as the problems involved refer largely to first principles, it might well be worth while for the various nations to try to co-ordinate their research on subjects connected with airships. Otherwise there is bound to be a good deal of' overlapping and duplication of work. We fully realise the difficulties, but with good will they should not be insurmountable. There is little doubt that, if some agreement could be reached as to which experiments each of the larger nations should undertake, much valuable time might be saved, and the rate of progress, which is otherwise bound.to be slow, would be considerably accelerated. The Report of the Accidents Investiga- R ort on ticn Sub-Committee into the details R.38 which led to the accident to R.38 was issued during this week, and a brief resume of the conclusions of the Committee is pub lished elsewhere in this issue. Several facts emerge from the report. To begin with, it appears to be estab lished that the accident was undoubtedly due to faulty design, and not, as has been maintained in some quarters, to manoeuvres being undertaken which were really outside the scope of the tests. In fact, the use of rudders and elevators does not appear to have been other than what might have been necessary during a straight forward flight in bad weather. The fundamental cause of the disaster appears to have been the failure of the designers to have taken into consideration stresses due to aerodynamic . forces, as distinct from static forces. Judged on a basis of static forces R.38 was fairly strong, ap parently, the weights being well distributed. And yet we are told that .information existed which would have thrown grave doubt on the structure. Indeed, in the case of R.29 calculations as to the aerodynamic forces had been made, but they showed such a large resultant bending moment that, in the opinion of the designing staff, such a basis of design was precluded by considerations of weight. R.29 was then designed to factors of safety based on static stresses, and, as she showd no signs of faimre, it was concluded that it was safe to design on a static basis, and the model results, uncorroborated as they were by full-scale experiments, were not thought to be reliable enough to be considered. Certain sections of the report throw a striking sidelight on the way in which, under the name of economy, we have neglected to carry out experi ments which would in all probability have furnished data that would have convinced the designers of R.38, and thus might have saved the many gallant lives whose value cannot be assessed in mere pounds, shillings and pen'ce, not to mention a very valuable ship. For instance, in para. 21 of the Report it is stated that " For some time prior to the trials of the ship the design staff of R.38 had pressed for full-scale experiments which would determine the aerodynamic forces acting on the hull of an airship and on its fins and control surfaces, and had fitted the necessary apparatus into R.32, with a view to making a series of such tests. Owing to the early deletion of the ship, only incomplete observations were possible, but these showed unexpectedly high fin pressures. Apparatus for the same purpose was also fitted into R.33, but the ship was put out of commission before the tests were begun." Comment is, we think, superfluous. Research is needed, both model and full-scale, and the existing ships could be utilised for experiments which would be of the greatest value in future design. In this manner we should be able, in the long run, to con sider that we had got value for money expended. If they are allowed to " rot in their sheds," the money must be written off as a dead loss. We are a nation of shopkeepers, to be sure, but even from that not very exalted point of view the idea of making some use of the ships should appeal to us more than writing them off, even if we do have Ministers of the Crown suggesting that we should sit down with our hands in our lap for the next ten years or so. * • • _,. .. Last week it became necessary for us Conference to hold over *ne paper read before the Air Conference by Major Scott, and the discussions which took place during the afternoon session of the second day of the Conference. In the present issue these are published, and thus we close our review of an event which should have considerable effect in letting the man in the street, the business man, the financier—in short, all who are not intimately connected with aviation—know the present position of aviation, what it has to offer, and at what price. That, -as we see it, is the object of the Air Con ference. It may be admitted that this object was not attained this year. The papers read were too long and too technical. Next year let us stick to matters of policy, matters of national and inter national interest, but for heaven's sake let us present a more united front to the outside world than we did in the Guildhall recently. The impression left on the non-technical section of the audience muit have been that the aviation world does not know what it can do and cannot do, nor how much it will cost to do it.
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