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Aviation History
1914
1914 - 0370.PDF
[705^] STEEL is being more and more extensively used in the construction of the aircraft of to-day, largely owing to the possibilities opened up by welding. Not so long ago, welding was essentially a skilled art, and most of the jobs of this kind had to be done " out." To-day, however, there is hardly a large factory where welding obtains that has not its own welding plant, and workers who thoroughly know their work. In aeroplane construction there are innumerable cases in which welding can be utilised, such as for the tubular work in "the APRIL 4, 1914. ACETYLENE AND AVIATION. temperature of about 6,ooo° F. The localisation of this intense and concentrated heat enables a weld to be done quickly and efficiently without 1 uraing the metal by oxidation or causing other injurious effects, whilst very little practice is required to make the workman proficient in the manipulation of the blow-pipe. Messrs. The Acetylene Corporation, Ltd., of 49, Victoria Street, London, W., who have had many years' experience of acetylene and its uses, have designed several acetylene generators for use with welding plants, of which there are many in use in various large works, including some aeroplane factories. Two of these generators are the " Atoz " stationary plant, which has two generating cham bers, and the " Atoz" portable plant. The latter can easily be moved about from place to place, the weight being only 112 lbs., and it will be found invaluable for general work on metal up to i in. thick. The former model is shown in the accompanying sketch. They are made of mild steel and galvanized after con struction. These and the other models are extremely simple to handle, and are quite automatic in action. The gas is slowly generated and stored in a gas bell, whilst a large volume of water surrounding the generating chambers prevents overheating. An efficient system of purification is employed whereby a cool, thoroughly washed and purified supply of acetylene gas is produced. This is of the utmott importance, as it is essential that the acetylene employed for welding purposes should be absolutely pure. A com plete welding outfit consis's of the acetylene generator and the necessary calcium carbide, one or more blow pipes, oxygen piessure regulator, hydraulic back pressure valve, flexible tubing, specially tinted spectacles for the protection of the operator's eyes, and, of course, the oxygen, all of which can be supplied by the Acetylene Corporation, Ltd. In addition to welding outfits, the above firm also supply various other specialities in connection with acetylene, one of which, being applicable in many ways to aviation, is the "Atoz" acetylene flare, also shown in the accompanying sketch. The uses to which these flares can be put are numerous, for in addition to supplying illumination in large hangars—for they are quite safe—they can be used out in the open for marking out aero dromes during night flying, or would greatly facilitate repaiis being carried out to an aeroplane at night when a forced descent has been made away from the aerodrome. The light given is very powerful and steady, and ordinary commercial carbide is used. Other flares similar to the one just described, but much smaller so that they can be carried about in the hand, are also made, which should be equally useful in connection with night flying. fuselage, chassis, and planes, in addition to struts, sockets, &c. For such work, perhaps, the most successful form of welding is the Oxy-Acetylene system, in which the intense heat of acetylene gas in conjunction with oxygen is utilised to produce a concentrated and extremely hot flame that is easily controlled. Acetylene generates over 1,500 B.T.U. of heat per cubic foot, and with the Oxy-Acetylene system about one volume of acetylene to 14 volumes of oxygen are used, producing a flame having a "LESSONS ® ® ® ACCIDENTS ® HAVE TAUGHT." (Continued from page 318.) THE DISCUSSION. IN opening the discussion Mr. Mervyn O'Gorman remarked that he wished the public were made fully aware of the fact that the Accidents Investigation Committee required funds in order to carry on their work effectively. The object of the Committee was to secure safety ; and in the exercise of their functions ihey had—(a) to interrogate witnesses in order to ascertain the facts concerning an accident as accurately as possible ; (/') to express an opinion as to the probable cause of the accident, and (c) to formulate a statement giving their recommendations based on that opinion. This,hesaid, necessarily involved considerable expense, ana it would be a great advantage to the Committee if they had sufficient money at their disposal as would allow them to maintain a trained staff to make and check calculations, pay for tests and experiments, and possess an independent expert to study and analyse these accidents. The Committee did not condemn flyers or constructors, but indicated weaknesses, errors and risks. He suggested that "wear and tear" might be included amongst the causes of accidents cited in the paper, as_ this was much greater than was generally supposed. He agreed with the author's remarks concerning the possibility of a pilot slip ping forward on to his controls when diving steeply, thus causing the aircraft to dive still more ; but thought it was probable that with the large machines which might come into existence in the near future, a servomotor would be used for operating the controls, in which event no harm would be likely to result. On the subject of hazardous flying, he said that very few pilots took the precaution to look round their machine before starting. Many did not insist on a new part, but permitted the re-adjustment, straightening, or patching up of an old part. As regards gusts and their effect upon the safety of the macnine, Mr. O'Gorman observed that in his opinion there was no warranty—in view of the knowledge they now possessed—for assuming that they were the actual cause of accidents, although they might be regarded as primarily responsible, and it was due to other factors that their effects were not corrected in time. He drew attention to the danger involved when pilots allowed their machines to attain extremely high speed before flattening out. No aeroplane, he said, should be permitted to dive at a greater speed than, say, 20 per cent, about the normal speed attained in horizontal flight, which figure was suggested as a basis for discussion, and he gave the following illustration as indicat ing the magnitude of the stresses induced in the various parts at excessive velocities. Supposing, from some cause, the loss of the sense of location, for example, that a pilot allowed his machine to dive for 10 seconds. In that time, it was possible for the speed to rise to as much as twice the normal speed, then assuming that the stresses varied as the square of the velocity, the stress induced by this increased velocity would be four times the normal. In flattening out, the machine would pass through all angles of lift, including that of maximum lift, at which point the loading might be three times the normal. Hence it was possible for the stress actually induced when flattening out under these conditions, to be as much as twelve times the normal stress and the limitations imposed by weight considerations precluded any possibility of allowing the high factor of safety that would be required to render the machine capable of withstanding such high stresses. Mr. O'Gorman also referred to the importance of keeping the aneroid in good order, as in flying from one district to another which might be immersed in fog, there was only the aneroid to tell the pilot that he was at a sufficiently low level to beware of high objects on the ground. He faid that the aspirations of flyers to describe a loop were growing in intensity and an unduly rapid dive might prove fatal. It would appear that successful exponents of this form of flying do not increase the speed of preliminary descent as much as was supposed, and the exchacge of information on these subjects would be of value to all concerned in flight while the application of a recording tautness meter to the wires of a machine used for this purpoe would be so instructive that he would be glad of the opportunity of obtaining readings if one of our skilful exponents of the art would permit of it. 37°
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