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Aviation History
1911
1911 - 0886.PDF
FIRE AND THE OF late months so great a percentage of aviation fatalities have been directly attributable to the escape and ignition of petrol on aeroplanes that it is surely high time for designers to devote their careful attention to eliminating as far as possible this source of danger. Those who are directly connected with the mathematical side of the question, with the quest for greater efficiency, greater speed, and greater stability are, in the excitement of the quest, prone to disregard the subject from the standpoint of the aviator's safety. Every accident that has occurred in the aviation world has, in a manner, been valuable in pointing out certain weak nesses—either peculiar to the pilot or to the machine. The former's shortcomings can only be deplored, as all the writing in the world would not serve to effect any difference, but in the latter case wc opine that every single accident should be carefully analysed, the remedy decided upon, and every effort be expended to render such a recurrence an absolute impossibility. Yet, considering the magnitude of this danger of fire, what steps have been taken to eliminate it since Louis Bleriot, at the first Rheims meeting, fell to earth from a height of 60 feet—a mass of flames ? One would have thought that this accident would have forewarned constructors to devote careful consideration to the absolute insulation of the petrol reservoirs and supply pipes. In some cases flexible rubber couplings were inserted in the petrol pipes to prevent the vibration from deteriorating the quality of the soldered joints ; in others, cloisons or partitions were fitted in the tanks in an effort to strengthen them and, at the same time, to prevent undue washing of the fuel from end to end. Neither of these efforts were serious enough to help materially in diminishing risks from fire. Let us for a moment analyse those fatalities that occurred between May 18th and September 12th of this year. In all 38 mortal accidents have been recorded during this period. Of these, nine have been ascribable to fires. For the remainder of these accidents the following list gives the various causes and the number of deaths in each case that they are respon sible for:— Inexperience .. 9 Equilibrium destroyed Engine failure .. 3 through severe wind gusts 7 Drowned .. .. 2 Trick flights .. .. 1 Structural ruptures 2 Cause unknown .. .. 5 It will thus be seen that fires account for as many deaths as inexperience, and considerably more than each of the other Causes enumerated. The appended list will serve to still further analyse the causes of these disasters, and it is significant to note that, with one exception, all the fires here recorded have occurred on engine-in-front machines that employ the fuselage as a feature of the design. Date. Names. Type of machine. May 18 .. Pierre Marie Bournique .. Monoplane Lieut. Dupuis (passenger) May 28 .. Cirro Cirri .. .. .. Monoplane June 8 .. Marra .. .. .. Biplane* June 18 .. Lieut. Princeteau .. Monoplane Landron .. .. .. Monoplane Sept. 2 .. Lieut, de Grailly .. .. Monoplane Marron .. .. .. Biplanet Sept. 4 .. Leforestier .. .. .. Monoplane * Engine behind. t Engine before. Further, in each case the burning of the machine and pilot has been directly caused by the bursting of the petrol tank and the escape and consequent ignition of the spirit through coming in contact with the hot engine. In one of the instances men tioned there is cause for doubt—that of the case of Marron, who met with a mortal accident on a Savary biplane. Accord ing to some reports the tanks burst, but the spirit did not becorre ignited until one of those who ran to his assistance lit a match. Marron was flying in the dark when the accident occurred. In addition, this bears out, in a remarkable way, the assumption that the fires have been caused by contact of the petrol with hot air cooled engines rather than by water- cooled ones or rather than by sparks leaking from the electrical ignition system, for to the best knowledge of the writer this single exception on record where the tanks have burst and not become ignited was connected with a biplane equipped with a water-cooled engine. Some are of the opinion that the hot engine would be insufficient to ignite petrol. OCTOBER 14, 1911. AEROPLANE. In contradiction to this statement it must be remembered that the incandescent particles of carbon that are invariably present in internal combustion motors are quite sufficientlto bring about the ignition of the spirit. As a proof of this the writer has, on more than one occasion, noticed that, in priming a hot Gnome engine, the injected petrol has become ignited. Little fear need be entertained from fire resulting from a stray spark, for machines nowadays are, with scarcely a single exception, fitted with magneto ignition, and this organ would in a case of a smash have ceased to generate current by the time the tanks had burst and the petrol had escaped. How then can these fatalities be avoided ? For in every instance mentioned the unfortunate pilots would have been living to-day if it had not been for the escaping of the fuel. The chief source of trouble is the rupturing of the tank itself. A broken supply pipe would not be so serious a matter, for the fire resulting would scarcely be of sufficient magnitude to prevent the pilot from making good his escape. To the material from which the tanks are made—sheet brass, for the most part—and to the way in which this unsuit able metal is unsuitably soldered in the manufacture of the tank, must be attributed the chief trouble. If these tanks were replaced by ones made of 1 or 2 mm. mild steel, the cylindrical centre portion drawn after the manner of weldless tubing, with the dished ends stamped or pressed from the sheet and securely welded in position, a recurrence off tank rupture would hardly be in the bounds of possibility. Again, the method of mounting the tank and the position it'occupies with regard to the rest of the machine is a matter of the utmost importance. The reservoir should naturally be arranged at the centre of gravity (or pressure) of the machine, or at least at a point on the vertical line passing through this centre. It would be preferable to strap it in position by means of very wide steel clips fastened strongly to the top two longitudinal members of the main body. Mounted in this position the chances of the tank becoming mangled in the smash are remote in the extreme, while the width of the clips would avoid any tendency of the tank to buckle or slit at the points of support. The practice of arranging an auxiliary tank of large capacity below the front part of the fuselage is one that should be severely condemned, for in case of chassis failure the reservoir could never be expected to survive actual and violent contact with the ground. A tank fitted in this way was responsible for the fatal accident to Lieut. Princeteau at the Start of the European circuit. As for the supply pipes from tank to engine, the use of armoured petrol-proof rubber tubing, much after the style of that used to connect gas rings, might be recommended. Of those cases of the machine catching fire in the air little need be said, for the causes are more simple. Bleriot's accident at the first Rheims meeting when the engine of his old low- centre-of-gravity No. 12 monoplane caught fire must be ascribed to the breaking of a petrol pipe directly above the engine. This could be remedied by replacing the rigid supply tubes by the flexible kind mentioned above and by conducting it to the carburettor without passing it above the engine. Another cause, perhaps the most likely one of fires occurring in flight, is the back-fire owing to the improper closing of the inlet valve. A mishap of this kin 1 recently occurred to Hamel while flying from Hendon to Windsor. He was using a rotary motor. A counterweight of one of his inlet valves broke, with the result that the automatic valve remained open owing to centrifugal action. The charge in the crank case fired and petrol became ignited at the " injector" jet. Had he not been fairly near terra firma at the time it is quite likely that the heat of the flame would have melted off the connecting nipple, and the burning of the increased flow of fuel would have been serious. As it was, he had the presence of mind to turn off his petrol and vol plant to earth, and so risk was avoided. The remedy in this case would simply mean the fitting of one or a series of gauges in the induction pipe. The use of solid petrol, a commodity which is yet in the experimental stage, should absolutely prevent the recurrence of fatalities due to fires on aeroplanes. But apart from this, and still using fuel in the liquid state, it is really by no means a difficult proposition to tackle, and if due consideration were afforded to the prevention of such disasters, they might be absolutely banished, much to the relief of the aviator who possesses a natural objection to the- prospect of being helplessly grilled.
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