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Aviation History
1922
1922 - 0260.PDF
MAY 4, 192s SAFETY FUEL TANK: AWARDS THE Air Ministry announces that the prizes in the Competi tion for Safety Fuel Tanks for aircraft have been awarded as follows :— First Prize, £i,/\oo.—The India-Rubber, Gutta-Percha and Telegraph Works Co., Ltd., Silvertown, London, E. 16. Second Prize, ^400.—Imber Anti-Fire Tanks, Ltd., West Road, Tottenham, London, N. 17. Third Prize, £200.—Comdr. F. L. M. Boothby (R.N. retired), " Overway," Tilford, Surrey. The Competition was arranged in order to promote the evolution of a reliable type of fuel tank for Service and commercial aircraft, which would reduce the risk of fire, due to crashing or hostile action, to a minimum. Twenty-six entries were received for the Competition, which was open to the world, and 18 different types of tanks were actually submitted for test. The judges appointed by the Air Council consider that the Competition has resulted in the achievement of the objects for which it was instituted, and has produced a type of safety fuel tank which, although capable of improvement in several minor respects, is available for immediate introduction on Service and civil aircraft and which, for a slight increase in weight ovef and above that of the standard Service steel tank, gives almost complete immunity from fire, either in a crash or in action with enemy machines. All the tanks tested, with a few exceptions, showed marked superiority in almost every respect over the standard Service steel tank now generally in use. The judges were : Group Capt. E. F. Briggs (Deputy Director of Research), Major B. C. Carter (Directorate of Research), Major J. H. Ledeboer (Directorate of Research), Mr. G. Cockburn (Accidents Investigation Branch), Major J. P. C. Cooper (Accidents Investigation Branch), Mr. H. Grinsted (Royal Aircraft Establishment). The regulations governing the Competition provided that each entrant had to submit two tanks for preliminary trials and that the three most successful competitors in the first stage should submit four more tanks for final trial. The principal features of the tanks submitted by the three winning competitors for the preliminary tests are as follows :— India-Rubber and Gutta-Percha Co., Ltd. No. 1. No. 2. Weight of tank .. .. 7875 lbs. 81-25 lbs. Capacity of tank . . . . 377 galls. 38-2 galls. Weight per gallon capacity . . 208 lbs. 2'I5 lbs. Shape of tank .. . . cubical. Each consisted of a welded sheet-steel rectangular tank with no frame or baffles of any sort, but with each side slightly dished inwards, inserted in a detachable rubber case. These tanks were slung in the fuselage by means of webbing. / Imber Anti-Fire Tanks, Ltd. Weight of tank .. . . 50 lbs. 515 lbs. Capacity of tank .. . . 30 galls. 293 galls. Weight per gallon capacity . . 166 lbs. 1/76 lbs. Shape of tank . . .. elliptical. — The tank consisted of a light-gauge tinned-steel shell which was separated from the inside by a framework of aluminium tubing and light-gauge aluminium baffle plates. After assembly the whole of the tank had been covered with india- rubber of a suitable thickness, and all joints vulcanised. Comdr. Boothby. Weight of tank ... .. 3323 lbs. 35'75 lbs. Capacity of tank .. .. 568 galls. 53-7 galls. Weight per gallon capacity .. 0-58 lbs. o 66 lbs. Shape of tank . . .. cubical. The tank consisted of an inner bag of four-ply rubbered fabric capable of containing the petrol with an outer cover of rubbered fabric which was gas-tight. Non-inflammable gas was introduced into the space between the two shells and maintained under slight pressure. A drain pipe was fitted to the outer casing. The tank was fixed to the fuselage by rubber shock absorber and stringing and encased in three-ply glued o*n. The three competitors qualifying for the final tests were required to submit four tanks of a type fundamentally similar to those entered for the preliminary trials, any minor modifications which it was desired to incorporate being previously submitted for the consideration and approval of the Judges' Committee. Certain modifications, under these conditions, were made to the tanks submitted by each of the three competitors, the details of these modified tanks* being as follows :— India-Rubber, Gutta-Percha and Telegraph Works Co., Ltd. No. 1. No. 2. No. 3. No. 4. Weight of tank .. 57 lbs. 54.5 lbs. 57 lbs. 54.5 lbs. Capacity of tank 29 galls. 29 galls. 29 galls. 28.8 galls. Weight per gallon capacity .. 1.96 lbs. 1.88 lbs. 1.96 lbs. 1.89 lbs. Shape of tank . . cubical. — — — Imber Anti-Fire Tanks, Ltd. Weight of tank .. Capacity of tank Weight per gallon capacity Shape of tank .. Weight of tank . . Capacity of tank Weight per gallon capacity Shape- of tank 52.5 lbs. 51.5 lbs. 50.5 lbs. 51.5 lbs. 30 galls. 29.7 galls. 29.7 galls. 29.5 galls. 1.75 lbs. 1.73 lbs. 1.70 lbs. 1.75 lbs. elliptical. — — — Comdr. Boothby. 36.5 lbs. 35.5 lbs. 33 lbs. 35.5 lbs. 31.5 galls. 31.5 galls. 31.5 galls. 31.5 galls. 1.05 lbs. 1.13 lbs. 1.16 lbs. 1.13 lbs. cubical. — The method of testing the tanks in the preliminary trials was as follows :— Each tank was mounted in a wooden structure similar in construction to the fore part of the ordinary tractor small- type aircraft. The concrete body formed to represent an engine was mounted in front of the tank. The structure containing tank and engine was released down an "I" section girder runway approximately 100 ft. high, so arranged that the body struck the ground at an angle of approximately 450 to the horizontal. It was originally intended to crash the structure on a concrete bed. It was, however, found necessary to modify the conditions, and the bed was covered with a 2 ft. 6 in. depth of sand. The conditions, then, briefly, were those of the typical aircraft crash, the engine partially burying itself, the tanks coming into violent contact with the engine. As, however, the fuselage structure at the moment of impact had attained a velocity—allowing for friction and air resistance—of approximately 50 m.p.h., the conditions were more severe than would prevail in a crash from which a human being could hope to escape with his life. In the final trials the following tests were imposed :— Two tanks of each type were submitted to acceleration and crashing tests, and the remaining two to firing tests, the acceleration test being arranged to imposed stresses approximately equivalent to four times that due to gravity. The tanks mounted in the fuselage structure were fixed to a pendulum raised to the requisite height and released by a trip gear. A tank of each type submitted to this test was given two swings, and was then placed on one side for 10 to 15 minutes, at the end of which, from outside examina tion, nothing untoward had occurred. The crashing tests were carried out in a similar manner to that adopted for the Preliminary tests, with the exception that flints were substituted for sand on the crashing bed. The tanks submitted to firing test were mounted to their fuselage structures and subjected to bursts of five rounds of Vickers machine-gun fire, composed as follows :—one armour piercing, one incendiary, two armour piercing, one incendiary. A system of judging was adopted whereby each judge was enabled to record an independent opinion on a common basis. For the preliminary tests this system was on the following basis :— As regards weight, the basis of 100 marks was taken as representing a tank which, complete with fittings, conformed to-the specified weight of 1.75 lbs. per gallon capacity. For each variation of a decimal-point of this weight- capacity ratio, six marks were added or deducted from the 100 marks. In addition, as a means of correction in the case of tanks whose capacity was outside stipulated limits, the following Marks x Required capacity Actual capacity. Tanks received marks for the attributes in the following proportion :— (a) Crash-proof qualities, 100 marks maximum ; (b) remaining attributes, 100 marks maximum. (b) was divided up as follows :— Durability under Service conditions in absence of accidents Indifference to extremes of temperature.. Adaptability of design to large capacities Simplicity of construction Adaptability of design to various shapes Accessibility of fittings . . Cost of production In awarding marks for the various attributes stated above, the ordinary mild-steel Service tank was taken as a standard. This resulted in the following competitors being placed in the order named at the end of the Preliminary Tests :— 1st, Comdr. F. L. M. Boothby ; 2nd, Messrs. Imber Anti- Fire Tanks, Ltd.; 3rd, India-Rubber, Gutta-Percha and Telegraph Works Co., Ltd. In the final tests the marking was made on the following basis :— 100 marks maximum for each crash test, 100 marks maximum for each firing test and 100 marks maximum for remaining attributes—a total of 500 marks. 260 formula was adopted; the • • 25 • • 25 10 10 10 10 10 marks. >» t» t* t* „ tl
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