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Aviation History
1928
1928 - 0368.PDF
MAY 10, 1928 HYDRAULIC BRAKES FOR AIRCRAFT THE question of fitting an efficient braking system to aero- planes has long been the subject of design and experiment. The increasing weight and landing speeds of aircraft has brought about an increasing demand for some extra means of pulling them up, besides any addition to friction which is usually the sole factor relied upon. The giant, all-metal monoplane, the " Inflexible," built by William Beardmore & Co., Ltd., for the Air Ministry, has been fitted with a form of braking—the Lockheed hydraulic system—that pulls the machine up in a remarkably short distance. When testing this system on one of the largest aeroplanes—weighing when fully laden, approximately 16 tons—the landing distance was reduced 30 per cent., and when considering that this was only a preliminary test wherein all the pressure was not applied, it is almost certain that, on further tests, the landing distance could be reduced from, say 40 per cent, to 50 per cent. The main characteristics of the " Inflexible " are :—wing span, approximately, 155 ft ; length, approximately, 76 ft. ; landing wheels, 7 ft. 6 in. ; inside diameter of the brake drums, 36 in ; total weight when fully laden, 16 tons. The hydraulic braking system fitted was exactly similar to that now fitted by many car manufacturers on their cars, with the exception that three master cylinders were fitted instead of one. We give below definitions (a), (b) and (c) against each of these cylinders, together with description of the various uses in the application :—(a) Master cylinder is fitted and worked in conjunction with the tail skid in such a manner as to prevent the piston moving more than 1 in, and this is ensured by a cam arrangement. (b) Master cylinder is fitted in the pilot's cockpit for the pilot to operate by hand. To enable the pilot to apply the brake easily, a system of toggles was incorporated which gave a leverage of 40 to 1—moving the piston li ins. (c) Master cylinder is, perhaps, the most interesting installation of the three, as it is designed specially as a pressure- limiting cylinder ; this is effected by fitting a large spring behind the piston with the ordinary adjusting arrangement for varying the pressure in the system to whatever pressure is required. Fitted direct to each wheel brake lever were special wheel cylinders not unlike those fitted to cars, excepting that only one piston was used working direct on to toggles to enable extra pressure being applied on account of the enormous weight of the aeroplane. D.H. " Moth " Lands in Battersea CAPT. A. S. WHITE, chief instructor of the D.H. school, made a successful landing in a D.H. " Moth " in Battersea Park on May 3. He was flying from Stag Lane to Croydon, and engine trouble developed when over Chelsea. The nearest open space was the park, although it was well popu- lated. In spite of this, no injury was caused to anyone nor the machine. Atlantic Airmen's Reward A PRIZE of 12,500 dollars offered by Mr. Alwenner Gren, of Stockholm, for a successful flight from Europe to America, was presented to Baron von Huenefeld on May 4. It was accepted by the Baron and then handed by him to Fraulein Herta Junkers, to be given to her father, who designed the " Bremen," the machine which recently flew the Atlantic. In honour of the Baron's Irish companion, Maj. Fitzmaurice, a new town in Saskatchewan will be named after him. The three airmen flew from Washington to New York on May 3 to remain a week. Germany's Second Bid for the Atlantic ANOTHER German Atlantic flight will start shortly. The pilot will be Herr Johann Risticz, of the Junkers Company, and his passenger will be Mme. Lilli Dillenz, the Viennese actress. A start is anticipated from Saalfield, Thuringia, to Baldonnel, Ireland, for the first stage. Their machine is similar to the " Bremen." Mme. Dillenz took part in an attempt last year with Herr Stark and Loose, when after reaching Azores the machine was damaged and the flight abandoned. . .. ... French Atlantic Machine Tested THE Couzinet monoplane fitted with three 180 h.p. Hispano-Suiza engines, in which M. Drouhin is to attempt an Atlantic flight from Paris to New York, is now being tested at Orly, in France. It weighs nearly 9 tons fully loaded. The connecting parts to the various master cylinders and wheel cylinders were standard hydraulic copper tubing and Lockheed patent flexible hoses, similar to those fitted on cars. The question of fixing suitable bleeding points was of vital importance, as the satisfactory performance of a hydrau- lic braking system depends largely upon the absence of air in the system, which once expelled cannot regain an entry owing to the circuit beirfg entirely enclosed. The bleeding points were arranged as follows —One at the extreme end of each master cylinder and one at the extreme end of each wheel cylinder, and finally, one at the highest point of the pipe line, making a total of 6. Of course, care had to be taken to ensure that the highest point did not come above the level of the main reservoir for replenishing. Upon taking off for flight—the pilot's brake being in the off " position and the tail skid on the ground, the piston operated by same, only displaced fluid to actually take up the clearance between the brake shoes and the drum, this ensuring that the wheels are properly free to revolve. Upon the plane taking off the tail skid piston is returned to its normal position by the strength of the brake pull of springs. At any time during the flight, the pilot applies his hand brake lever to exert a given pressure in the system previously ascertained and registered on a pressure gauge. To overcome the force exerted by the brake pull off springs —thus once more taking up the slack between the brake shoes and the drums so that upon landing the pilot is able to forget entirely his braking system as this will automatically be taken care of by the tail skid coming into contact with the ground and thus causing the actual braking force through the addi- tional displacement of the fluid by the tail skid piston. It will readily be seen that should the brakes have any tendency to cause the machine to nose dive, the tail skid will once more leave the ground, thus allowing free rotation of the wheels. Alternatively, the pilot can actually land in the usual manner, letting his tail skid take up the slack between the brake shoes and the drums and apply such braking force by means of his hand lever as he may consider necessary. To avoid any excessive braking force being applied to the wheels so as to actually skid the tyres, the third master cylinder referred to is interposed in this circuit the piston of which is controlled in its movements by a spring having a predetermined strength acting against the piston in the said master cylinder. The spring actually used limited the maximum pressure in the system to 360 lbs. per square inch. H E Belgian Flying Club A COMMITTEE presided over by M. Jaspar, Prime Minister of Belgium, has authorised the formation of a Brussels flying club, to be subsidised by the Treasury. It will train young pilots, from whose ranks the future military pilots will be drawn. The Royal Air Force Memorial Fund THE usual meeting of the Grants Sub-Committee of the Fund was held at Iddesleigh House, on May 3. Mr. W. S. Field was in the chair, and the other members of the Com- mittee present were :—Mrs. L. M. K. Pratt-Barlow, O.B.E. ; Squadron-Leader Douglas Iron, O.B.E. The Committee con- sidered in all 13 cases, and made grants to the amount of /T51 19s. Id. The next meeting was fixed for May 17, at 2.30 p.m. New Director of Works and Buildings, Air Ministry THE Air Ministry announces :—The Secretary of State for Air has appointed Colonel Commandant H. Biddulph, C.B., C.M.G., D.S.O., to be Director of Works and Buildings, Air Ministry, as from July 7 next, in succession to Major- General Sir William A. Liddell, K.C.M.G., C.B., who is retir- ing from the public service. Commdr. Bird on the Southampton Harbour Board COMMANDER J. BIRD, Chairman and Director of the Supermarine Aviation Works, Ltd., has been elected a member of the Southampton Harbour Board, and recently attended his first meeting as representative of Waterside Frontages of the Port of Southampton and District. It may be of interest to note that included in the latter are Messrs. A. V. Roe and Co., Ltd., and the Fairey Aviation Co., Ltd. In addition to representing the Waterside Frontages, Commdr. Bird will be in the position to look after the future of aviation so far as the Harbour Board may be concerned, and there is no doubt his services in this case will be of valuable assist- ance to the Board. 332
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