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Aviation History
1934
1934 - 1297.PDF
DECEMBER 6, 1934. FLIGHT. 13©* COMPOSITE AIRCRAFT A " Double " Seaplane being built by Short Brothers : Lower Machine to carry Upper One to its Operational Height, then Release it AWELL-KEPT secret having leaked out, it has becomepermissible to refer to some extremely interestingexperiments which are to be made when two new air- craft types, now being constructed at the Rochester Works of Short Brothers, have been completed. The scheme owes its origin to Major R. H. Mayo, the well-known con- sulting engineer, and the Air Ministry, as well as Imperial Airways, are interested in it Briefly explained, the Mayo "Leap Frog" scheme consists of joining together two separate aircraft, the upper having a high wing-loading and the lower a less high wing-loading. The two machines take off under the combined power of the engines of both, and when the desired height has been reached, the upper machine is released from the lower by means of certain devices which Major Mayo has patented. These could, of course, be arranged in a number of different ways, but an essential condition seems to be that ihe pilot of what may be termed the " carrier " aircraft should have full control of the combination until just a moment before the act of separation, when, it would seem, it would be preferable for the pilot of the upper machine to work the release mechanism. Superficially, the Mayo scheme appears fantastic. One's first reaction is to jump to the conclusion that this is a very- wasteful way of getting a heavily loaded aircraft into the air, and that the catapult would do it much more cheaply. Upon looking into the matter, however, certain very good reasons for adopting this method begin to appear. If one examines the performance curves of any normal air-craft, it is seen that, from considerations connected with take- off and landing, a much larger wing area is used than isdesirable for actual flying. If the wing area could bo cut down to a third of the normal, for instance, and the designerwere relieved of the necessity of thinking of his take-off and climb, he could design the machine specifically lor cruisingconditions, with the result that the machine could be flown at an angle much closer to that corresponding to best L/D.This would mean that the power required would be less lor a given speed, the saving in power "being used to increase therange and/or payload. Obviously, the Mayo scheme is only of advantage when nights of very considerable distances arebeing considered. The orthodox aircraft cruises at an attitude usually muchcloser to the angle of maximum speed than to that corre- sponding to maximum L/D. It must do this in order toprevent climbing. At maximum L/D the lift coefficient is, with normal wing-loadings, so high that the engines have tobe throttled to prevent climbing. But as the wing-loading goes up so does the speed at which the machine flies at thatparticular angle. It seems to us that it is this fact which is at the bottom of Major Mayo's idea. That certain technical difficulties will arise is to be expected,but they should not be insuperable. And if, as seems probable, the '' carrier '' aircraft can be used for other work, its costand upkeep should not prove prohibitive. TOWARDS THE "FOOLPROOF" IDEAL The Hammond Model Y : A Two-seater " Pusher " for the U.S. Department of Commerce ABOUT a year ago Mr. Vidal, of the U.S. Department ofCommerce, startled the American aircraft industry byL stating that he believed that there was a market for10,000 easily flown, safe aeroplanes, provided they could be sold for 700 dollars each. It subsequently appeared that he might be grante 1 a fund to assist him in proving the truth of his contention, but the money was not forthcoming, and so he called for bi Is on twenty-five small economical aircraft to replace the machines in use by inspectors of the U.S. Department of Commerce. Last month a contract was awarded to the Hammond Aircraft Company, of Ypsilanti, Michigan, for fifteen of the originally specified twenty-five at a cost of 2,190 dollars each. According to Western Flying, it was stipulated that the machine to be ordered must be capable of clearing a 35-foot obstacle 800 ft. from a standing start; that it must be capable of being brought to a stop within 400 ft. of the same obstacle, cleared in a straight and controlled glide by a private pilot; that no movement of the control or sudden loss of power should cause either a spin or a steep recovery dive; that the undercarriage should withstand a landing with a vertical velocity of twenty feet per second; that both pilot and pas- senger should have an uninterrupted view; and that the machine should be capable of being brought to a stop in 150it. from a ground speed of 45 m.p.h. The Hammond Model Y will resemble few aeroplanes thathave been produced during the past few years—with the ex- ception, perhaps, of the Stout " Skycar." It will bo a low-wing three-wheeled "pusher" cabin monoplane of all-metal construction with the pilot and passenger seated side by side.The tail will be carried on two booms and the engine specified is a four-cylinder inverted Menasco. But it is in the three-wheeled undercarriage that the realinterest lies. By arranging two normally braked wheels, braced through the wing by four struts to the cabin top, andan additional fully-castoring wheel in the nose, a number of operational advantages should be obtained, the most notice-able of which will be the ability to use the brakes really hard at all speeds without nosing over. It is claimed also that the gliding angle can be made verysteep for landing in small spaces, and that the actual land- ing can be made simply by pulling tho stick back. In anycontrol position it will be impossible to stall the machine. A good, bui not exceptional speed range is promised—.35 to no m.p.h. Demonstrations will be made in March next vear. castor nose wheel allows the fullest use to be made of the wheel brakes of the Hammond Model Y. This photograph is of a model.
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