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Aviation History
1927
1927 - 0927.PDF
DECEMBER 8, 1927 landing speed, folding wings, etc. This all added to the structure weight. WING-COMMANDER MAYCOCK said he would like to bring up once more the old subject of seaworthiness. The lecturer had tried to define it, but he thought the definition could be put still more briefly. A clear definition was badly wanted, and he would repeat what he had said on a previous occasion : that seaworthiness was of two kinds, which he would call A and B. Under A came seaworthiness when handling the boat on the water, such as in taxying, towing and when moored. Under B came the problems of taking-ofi and alight- ing. His own view was that we were going a little too fast as regards B. The only time when a boat was really required to get off a rough sea was after a forced landing. Before attempting to design for this, it would, he thought, be better to devote attention to other things of more immediate import- ance. He called attention to the fact that already boats were so seaworthy when moored that at times it was impossible to get on board them from a motor-boat or dinghy. The wings got in the way, and designers might usefully devote their attention to this subject. The lecturer had referred to the need for seamanship. He (Wing-Comdr. Maycock) preferred to call that quality " marine airmanship." They had had experience of what sailors with seamanship could do to a machine (Laughter). He thought if a satisfactory type of slot could be evolved, that would be a great help in flying-boat work, because it would give that control which now they feared to lose, if thrown off the water bv a wave. same could be done in other branches of aeronautics, the knowledge would become widespread instead of being the property of a few specialists. He deprecated the loose use of the term " cruising speed." What they were really after was range speed, which was a very different thing. In practice cruising speed was not the most economical speed but an arbitrary speed chosen by the pilot to suit his own con- venience and comfort. He did not know whether or not figures were available concerning fuel consumption in flight as distinct from test bench figures. If they were, they would be interesting. Certainly practical experience did not bear out the consumption figures given in the paper. If some new form of consumption control was to be introduced, he pleaded that it should be made automatic. SQUADRON-LEADER HAIGH wished to ask one or two ques- tions. On the subject of the curves for aspect ratios, he would like to know whether change in structure weight had been taken into account. Also, as cruising speed decreased with aspect ratio, would it not be possible to cross-plot in such a way as to read off direct the aspect ratio suitable for a given range. On the subject of fuel consumption, he would suggest that the use of oil engines would pay, "since with them they could get down to consumptions as low as, 0-36 1b./h.p./hr. SQUADRON-LEADER ENGLAND said Wing-Commander May- cock had practically taken the words out of his mouth by speaking on the subject which he (England) had intended to bring up, namely, that of slots. He would add that not only *,?*~,-, I" FLIGHT " Photograph THE BLACKBURN "IRIS II": Generally similar to the " Iris I," this flying-boat has an all-metal hull. Our photograph shows the machine taking off at Felixstowe at the start of the Baltic Cruise last summer, with Sir Samuel Hoare, Secretary of State for Air. on board. Note the exceptionally clean running. The three engines are Rolls-Rovte " Condors." MAJOR BARLOW said what had struck him in the paper was the outstanding features of cruising speed and range. Cruising speed depended on L/D, TJ, and petrol consumption. L/D threw back the cruising speed. That was shown in the curves. TJ led to higher cruising speeds, while fuel consumption (at 91) per cent, of full power) led to still higher cruising speeds. The high cruising speed reduced the range. Very little could be done by reducing body drag. He personally wanted to gp for the carburettor man. It was disheartening for a designer to give of his best in getting out a machine and then find his effort largely nullified because the carburettor wasted 20 per cent, of the power. What was wanted .was a carburettor that would give the same consumption ovdr the whole throttle range. In short, the best consumption must coincide with the best cruising speed. COMMANDER BRIGGS said he had a communication from Mr. Rowledge on the points raised by the lecturer in connec- tion with consumption. The possibilities of fuel reduction were greater than stated by Major Rennie. The problem was solved as regards the engine, but it still remained to be solved under actual service in a machine. Personally, his view- was that 90 per cent, of normal to normal was the speed at which an engine should be run. The variable pitch airscrew- was important, and was now in sight, but if it failed to materi- alise, then a two-speed gear-box was available. MAJOR LEDEDOER expressed his indebtedness to the lecturer for having, for the first time it had been done as far as he knew, stated clearly the first principles of the problem. If the control slots but also lift slots would be of great advantage in a flying-boat, as they would enable lower speeds to be attained. He referred to the question of seaworthiness, and to the fact that usually, after a forced landing in a rough sea, the lower plane got smashed up in 20 mins. He was a bit uncer- tain how pilots measured 8 ft. waves, which were supposed to be not outside the capabilities of a modern boat for taking off. Usually propellers got smashed in taking off in a rough sea. The whole problem in the end seemed to come down to one of engine reliability against seaworthiness. He had been interested in the film shown, and especially in the flat angle of the hull. With older flving-boats it had been found desirable to enable the hull to be trimmed back to an angle of 16 or 18 deg. In the early days of the flying-boat there was one in which this could be done and that machine was very much more seaworthy than others in which such a large angle could not be attained. MR. WYN-EVANS said he would prefer that evening to confine himself to general questions. He had, he said, recently been privileged to see the outline drawings of a new type of flying- boat in which the stability on the water did not depend on wing tip floats. In fact, for docking purposes the wings could be removed from the centre-section, leaving the hull to be docked in the ordinary way. By such arrangements all the existing harbours of the world would become available to flying-boats. The Airworthiness Department at Farn- borough had recently been requested to examine the possi- bilities of further lightening the metal hulls of flying-boats, 835 c2
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