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Aviation History
1924
1924 - 0018.PDF
Those wishing to gel in touch with others interested in matters relating to gliding and the construction of gliders are invited to write to the Editor of FLIGHT, who will be pleased to publish such communications on this page, in order to bring together those who would like to co-operate, either in forming gliding clubs or in private collaboration. WITH reference to our remarks last week on the Solex prize for flying from Paris to Rouen, using only 1 kilogramme of fuel and oil, we have received from Mr. W. S. Shackleton, designer of the A.N.E.C. monoplanes, the following notes which were, incidentally, written before Mr. Shackleton saw last week's issue of FLIGHT. The letter runs as follows :— " An interesting announcement appears in the current issue of that excellent little journal Les Ailes, of an offer of 50,000 francs made by the Societe du Carburateur Solex for the first non-stop flight between Paris and Rouen, using not more than 1 kg. of petrol and oil. This calls for a flight of nearly 56 miles on, say, 2 -3 pints of petrol—or at the rate of 194 miles per gallon. * * * " Is this formidable performance possible ? In the light of the recent trials at Lympne, it would certainly appear to be asking too much, but it must be remembered that even in calm weather the triangular Lympne course reduces the actual distance flown to a greater extent than a point-to-point contest, JANUARY 10, 1924 efficiency of the small engine. The petrol consumption, therefore, works out at 3 -66 X -52 = 1-9 pints per 41 miles, or, with the allowance of 2 -3 pints, 49 -6 miles, which is only about 6 miles short of the required distance. With a following wind it should, therefore, be possible to win the Solex prize. * * * " THE above figures indicate that it should be possible to fly 172 miles on a gallon of fuel. The two factors tending towards economical flight are a good gliding angle and low weight. Engine size, within limits, has little bearing on the question" * * * THE above remarks are of more than usual interest, especially those relating to the two main factors making for economy, and the statement that engine size has little to do with economy, within limits. As the finishing sentence sums up the situation in a few words, we have printed it in italics. These, it should be pointed out, are ours and not Mr. Shackleton's. It will probably come as a revelation to most people that a mileage of 172 miles per gallon is considered possible by the designer of one of the most successful light 'planes at Lympne, and the concluding statement—that, within limits, engine size has little effect—seems to be borne out by the Lympne trials, the AIN.E.C. monoplane, with 698 c.c. Blackburne engine, doing as good mileage as the " Wren " with 400 c.c. engine. Incidentally, the fact that -TT- \L 7\ s-i ] LENGTH tS'-9" SPAN 39-6" WING AREA. 193-5 Sq.R "KONIGSBERG1' GLIDER O £ 4 6 b' "". ' 6 FEE^ 2 METRES THE MONOPLANE GLIDER " KOENIGSBERG " : General arrangement drawings, to scale. is designed for alighting on the water. The machine and it is fairly certain that the ' Wren,' for example, would be capable of doing 125 m.p.g. under favourable conditions. Again, with a triangular course any ordinary wind increases the petrol consumption considerably, particularly affecting the slower machines. On a point-to-point course like the Paris-Rouen with a favourable wind the exact reverse is true. The slower machines would be helped proportionately more than the faster ones, and it is conceh'able that the actual m.p.g. might be doubled. * * * " IT is interesting to form some idea of what it should be possible to obtain in the way of m.p.g. in still air. It would be difficult, for example, with our present knowledge to pro duce a machine having a better value of KL/KD than say 17, or one weighing less than 400 lbs. in flying trim. Such a machine would probably have an absolute lift coefficient at the best gliding angle of about 0 -36, and with a wing loading of 3 lbs./sq. ft. would maintain level flight at that angle of attack at a speed of 60 ft./sec, or 41 m.p.h. * * * "THE drag at this speed would be 23-5 lbs., and thrust horse-power required just over 2 -5 h.p. With an oversize propeller designed to limit the maximum engine r.p.m. to the lowest possible, the engine should not be called upon to develop more than 3 -66 h.p. at 41 m.p.h. The petrol con sumption can be brought down to -52 pint per b.h.p./hour on an engine like the 698 c.c. Blackburne, which figure is remarkable in view of the necessarily lower mechanical light 'planes are able to cover great distances on a small' quantity of fuel, although, perhaps, of little practical value, is of interest inasmuch as it indicates that very long non-stop flights, say, of 2,000 miles or so, should be possible provided the engine used will stand up to the work. LIEUT. THORET, who, as previously recorded in these columns, has been on a mission to Czecho-Slovakia, has now returned to France, and has succeeded in discovering a site suitable for gliding. On December 19 he glided for 2 hrs. 7 mins. over the slope of the Zibrica mountain, whose greatest height is 618 metres (just over 2,000 ft.). The machine used was a Brandenburg with fairly heavy wing loading. Thoret even succeeded in making a complete circuit. While on his visit to Czecho-Slovakia Thoret has taught several pilots to. fly the Dewoitine light monoplane. * * * THE Tour de France by light aeroplanes, which will take- place during the coming summer, is still being considered by the French authorities, and it is stated that the final rules and regulations will not be published for another fortnight or so. In the meantime it has been decided that the machines, before being allowed to compete, must obtain an airworthiness certificate, a special form of which is to be issued. It is believed that sand loading tests to destruction of the wings will be demanded, and that the fuselage must have a factor of safety of at least 5, while the engines used must have passed an acceptance run on the test bench of 4 hours, f hour of 18
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