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Aviation History
1924
1924 - 0453.PDF
T 'PLANE AND QLJDER NOTES THE announcement that the light 'plane trials at Lympne have been postponed from September 8-13 to September 29- October 4 will come as a disappointment to many. When we approach the end of September and the beginning of October the weather becomes a somewhat uncertain quantity, and if fair judgment is to be given in these competitions it is essential that the weather should be as favourable as possible. The tests, it will be remembered, are intended to produce low-power light aeroplane two-seaters suitable for school work. The cylinder capacity is limited to 1,100 c.c. The Air Ministry are offering a first prize of £2,000 and a second prize of £1,000, while the Duke of Sutherland has offered a prize of £500 for the best take-off and pull-up. Other private individuals have offered prizes as well, so that the competitions should draw a very full entries list. Speed range, it will be remembered, is the feature aimed at, and no restriction on fuei consumption is imposed, it being presumably taken for granted that the limit on engine capacity is sufficient to ensure good fuel economy. The speed range will be determined from the formula —~= " — 0 • 333, where * s V,„ is the maximum speed, and V, the slow speed. A minimum speed range percentage of 33 is required before any marks are awarded, and for each per cent, above the minimum eight marks will be awarded. Thus, if the maximum speed of a machine is 80 m.p.h. and the slow speed 30 m.p.h. the percentage figure will be —— — 0-333 = 1 -334, or 133-4 per cent., and the number of marks awarded will be 1067-2. * * * As the high-speed tests are to be flown over a course of 75 miles and the low-speed tests over four short runs, two out and two back, it will be seen that the effect of wind on the results maybe very pronounced. Thus, if a machine has a top speed of 75 m.p.h. in still air and there is a wind blowing, parallel to the course to be flown, of only 15 m.p.h., which is not a high wind, by any means, the average speed over the out-and-home course will be reduced to 72 m.p.h. Although this reduction does not appear to amount to a great deal. if. will be found to have a most detrimental effect on the number of marks awarded. If we suppose that the machine with a top speed of 75 m.p.h. in still air has a slow speed of 35 m.p.h., the speed range is 40 m.p.h., and the number of /40 marks awarded would be I — — 0-333) x 8 = 647-2. With the top speed reduced to 72 m.p.h. the " figure of merit " 37 would become g= — 0-333, and the number of marks would only be 579-2. During the low-speed test a strong wind would, of course, tend to improve matters, giving a lower figure than would be obtained in still air. In either case it is highly desirable that the tests should be flown in a calm, but absence of wind at that time of the year usually means fog, which is nearly as bad. * * * THE reason given for the postponement of the competitions is that, owing to the demands of the Air Ministry in the way of engine alterations to conform to Air Ministry ideas, there has been considerable delay in getting engines ready, and consequently aircraft manufacturers have been hung up. Naturally it is important to have at least a month in which to test out a new type before putting it into a competition, and in most cases designers were doubtful as to whether this would be possible. There seems thus to have been fairly general agreement that postponement of the trials for a fortnight was desirable, and the Royal Aero Club agreed to defer the meeting until September 29. The Grosvenor Cup race will, presumably, be flown on the last day of the Lympne meeting, i.e., October 4. * * * WITH reference to our Editorial Comments in last week's issue of FLIGHT headed " Light 'Plane or ? " we have received from Capt. Geoffrey de Havilland the following letter :— " I note in today's FLIGHT yon refer to a conversation in which I expressed certain views of the light aeroplane. " I had no idea at the time that these remarks would be published, and in view of the fact that they may appear disparaging to the light aeroplane, I should like to make the position clear. " The design and construction of new machines is a very costly business, and it was not considered policy to embark on the design of a new-type machine, rather highly experi mental, when there was little production work going through the shops and when the type in question was of doubtlul value with the specified engine power, as a future production type. " One has great confidence in the light aeroplane becoming a popular and important type with certain definite modifica tions as regards engine power. " The forthcoming trials will be invaluable in providing useful information on many interesting points in design.— Yours faithfully, (Signed) G. DE HAVILLAND." * * * WE are glad to note that Capt. de Havilland has confidence in the future of the light 'plane, provided more engine power is employed, and if we, in our comments last week, conveyed any different impression it was done unintentionally. The only point that really arises in this connection is : When does a light 'plane cease to be a light 'plane ? Not so very man\ years ago a two-seater fitted with 50 h.p. engine was con sidered a fairly powerful machine, although it certainly did not equal in efficiency the modern light 'plane. It seems to us that when this power is employed we are getting somewhat away from the light 'plane idea and ideal. We are not disputing that a better all-round machine will result, nor that this may ultimately be the type to survive. Hence we headed our comments " Light 'Plane or ? " * * * WHILE on the subject of entering machines for the Lympne competitions we should like to quote from a letter which we have received from the managing director of another well- known British aircraft firm. Our correspondent does not wish his identity to be disclosed, but his views are interesting. " As I see it," the letter runs. " there will be about 10 com petitors and perhaps 15 machines. It will cost about /1,000 to go in for the competition, the first prize is only £2,000, and therefore I do not think it is worth it. I cannot see any possibility of building these machines to A.I.D. requirements under £700 or £800, which I consider much too expensive a price for anybody to buy at now." * * * HERE we have yet another view, which tallies with that of Capt. de Havilland in regard to the cost of entering a machine, but which does not object to the small engine power allowed. On the other hand, the added objection is raised that machines of this type will cost too much to build to A.I.D. require ments. If an even larger engine were fitted presumably the cost would be still further increased, and it seems as if the only way to popularise flying will be to give constructors an absolutely free hand. By the time the Air Ministry had finished "faking up" the Blackburne engine this excellent little power plant had increased in price from £35 to £85 approximately. Yet last year at I.ympne Bert Hinkler in the Avro monoplane flew 1,000 miles in one week without a single forced landing. This, be it noted, was before the Air Ministry " experts " had started meddling with the engine. If Air Ministry interference has doubled the price of the engine, it will doubtless have added also very considerably to the price of a machine, and in this connection it is interesting to read an announcement in our French contemporary, Les Ailes, of July 10, 1924, to the effect that the de Havilland Company has been obliged to raise the price of the D.H.53 to £550. We are under the impression that last year's D.H.53 with the " unfaked " Blackburne and the original machine, was about £350. It looks uncommonly like paying a couple of hundred for the (compulsory) "privilege" of having the Air Ministry's blessing. * * * As already pointed out, the competitions at Lympne in September place a premium on speed range, this being the great feature aimed at. In order more easily to form a picture of the manner in w-hich the rules will operate, we have prepared the chart given on p. 454 which shows at a glance the number of marks awarded for any particular performance. Curves of slow speed, ranging from 25 m.p.h. to 45 m.p.h., have been plotted on a base of speed range in miles per hour, and the number of marks can be read off on the vertical scale. It will be remembered that the top speed of a machine, to make it eligible for the competitions, must be not less than 60 m.p.h., while the slow speed is not to exceed 45 m.p.h. We have previously pointed out that the rules appear to aim at a medium-speed machine, using the expression as applying to 453
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