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Aviation History
1911
1911 - 0619.PDF
JULY 15, 1911. experiment " should have resulted in so entirely fallacious a theory of insect flight as that he has described. In the hope of saving similar wasted effort on the part of others, I ask you to give similar publicity to the above-mentioned facts as you gave to Mr. Dring's article. As regards the " vortex principle of flight " apart from insect flight, it is obvious to those conversant with the matter that the "vortex propeller'' flagrantly violates the fundamental conditions of efficient propulsion and cannot but have a very low efficiency. I propose to write further on this matter, with your permission, next week. Tooting Graveney. BERTRAM G. COOPER. Man-Carrying Glider. [1264] In answer to Mr. Mallet (1243), the distance between the leading edge of the main plane and the elevator should be 10 ft. I should advise an elevator 10 ft. by 3 ft. having a normal angle of incidence of 1 "5 times that of the main plane. The control of the elevator should be so adjusted that its minimum angle is not less than two-thirds of the normal, otherwise the machine would under certain circumstances be unstable. As regards the section of the spars, this depends largely on the design. Presumably a machine of this type having such small area would be provided with some sort of landing chassis, in which case the Valkyrie type of skid-outrigger could hardly be improved upon. For an outrigger of this type g in. by f in. spruce might be used throughout; if, however, two spars only are used, 1 in. by I in. would be necessary. As regards the planes, the front spar should be i£ ins. by £ in. and the rear I in. by fin., both having the greatest measurement horizontal for single-surface planes, or vertical for double surface. Silver spruce might be used everywhere unless it be for the lower part of the skid, where, perhaps, ash would be an advantage. It is rather difficult to give advice with the meagre data supplied by Mr. Mallet. If, however, he cares to communicate with me, I have no doubt I shall be able to give him some useful hints as regards construction and design. Woolston. J. D. NORTH. Experiments with Flight Propellers. [1265] Some weeks ago you published a letter from Mr. A. V. Roe containing a really praiseworthy proposition, which I for one confidently anticipated would have met with immediate resoonse. Briefly, he offers to test in actual flight on a tried machine different propellers of various design, with a view to evolving one superior to all others. The really ideal conditions of testing propellers so kindly advanced by Mr. Roe, i.e., under true flight conditions in the air itself, should commend itself to all I should imagine. Should Mr. Roe's proposi tion still hold good I personally would be very pleased indeed to enter a new type of propeller, 7 ft. diameter, built of white wood, and should be glad if he will infirm me of size of bore for shaft. The results of these tests of various designs in England should be of value throughout the civilised world where flight is proceeding, particularly when we consider that as a nation the British have in reality accomplished little in /rarf/fa/aero-dynamics so far compared with France. There is another point connected with propellers which I should like to bring forward. Mr. T. W. K. Clarke claims the record for highest efficiency, viz., 81'6 per cent, obtained by one ©f his propellers, tested by Messrs. Vickers, Ltd. May I inquire if this propeller was tested against others of precisely equal diameters, pitch, weight, and form ? If so, what were the results as compared with that of Mr. Clarke's ? EDGAR E. WILSON. Races and Prizes. [1266] Are we mothering our infant industry, aviation, correctly ? In my opinion, considering the long-distance flights men and machines are capable of, we are not organising our flying races on lines which are calculated to bring to perfection both types of machine, biplane and monoplane, because the conditions under which our present flying races are held only favour one class of machine, the machine of speed, the monoplane ; thereby doing a great injustice to the men who are putting both time and money into the perfection of the biplane. Not that I am interested in the one type of machine any more than the other, but if we are to have flying races, let us organise them along lines which will give both types of machine an equal chance of competing for the prizes which are being offered. I think if we organised our flights in a manner which I now submit, that is, the dividing of the prize money, half of it going to the first monoplane to finish the course, the other half going to the first biplane to finish, it would give the men of the biplane class, a type of machine which is j/UGHTJ slower than the monoplane, some encouragement to enter into these long-distance flights. We must not forget the tact that these long distance flights are going to be the means of the perfection of the aeroplane, for the simple reason of the splendid opportunities they offer for the finding out of the good and bad qualities of a machine whilst flying under such strenuous conditions. The flying over long courses means that the flying has got to be carried over a period of two, three, or more days, which is the finest thing possible for the finding out of the faults of a machine on account of the different weather conditions which prevail on different days, and also the different air currents which are experienced over different kinds of country. That is why I say the races should be organised so as to give both types of machine an equal chance of competing, so that each may have the same opportunity of gaining the valuable information that these flights offer for the perfection of these machines. Another thing is the offering of too big a prize for one race such as the Daily Mail £10,000 prize. I think if this money were divided into two _£5>o°o races it would be a greater benefit to the aviation industry, because there is more to be learnt in two 1,000 mile races than in a single 1,000 mile race, and I don't see why such prizes are not worth going for here in England when they are competed for on the Continent, and flown for by experienced men in the aviation world. Birmingham. H. HARRISON AND E. BRIDGES. Plying Bulletins. [1267] Surely some means could be found of letting the public know when flying is impossible, owing to weather or other circum stances, at Brooklands or Hendon, so that a long and none too easy journey may be avoided in the vain hope of seeing some flying. Perhaps some arrangement might be made whereby notices would be placed in various parts of London (if I might suggest it, Messrs. Keith, Prowse and Co.'s various offices might be used for this purpose), saying whether there would be flying or not. The cause of iny writing this is that on last Saturday afternoon I spent, or rather wasted, several hours at Brooklands seeing one machine (the Howard Wright) only in the air, though there was not enough wind to stir the flags hardly, and this in spite of the fact that advertise ments promise flying every fine day at Brooklands. London. A. E. DUNBAR. MODELS. Model Duration Records. [1268] Re letter No. 1259, of Mr. Grimmer. Evidently Mr. Grimmer does not think it possible for anyone to beat the Grimmer-Mann monoplane, which has been timed to have done 74 sees, duration. In regard to the last part of his letter he congratulates D. Holmes on the success of his Holmes-Ridley- plane on Mitcham Common. If the suggestion is that I do not construct my own machines myself, the suggestion is absolutely false. Moreover, the one I used at Mitcham was the same one with which I secured a first prize at the Crystal Palace. Thames Ditton. C. B. RIDLEY. [1269] May I call your attention to a slight printer's error which occurred in your publication of my letter (No. 1260) in FLIGHT last week? The word "Flemings" was printed " Hamings," a mistake which I think must have puzzled anyone who professes to know all the most successful models by name. Mr. C. B. Ridley seems to have aroused Mr. Grimmer's curiosity, by reporting in FLIGHT last week the times of three record flights which I made with one of my models on June 23rd. For the benefit of any who may be inclined to doubt their authenticity, I may say, if any better testimony than that of a disinterested rival is required, that the last two durations were checked by a second independent witness, and that the model I used was a light one. which I find has great advantages over the heavy type for duration, although it is handicapped in most open competitions. Mr. Grimmer's prize offer is indeed a generous one, and reflects great credit on his desire to advance the progress of model aero nautics. I venture to think, however, that the possibility of my repeating the record is less remote than he supposes, and I shall be very pleased to make the attempt in his presence. Thames Ditton. D. C. HOLMES. What are Freak Models ? [1270] Re letter 1260, I am greatly obliged to Mr. D. C. Holmes for his criticism of my remarks in a recent instalment of " School Aero Club Notes" on the subject of freak models. I
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