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Aviation History
1938
1938 - 1097.PDF
APRIL 31, 1938, FLIGHT. 391 by "Indicator " of a ground speed of 25 m.p.h. and 45 m.p.h. at 2.000ft. is about normal. This greatly assists take-off into wind, especially when flying a fast machine which unsticks at 55 m.p.h. If the machine is held down after taking-off until normal climbing speed is reached, the stick may be pulled back and held back. While the machine climbs to ioo-i5oft., it is meeting air of an increasingly greater velocity and the climbing air speed will be found to remain the same, although the machine is being climbed at an alarmingly steep angle. Above the 150ft. the rate of change of velocity of the air is comparatively small, and the climbing angle requires to be eased off in order to maintain the normal climbing rate. The majority of private pilots have realised that the machine ap- pears to drop during the last 150ft. of the glide into land, and they will have been taught by the instructor that they must have extra speed. Very few pilots realise that the extra speed is necessary to make up for the sudden change of velocity of wind which occurs when levelling out and when the pilot is 1:0 longer watching the air-speed indicator. When flying a Drone one can feel every little variation of wind current, and the climb of a Drone in windy weather by an experienced pilot appears to be very ragged, as he makes use of every slight gust of wind to increase his climbing angle and height. Up to 1,000ft.. quite prolonged down-draughts exist and the Drone often loses height while attempting to climb. With wind-cum-thennals, extraordinary rates of climb can be maintained. On one particular occasion two pilots fly- ing two Drones, each with recording barographs, ascended on the same thermal whilst circling each other and using only one- quarter throttle, from 600ft. to 5,000ft. in 4 minutes. I have personally made use of thermals to do journeys of 20 miles or more with the engine switched off completely. In the Drone one is really flying, and not just doing mechani- cal operations. May I repeat my invitation to "Indicator" to come and learn to fly at Ely. His subsequent written observation would probably do a lot to kill the objectional preju- dice which is met with everywhere on the subject of flying ultra- light aeroplanes. _,»„.. H. R. DIMOCK. Ely, Cambs. "Zl'r~:" ["Indicator" comments: "Oh, Mr. Dimock! If he reads my remarks again he will see that the wind variations are, so to speak, on a downwatd grade—i.e., 45 m.p.h. at 2,000ft. and 25 m.p.h. All I said was that in certain conditions the change in wind speed occurs fairly suddenly and the machine's ail speed consequently drops rapidly until ground speed has been picked up. "In Mr. Dimock's own words, 'a Drone climbs vertically upwards . . . and then travels backwards at considerable velocity.' There you have the variations of which I spoke. These variations cannot, obviously, be instantaneous, but they are quite marked when one is flying a machine with a steep glide and a strong climb. The Drone passes more slowly through the levels of change and has time to adjust its ground speed to the new conditions. For the rest, Mr. Dimock's letter entirely supports my contentions. "And one day I really will learn to fly. Searching through the type-names in my log-book I find that I have put in 7hr. 3omin. en ultra-lights. Hardly enough, I fear."] FRONTOLOGISTICS More About Navigational Niceties WITH ieference to Mr. Martin's communication appearingin Flight of April 7 (page 345), I would like, at the out- set, to state that my letter of March 10 was not written with the sole purpose of bombarding Mr. Martin with criticism, but merely as an endeavour to dispel the gloom which I consider he had cast over the realm of prospective navigators. Mr. Martin has misconstrued several of my remarks and has issued what, in my opinion, constitute ridiculous challenges. 1 did not, for example, quote "constitute astronomical navi- gation" as a phrase employed by him; those were entirely my own words and were employed to show that Mr. Martin's article was liable to had prospective students and candidates to believe that the subject of astronomical navigation now formed part of the second class syllabus. I regard Mr. Martin's challenge' with reference to the appli- cation of the hour angle as absolutely absurd, in view of the fact that I expressed quite clearly the "opinion that the syllabus was not perfect ; 111 fact. I consider that there is quite a lot <|f room lor improvement so far as the whole examination is concerned My criticism under this heading was to the eflect that Mr. Martin's article gave readers the false impression that the calculation of hour angles was an involved problem, and that the introductory elements of astronomical navigation in- cluded in the syllabus were not only difficult of mastery but useless. Anyone connected with even elementary instruction m navigation is aware that the hour an trie is a necessary factor. In view of certain statements made by Mr. Martin I •would like to point out that when I commented on that gentleman's article I did so as one who has had considerable practical ex- perience, not only as a navigator but also as a meteorologist and, incidentally, as a frontologist; that being the case, I am very strongly opposed to the inclusion in any syllabus of any unnecessary theory. I do, however, realise the great necessity for improvement and advancement of navigational knowledge generally, and the science cannot be fully developed unless various theories which have definite places in actual navigation are accorded simple presentation, careful study and efficient application. With regard to the question oi fronts, had I stated, or even inferred, that Mr. Martin evolved the terms " frontology" and "frontologists," I would have been guilty of a highly ridiculous and inexcusable error. He most certainly lias not any claim in that direction; the fact that he had, in my opinion, misused them caused me great surprise. The term "frontology" refers to a modern branch of meteorology, and the status of a "frontologist" is a little higher than that of an inserter of fronts on synoptic charts. The question raised by Mr. Martin of international differences of method is entirely irrevelant so far as the syllabus under criticism is concerned. In reply to Mr. Martin's concluding paragraph, I would like to point out that qualified, up-to-date dentists do not hurt their patients in the practical application of their work. Perth Aerodrome. H. W. SIMS-WHITE. [This correspondence is now becoming unduly protracted, and the letter above must, we are afraid, be the last word.—ED.] :« MILITARY AIRCRAFT SPEEDS A Plea for Officially Admissible Record Attempts "Y7DUR correspondent, M. J. West (p. 346, April 7) is, of JL course, quite right in his comments on the alleged perform- ance of the Hawker Hurricane. But I would like to point out to him that although the Supermarine Spitfire is advertised as "the fastest military aeroplane in the world," that statement also leaves something to be desired. Germany holds the world's record, under official observa- tion, for the speed of a military type aeroplane. As neither Hawkers nor Supermarine have got confirmation of their claims one is forced to place their assertions in the same category as those of Kipling's Bander-Log. ("We all say so; so it must be true.") Seriously, as Flight has a world-wide circulation, would it not be better for our aircraft makers to support theii claims in some proper manner so that foreign nations have FACTS about our machines? JOHN V. HEWES. Ashstead, Surrey. THE POOR PRIVATE OWNER Subsidised Hangarage ? ON the subject of private ownership, surely "Indicator" iswrong in assuming that flying clubs lose the flying subsidy when a member buys his own plane. My information is that 'the ciub continues to draw a subsidy per hour if the aircraft is stationed 011 their premises. Perhaps you will make the matter clear to us. [That is so, provided that the owner is a member of the club.—ED.] As I am easily the poorest P.O. on record I am vitally interested in the sunsidy question, although one recognises that to the general public this must sound rather like subsidising yachting or hunting. The question of what form the subsidy might take is not a simple one, as "so much per hour'' does not achieve' any real end except burning petrol, and is also very open to fraud. I would suggest that if the Government would guarantee to pay housing charges at standard rates one of the major snags of private ownership wouJd be immediately overcome. Aero- drome proprietors would benefit and would be encouraged to enlarge their premises and to cater for private owners instead of regarding them as rich nuisances who deserve to be stung. The subsidy would be in the neighbourhood of ^50 p.a. and would, of course, be applicable to P.O.s keeping their planes in private landing grounds, provided these were available for use all the year round, and conformed to certain standards in the matter ot dimensions, surface, etc. Obviously, here is a means of breaking the vicious circle (no planes; no landing grounds ; no planes) in two places. Increase the landing grounds and the number of private owners simultaneously so that neither is writing on the other, and they will react on °ach other to bring about further increase, all at a really trifling cost. W. B. SHAW. Ipswich.
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