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Aviation History
1912
1912 - 0433.PDF
MAY II. 1912. [/JJGHT many other ways. His departure, therefore, will be a distinct loss to the club and it is to be hoped that he will continue his efforts in the new land he goes to. Next flying meeting, monthly competition at Barrhead, on May 18th. Sheffield Model Aero Club (Hon. Sec. C. F. W. CUDWORTH, 35, PENRHYN ROAD, SHEFFIELD). MEETING on May 2nd, Mr. A. V. Kavanagh in chair. Mr. E. W. Colver, who was present, was heartily thanked for his cup, to be known as the Colver Cup, and silver aviation medal, &c., to be competed for by self-rising model aeroplanes. Mr. Colver has offered to lend aeronautical books to the members, including some of the finest books written on aviation. Main item on programme for, Whit Monday, the Colver Cup. The other event, time permitting, ' for duration. Great things are being looked forward to from Master C. E. Worrall, a member aged 8, who, under the supervision of his father, has himself constructed models which have flown over 1,000 ft. Stony Stratford and District Kite and Model Aero Club (Hon. Sec, O. HAMILTON, JUN., OLD STRATFORD). OWING to rain on Saturday, the postponed competitions were urther postponed. Members who intend to fly for the monthly prize can obtain entry forms from the secretary, together with the Club Competition Rules. Members wishing to set up club records under the new rules, please give a day's notice to secretary, so that arrangements can be made for observers. Only flights on the club ground on open days, viz., Wednesday, Thursday, and Saturday, can count in monthly competitions, but flights made on any other ground, so long as the flights are witnessed by two club members, will count for record establishment. Whitehead (Belfast) Model Aero Club (Hon. Sec, JACK TURTLE, INNISFALLEN, WHITEHEAD, CO. ANTRIM). ON Saturday, in gusty wind, Whiting's Trykle-type model rose against wind to great height, flew 40 yards, turned, flew over his head with wind at high speed, out of flying grounds, and landed in a garden 200 yards away. On several evenings during the week good work has been done. The secretary would like to know if there are any other model clubs in the vicinity of Belfast, and if so, would the sees, please communicate with him. Windsor Model Flying (Sec, S. CAMM, 10, ALMA ROAD). SUNDAY, Camm, Dowsett and Stanbrook in the Great Park, had flights, average 45 sees. To-day (Saturday) at 2.30, a contest under the formula : Duration x total weight of machine r . t ! I i ri.i.. V- \i •, - 11 1 I 1 * , . rnKKiir Area of planes x weight of rubber propellers, kindly offered by Mr. M. L. Rolfe. ® ® ® ® CORRESPONDENCE. The natne and address 0/ the writer not necessarily for publication) MOST in all cases accompany letters intended /or insertion, or containing queries. Correspondents communicating with regard to letters which have appeared in FLIGHT, would much facilitate ready reference by quoting the number of each letter. Gyroscopes on Aeroplanes. [1545] Referring to your criticisms of the Clarke-Johnson system of gyroscopic control in your issue of April 27th last, I would like, with your permission, to make the following reply :— Rounding a Curve.—The gyroscopic disc being vertical, with its plane transverse to the machine, then on turning either to the right or left—the gyroscopic disc will (as you observe) in either case, tend to be left behind ; its tendency being to keep its plane of rotation constant—if arranged for longitudinal stability—this would at once interlere with the proper control of the elevator. Supposing we place the gyroscope, with its plane of rotation horizontal, then there will still be interference when rounding a curve, in one direction, if not in both. But, if we use two gyroscopes, as shown in the accom panying sketch, then this difficulty is quite successfully overcome. For such a system does not offer any resistance to purely lateral displacement, but only when its plane of rotation is altered. Referring to lateral stability (the one to which the reference was more specially meant), there banking is requisite and therefore (presumably) one gyroscope is, or may be sufficient in this case, if the " lag" of the gyroscope be so arranged as to give the correct banking. If this be not feasible, or if it be objectionable, then, here also two gyroscopes must be used as in the case of longitudinal stability. In any case this objection can be quite successfully over come. As the gyroscopes need only weigh 3 or 4 ozs. each the weight is no objection. For the complete stabilisation of an aero plane, at least three gyroscopes are essential, and if three be found inadequate, then the correct number is four. The Neutral Point.—In order to avoid " hunting," there must, of course, be perfect synchronism between the controller and the balancing devices, but it is by no means essential, as Mr. Clarke clearly showed, that either the relay system or the gyroscope need have 2. fixed point of reference, i.e., that the neutral point should be a fixed one on the apparatus, though fixed in a sense as to their combined movements. There must, of course, be absolute proportional agreement, and when one of the balancing devices is in its normal posiiion—the gyroscopic control must be similarly situated ; but this position need not be fixed absolutely. It is extremely difficult to make this point clear in writing, though easy enough to demonstrate with the apparatus in question. As to whether there always would be this proportionate agreement in the apparatus and an entire absence of hunting, is one which practice probably alone could really show. It is the crux of the whole problem, and one on which I have reflected much, with the result that I have personally evolved another system of gyroscopic control in which hunting is impossible. It may appear somewhat cocksure to speak thus confidently, but the reason is simply that in 1 his device every position in which the balancing device is left is a normal one, from which it is an obvious inference that the balancing device is different from those now in use, but such a necessity might be a vital point in the solution of the problem. Referring to your remarks on " the idea of using the gyroscope itself for the operation of the balancing planes, &c," I can only refer you to Comptes Rcndues, January 16th, 1911, and to the successful results there claimed to have been accomplished by Mich a stabilising system on the part of Captain L. Girardville. Re luiii J.ag—on the pait of the system—this is the one part of the system on which I have not a particle of doubt, basing my conclusion on a very large number of experiments made with hand-worked and automatically controlled stilt gyroscopes. In such experiments the at least I Mind lag 1 : time lag 1 , _ , i i Hand-controlled ) automatic / ' ' -> ' \ ' Moreover, another point (a point not especially dwelt on, even if alluded to by Mr. Clarke) is the highly anticipatory character of the gyroscopic controller after the initial disturbance—it being this peculiarity which is a main factor in successfully damping out all oscillations in all forms of gyroscopic control. It is, of course, important to keep the inertia of the moving parts as small as possible. This anticipatory action referred to can be clearly demon strated experimentally, but cannot be briefly explained in writing. I quite agree with your remarks that an ordinary relay mechanism does not permit of much or even, sometimes, of any variation in its rate of operation. And in devising my new system I have employed the idea of time as well as rate. A small rate of recovery, if it be continued long enough, will effect the desired result—always sup posing that the circumference of the machine's radius of recovery is nowhere a tangent to mother earth. In the Clarke-Johnson system the rate of operation can, however, clearly be further regulated by employing more electrical contacts should such be found necessary. With respect to possible interference between the coupled-up hand and automatic control, the mere turning of a switch, or the pressing of a button can instantly put the gyroscopic control out of action. V. E. JOHNSON. Natural Stability—The " Redivalls " Principle. [1546] In reply to your correspondent, Mr. B. F. Hussey (1543), I beg to point out that what he terms the "diamond-shaped piece in the centre of the main plane " is the only patent I possess re aviation. My letter (1504) therefore refers to same. I hope to write an article very soon, which will enable FLIGHT readers to easily make a " Redivalls" type model monoplane, at a small cost. " Redivalls," Eccles. WILL. H. BOOTH. [1547] For the benefit of Mr. B. F. Hussey, the public in general, and posterity in particular, let me once for all clear up the confusion which has evidently arisen. " Redivalls" (Mr. W. H. Booth) is the designer and patentee of the model with the " diamond-shaped piece, or chamber, in the centre of the plane + dihedral angle." 433
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