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Aviation History
1912
1912 - 0316.PDF
I/XIGHT (a) Longitudinal Stability.—In the low centre of gravity model this stability was nil ; it was with great difficulty that I obtained respectable glides at all, head and tail dives were the usual results. Longitudinal stability in the high centre of gravity model was fairly MODEL GLlOER CARTRIDGE P*PEK* DOUBLE THICKNESS FOR MA|N PLANCb L POSiTlO* OF WE (OUT FOR. HIGH C& MODEL POSITION or WEIGHT FOR LOW Co MODEL tz-zf^j good ; though the flights were anything but straight the model in variably kept on an even keel. Knowing how misleading experimental results can be, I reversed the conditions of the centres of gravity on the two models ; this change did not affect the results obtained at all. (b) Lateral Stability.—When disturbed by a gust in a lateral direction the low centre of gravity model developed violent pendulum oscillations which up to a certain point (depending on the form of the disturbing gust) did not affect the flight at all, but beyond that point completely upset the glide. Imagining these conditions on a full -size machine, this critical point would hardly be reached on a present-day machine, but the pendulum oscillation would be there and would, beside giving the pilot an uncomfortable time, strain the framework to an enormous degree. Lateral stability on the high centre of gravity model was by no means satisfactory, but it lacked the pronounced sluggishness noticed in the low centre of gravity one. ® ® PROGRESS OF FLIGHT Notes regarding Clubs must reach the Editor of FLIGHT, 44, St. MODEL CLUBS. AercModels Assoc. (N. Branch) (Sec, MALCOLM B. ROSS 15, HIGHGATE AVENUE, N.). ON 25th, O. W. Root, at Finchley, covered 400 yards at good altitude, M. B. Ross 210 yards with his J-oz. model. On 27th, Ross' best, 371 yards ; Roots, 200 yards. On Saturday, R. G. Corder'sold model climbed to 150 ft. before coming round into the wind and doing a measured flight of 372 yards before colliding with tree. Corder did 32 and 31 sees. Owing to Easter holidays the match with Palmer's Green Ae.C. arranged for April 6th has been postponed until April 13th. On April 6th, open duration competi tion at Finchley 10.30 a.m. Birmingham Model Aero Club (Sees., R. COBHAM, G. H. WOOD, 8, FREDERICK ROAD, EDGBASTON). THE silver medal offered at the Coventry Exhibition was won by one of the club members, Mr. G. Wilde. Nine members of the club have now made the qualifying flight of 40 sees, for the team, which will be selected this week-end, for the contest at Coventry. Saturday a gale, but Mr. W. V. Jones, with a model rigged up from some old planes, &c, in the shed, made some fine flights of 30 sees. Next day, Mr. G. Wilde, flying one of Mr. Trykle's models, APRIL 6, 1912. The sluggishness, if present in a full-sized machine, would show itself also in the controls, a most disastrous condition of affairs. Circular Flights.—Circular flights were obtained by means of the vertical rudders ; both left-handed and right-handed circles were tried, and any differences in the results rectified. While circling the low centre of gravity model oscillated violently from side to side, giving the appearance of going round in jerks ; these jerks were very violent for small circles. While the high centre of gravity model was circling a tendency to dive was noted ; this was probably due to the lift of the main plane being affected by the circling. Exactly what it was due to I shall determine by means of another set of experiments. Replies in Brief. W. E. MAINE.—There is no difference between a tractor- propeller and any other save of position. Try one of Bonn's Centrale or Chauviere, with which we have recently been obtaining such good results, as stated in FLIGHT. Diameter—same as you are now using. We presume your h.p. is an estimated one, possibly you are not getting anything like the h.p. you think—also your motor—single cylinder is not, of course, so efficient as a twin or multiple cylinder one. You do not state the actual thrust. This should be at least one-quarter total inclusive weight of model. You cannot construct an efficient propeller from a rough sketch and a few hints, especially for a 3 h.p. motor. F. CoorER.—It is designed to lift a model weighing from 3 to 4 lbs. inclusive, i.e., the weight of the plant is such that in order to construct a model of sufficient size to carry it, the total weight (steam plant and aeroplane) will have a minimum weight of 3 lbs., and up to 4 lbs. at any rate is allowable. The model we are building for it is designed to weigh 20 to 24 ozs. The plant is not on the market, nor can we say when or if it will be, although a plant of this type is, we should think, certain to be on the market before long. It is very questionable, however, if it can ever be made a cheap plant. Experi ments are being conducted with a similar type of plant designed for smaller models, probably about the weight you mention (8 ozs.), but some little time must elapse before the results are known. From the experiments and the results which have been obtained with the larger type, we see no reason why the smaller should not be Proportionately successful. F. H. H.—There is no hard and fast rule, considerable divergence exists in actual practice. A fairly general practice is to take the span one-third and the chord from one-third to nearly one-half. See also FLIGHT, December 16th, 1911. E. HURLSTON.—Am glad to know matters are not as I thought, shall be pleased to receive report. Am afraid cannot go further into the matter just now. B. J. KIRCHENER.-Many thanks for your letter and P.S. I will write you re the latter in a few days. Reply to Query. HERBERT YOUNG, referring to Mr. F. Weidmann's query re power-driven model, writes :—" I suggest a Davis twin petrol engine, as described in P'LIGHT recently, i-h.p. [we thought it was i-6-h.p.]. Diameter of propeller, 20 ins. The length of my model is 7 ft. 6 ins. ; span, 8 ft. Should advise Antoinette type of model from FLIGHT drawings." ® ® ABOUT THE COUNTRY. Martin's Lane, London, W.C., by first post Tuesday at latest. made flights of 58 sees., Mr. Trykle himself only obtaining 39* sees. Mr. Wood, with a twin, 47 sees. Mr. W. Lunn 35 sees., and Mr. V. L. Thompson 40isecs., both with Trykle-type models. Blackheath Aero Club (Hon. Sec, A. E. WOOLLARD, 48, HAFTON ROAD, CATFORD, S.E.). AT Kidbrook last week-end Mr. Bailey's 6J-oz. model repeatedly flew long distances, Mr. Brown'b Fearless biplane obtained duration of 26 sees. Others flying were Mr. Clark's 5-oz. Victor, Mr. Egelstaff's single propeller'd mono, and Mr. Woollard a single stick machine. At Blackheath, Mr. A. B. Clark flew his " floating tail" biplane, also his 2| and 5 oz. Victor machine. At Lee, Mr. Bailey obtained a duration of 42 sees. Mr. A. B. Clark flew his "ABC 42," Mr. Packham an A frame, and Mr. Dodd a single stick mono. Mr. Whitworth had a 1 (main)-i-P-O machine which flew very well. Flying at Lee next week-end, only im promptu meetings will be held owing to the large number of members who will be visiting Hendon. Cardiff Aero Club (114, MISKIN STREET, CATHAYS). OWING to the situation in South Wales regarding the coal strike, the exhibition arranged for April 17th has been postponed until October 16th. 316
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