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Aviation History
1910
1910 - 0263.PDF
APRIL 2, 1910. ment by what was then demonstrated as possible, probable, and impossible. In my case the result has been the construction of a new type entirely of aeroplane, now undergoing its trials. It has absorbed much time, more money, and all patience ; but, at least, it is new, and not one of the gorgeous copies lately on show. But, in this Exhibition, I have seen little new, and nothing provocative. There are endless beautiful copies of the two accepted types ; it appears to be taken for granted that there are only two possible types ! Our constructors have taken the biplane (with or without tail, &c.), and the monoplane ; they have varied the details infinitely, and—turned out nothing to show any material advance on what has been done elsewhere. And it is really curious that a nation, inventive and ingenious as is ours, should have been hypnotised in this way by a cross-Channel flight, and by the achievements of the biplane school. It is really curious that we should have already come to the conclusion that there is no other design or arrangement of planes possible. It is not only curious, it is fatuous nonsense, and, to me, at least, very disappointing and tragic. All honour be, however, to Mr. Roe, one of the "cranks " who has won through—whatever one may think of his design ; and honour, too, to Weiss, whose wonderful glider was, to my lasting regret, not on show. And let us hope that the next Exhibition will contain a few really British machines and not be confined to the beautiful replicas characteristic of the Exhibition which has just closed. Belvedere. A. THIERSCH. 1/UGHT] THE DIHEDRAL ANGLE. [434] With reference to the recent discussion in your paper on the dihedral angle, I beg leave to submit my views on the subject. Fig. 1 represents an aeroplane in its normal position, whose wings OA and OB, each / feet long, are inclined at a dihedral angle 20. Let Pi. and PR denote the normal pressures on OA and OB respectively. iW • Now we may replace P L and P R by a single force R, which will always pass through O and be the bisector of the angle MCN. Now we have, remembering PL = PR W = R= (PR+ PL)coso = 2Pcoso. Fig. 2 represents the same aeroplane, but having a lateral cant of 6°. P L , P R and R are still unchanged, but tawing to the fact that R is inclined 0° to the vertical, the aeroplane slightly falls, thus causing extra pressures, p and q say, on OA and OB. So we get 2P cos o cos 8 + p cos (a + 6) + q cos a - 0) = W, or p cos (o + 8) + q cos (a - 8) = W (I - cos 8). Now if 8 be small, say less than 300, / and q may be neglected and the resultant of W, R, / and q may be taken as a force F acting along OF and perpendicular to OC, where F = W </i (1 - cos 9). Now since OF is perpendicular to OC, the path the aeroplane will describe (laterally) is an arc of a circle of radius OC (Fig. 3). Now, if the aeroplane had no resistance to lateral motion, it would describe a series of oscillations, OYZ, ZYO, &c, about O, whose period, &c., could be determined by the laws of harmonic motion. But in every practical aeroplane this resistance is considerable, and so these oscillations are speedily damped and the aeroplane comes to rest at Y. This investigation is of practical interest a? it gives the distance an aeroplane falls in the act of righting (a frequent cause of disaster), this distance being • OC [1 - cos 9 + 1 - cos 9' + 1 - cos 9" .... 00] (A), where 8, 9', 8", &c, are the successive values of the maximum cant on either side of CY. But in all practical cases 8", 8'", &c, may be neglected, so we have that expression (A) equals / (2 - cos 6 - cos 6') _ 2 tan a Apologising for taking up so much valuable space. Waterloo, Liverpool. W. W. HASTINGS RIDER. BLERIOT MODEL WORKING DRAWINGS WANTED [435] Icm about to construct a Bleriot monoplane (model), and would be very pleased if any of your readers could supply me with drawings of the same. It might interest you to know that I have already constructed a man-lifting kite, which I propose to practise with this season, and I have also in the course of construction a glider. I wish every success to your excellent paper. Scarborough. R. TYZACK. MODEL PETROL ENGINES. [436] Having been a constant reader of your valuable paper for some months, I have constructed a scale model of the famous vW Antoinette monoplane, and intend fitting it with a small petrol engine of about i-h.p. Could you recommend any book on these small engines, and how is it possible to regulate the length of flight of a machine worked by one ? Brownswood Park. R. W. SPOONER. [We are not aware of any book on the subject mentioned. We would suggest that limiting the fuel supply would be the most satis factory method of limiting the length of flight.—ED.] WRIGHT MODELS. [437] In answer to (279) FLIGHT, G. Alchin, Tunbiidge Wells, regarding models of Wright machines. 1. If he tries 2"8 in. Cochrane propellers he will find them 26l
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