FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1910
1910 - 0020.PDF
I wonder if your readers know a very simple way of finding out suitable gliding slopes. I get my gliding angles with an Ordnance map. I mean, to find suitable places—and, of course, one has to know the country—but say, for instance, one locates a suitable hill on the map, one measures A, B, horizontal distance from map, C = A C vertical drop from map, you then draw the line C, B, and measure with protractor A, B, C, which gives the gliding angle. •• Antoinette Bleriot <C.-C. type) Farman ... Curtiss- Voisin Wright Fernandez Belfast. ght . We i lbs. 1,138 496 1,212 S5o 1,135 1,028 1,050 p. M So 20 So 30, So 2.S So feN Sue <u uj CT < - 500 2*2 150! 3'3 410 2'9 265 2'0 500 2'2 500 2-0 500 2- I * Wright geared 33 to 9. G jS* ~~ 22 24-8 24'2 i8-3 22-7 41 21 LILIAN 1 C ft. in. 7 2 0 5 8 3 6 0 6 6 8 3 6 6 & a. tM I,TOO 1,400 1,200 1,300 1,000 *4S° 1,100 E. BLAND. [The many and interesting points referred to above are of a character that will surely prove most useful to our readers, who cannot fail to appreciate, as we do, the desire to be of assistance that characterises our correspondent's letters. —ED. ] [273] The table prepared by Mr. K. H. Evans, and published in your issue of December nth is, I think, the first attempt which has been made to tabulate and compare the main dimensions of the various " flyers," and is accordingly most valuable. I feel, however, that there is a tendency to lay too much stress on the nominal horse power of the engine fitted, and one cannot help being struck by the fact that the substitution of a more powerful engine on a given machine has usually been found to have very little effect on its performance, except possibly in the direction of increased reliability. This being so, I do not think that such comparisons are quite fair, unless what might be called " the minimum horse-power of flight," of the aeroplane in question, is known. If this is given, then the pounds lifted per horse-power developed in that particular machine seems to me to be the true criterion of efficiency. I cannot quite agree with Mr. Evans in his proposal to introduce the area of the wings into the expression, since the question of area seems unimportant. Is it not the overall dimensions which actually tell in comparing the convenience of one machine with another ? Again, I venture to think that it is somewhat unwise to apply the word "efficiency" to any such expression, seeing that this word has already a definite and well-known meaning in mechanics. The expression "figure of merit" is one often applied in analogous cases, and would, I think, meet the case. . For the reasons just given, I do not feel tint " horsepower area per pound" is reaUy what is wanted, and it seems to me that the true figure of merit is the ratio of weight lifted to propeller-thrust, that is, the weight lifted per pound thrust. This ratio can easily be measured in the case of a finished machine, since it is equal to the cotangent of the " least gliding angle," that is, the angle with the horizontal made by the path of an aeroplane when gliding to earth, in still air, with power shut off. For example, if in coming down from a height of 100 ft. the horizontal distance travelled over is 1,000 ft., the gliding angle is I in 10, and the "figure of merit " would consequently be 10. A very usual figure is 6 or 7 ; anything less than 4 must be considered as bad, and anything more than 8 is exceptionally good. It would be extremely useful if makers could be induced to furnish this figure for their machines, but I have always, in the past, found them very reticent on this particular point. KENEI.M EDGCIJMBE. [The above most interesting and valuable letter draws attention to matters which will certainly have to be investigated in the near future by those who are really working seriously at the problem of flight. So soon as aviators get accustomed to their machine and the first glamour of the air has worn off, a little experimental flying with a view to establishing reliable data relating to gliding angles and other matters of fundamental importance will, we hope, be strenuously practised. —ED. ] PUBLICATION RECEIVED. Catalogue. Gnome Moteurs d* Aviation. Societe des Moteurs Gnome, 49, Rue Laffitte, Paris. ® ® ® ® NEW COMPANIES REGISTERED. Beedle Propeller and Aeroplane Co., Ltd., 40, High Street, Watford.—Capital ^50,000, in £l shares. Formed to acquire the interest of W. Beedle and the Beedle Propeller Syndicate in patent rights in connection with propellers for ships, aeroplanes, and dirigible balloons, &c. First directors, A. A. James and H. J. Rogers. Blair Atholl Aeroplane Syndicate, Ltd.—Capital ^3,750, in £1 shares. First directors, the Rt. Hon. Marquis of Tullibardine, Rt. Hon. Earl Fitzwrlliam, and Lieut. J. W. Dunne. ® ® ® ® Aeronautical Patents Published. Applied lor In 1908. Published January 6th, 1910. Z7,8r2. G. P. B. SMITH. Aeroplanes, &c. Applied for in IOOQ. Published January 6th, 1910. 47. P. A. WATSON. Flying machines. 2,926. C. MAHNKOPF. Airships. 5,391. J. R. PORTICR. Airships. 16,274. ". H. HOWARTH. Flying machines. BACKNUMBERS OF FLIGHT." j SEVERAL back numbers are now becoming very scarce, and when exhausted no more complete sets will be procurable. The publishers have pleasure in announcing that they have secured a few of these back issues of FLIGHT, and any of our new readers who may wish for sets, No. 1 up to December 31st, 1909, except Nos. 2, 3, 4, 6,8, 10, 12, 15, and 16, but including the numbers containing full description and Scale Drawings of the Bleriot, Curtiss, Voisin, and Cody biplanes, the Wright full-size glider, and of Santos Dumont's " Demoiselle" monoplane; can obtain same for •js. 2d., post free (abroad gs. id.). Sets to December 31st, 1909, including all the above and in addition the scarce higher-price numbers : Nos. 2, is. 6d.; 3, y.; 6, if. ; 8, is. ; 10,1$.; 12, is.6d.; 15, is.; 16, y. 6d.; and 31 (with scale drawings of the Bleriot cross-Channel flyer, 2s.), but exclusive of No. 4, which is now obtainable in bound volumes only, can be obtained for 21s. id., post free (abroad 231. 2d.) from the Publishers, 44, St. Martin's Lane, W.C. Orders for Volume I complete for year 1909—ready end of January—with Index and Title Page, can now be booked at the price of 25J., bound in cloth boards. If bound in two Parts, January to June and July to December," 3J. 6d. extra. Orders will be booked for these in rotation as received. FLIGHT. 44, ST. MARTIN'S LANE, LONDON, W.C. Telegraphic address : Truditur, London. Telephone : 1828 Gerrard. SU BSCRIPTION RATES. FLIGHT mill be forwarded, post fiee, to any part of the world at the following rates: — UNITED KINGDOM. ABROAD. s. d. $. d. 3 Months, Post Free ... I 8 3 Months, Post Free... 2 6 6 » •» —33 6 „ „ ... s o 12 „ „ ... 6 6 12 „ „ ... 10 o Cheques and Post Office Orders should be made payable to the Proprietors of FLIGHT, 44, St. Martin's Lane, W.C., and crossed London and County Bank ; otherwise no responsibility will be accepted. Should any difficulty be experienced in procuring FLIGHT from local newsvendors, intending readers can obtain each issue direct from the Publishing Office, by forwarding remittance as above.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
