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Aviation History
1913
1913 - 0411.PDF
APRIL 12, 1913 pM\ NATURE'S WHEN the autumn winds begin to blow, the maple seeds start dropping in their thousands. Miniature helicopters, all of them, they whirr downwards, revolving so fast that the small wing attached ONE-WINGED By D. TOWNESEND FLIERS. t. 2T A B c D H K to each pod cannot be followed in its turns, and they are blown along with the wind like some diminutive air-fleet of the future. While watching these miniature flights, I thought it might lie ol interest to ascertain a few facts with regard to the load, area, and efficiency of these seeds. The seed consists of the pod and one wing ; the former is covered with hairs of a yellow-brown tint, while the latter has a main spar in front tapering to its end. For the purposes of my research I was deficient in apparatus, lm: in this country one has to do with what one can get and Uc pleased. 1 managed to procure a chemist's hand scales, whose accuracy only went to 4 grain*, and a folding a-ft. rule ; for finding the areas of the wings, I constructed on a piece of tracing paper a gridiron 3 ins. by 1 in., the sides being divided into 1 in. In order to get a reasonable average, and to show the variety of shapes, 1 measured up five different examples, but i«>' ments in flight 1 used other seeds owing to the fact that the original <<nes were cut up far weighing. I now give a table of the five examples, and the average of them. The inferences of the sixth example are worked lr>>m fat dal.i which is the avetage of the others, except in the first case when- two results, A and B, are given, A being worked from the average data, b on the other hand being the average of the five examples, as also are the aspect ratios. The positive and negative signs when given Ut to show that tl» J grain was not accurate enough, and a little ought to be, but is not, added or subtracted. Example A B C I) i Average V. Averag e aspec t ratio . •3-5 J-83 •3-9 .4-2 •3'9 3"86l • h. S "a s 2'0 2'Ot) 2'9I 2'8j 2'9l 2 '845 Infereno •, IttfU 1 g2|.§8 S fc "£, fc £ B ^sLs < - % % M\? 857 1,584»q. m. or 11 sq. It. 2S'6 71-4 1,801 sq. in. 01 I2*50sq. ft. 30 80 I,6l2 sq. in. or inqsq. ft. 20 80 1,517 sq. in or 10*54 sq, ''• 20 80 1,593 sq. in. or iroosq, fi. 207 79,3 1,621'4 sq. in. or A. 11 -26 sq.ft. B. 11'as* , ft, 1 3 + **S 1 2 2 a- *'3 Data. Weigh t o f wing . grams •5 1 "5 + 5 •5 + •0 1 1 < Si j. 111. i-«7 «"33 •85 'i •84 •098 In working out the asnect ratio of the wing 1 look two leadings, the first being the actual aspect ratio found by dividing the greatest span by the greatest chord ; the second being an average ratio found by dividing the greatest span by an average chord, which I found by drawing the imaginary rear spar in such a way as to fill up the spaces by the surplus area. To facilitate the working out of my first inference 1 used the Fi ere SECTION (i, THR0"A5<,! formula: Area to support 1 lb, . M* **!* ' A' where W A = area of seed-wing, W • weight of wing and pod ; but, as I worked with logarithm tables, I used the above formula in the form : Area to suppoit 1 lb. antilog. of log. A + 3*6758 - log. W. Next, I turned my attention to the flight of these seeds, but, owing to the deficiency in apparatus, my experiments were of a very elementary character. Using four different types of seed-wings, 417
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