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Aviation History
1920
1920 - 0571.PDF
MAY 27, 19.20 Si 1 o oo q 1 '» g ^wK 39 3 O O\ M IT t-t 1 O m OO O H 1 CO O\ 48 , Erro r " "n O H O ' Di t 1 ? i 1 00 1 HCi. O "C 0 M 1 i load a i. 1 ! | ill 1 N &* *-" "*U • £ °W ° 00 ft 0 N 1 j ^ 50 J3 to <O <£ ••§= •2 e M | SO 1 •1 •a 1 0 U"i 0IT) XP -S & 0 0 11*3 O «n t>» •n w O N O OO <n O "0 >» cL 0 8 0 m ts in ct N 0 VO 8- g O10 Z3 0 p^ O M O ri f^. | 00 O R 0 • d • »n •;<£• H 0 •-• o> >o OG OO •r *c 02 0 ID £ 0 0 £ft ^s lic a c Ui 0 to * All these boats wereweighed and balanced in the writer's presence, theweighing machines being carefully calibrated bothbefore and after use. It has proved verydifficult to obtain accurate weights and C.G.s of other5 types of flying boats, but considerable variation inweight occurred in the case of the F. type boatsbuilt by various firms, nearly all of them beingwell over the weights given for the original boat ofthe type built at Felix- stowe. The table of data givesthe dimensions, weights, etc., so far as ascertain-able, of most of the boats in use from the commence-ment of the War, with the exception of the " Donnet-Leveque " and the " Sop- with Bat-Boat," whichwere the pioneers of flying boats in this country. Un-fortunately particulars of these two were unobtain-able by the writer in time to be included in thispaper. Estimation of Weights and Proportions Flexible Type Construction.—In ordinary boat-build- ing it is necessary to care-fully calculate the weight of each detail of the con-struction separately, and with the early examplesof flexible construction the weights were esti-mated in this very laborious manner. As subsequent experienceproved the variation to be very small between esti-mated and actual weights, it was found possible toestimate the weight of the bare hull with sufficient ac-curacy for preliminary cal- culations by means of ascertained weights of the whole structure per square footof surface for any given thickness of skin. The pro-portion of stringers, ribs, hoops, and other parts ofthe frame always bear the same relation to the thick-ness of skin, regardless of size, unless a proportionateincrease or decrease of strength is desired forspecial purposes. The simplest method ofascertaining these weights is to take length, breadth,depth, and thickness of skin in 32nds of an inch. The length (L), in thefollowing table of weights of seaplane floats, is themean of length over all and that of the planingbottom, while diameter (D) is the mean of breadthand depth, ^nd (C) is a constant (=1-08 for sea-plane floats), then :— Weight = LDSC. -xample. No. 1 .. „ 2 .. ., 3 •• „ 4 •• L. ft. II -OO I3'i8 17-77 18-90 D. ft.1-79 2-28 2-80 • 2-88 S. i&8. 3/32 3/32 4/32 4/32 LDSC. :" lbs. 64 07-6 214 -e> 235-5 ActualWt. lbs. 64-75 97-00 208•00 242-00 A similar method to the above can be employed for boatsand for other types of construction, provided the same pro- portionate weight of the various parts of the structure remainthe same with regard to the thickness of skin ; the constant, C, will have to be ascertained from existing floats or boatsof each type. For stepless floats it is only necessary to take the length over-all as L. In estimating the weight of flyingboats, the area of the thicker planing bottom should be treated as a separate item, as in the table of data, unless all the boatshave exactly the same proportion of this planing bottom to *">? plank stnnatr O' * F/G. 10. Fig. 10.—Some constructional details of N. 4.—Timbers : Am. elm, T 5, in. x f in. sided, spaced 2 ins. (main hull, planing bottom, and fin top). Stringers : T 5 5 in. x 2\ in. spruce (except Nos. 14, 15, 16). All fillets T B T in. x TV in. at hoops, \ in. x | in. at skin (spruce).A, King plank 2 ins. x \ in. spruce, joggled over timbers. B, 2 double hoops, spaced width of spars apart.C, Inner hoop 1J in. x \ in. D, Outer hoop 1J in. x 1 in. E, Am. elm strap •& in. thick x 14 ins. wide.F, Planking F. and A. T\ in. mahogany, diag. ^\ in.mahogany. G, Fin top false stringer \\ in. x \ in. spruce. H, Doubling Eng. elm f in. thick at No. 11,tapering to \ in. at Nos. 10 and 12 stringers. Length 30 ins. Taper to 6 ins. wide (C.L.of No. 11 stringer) xI in. thick at F. and A. ends. I, Fin top planking F. and A. -^ in. mahogany. Diag. ^ in. mahogany.K, Chine 1J in. x 1J in. L, Planking F. and A., t\ in.mahogany diag. •£% in. ditto (carried down to main planking). M, 1 in. 3-ply. N, Solid spruce filling,j oggled over timbers. O, Spruce filling, from stringers Nos. 9 to 13. Total width 6£ ins. From stringerNo. 13 to keel, filling 1J ins. wide under hoops. P, Diagonal planking on planing bottom finishes here.Q, Top rail 2£ ins. x | in. spruce. R, Keelsson f in. spruce. S, Keel 3 in. sided x 11 in. R. elm f
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