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Aviation History
1915
1915 - 0060.PDF
I/QGHTI JANUARY 22, 1915. HYDROMECHANIC EXPERIMENTS WITH FLYING BOAT HULLS- By H. C. RICHARDSON, Naval Constructor, U.S. Navy, Chairman of Sub-Committee on Hydromechanics in Relation to Aeronautics. Concludedfrom page 41 J. FIG. 6 shows the resistance of the preceding models towed sub merged at speeds up to 15 knots on a logarithmic diagram ; and also for model 1350-15, a quarter sized model of the original Curtis pontoon. It will be seen that a straight line on the diagram very closely represents the locus of the observed points and thus indicate that the resistances of the models closely approximate the law of the square of the speed. As is well known, any equation of the 1 form from the equation Rx V", the points being taken direct from the straight line plots. Table I shows the computation of the head resistance in water for each of these models, in detail, the final results appearing in lines 19, 20 and 21, giving results by three different methods of computation. Table II, line 22, gives the head resistance 1 1 s* t • * • % ia ,!»-. / / Y TBV—•* 0/ n / * .uje-ttmra)-^ zf ^4 V, / ' ifcoa-i Ji. $ iZ r— " j . , . , ' 7 ' / / •AA-fiJ-1 L/H A'' u • n AOO 1 EXPERtM > —• „ tZ-Z r , // 1 w < t / I INA - .'N l 1 Ft*'"* COAT* AND M«e»u*»t tmTowo TburlO TOTALLV SijfcMEHfiED r0 Dn-EHWi*. -H.A.O RiJivwcr 'JUBWtno.t.O >'-0" 1 1 1 1 i i i ! i ; ; ' a • • SCALC Pon S*t«o IN KNOTS J«OTOTIME!JTS*t 1350-16.MYWOPUJit wxi wooti-45IIE MAXiUuw CBOSS StCTi I591-2,FIY'HGB0AT '.->%•.•_.• HM-U- " --".-. * *-.*»* . ... _.' tMI-4*-. *. -....-•. -._*.•. ' _,- _". not-Zy. • -..-*• • W-i,, :\- -. '..•-/».".. .^ •_ .... -id n n rt- &M [OR SP£B !t!MU5 P£B (ffiB Fig. 6. Fig. J.—Curves oE net total resistance for aeroplane hulls and flying boats towed submerged one foot to determine head resistance. Y = a x" will plot as a straight line on a logarithmic plot, and the slope of the curve transferred to the origin passes through the margin at the upper end at a point corresponding to the exponent n. The exponents are given in line 12 of Table I, which shows the value of the exponent n in the equation of the lines plotted on Fig. 7 computed by analysis of the total resistance of the model into fric- tional resistance and residual resistance, and then augmenting these values to the "full size " values in accordance with Froude's method. Line 23 gives the head resistance in the same manner as line 22 TABLE l.-Computaticn of Head Resistance of Aeroplane Hulls, fromjesistances of Models Towed Submerged in Model Basin, I, 2. 3 4-5- 6. 7. 8. 9- 10. u. 12. '3-14. '5-16. 17- 18. 19- 20. 21. Model. Numter Linear ratio, full size to model Wetted surface of model in sq. ft Wetted surface, full size, in sq. ft. ... Maximum section of model in sq. ft. Maximum section, full size, in sq. ft. Speed of model, m.p.h. Speed of model, k.p.h Corresponding speed, full size, m.p.h. Corresponding speed, full size, k.p.h. Total resistance of model at v m.p.h. Exponent of v with which rt varies Frictional resistance of model o-oil7sv'2 Residual resistance of model Exponent of v -with which rr varies Residual resistance of full size at V m.p.h. Residual resistance of full size at V m.p.h. x" x v Frictional resistance at V m. p. h., full size "oi Total resistance at V m.p.h., full size Total re-istance at V m.p.h., full size Total resistance at V m.p.h., full size K2s V'KV r. = (*) x K8' (V) S X V'1'85 : R, X R, : R'r X Rf : ... K3r, : K s S a A v v' V V rt n rf rr n' Rr R'r Rf R, R', R", A-1. 1350-15 4 5'9S 95-25 0118 1-91 20 17-38 40 34-76 41-25 2-0 21'0 20*25 2'0 1.295 1,296 672 1,967 1,968 2,640 C-i. 440 5 no 65 60 1592 2 9 2 197 o 9 20 I7-38 60 52-14 25-4 2 "07 8-63 16-77 2-06 12,250 13,060 2,970 15,220 16,030 18,500 •5 •081 •55 D-i. 1593-2 9 2-48: 201 o 6 20 I7-38 60 52-14 21'2 2-27 8-8 12-4 2-48 9,050 15.490 3.025 12,075 18,515 i5.45o N-, I59I-4 9 2-688 218-0 0-103 8"3 20 17-38 60 52-14 18-65 2-03 9-54 9-u 2-00 6,630 6,570 3.270 9.9O0 9,840 13,600 N-2. 1602-2 9 2-618 212-0 0-116 9-4 20 17-38 60 52-14 »3'°5 21 9-25 4-4 2-28 3,210 5.183 3,l80 6,390 8,36.3 9,950 N-3. 1617-2 9 2-144 173-6 0-146 n-86 20 I7-38 60 52-14 15-8 1-96 7-58 8-22 I-9I 5,992 5,430 t,5o6 7,498 6,936 11,518
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