232 SYMPOSIUM ON AERONAUTICS. 



Ssi = 



532 = 



g-YpD U-Yr\ 

 k/D-^ - L,D -Lr \ 4-^43^- + 36270D - 1776, 



U-Yr D-Y, 



= 55-2-0 + 111.2, 



I D - F. g- YpD I 

 533 = I _^^ ^J^o_^^^| =36.7^' + 323.1^- + 77-88Z) + 27.15, 



where the numerical values are those arising from the data de- 

 termined for the Curtiss Tractor (which is the machine under in- 

 vestigation) by Dr. J. C. Hunsaker as given on page 78 of his paper, 

 "Dynamical Stability of Aeroplanes,'' Smithsonian ]\lisc. Collect., 

 Washington, Vol. 62, No. 5, pp. 1-78, 1916, namely, 



Ft, = — 0.248, Fp = o, Fr = o, 



Lv = + 0.844, Lp = — 314, Lr = + 55.2, 



A''.; = — 0.894, iVp = o, Nr = — 27.0, 



V = 36.7+> fe^^ = 70.6--, t7 = — 115.5, ^ = 32.17. 



The value of A is then {D —Yv)h^^-\- gh^^-\- U8^^ or 



A = 2592Z}* + 23780/)^ + i8oooZ)2 + 346 1 oD — 854. 



This result checks with Hunsaker's (loc. cit., p. 78) as well as prob- 

 able. The equation A = o may be written as 



D* + 9.1721)3 + 6.943/}= + 13.35Z) — 0.3295 = 0. 



32. From the last two terms, one root is indicated as D 

 = 0.02468 ; and the correction can readily be found, giving 



D =; 0.02436. 



There is another root near D= — 8.5, the exact value being 



Z} = — 8.542. 



The other factor of the biquadratic equation is 



^' + 0.6537!)+ 1.583=0, 



of which the roots are 



Z) = — 0.3268 ± 1. 21 51. 



