NO. 5 STABILITY OF AEROPLANES ITl'XSAKER AND OTHERS 



65 



the lateral motion. The quantities )',, Yp, are made equal to zero. 

 Then : 



A,D' + B,D'' + C,D- + D,D+E, = o. 



^^ here : 



D,= - YriNrLp-LrNp) + U(NpL,-N,Lp) +gKlU 



E, = giNrLr-LrNr). 



These coefficients may now be calculated from the known constants 

 of the aeroplane, and Routh's discriminant, B^CnD^_ — A..D.f — B.2'Eo, 

 found. The condition that the motion shall be stable is that A^, B^, 

 Co, D.., En shall each be positive as well as Routh's discriminant. 



The numerical work is laborious and the results only are given in 

 the table. 



Coefficients Afffxting Lateral Motion 



High 

 speed 



Angle of incidence, i o 



Velocity, ft. -sec, U — 112 



Mass, slugs, ;// 



Ka 



Kc 

 Yv 



Nv 

 Vp 

 L, 



Np 



Yr 

 Er 



Nr 



50 



5 

 6 



+ 3 



5 

 o 

 2 



975 

 204 



06 

 449 



o 

 -631.0 

 o 

 o 



+ 77-0 

 - 39-4 



A.. 1310.0 



B. 31830.0 



c 3-274-0 



D., 41780.0 



£2 2770.0 



B.,C.D._-A,DI-BIE^_ 37400 X 10" 



Character of motion Stable 



Intermediate 

 speed 



6° 



- 65.3 

 50.0 



5-2 



6-975 

 . 0878 



+ 3-44 

 -351 

 o 

 -319.0 



+ 33-5 

 o 



+ 13^-5 



— 26.0 

 1310.0 



16350.0 

 5910.0 

 5490.0 

 1386.0- 

 123 X 10'' 

 Stable 



Low 



speed 



12° 



- 54-0 

 50.0 



5-2 



6.975 



- .106 

 4- 1. 91 



- -53 

 o 



- 224.0 



+ 57-0 • 



o 

 + 160.0 



- 38.9 

 1310.0 



12090.0 



1630.0 



3490.0 

 -335-0 



3.7x10" 



Unstable 



