Paidoussis 



Based on such complex-frequency calculations It was possible 

 to construct stability daigrams illustrating the effect of various 

 parameters on the stability of the system. Examples are given in 

 Figs, 6 and 7 showing the effect of stability of fg and A, respectively. 



Other similar stability diagrams may be found in [ 26] . 

 general conclusions may be drawn: 



The following 



(a) for optimal stability the tall should be blunt (fg smeill, 

 Cg large), the nose should be well-streajnllned (f, -♦ 1), 

 and the tow-rope length should be short (A small); 



(b) a system that Is unstable by yawing, within a range of 

 towing speeds, can be stabilized by blunting the tall, but 

 not by manipulating the length of the tow-rope; 



(c) In Sonne cases It Is possible to stabilize a system which 

 is unstable at low towing speeds, by towing It faster, 

 within a specified range of towing speeds. 



Conclusions (a) above are not contrary to reported experience 

 with rigid bodies. On the other hand, (b) may sound surprising. The 

 fact Is that the onset of yawing Is not a function of A, nor Is Its 

 cessation (§6»2). This Is also true with i^, Finally, conclusion (c) 

 is characteristic of the dynamical behaVior of towed flexible cylinders, 



3- 



2 - 



0.3 0.4 



BLUNT TAIL «i_ 



0.5 6 7 0.8 0.9 



f, ^ELONGATED STREAMLINED TAI L 



Fig, 6 Stability map showing the effect of the tall shape for a 



flexible cylinder with ec^^ =€0^=1, f , = ^ » c, = , A = 1 , 



X| = X2 =0-0^ aJ^^ ^2- ^ 



fg, (Theory of 



[26]*). 



994 



