438 BELL SYSTEM TECHNICAL JOURNAL 



The frequency of vibration of the tube in its cushion will be 



4/1 = /-^ 



X ^86 ^ J39 rad./sec. 



Hence coi/co2 = 2x X 25/159 = 0.99 and, from Fig. 3.5.6, ^lo = 1.4. Hence 

 Ge = 90 X 1.4 = 126, which is greater than the allowable Gs = 90, so 

 that the 101 Ib./in. cushion is unsatisfactory. 

 To obtain satisfactory cushioning, set 



^oGo = 90, 



that is 



90 



^oco2 = — 7^ = 159 rad./sec. 



/! 



Noting thatcoi = 27r X 25 = 157, we find from Fig. 3.5.6 that there are two 

 values of C02 (90 and 600 rad/sec.) that satisfy the criterion A^p^i = 159 

 rad/sec. The first gives 



C02 = 90 rad/sec. 



A,= 1.8 



^2 = 31.5 Ibs./in. 



Go = 50 



Ge= 90 



dm = 2.4 in. 



The second gives 



CO 2 = 600 rad/sec. 



Ao= 0.27 



k. = 1400 Ibs./in. 



Go = 335 



Ge = 90 



dm = 0.36 in. 



The second solution requires less space for cushioning than the first but 

 should be used only if the remainder of the tube can endure the high ac- 

 celeration of 335g. Otherwise the 50^ package should be used . 



