Thus far only the case of towed bodies has been considered so that 

 the maximum value of </> is 71-/2 — since negative drag cannot be realized in this 

 case. There are, however, some cable configurations in which the values of 

 <t> greater than n/2 are possible; i.e., configurations where the cable forms 

 a loop. An example of such a configuration is a cable joining two self- 

 powered bodies such as two airplanes or two submarines. When the speed of tow- 

 ing is high, so that the effect of weight is negligible, the plane in which the 

 cable lies need not include the direction of gravity; so that a line strung be- 

 tween two surface vessels may also present such a problem (see Figure 2). In 

 such cases, if the angle of the cable at one end may be considered fixed this 

 end may be referred to as the lower end, the other end of the cable may be 

 called the upper end and the fixed angle can still be designated as <j> . Then 

 the foregoing analysis still applies and Equation [5b] gives the condition 

 that the tension at the upper end of the cable is minimal. 



It is found that when the angle <t> is increased beyond n/2 the ten- 

 sion at the upper end of the cable will continue to be reduced. Nevertheless 

 there is a limiting condition beyond which minimizing the tension at the upper 

 end of the cable is no longer a reasonable procedure: When further increase 

 in </> will cause the tension at the lower end to become greater than that at 



Figure 2 - Cable Configuration for Two Powered Vessels 



