AIRPLANE PERFORMANCES — HAMLIN AND SPENCELEY 437 



ever, the individual rocket motor units are operated at their maximum 

 efficiency conditions dictated by design. In other words, a selected 

 number and size of individual rocket motors are chosen so that thrust 

 available exists in steps according to the motors selected during 

 operation. 



Figure 6. — S. F. C. variation with thrust. 



Having analyzed the airplane range characteristics, the following 

 table comparing the S. F. C.'s for conditions of maximum range is 

 obtained : 



S. F. C. at economical cruising conditions 



