442 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1947 



Figure 9. — Engine air requirements. 



Cooling air requirements for the propeller type represent about 80 

 percent of the total shown. Constant air volume requirements dictate 

 scoop design for particular conditions, generally for maximum speed. 



In the case of the rocket no air is required. 



PART B— AIRPLANE DESIGNS 



Since the characteristics of the four power plants are extremely 

 diversified, it is difficult to determine which type is most suitable for 

 a given application until each is translated into an airplane -design 

 study and the respective performances are evaluated. As the majority 

 of the power plants potentially represent premium performance air- 

 craft at a sacrifice in pay load, it is reasonable to use a fighter or 

 interceptor-type airplane as a basis for comparison. This represents 

 the type of military application where performance is decidedly at a 

 premium and economy and practicability are sacrificed as a matter of 

 self-preservation. Arbitrarily, for expediency in the comparison, 

 these aircraft will be considered as single-place, single-engined air- 



