54 AEROPLANE PERFORMANCE CALCULATIONS 



Again I' = H' + F' ..... (9) 



and I T ' = H T ' + F T ' (by definition) . . (10) 



P P T ' 

 H' = IV ' 

 for reasons of propeller theory from (i) 



Q T ' = Q (by definition) . . . (12) 

 Q = <7G(from page 53) . . (13) 



1<= F N -. 04) 



- ..... 



because the friction losses are proportional to the revolutions and 

 independent of altitude. Also, of course, 



N7Q7 = ^G ' 



The letters in italics without dashes refer, of course, to the 

 full revolutions and full torque condition in standard density air. 

 Now from the above we deduce 



I' H' + F' 



j = - -^ from (9) 



= Tjb- + TjyT from (") and 

 (I/- F T ')P' FK' 



/PT ' T + 7/vr from 



FrIJ 

 -p^li 

 P' rN 'O' 



t 



from 



P'r N ' N T '7n N'F 

 = p-> ^N 7 " N 7 + W^f ^ rom ( I2 ) J ^ J ^) J and 



P^ NJ N'r R Fn N' 7^ 



v'\ 3 v ' Vr ^i V' F 

 \T')~rf ' v"! " ~ 7 

 rF / A/v' 

 = v?L7 + (* ~ lAv: 



v'\ 3 v ' Vr ^i V' 



\T')~rf ' v"! " ~ 7 J + v^ ' 7 from W* ^ and 



