PROPELLER PERFORMANCE CURVES 19 



and / = -j . (p) 



and q I - p . . . . (q) 



v 



..... (V) 



p ' /V'\ 3 /P ' 



Again, ^ = <r( J from equation ^ 



Equations (V) and (P T ') enable us to plot the full torque 

 propeller curve at the altitude from the one for standard density 

 air, with the aid of equations (o-J, (/>), and (a}. The full torque 

 at the altitude, corresponding to full throttle at the altitude, is 

 <j times the full torque for standard density air. 



As for / and q, we may take / = -262 and q = '738 for 

 rotary engines, and/ = 'i6i and q '839 for stationary engines. 



The Constant Revolutions Curve at an Altitude : 



On this curve for P R ' on a base V", the revolutions are the 

 full revolutions for standard density air (unlike the case of the 

 curve for P T ' on V, where the torque is reduced at the altitude). 



Consider a point on the P R , V curve and one on the P R ', V' 

 curve, and let them be related by the equation 



v = N; 



V" == N* 

 Then as before we have 



T_ /V 

 T 



and -^- 



TV 



