Lehman and Kaplan 



10. Op 

 8.0 



6.0 



0.6 



0.4 



0.3 



I.2L 



,D— D — D-,__-a^^ 



^^ 



J = 0.50 K„ 



0.157 



1st Harmonic 



0.2 0.4 0.6 0.8 

 Spacing/Propeller Diameter 



l.u 



Fig. 33 - Induced force ratio vs spacing ratio for a 

 two-bladed propeller upstream of an appendage, 

 transverse measurements, and an appendage angle 

 of 10° 



12. For the rudder case the most important observation is the undulatory 

 variation of both the axial and transverse forces with an increase in propeller 

 spacing. This condition holds for all cases, both with and without attack angles. 



13. For the rudder case and a two-bladed propeller the axial induced force 

 at a 10° rudder angle reduces to about 20 to 25% of that existing at a 0° rudder 

 angle. At 10° the transverse force approaches 50 to 60% of the axial force at a 

 0° angle. 



14. For the rudder case and a three- bladed propeller the transverse force 

 generally reduces with the introduction of attack angle. Little axial force is in- 

 duced with a 0° rudder angle, but with a 10° rudder angle the axial force is about 

 1/2 the transverse force. 



204 



