Pien and Strom-Tejsen 



PREDICTED LOAD 

 DESIGN LOAD 



0.0 

 IE 



0.4 0.6 



CHORDWISE POSITION 



1.0 



TE 



Fig. 8 - Chordwise load distribution from the inverse 

 calculation as compared with the design load distribution 



6. Since the camber ratio involved in a practical marine propeller is only a 

 few percent, especially at the outer radii where most of the loading is carried, 

 the load distribution is placed on the chord rather than on the meanline. This 

 saves computer time without losing the accuracy required for engineering pur- 

 poses. However, the theory takes into account the difference between the blade 

 element pitch angle /^q and the advance angle /? . The former is a function of 

 blade geometry, and the latter is a function of operating condition. They are in- 

 dependent of each other and may differ appreciably. 



7. All geometrical features of a propeller blade are incorporated in the 

 theory. Therefore, it is applicable to any practical propeller as far as propeller 

 geometry is concerned. 



8. In view of item 2 the present theory can be easily extended to cover 

 multiple propeller systems such as overlapping and contrarotating propellers. 



124 



