1. For nonseparating hull forms, potential flow theory predicts the 

 change in afterbody pressure distribution and total thrust deduction within 

 experimental accuracy. 



2. Calculations of the thrust deduction fraction based on pressure 

 integration and Lagally's theorem agree to within 4 percent. 



3. The influence of the propeller rapidly decays with distance. In 

 all cases, the thrust deduction develops within the last 30 percent of the 

 hull length. 



4. Corrections to hull source strengths (interference or diffraction 

 effect) changes the thrust deduction fraction by less than 3 percent. 



5. Lifting-surface corrections reduce the calculated thrust deduction 

 fraction by as much as 20 percent for conventional propeller geometries (or 

 equivalently, a 2 to 3 percent reduction in required thrust) . This correc- 

 tion will increase for more highly raked propellers. 



6. Conventional cruciform stern appendages contribute up to 25 percent 

 of the thrust deduction fraction. 



7. The use of an afterbody image to represent the forebody reduces the 

 computational effort without loss of accuracy. 



In view of these findings, the following extensions and applications 

 are recommended: 



1. Further comparisons with available experimental data should be 

 conducted to aid in refining the analysis. 



2. For purposes of preliminary design calculations, the thrust deduc- 

 tion analysis based on the lifting-line model, as described in the report, 

 should be incorporated into existing propeller design computer programs. 



In order to properly account for rake, it will be necessary to develop a 

 curved lifting-line representation of the propeller. 



3. A parametric study should be undertaken to systematically examine 

 the role of hull form and propeller characteristics (e.g., diameter, axial 

 location, radial distribution of loading, and rake). 



4. The method should be extended to include other propeller configura- 

 tions — contrarotating, tandem, ducted, and twin-screw. 



5. The method should be extended to apply to surface-ship configura- 

 tions. 



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