INTRODUCTION 



With the increasing use of controllable-pitch (CP) propellers for high powered 



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ships, ' the U.S. Navy has been conducting a research and development (R&D) program 



to establish the technology for producing reliable CP propellers. The program 

 undertaken at DTNSRDC included: 



1. Blade Loading of CP Propellers 



a. Model measurement and theoretical prediction of blade loading 

 on CP propellers 



b. Model and full-scale wake measurements and theoretical 

 predictions of wake 



c. Full-scale measurements of forces, pressures, and strains in 

 CP propellers components. 



2. Structural Design of CP Propeller Blade Attachments. 



3. Development of Materials for CP Propeller Systems. 



The current report presents the results of work conducted under Section la of 

 the CP Propeller Research and Development Program, i.e., model measurement and 

 theoretical prediction of blade loading of CP propellers. Work under the other 

 sections of this program will be reported separately. 



An accurate estimate of the maximum time-average and alternating loads under all 

 operating conditions is necessary in order to design the blades and pitch-changing 

 mechanisms of high-power CP propellers so that they possess adequate strength with 

 regard to both yield and fatigue stresses. High time-average and alternating loads 

 occur at steady full-power ahead conditions and during high-speed maneuvers, 

 including full-power crash astern, full-power crash ahead, and full-power turns. 



The total unsteady and time-average propeller blade loads, as represented by 



3-7 

 three force components and three moment components, have been evaluated in other 



portions of Section la of the CP Propeller R&D program. These results have demon- 

 strated that the currently available analytical techniques substantially under - 

 predict periodic propeller blade loads for operation in inclined flow. However, 

 these available results do not yield significant information on the distribution of 

 the periodic loadings over the blade. 



*A complete listing of references is given on page 217. 



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