UNCLASSIFIED 
—__ eee 
SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered) 
(Block 10) 
Task Area S0379-SLOO1 
Task 19977 
Work Units 1544-296 and 1544-350 
(Block 20 continued) 
2. An unsteady lifting surface theory developed by Tsakonas and 
his colleagues at Davidson Laboratory, 
3. An unsteady lifting surface theory developed by Kerwin and Lee 
at MIT, 
4, A refinement by Kerwin to the method of Kerwin and Lee to 
consider the inclination of the propeller slipstream. 
In inclined flow, all four of the calculation methods evaluated 
consistently underpredicted the experimental values of the periodic 
single-blade loads. The method of Kerwin, which considers the in- 
clination of the slipstream relative to the propeller axis, produced 
the best correlation with experimental values. These correlations 
show that the inclination of the propeller slipstream relative to the 
propeller axis significantly influence the periodic single-blade loads. 
The importance of this inclination increases with increasing time- 
average loading. 
In longitudinal flow, all of the calculation procedures predicted 
periodic single-blade axial force at design advance coefficient to 
within 20 percent of the experimental values, but agreement was not as 
good at off-design advance coefficients. The method of Kerwin and Lee 
produced the best overall correlation with experimental results 
considering both amplitude and phase of the periodic single-blade axial 
force over a range of advance coefficients. 
UNCLASSIFIED 
SECURITY CLASSIFICATION OF THIS PAGE(When Data Entered) 
