2. Quantities averaged over one run: 



P o (N) , V, n, WH, J , p (N) , C (N) , N = 1 to 40 gages where 



C(N) = [p(N) - p o (N)]/l/2p [V 2 + (27rnr) 2 ] 



3. First harmonic analysis of averaged variation of pressure coefficients 

 with blade angular position , 



C (N,0) = C (N), + C cos (6-c)^) 



4. Graphs of average pressure variation with blade angular position, 

 p(N,6) versus 



5. Graph of mean pressure coefficients as a function of chordwise station, 



C (N) versus x/c 

 P 



EXPERIMENTAL RESULTS 

 LOADING CORRECTIONS 



The pressure-gage installations were designed for minimum interactions due to 

 loading. Propeller 4679, constructed first in the program, demonstrated small load- 

 ing effects on the gage pressure measurements. Propeller 4718 was constructed later 

 using the same gage installation procedures, but was found to have significant load- 

 ing interactions for gages installed in the thicker portions of the blades, as shown 

 in Figure 5a. The cause was thought to be related to variation in the details of the 

 gage installation procedure. In this configuration the pressure gage was seated 

 against an o-ring with a set screw, and then covered with potting resin. Variations 

 in the torque applied to the set screw would cause variations of the pressure acting 

 on the o-ring, therefore, causing variations in the ability of the o-ring to isolate 

 loading interactions. Unfortunately, there is no practical method of checking this 

 because of the permanence of the potting material covering the set screw. 



12 



