_ maximum value occurs when the blade is nearly vertical downward (6 
o'clock position). This is again as would be expected from geometry. The 
phase angles would not be expected to be precisely +90 degrees or 180 
degrees since the propeller has 22 degrees of skew. The amplitudes of 
Dig and Cag each should be equal to the combined weight of the 
blade and that portion of the appropriate flexure at radii greater than 
‘the radius of the appropriate strain gage. The values of Oia and 
ete wei confirmed by weighing the blade and appropriate flexures. 
The values of CO ag and Cae are essentially zero because the blade is 
skewed and raked so that mass of the blade is balanced about the spindle 
axis in both the plane containing the spindle axis and the propeller axis, 
and the plane normal to the propeller axis which contains the spindle 
axis (see Figure 2 and Table 1). The value of Cis is nearly zero since 
lies is always in a nearly horizontal direction. For all components the 
experimentally determined amplitude and phase of the first harmonic were 
essentially independent of rotational speed n. The experimental air-spin 
results were faired so that values of the amplitude and phase of the first 
harmonic of the loading components used for separating hydrodynamic loads 
from total loads were constant, independent of n. 
Approximate scaling parameters for centrifugal loads are (F/ppn°D") 
and (M/o,n°D>), whereas appropriate scaling parameters for gravitational 
loads are (F/opgD°) and (M/0p8D"). The model experiments presented in this 
report were conducted at full scale values of Froude number FA = (V/VveL) 
and advance coefficient J = (V/nD). Constant Froude number implies that 
V~(gL) ?~(gb)? 
V-~eD 
Constant advance coefficient implies that 
V~nD 
vee nee 
Therefore, 
ened 
ppeD’~ppn-D* 
5 
‘PpsD ~Ppn D 
27 
