Calculations made by the methods of Tsakonas et aie? and MeCArEnyaG indi- 
cated that the influence of the downstream body alters the peak-to-peak 
circumferential variation of the loads by no more than 2 percent. How- 
ever, these methods did not agree well with the experimental results, as 
discussed in the section on correlation with full-scale data and theory. 
STEADY-AHEAD OPERATION 
For operation near the self-propulsion point (Condition 1 in Table 
3), Figure 12 presents the variation of the various components of total 
blade loading with blade angular position and Figure 13 presents the 
amplitude of the first 25 harmonics of the various components of total 
blade loading. 
Based on the dynamic. calibration, as discussed in the section on 
calibration, it was judged that for all loading components the data are 
valid for the first 10 harmonics. In addition, the wake data shows no 
significant amplitudes for harmonics greater than the tenth; see Appendix 
A. Therefore, all data and analysis except Figures 12 and 13 are based 
on reconstructed signals using the first 10 harmonics. The symbols shown 
in Figure 12 indicate unfiltered values determined from the experiment; 
each represents the average value at the indicated blade angular position 
for over 200 propeller revolutions. The variation in measured values at 
a given angular position is discussed in the section on accuracy; see 
Figure 8. The lines on Figure 12 are the signals reconstructed from the 
first 10 harmonics. Figure 12 indicates that the variation of the 
signals with blade angular position are adequately represented by the 
number of harmonics retained. 
Figure 13 shows that there are no significant resonances for any of 
the loading components below the 23rd harmonic, which corresponds to 
(23)x(14.08)=324 hertz. This is higher than the lowest frequency reson- 
ance obtained in the results presented in Reference 2; i.e., 247 hertz. 
As discussed in the section on calibration, the higher frequency of the 
fundamental significant resonance obtained in the present experiment was 
anticipated because smaller and lighter blades were used in this experi- 
ment than were used in Reference 2. 
Bilt 
