22S calculations were conducted 
For the method of Tsakonas et al, 
for the first ten harmonics of the Tae The "normal'' components of wake 
harmonics, as required by this method, were defined as the wake harmonics 
normal to the chord line of the blade section at the local radius rather 
than normal to the advance angle at the local radius as recommended by 
oh) With the wake harmonics resolved normal to the blade 
Tsakonas et al. 
chord, this method apparently considers both the unsteady flow normal to 
the resultant inflow and an approximation to the unsteady flow parallel to 
the resultant inflow. 
The quasi-steady calculations are based on the circumferential vari- 
ation of the wakes measured at the 0.7 radial station. These calculations 
were made at 10-degree increments of blade angular position ®. It is 
assumed that the radial centers of the unsteady thrust and tangential 
force are at r/R=0.70 for all blade angular positions. 
Figure 28 presents values of HO. 3y and one with and without the 
downstream dynamometer boat, calculated with the methods of Tsakonas et 
aio and Me Carew, Based on these calculated results it appears that 
the dynamometer boat does not have a significant influence on the cir- 
cumferential variation of the blade loads. 
Figures 29 and 30 present the variation with blade angular position 
and the first ten harmonics of My 3 and My I from the model experiments 
34 “4 
and analytical calculations. All data are nondimensionalized on the same 
quantity, i.e., the time-average bending moment determined from the model 
experiments and corrected for the downstream body as discussed in the sec-— 
tion on experimental results. This comparison indicated that the experi- 
mental unsteady hydrodynamic bending moments were substantially higher than 
the calculated results. A typical comparison is as follows: 
*These calculations were made by using the computer program developed by 
the Davidson Laboratory including refinements made through April 1977. 
None of the refinements made since December 1975 influence the calculated 
unsteady loads presented in this report. Therefore, this calculation pro— 
cedure is the same as that used in Reference 2 for calculating the unsteady 
bending moments on the propeller on the FF-1088. 
Tsakonas, S. et al, "Correlation and Application of an Unsteady Flow 
Theory for Propeller Forces," Transactions of the Society of Naval Archi- 
tects and Marine Engineers, Vol. 75, pp 158-193 (1967). 
45 
