The results presented here follow trends similar to those in Refer- 
ence 2 for the FF-1088 which is a single screw transom stern configura- 
tion. The component Oe which is the largest moment component for both 
cases, yields He ae =1.40 for the present configuration (DD-963 Class) 
MAX 
and M /M =1.38 for Reference 2 (FF-1088). The maximum and minimum 
YMAX yi) 
values occur at approximately the same angular position of the blade mid- 
chord at the 70 percent radius for the two configurations. 
HULL PITCH 
Figure 19 presents the variation of the peak values and time-average 
values per revolution of the various components of blade total (hydro- 
dynamic, centrifugal and gravitation) loading* with hull pitch angle yp for 
both quasi-steady simulation (time rate of change of hull pitch angle 
b=0) and unsteady simulation (W#0). These data show that for the quasi- 
steady simulation the time-average value per revolution of each loading 
component remains within 6 percent of its value corresponding to self- 
propulsion in calm water. The time-average value per revolution for the 
unsteady simulation, deviates by up to 12 percent from its value corre- 
sponding to self propulsion in calm water. 
Data at each specified value of hull pitch angle w for the quasi- 
steady runs were recorded and averaged for a minimum of 200 propeller 
revolutions whereas data for the dynamic pitching runs at each specified 
W represented an average of from 10 to 35 propeller revolutions. As dis- 
cussed earlier, the selection of a propeller revolution at a specified yp 
during the dynamic pitch runs necessitated a tolerance of only 0.05 degree 
to ~. Therefore, the differences between the results for the quasi-steady 
and unsteady simulations, including the time-average values per revolution, 
were Significantly larger than any errors which may have arisen from inac-— 
curacies in setting the experimental conditions. 
For quasi-steady simulation, the absolute value of the time-average 
value per revolution of all loading components, except spindle torque M,> 
+ 
No results are ahown for F_ since the F_ loading arises primarily from 
centrifugal effects, as discussed previousl¥, which are independent of 
hull pitch. 
34 
