Prediction Method 
M -M M —-M 
0 34 MAX 0.3, 0.45 MAX 0 4 
My 3 (experiment) My 4 (experiment) 
H H 
Model Experiment 0.36 0.36 
Quasi-Steady 
Procedure26 0.25 0.24 
Unsteady Pregecdeae = 0.20 0.19 
For this typical comparison the experimental result is approximately 47 
percent higher than the quasi-steady prediction and approximately 85 per- 
cent higher than the unsteady prediction. 
The circumferential variations in the model experimental results of 
other components of blade loading F_ , F_ ,M _,andM_ were larger than 
x y x ny; 
H H H H 
the values calculated by the two indicated procedures by approximately 
the same ratio as shown for My 3 and Mo 4 . These comparisons are not 
H H 
shown. 
Previous investigators have compared experimental unsteady forces 
and moments on a single blade of various propellers in inclined flow with 
forces and moments calculated by a quasi-steady procedure similar to that 
described by MEGAE Uy Mae These, experimental loads were obtained by direct 
measurement of unsteady forces and moments on a single blade (References 
2, 3, 17, 18, and 19) or were deduced from measured steady transverse 
forces and moments along axes fixed relative to the flow, i.e., not rotat— 
ing with the propeller (Reference 36). References 2, 3, 17, 18, 19, and 
36 all show that for noncavitating conditions, the experimental unsteady 
blade loading was from 1.5 to 2.0 times as large as the values calculated 
by the quasi-steady method. This agrees with the results of the present 
investigation; see Figures 29 and 30. 
eo enrachen F., "The Study of Ships' Propellers in Oblique Flow," 
Defence Research Information Centre Translation No. 4306, Copyright Con- 
troller: Her Majesties Stationary Office, London, England, October 1975; 
English Translation of "Untersuchung von Schiffsschrauben in schrager 
Anstromung,"’ Schiffbauforschung, Vol. 3, No. 3/4, pp 97-102 (1964). 
46 
