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EXPERIMENTS ON THE FROUDE. gt 
the propeller for the Froude at the Model Basin under the supervision of 
Naval Constructor D. W. Taylor, U. S. N., to whom the writer is indebted 
also for advice and sympathy in carrying on the tests described in this paper. 
The results of the towing tests of the model are given by Fig. 3, Plate 37, in 
which the abscisse are speed in knots per hour and the ordinates are 
resistances in pounds. 
TESTS OF FROUDE’S PROPELLER. 
A propeller for the Froude was correctly planed according to the 
working drawing of the Manning’s propeller, by the Fore River Shipbuilding 
Company and was tested under the supervision of Naval Constructor Taylor, 
the writer was given opportunity to witness these tests and is glad to take 
this occasion of expressing his admiration of the work done at the Model 
Basin. It will be remembered that the standard size for model propellers 
at the Basin is 16 inches, and that the axis of the propeller shaft in the 
testing apparatus is 16 inches below the surface of the water so that such 
models have 8 inches of water over the tips of the blades. The Froude’s 
propeller had only 2.8 inches of water over the tips of the blades, but that 
condition is normal for that propeller which has nearly that immersion 
when in place. 
Fig. 4, Plate 38, gives the torque required to drive the Froude’s pro- 
peller and the thrust delivered by it, when tested in the Model Basin, 
together with the efficiency, all plotted on real slips of the propeller as 
abscisse. This is the standard method of reporting tests at the Basin. 
From the torque and thrust the gross power and the effective power can 
be determined by the equations— 
Be 2 OP AOL 33 Vase Al ee 
~ 3300°° p(1 —5) re ene Ve ) 
coe DVOGION BS Sas eV3 (2) 
33000 1000 
as is explained by Naval Constructor Taylor in his “Speed and Power of 
Ships,” page 102. In these equations, Q and 7 are the torque and thrust 
from the curves of Fig. 4, Plate 38, d and p are the diameter and pitch of the 
propeller in feet, while V, is the speed of the propeller through the water in 
knots per hour and s is the real slip. The report from the Model Basin ~ 
gave also curves of A and B on the real slips as abscisse, but as those 
curves are intermediate curves, for our present purpose it has not been 
