39 



Towing Speed, 2.0 Knots 



Towing Speed, 4..0 Knots 



Towing Speed, 7.0 Knots Towing Speed, 9.0 Knots 



Figure 33 - Photographs of the TMB 48.6-Inch Displacement 

 Float Being Towed 



These tests were made under loads imposed by the 75-pound weight towed from the forward towpoint. 



DISCUSSION AND ANALYSIS OF THE 

 TMB DISPLACE^ENT-FLOAT DATA 



Turning now to the resistance of the float, the frictlonal drag Is 

 apparently a small percentage of the total drag for Reynolds numbers that are 

 adequately large. The transition from laminar to turbulent boundary layer 

 occurs at comparatively low Reynolds numbers for the type of form tested, 

 about 5 X 10^ to 2 X 10*, as verified from comparison with ship model data 

 as well as with a highly streamlined airship form (10). In general, the 

 frictlonal drag coefficient for smooth streamlined bodies is small in turbu- 

 lent flow and decreases with increasing Reynolds number; this condition holds 

 for the float under discussion. Estimates of the frictlonal drag at the 

 highest Reynolds number attained in the tests, 6.8 x 10', show that the fric- 

 tlonal part of the drag is only of the order of 15 per cent of the total. 



