470 F. W. Boggs and N. Tokita 
ai: 2m. ( Ato ) 
Be pXA MENA 
XA 
THEORETICAL TURBULENT XA lls 
(Ato) (A t)) 
“DRAG AREA FOR 
V=10, 20, 30 FT/SEC 
0.20 5-39 
c 
& 0.16 
pole FAIRED 
< EXPERIMENTAL 
i 0.08 ‘ DRAG AREA 
ie 5-1 1 
2 0.04t | 
= 615-19 15-90 H 
a fe) Q 
(0) 0.2 0.4 06 08 1.0 
RING THICKNESS (INCHES) 
Fig. D5. Drag area versus ring thickness 
Figure D6 shows the maximum recorded speed versus ring thickness. With no ring, the 
maximum speed was 25 ft/sec, which is only 15 knots. It is noted that the water depth has 
no effect on top speed, since it was 4-1/2 feet for the runs on June 3, 4, and 5, and 6 feet 
for the June 15 runs. Figure D7 shows the drag horsepower versus ring thickness. The 
drag horsepower was not measured but was calculated using the dotted-line experimental 
drag area of Fig. D5 and the top speed from Fig. D6. Of primary interest is the fact that the 
2.0-horsepower maximum, recorded for the no-ring condition, agrees well with the recorded 
maximum acceleration horsepower. These results tend to indicate that the effective drag 
while swimming is essentially the same as that while gliding, and that the boundary layer in 
each case is effectively turbulent. It is noted, however, that the horsepower for the runs - 
with rings is only 0.8 rather than 2.0. This fact would tend to indicate either that the rings 
had a large effect on the boundary layer while swimming, that they caused the porpoise to 
exert less effort due to irritation or some other cause, or else that the experimental ring 
drag values are low. The time during which the purpoise traveled at top speed was several 
seconds longer when a ring was carried than when it was not, so the expended horsepower 
with rings would have been expected to be around 1.3 to 1.6 rather than 2.0. 
Figure D8 shows the porpoise body movement during a typical cycle while accelerating. 
The nose stations are aligned and the body position is sketched from different film frames 
MAXIMUM RUN VELOCITY 
(FT/SEC) 
fo) 0.2 0.4 0.6 0.8 1.0 
RING THICKNESS (INCHES) 
Fig. D6. Maximum velocity versus ring size 
