Page 281 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

13.1 NASA TROV craft. Photo courtesy of NASA

could design a ship that could move that fast, that suddenly. It’s
not surprising then that the U.S. government is funding some of
these studies.
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How efficient are fish at swimming compared to our current
method of water propulsion? Let’s glimpse at a partial analysis. In
1936 James Gray, a British zoologist, studied dolphins. His pur-
pose was to calculate the power a dolphin needed to move itself at
20 knots, a speed at which dolphins are commonly reported to be
able to swim. Gray’s model of the dolphin was rigid, assuming that
the water resistance for a moving dolphin is the same for a rigid
model and flexible model. This is not true, but even accounting for
this error, the conclusion Gray calculated is interesting. The dol-
phin is too weak, by a factor of 7, to attain the 20-knot speed. One
may further deduce that the dolphin may be able to reduce its water
resistance by a factor of 7 to compensate. But this probably isn’t the
entire answer either.
Well, for the last 60 years no one has been able to prove or dis-
prove Gray’s calculations conclusively. Any swimming mechanism
that mimics fishlike swimming is grossly inefficient. Recently new
studies are under way to again study fishlike swimming. With new
computer technology behind this endeavor, scientists hope to an-
swer these long-held questions.
Researchers at the Massachusetts Institute of Technology (MIT) in
Cambridge have been studying the bluefin tuna for the last several
Team LRN
Chapter thirteen