While
reading an introduction to circulation theory, as applied to
understanding the lift force, it occurred to me that a rotating
cylinder would be the ideal motive force for a boat. The idea entered
my mind fully formed, as it were, and although it was a very difficult
road from conception to execution, the finished rotor is exactly as I
first saw it. In fact more than ten
years elapsed before I had the opportunity to apply the idea, and begin
to answer the many questions the concept raised.
During
those
years I discovered that the idea was far from new. In the 1920s a
barquentine called Buckau was converted to the design of Anton
Flettner, supported by other aerodynamicists, to run with two rotors.
The technology was never developed at the time because design
limitations made it no more efficient than other means of propulsion,
and because there were no constraints on fuel use or consequent
pollution.
I persevered with my own project because,
ignorant of
what had gone before, I was equally unaware of the attitude that the
idea had run its course, and of other presumptions applied to the
concept which perpetuate to this day. I approached it from a lifelong interest in aviation, and
right from scratch saw the rotor as a glider's wing. Besides this, I
had fallen in love with the idea aesthetically, and as a means
of
ultra-short handed sailing.
The more I found out the
more
daunting the task became. Although the design you see on this website looks very
simple and pure, the engineering problems are significant, especially
for an amateur with very limited resources. Since the 1920s the idea
has been revisited in theory (notably during the fuel crisis of the
1970s), and again took the wrong tack, to my mind. I tested a
radio-controlled model in early 2002 which worked alarmingly well (it went off like a little speedboat), and
ultimately I have been
able to exploit modern materials to make a rough prototype rotor
approaching an aerodynamic ideal beyond the material means and perhaps
theoretical understanding of previous decades, and to sail it on the
small proof of concept boat you see in these pages, which first
sailed on the 31st of July 2004, and has been baffling and intriguing people
ever since. I am able to
demonstrate what I believe is the only extant device to show convincingly that:
1)
A small power input to the rotor can generate a propulsive force equal
to a conventional sail or sails of much greater surface area, in the
same wind. Importantly, at
smaller scales this power input is within the range achievable by
renewable energy sources alone.
2)
The rotor has many smaller practical advantages over conventional
sailing boats, when considered as anything other than pleasure craft.
Whether these features are felt as advantageous by recreational sailors
is a different question.