Re: [Paddlewise] gyroscopes for kayaks

From: Michael Daly <michaeldaly_at_rogers.com>
Date: Fri, 1 Feb 2002 00:57:49 -0500
From: "robert werner" <cryocycle_at_hotmail.com>

> My daughter and I are thinking of doing a science fair project on gyroscopic 
> stabalization of kayaks.  We are building small models for this and testing 
> them in a wave tank.  Has anyone ever done this before or have any ideas if 
> it would work?

Sounds interesting!

Ever notice that a top, if it isn't spinning perfectly vertically, starts
to rotate in a circle about its point?  This motion, called precession,
is due to conservation of momentum.  The same thing will happen to a 
gyro-stabilized kayak.

Imagine this scenario.  You are sitting in the kayak, gyro spun up and
in perfectly calm water.  A boat crosses your bow at a distance, creating
a wake.  The first wave strikes your bow and the kayak pitches up.  You
have created the same situation as a spinning top.  The kayak will 
precess.  The result will be that the kayak will heel over.  If the gyro
is spinning clockwise as seen from above, the kayak will roll to port
(I think that's correct, having done the vector analysis with my hands
here - the physics equivalent of counting on one's fingers :-)  (Wait,
I have a gyroscope here... hmmm can't get enough force to feel it,
ok - it remains an execise for you).

This assumes a single gyro wheel.  If you want to counteract this, you
can add another wheel that will stabilize it against this rolling,
say by mounting a wheel on an axis that runs athwartships.  With two
gyros, you'll still get precessional effects (yaw).  Add a third, 
mutually perpendicular wheel and you get the equivalent of an 
inertial guidance system in which the precession of each wheel is 
countered by another wheel.  The trick is to create three wheels 
that will fit into the kayak with sufficient angular inertia to 
have an effect and not make the kayak too heavy.

I would say that if you could show the precession problem with one
wheel (pitch causes roll) and explain it, this would be a reasonable
project.  Showing that three wheels solves this (and demonstrating
it is or is not feasible) would be a super project.   Just figuring 
out how big a gyroscope is needed for a kayak is pretty fancy stuff
for high school!

Mike
(Who spent a year teaching high school physics while in grad school)

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Received on Thu Jan 31 2002 - 21:56:21 PST

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