Hi folks, this is for the physicists and engineers in this forum, got a
question that's beyond my capability.
I previously told you that an interview with Dave Campos about his
(existing) 1990 FIM World MC Speed Record(322.149 MPH) is just about to
begin in Bonneville Racing News.
Dave told me at the beginning of 1990, for lack of good fresh high-speed
rubber tires, their team tried to use a 75 lb, 25" one piece aluminum
front wheel. This was made in the form of a disc with a roundish
cross-section rim on it. I would estimate that half of the total weight
of the wheel was in the rim portion.
This wheel was not successful, at first because the weight of it made it
bounce over the bumps on the salt flats, and stay in the air too long at
high speed(no steering then needless to say), but even more serious, the
'liner crashed with it at close to 300 mph, and they lost confidence in
it; and reverted to a 500 x 15 rubber tire(only 15 pounds for wheel and
tire) for the rest of their program.
The question I have is about the amount of gyroscopic effect that this
75 lb aluminum wheel with its heavy rim would produce. I discussed this
with Dave. It seems to me that such a wheel, spinning like a heavy
flywheel at 300 mph, would build up a very sizeable gyroscopic force,
possibly to the point that it would take a lot of force to get it to
react to the rider's steering effort input. Because the heavy wheel
would want to stay in its plane of rotation, and resist an attempt to
change that plane.
Can anyone compute the forces that would be involved here for us? Bill
Hoddinott
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