> Jake Anderson wrote:
>> The field of stopping a rotating metal disk is a fairly thoroughly
>> explored field, they are called car brakes.
>> I'd wager with a hydraulic accumulator, shop air, and some ABS/brake
>> components you could stop the blade near arbitraily fast.
>> damage to the blade would be minimal, though you would want to check it
>> for warping if it got used often.

> I don't think that car brakes are designed to stop "arbitrarily fast",
> compared to the time scales in question.

True, but the components may be useful.

A very significant part of Porches real world advantage on "real"
roads comes from the attention put into the braking system. A top
automotive braking system needs to have a horsepower rating similar to
that of its engine. F1 brake disks provide pretty images for
cameramen.

Automotive components are designed to handle instantaneous energy
transfer levels vastly in excess of that liable to be encountered  in
"very very fast" blade stopping. I suspect that even a very modest
automotive caliper brake would be a good enough foundation, provided
response times were adequate. Significant issues may be controlled
coupling to the blade surface rather than using the teeth. Servo
braking may be required to modulate the braking force to maintain a
desired braking profile. Electrically applied force  braking also
entirely feasible. *IF* blade can be adequately coupled to hub then
the hub could be braked allowing far more controlled design of brake
ie doesn't have to friction couple to a blade surface. Existing hubs
are usually friction afaik which almost certainly would not be good
enough.



                   Russell
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