jimlux wrote:
> Richard (Rick) Karlquist wrote:
>
>>
>>
>> What I wish someone would make is a conventional gear winch
>> with a brake that worked on air resistance. A gear train
>> would make a paddle on an axle rotate at high speed such that
>> the winch would free run downward at a controlled rate without
>> anything overheating. Schwinn make an exercise bike that worked
>>
Something a little classier: We have "Wind Trainers" set up for our road
bikes. It takes less than a minute to put the road bike on it and be
ready to go. The faster you go the more the resistance. UNFORTUNATELY
even at 20 MPH you are generating a fraction of the resistance to even
slow the tower noticeably. Even a step up gear ratio would unlikely
prove satisfactory. For instance, watching the Tour De France today I
noticed the riders were going up the mountain at an average of 20.1 MPH
and developing 285 Watts or 1.6 HP and a heartbeat of 177 bpm and that
is a tiny fraction of what a falling body would take. You have to move
enough air that the energy equals that of the falling body minus system
friction. I wonder how many of us could hit 20 MPH, let alone sustained
on a level surface. Then think of doing that while going up a mountain.<:-))
What might work (although it might be a bit technical to implement)
would be to drive a generator or alternator into a variable load.
However, every gear, shaft, bearing, control, and connection is an
additional failure point and for safety of life, limb, and pocket book
these need be kept to a minimum.
73
Roger (K8RI)
>> on this principle. It eliminated the troublesome resistance
>> pads. We now return you to your regular winch.
>>
>
> This is a pretty standard thing they use in the special effects industry
> to regulate the rate at which someone falls. But it takes a bigger air
> paddle than you think.. Water might actually be a better drag medium.
>
> The challenge is actually not in the drag (an electric generator would
> also work) but in reducing the gear train losses. For the falling
> person speed regulator, they feed off a fairly large diameter drum, to
> keep the rotation rate reasonable.
>
>
>
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