Thanks Mark,
Along the similar topic/discussion; What type of airspeed is typical
right at ping of zoom? And also what would be a general figure to
determine velocity vs seconds of vertical climb? You could even use
Supra values.
Steve Meyer
SOAR
LSF IV
At 11:36 AM 9/26/2006, Mark Drela wrote:
First of all, if the glider is being pulled level,
the winch doesn't see the weight, only the drag.
The drag is tiny compared to the winch's pull capability,
so it will be spinning at nearly its zero-load speed.
I think a typical Ford LS 6V has Kv=350 rpm/Volt,
so at 12 Volts it will be spinning at
rpm = 350*12 = 4200 rpm = 70 rps
With a 3" diameter drum, the line speed will be
3" * pi * 70 rps = 660 in/s = 55 ft/s = 37.5 mph
Seems about right. In any case, you can check it
by timing how long it takes the winch to pull the chute
some measured distance.
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