I don't think there is a formula as such because the speed of the shaft
will
 depend on the construction of the cones and the bearings, weight of the
 rotating part etc.

 Do what I do. Construct the thing, get in your car and calibrate against
the
 speedometer or better still a GPS Receiver. I find it easier to do if
 someone else is driving the car   :-)

 Regards
 Chris

 >      I'm thinking of adding a wind speed measurement device to my house
 > monitoring system and I was wondering if anybody can point me to a
> formula
 > that relates the wind speed to the RPM of the "vane". I am using the
> device
 > with several "cups" connected to a bar that rotates in response to wind.
 > Thanks for any pointers. TTYL
>

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads