Culver10

I found a program that figures out servo torque for control surfaces based on area, deflection and airspeed. I have flown my Windfree lots, but have no idea how fast it is going? Does anyone know the actual airspeed of old flat bottem airfoil woodies like the Windfree, Aquila, Gental Lady,BOT, etc, etc?? How fast do the new high performance carbon ships go??

BMatthews

For the calculations you need to figure the worst case condition. That would be a vertical death dive. Since you would LIKE to be able to have the elevator pull you out of such a dive you need to input THAT speed into the calculator. Since it's safer to err on the fast side I'd suggest you use 60 mph. The torque it gives you should be a guide to chooseing a servo with at least 50% more torque. The stated torques in the specs are STALL torque and you don't want the servos to be stalled when they are supposed to be moving the surface. Hence the 50 to 100% safety margin that is desireable.

As for general speeds I belive your Windfree cruises around at about 12 to 15 mph in level floaty flight. That's pretty typical of such models at the Gentle Lady and probably the Spectra as well. THe BoT is probably in the same ballpark but has a wider cruise speed range before the glide slope becomes what we would consider a shallow dive. The high speed cruise probably being in the 25 to 30 mph range. The Windfree and Lady would top out at probably 20 before the glide looks more like a shallow dive.