Flap Torque

mmarien

Murray M.
Joined
Dec 26, 2009
Messages
1,206
Location
Saskatoon SK CAN
I run into a snag with my upgrade to VP-X. The electric flap actuator on my Glasair II requires a 15A c/b. The VP-X (and FPS) only allow a 10A c/b. It's been suggested that most flap actuators require less than 10A. So I did some digging and found a nice linear actuator with a potentiometer built it. Solves the other problem of the slack linkage on my Ray Allen potentiometer that gives me a stop at 15 degrees going down and 8 degrees coming up.

The problem is the original Glasair flaps actuator is rated at 500 lbs/ft. Anything on the market with that much torque doesn't have a potentiometer and requires >10A c/b which doesn't solve the problem. So the question is, 500 lbs/ft seems excessive. Is it? How much force is required to pull on manual flaps? If it's 10 lbs on an 18" flap lever as shown on the sketch below, then it can only be 60 lbs on a electric actuator lever 1/6 as long.

500 lbs on the shorter lever would be 83 lbs on the longer lever. It would take me two arms and some to pull 83 lbs. Doesn't sound reasonable. Can someone hook a fish scale to their flap lever and let me know how much force it takes to pull full flaps on at max flap speed Vfe.

FACals.jpg
 

Rapidshot

I love flying!
Joined
Nov 18, 2012
Messages
11
my evektor needs around, say 2-3 lbs for 15 degrees and 6-8 lbs for full flaps during flight, lever arm length is about 10 inches
 

mmarien

Murray M.
Joined
Dec 26, 2009
Messages
1,206
Location
Saskatoon SK CAN
Thanks. That kind of confirms my logic even though the Evektor is a lighter aircraft. For now I took the easy route and installed relays to handle the 15A draw but haven't ruled out replacing the actuator during some future upgrade.
 
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