Finding Torque for Flaperons
 

Hey we're trying to figure out what torque will turn our flaperons of the following dimensions require

chord: 6.2 cm
span: 11.5 cm
max angle: 45 degrees from wing camber line

our wing dimensions (just in case)
MAC: 20.25 cm
span: 40 cm

is there anything else we should be looking at to calculate torque? Maybe velocity, etc?

Thanks!

RE: Finding Torque for Flaperons
 

As small as this airplane is, I would guess you'll have to live with what ever torque is available from a micro servo.

RE: Finding Torque for Flaperons
 

you should also concider the distance between the pushrod and the servo spline, and the distance between the pushrod and the control surface.
You can use very little raw torque if you're leverage is right, or just the opposite. Those factors will also directly influence your travel distance.
HINT: It doesn't take a whole lot of flap to make a difference.

RE: Finding Torque for Flaperons
 

45 Degrees of flaps..I think at that point they just induce enough drag to slow the plane down but no longer increase lift...

RE: Finding Torque for Flaperons
 

You also need the heaviest weight at the maximum velocity you expect to have the flaperons extended to 45 degrees. So if this were a glow plane weighing 5lbs moving at 45mph and you extend the flaps to 45 degrees, that is the most load they will see. Now I know that's a little exaggerated but it gets the point across. Even at 5lbs 45 degrees will make for some extremely slow landing speeds and one heck of a short takeoff run.

To give you a better idea, most retract servos run around 90 ounces of torque. It has to compensate for the speed of the plane, the weight of the retracts in transition, it can also survive if one of the down or up locks breaks. I've seen a couple of 8lb P-40's using standard 50 ounce torque servo have their flaperons lowered to roughly 40 degrees at better than 40mph and the servo easily survived. Yes, there was a mix for the elevator to compensate for the pitch change, which at that speed would have been pretty violaent

RE: Finding Torque for Flaperons
 

Thanks everyone!

We found out that the servos we originally bought (cirrus cs-3) will DEFINETELY not turn the flaperons in flight. We bought new ones - Megatech FX Minis which provide more torque (28 lbft), albeit about 12 g heavier :(. They will do the trick.

Thanks again!