Shouter

My Feedback: (1)

I have a Dave Patrick Ultimate .40. I love it! But the problem is when you give it "too much" elevator, it wants to snap out of it. Is this a CG problem?

fancman

My Feedback: (16)

Most likely. Move cg forward and or reduce control surface throw.

da Rock

Ultimates are designed to snap and do the aerobatics that require a stalled wing. Lots of airplanes are. They have tapered wings since that planform naturally stalls from the tip and elevators that are sufficiently powerful to pitch the wing into a stall AOA.

The plane is doing what it was designed to do. The way to deal with it is what most do. Setup dual rates on the elevator and use it. You test fly to find the amount of elevator throw causes you the snap problem. Then you set your low rates to give just a bit less than that throw. You will then have high rate elevator to do all the snappy maneuvers and low rate to do all your milder flying.

Many of the aerobatic designs really suffer overall with a too far forward CG. The tapered wings don't change where they stall with different CGs. They're still going to stall from the tip. And as the CG is moved forward the overall efficiency of the airplane suffers. The stall speed actually increases, as does induced drag.

With a lot of these planes, you'll find that the suggested elevator throw is really not needed. Rigging for less throw gives a model that winds up flying better, more efficiently, and with no change in stability. And of course, an elevator stick movement that is more comfortable.

Shouter

My Feedback: (1)

Wow, thanks so much for that explaination. I will do what you recommended. Again thanks!
So the same thing happens to my Funtana .40, is that a cg problem then?