Symmetrical Airfoil

Well, we both know that a symmetrical airfoil must have a bit of a positive angle to the oncoming air in order to generate lift, but I've never noticed any of my models having to fly particularly nose high unless they were very over weight.

To do so, with the wing, horizontal stab and propeller disk all at zero degrees would require a bit of "up" elevator/tail heaviness to the model. Are you holding any up elevator in order to fly level? If not, it sounds as though the model is tail heavy.

Ed Cregger

That is a good looking model, Anthony R.

Ed Cregger

Honestly, having only flown it once, it's hard to tell what exactly is going on. It was a bit windy and the plane seemed like it really wanted to climb, it may even simply be out of trim (or tail heavy like you say). Others have had success on this plane at 18 ounces so I don't think it is from excessive weight.

I guess I just need some more stick time on it to figure it out. I just wanted some preliminary thoughts on what is going on. Hopefully I will get to fly it tommorow morning. It is supposed to be a great flyer, and being my first 'full house' plane I'm sure I will improve my flying skills a lot with it.

And thanks for the compliment, this is my quickest plansbuilt yet, only 1 month.

Hey, I noticed that I have some washout at the wingtips, which shouldn't be there. I can easily adjust it out with the covering, but wouldn't this cause a nose high flying condition also? If the wing tips are pointing down the wing would have to fly at a higher angle of attack to maintain lift, wouldn't it?

That sounds logical enough to me.

Ed Cregger

If it is nose heavy AND wants to climb, then you have a trim problem that needs to be worked out. The nose heavy condition will require more up-trim to keep the plane flying level. One way to tell if the CG is correct is to trim the plane for straight and level at full throttle. When you cut the throttle back to idle, the plane should slow down and start to descend gently. If the plane starts to dive, the CG is too far forward.

SNIP

interesting! Years ago I built The spirit of St. Louis with a 34" span (188 sq in area) and flew it with an old golden bee .049 (T.D. CYL) at 15 oz. and saw the same effect. it had a flat bottom airfoil. I'm starting to think that the wing loading had a lot to do with it, because when flying inverted I still had to keep the nose very high to maintain level flight. The plane is hanging in my living room after 20 flights and I still toy with the idea of taking out the rudder servo and use aileron-elivator to save weight? could the whole problem be wing loading? George J.

I have flown it more and it seems to be all worked out. I removed the washout in the wingtips and moved the cg a bit forward and now it is flying fine. I have flown it with the motor off and it glides nice, inverted is good, etc.

Thanks for the tips.