Extreme stall & snap with very little elevator input

[hyper7]

Hi Guys, hope this is the right forum for my question:

I have recently completed a CA Models Extra 330L 26%. It is built from a kit (not ARF).

The plane is exhibiting a weird behavior, I hope somebody can give me an idea where to look. It stalls and snaps violently with very little (less than half of the recommended elevator throw, about 2mm on the stick). This happens even with the throttle at 50% open, so it is not just a slow speed stall. What can cause this? I am thinking incidence (wing or stab?) or wingloading?

Thanks!

[David A Ramsey]

Most likely it's the balance point and you're on the tail heavy side.

[Texas Buzzard]

Hi Guys, hope this is the right forum for my question:

I have recently completed a CA Models Extra 330L 26%. It is built from a kit (not ARF).

The plane is exhibiting a weird behavior, I hope somebody can give me an idea where to look. It stalls and snaps violently with very little (less than half of the recommended elevator throw, about 2mm on the stick). This happens even with the throttle at 50% open, so it is not just a slow speed stall. What can cause this? I am thinking incidence (wing or stab?) or wingloading?

Thanks!
.................................................. .........................................
After I had thought I was a proficient pilot with std. high winged glow trainers I spent extra time building a beauty : a glow .40 powered RCM Trainer. That first day I had several successful flights and then "just one more". I was coming in too low on idle, at about 10 ft. I jammed the power on and it SNAP-ROLLED into the ground...... Yes I think it was in a slightly nose high attitude when I punched the throttle.

Today I think it was the "P" Factor that did it ---- NOT Torque. From my reading the "P" Factor only takes over at lower air speeds when there is a nose high attitude. At high speeds there is no "P" factor. It has to do with the part of the prop that is moving down being more effecient than the upward moving blade -if the plane has a nose high attitude - so say the exsquirts. To correct for "P" Factor the big boys say use right thrust. Ha, Ha, I thot' right thrust corrected for torque - what do I know? Nada.

Sometimes we hear about giving right thrust to compensate for Torque.
Fo years I have always built-in a bit of right thrust and of course I can't measure what it's doing but it doesn't hurt at all. Moral of the story ----> use 2 to 3 degrees of right thrust to counteract that "P" Factor.

If there are some exsquirts out there who know a little more....please post.

[BMatthews]

How well and consistently did you round over the leading edge to match the airfoil on the plans? That would be my first thought. Second is what is the weight and wingloading of the model. Does it always snap the same way. And finally does it seem to be flying nose high even during the 50% throttle running and does it have good airspeed?

[JetPlaneFlyer]

And are there any warps in the wing, especially warps that produce 'washin'..i.e. the tips ending up at a higher incidence than the root?

If the wings came ready made (i.e. foam or whatever) and if they have a symmetrical airfoil are you sure you did not build the wing upside down such that any washout built into the wing panels became washin?

Steve