Airplane tilts left when up elevator is given...what's wrong?

[Reformed Nitroaddict]

This is a post from RCU that wasn't getting alot of attention, and I wasn't sure of the answer. Here is the question, and the link to the RCU thread. I also posted a link in that thread to this one. Anyone have any ideas?

Well I fixed my aileron problem but now it doing something funny. If i give it really hard up elevator, it turns hard left too, as if I input left aileron. Any ideas?

Link to orignal thread:
http://www.rcuniverse.com/forum/m_3131597/anchors_3227728/mpage_2/key_/anchor/tm.htm#3227728

[rcers]

It is a high speed stall. Very common in aerobats with high throws.

Caps are very notorious for this. Mine would snap 3 times at full up elevator at speed. Don't forget stall is not just a low speed issue, it can happen at any speed.

The cure is less elevator, dual rates, or expo.

Mike

[Mike Parsons]

Hmmm...He needs to check the rigidity of his Elevator wire on that Formosa. The elevator control horn is on the left side if looking from the rear. If the left side is getting more input (up) than the right, it would be the same as inputing left aileron. I had this problem with a plane that had two seperate servos. My right servo was going out on me and it took this problem to figure it out.

If that is rigid and providing the same amount of throw, then I agree with Mikes assesment.
-Mike

[Reformed Nitroaddict]

Two very interesting ideas that I would have never thought of. Glad I posted it here!

[rcers]

He needs to check the rigidity of his Elevator wire on that Formosa.

Nope - it isnt that, I have one and it will snap. Mine is glassed and totally rigid. It is the high speed stall, I promise!

Mike

[Mike Parsons]

That is strange. I have had two and neither one showed that characterstic. Of course I had a pretty forward CG.

[rcers]

That is strange. I have had two and neither one showed that characterstic. Of course I had a pretty forward CG.

Mine was nothing like a CAP, but at high rates and full speed mine would snap out every time.

At low (normal) rates no issues at all at any speed. I think many have far too much elevator throw and that is why they see this more often.

A great little plane that Formosa....

Mike

[Mike Parsons]

A great little plane that Formosa....

Mike
I completely agree. Hopefully one day, GWS will release the Formosa II

[rcers]

No kidding - I can't wait for the bigger one.....especially now that my first one is dead. I got t-boned! But is was going straight up doing rolls, so I have to say it died with a smile!

Mike

[flypaper 2]

Another trick that doesn't work for all planes, is to get it to snap, then try a little aileron in the opposite direction that it's snapping. If it does work, use ail trim to set it. then fly level and see if you can use rudder trim to get it to fly straight. As I say it doesnt work on all planes. May have to borrow a buddies Formosa to try it out:D

[Slowroll90]

hey rcers mabey his isnt rigid like yours and in your case it is stalling but i think mike p was on the right track with the control horn placement if so then down elevator will make it roll right if it rolls right that is most likely it
or mabey the stabilizer isnt perpendicular to the rudder fin and parallel to the wing , if its tilted down on the left side (if viewed from behind) then that couls cause it
but if the elevator is parallel to the wing then this probaly is not the case
or if reformed nitroaddict's elevator is rigid like rcers then rcers is right and it is most likely stalled

[stuff]

I think it is broken so you may as well give it to me and get on with it:) Stuff

[Buzz Job]

OK testing the watters here but without seeing the plane in action and comparing controll throws with flight action. To some extent yawing to left on up elevator and yawing right on down is normal.
Dont want to get too complex but the above is from P-Factor and is the bite of the prop in relative wind. the blades have unequal pitch at different angles of relative wind
If you can get the plane to give equal ammouants of yaw with the same in elevator movement up and down you are trimed perfect for aerobatics.:cool:

[bronicabill]

Since he didn't specify whether it was rolling or yawing (or both), it could definitely be P-factor at work here if it is a yaw problem, especially with the larger props that many of the electrics use! Remember, P-factor also includes gyroscopic precession, so it's not just the difference in blade bite that creates yaw.

Cheers,

[nova801428]

my gws zero does the same thing, its probably the elevator when you pull up one of the peices of the elevator comes up higher and causes it to role.

[Matt Kirsch]

Sometimes that's true, but generally, uneven elevators only has a very small effect on the airplane as far as rolling.

A violent tendency to roll over to the left means that there is too much elevator throw, or you are pulling back on the stick too much. If you want the plane to snap roll well, you may want to have excessive elevator throw. However, if you're still at the stage where your panic response is to yank full back on the elevator, try reducing the elevator throw.

[rcers]

uneven elevators only has a very small effect on the airplane as far as rolling.

Quite correct. I have had an incident in a plane where the joiner broke. I no rolling, no nothing, in fact I didn't know till I landed!

Remember guys planes can stall at any speed - yep that is right. High speed stall and snap (roll) are not uncommon at all.

As has been said - reduce elevator throw, that is the issue.

Mike