trim help needed

[Glenn Quarles]

Friends, I flew my 1/2A Waco yesterday and it acted completely different than the one I built a few years ago. My problem is that the plane flies VERY nose out. The plane is built exactly per the instructions with the lead outs as shown on the plans, about 1/4" rudder offset and I had one thin washer under the front engine mounting bolts for some out thrust. After the first flight I removed the washer to set the motor straight ahead and it didn't help any (not enough to tell anyway). So my question is on what should I do next, move the lead outs forward or get rid of some rudder offset, or both.

Any help will be appreciated!
Glenn

[Tim Wescott]

I'd lose the rudder first.  Are the leadouts adjustable?

[Akihiro Danjo]

Have you checked out the C/G location? It may be too far forward.

Aki

[Glenn Quarles]

I'd lose the rudder first.  Are the leadouts adjustable?

Hi Tim, no the lead outs are not adjustable, but it would be easy to do.

Thanks,
Glenn

[Ron Cribbs]

Sounds like a leadout issue. By nose out do you mean yaw? Can you see both LG wheels during flight?

[Glenn Quarles]

Have you checked out the C/G location? It may be too far forward.

Aki

Hi Aki, yes it is a slight bit nose heavy. I was gonna add a bit of tail weight before the next flight, but I didn't  think about it helping the nose out problem.

Thanks!
Glenn

[Glenn Quarles]

Sounds like a leadout issue. By nose out do you mean yaw? Can you see both LG wheels during flight?

Ron, yes it is yaw. There is no landing gear, but yes the outboard wingtips are  visible well behind the inboard.

Glenn

[Tim Wescott]

I'd lose the rudder offset and make the leadouts adjustable.  Adjustable leadouts on a 1/2A is a bit overboard, but what the hey.

The CG issue is probably a productive line of inquiry, but I suspect it's not the whole answer.

[Glenn Quarles]

How much should I move the lead outs? Is there a general rule of thumb for leadout position relative to the bellcrank? Right now the rear leadout is about even with it's position on the bellcrank and the front leadout is about even with the pivot point on the bellcrank.

Glenn

[Howard Rush]

 Leadout location is a function of CG, not bellcrank position.  You can use this to get close: http://www.tulsacl.com/Linelll.html .

[Tim Wescott]

The only general rule for leadout position vs. bellcrank is that if the leadouts have a severe bend at the leadout guide, then friction will be increased.

That, however, isn't a big problem unless the bellcrank is absurdly placed.

Set the leadouts correctly with respect to the CG, and you'll be a happy camper.

[Glenn Quarles]

Awesome! Thanks for the help guys!

Glenn

[john e. holliday]

If the CG is spot on, hang the plane by the lead outs.   That will tell you if you need to move them or not.

[Dave_Trible]

With the airplane hung by the leadouts on one hook the fuselage should hang nose down 1-2 degrees.  The bellcrank location is not important.

Dave