Loose on insides

[Bob Reeves]

Have a stunt ship that gets a little loose on insides, not terrible just enough so you can tell a definite difference bettween line tension on inside loops verses outside loops. Outsides are great...

I have tweaked the flaps both directions in case it might be a slight wing warp or flap misalignment, didn't help but sure had the wings flying at funny angles. The stab is straight and square, tip weight is good, turns flat in a hard corner etc. Good overhead tension, leadouts may need to be moved a tad forward but it's close..

Had another pilot fly it just to make sure I wasn't chasing a ghost and he came to the same conclusion. Only difference was he felt it turned tighter outside than inside and I think it turns tighter insides.. This is probably just our brains playing tricks.

Any ideas on the loose insides ?

[RC Storick]

Check parallels of hing lines.

[Bob Reeves]

Check parallels of hing lines.

First thing I checked, they are right on the money.

I never have normal trim problems, always something weird.

[Charlie Pate]

Bob
The plane I flew at the Memphis contest does Exactly the same thing.
 Its ,as yours, not really bad but definatly different.
 I have tried the same things as you , with difference, but not the right diference.
I have the hinge lines sealed from the start and its a better flying plane than pilot.
but just  a bit lite on the insides.
By biasing the manuever left, I am O.K. , but not correct.
 If you correct the problem PLEASE let me know.
Thanks

[Bob Reeves]

Hi Charlie.

Maybe we can come up with what is similar between the two that may be contrubting to the light insides. Mine is the Skylark I just put the ST 51 in but it did it before I switched engines..

It has a slightly larger outboard flap with about 1/2 inch of wing offset, airfoiled non adjustable rudder and everything I can measure says it's a straight airplane. Other than this little quirk it flys fantastic.

Probably wouldn't bother me except I don't always hit the wind exactly right, sometimes around here it's impossible as it can seem to come from two directions at the same time 

[Richard Grogan]

Bob,
Did you put any offset on the engine?

[Bob Reeves]

Bob,
Did you put any offset on the engine?

Good question, just enough to know it isn't pointing in, maybe 1 deg.

[Richard Grogan]

Try maybe 2 or 3. It might be the extra spice thats needed ! It'll at least add an constant to help eliminate a slight fuse bend that you might not be able to physically see.Probably more to it than that, but just a thought!

[john e. holliday]

Something I haven't seen mentioned:  is the front leadout your up line?   DOC Holliday

[Allen Brickhaus]

You might try more or less hinge sealing tape on the flap gap.  Simply do all of one and less of another.  This tape should come off easily after each flight. 

Another solution might be if your vertical rudder is tilted one way or the other.  Check that also.

Allen Brickhaus

[Allen Brickhaus]

Tom Hampshire suggested that you might have the leadouts too far forward.  Check trhat also.

Allen Brickhaus

[Bob Reeves]

Tom Hampshire suggested that you might have the leadouts too far forward.  Check trhat also.

Allen Brickhaus

May be... I removed a ST 46 and installed a ST 51, net result was adding an ounce to the nose. Didn't change the leadout position and the problem didn't change, it did the same thing with the 46. The up line is forward and could be I had them too far forward even with the 46 but would think adding an ounce to the nose would change something or make it worse. Just thinking out loud.. The leadouts with the 46 were set using LineII which ended up right at 1 inch behind the CG.

I have since moved them a little farther forward as the CG moved forward with the engine swap but haven't flown it yet, will try moving them farther back... maybe this evening or tomorrow if I get done with todays honey-do's.

Thanks for trying to help guys, this one has me baffeled.

[Allen Brickhaus]

Make small changes at a time and return to a better setting if what you have done is to the detriment to the trim.

Allen Brickhaus

[phil c]

It probably has a warp.  Tweak the wing until the tension is equal on inside and outside maneuvers.  I'd recommend keeping the flaps straight and twisting the wing.  Having the flaps at different angles adds another assymetry to the plane that you have to trim out.  It's a quick fix for slight warps, but dewarping the wing is better.  Once you get the wing straight some other undiagnosed problem may be easier to spot.

[Bob Reeves]

Hi Phil,

Understand what you are saying but this is probably the straightest airplane I have ever built. First thing I did when I noticed the problem was block it up on my building bench and measure everything.

Have to put breaks on my van today and it's supose to rain tomorrow so may be a few days before I get back to it

[phil c]

Bob, you can't measure the plane as accurately as the air flows over it.  unless you find something else, there is uneven airflow over the wing, causing it to roll.  Could something as simple as getting a VERY  slight bias in cutting the ribs and ending up with just a touch of up camber in one wing and down camber in the other.  I see that in the current batch of combat planes I'm building.  Virtually every one comes off the building board with a very slight right roll- actually kind of nice for a combat plane.  At least it won't roll into the circle on take off.  They're glued together on a jig and as straight as possible.  But with all the fuzzy edges on the foam etc. it's impossible to measure the wings as anything but straight.

If you don't want to warp the main panels, glue a trim wedge on the bottom of the appropriate wing.

[Bob Reeves]

Good point Phill... Something is causing it.. Going back to square one, starting with going through bench trimming and see if it ends up with the same problem. If it does I will follow Allens advice and only change one thing at a time..

Thanks
Bob