A friend just built a trainer, and he left a gap betweeen all his control surfaces about the thinkness of 2 quarters stacked... Is this going to affect the planes handeling? Or is it ok to just leave it be? He did it to the elevator, and rudder... Any help would be appreciated! Thanks

It may effect the strength of the hinge, and have a little wobble. They just may tare sooner in a crash. As long as the hinges have a good bond it should be fine. It would probably cause more head ache, and some minor damage trying to debond and redo.

It is excessive gap. 1/2 the thickness of one quarter is maximum acceptable gap for a CA hinge.

Its going to create a LOT of slop in the controls.

Its going to invite control flutter. (which can rip the control surfaces ff the aircraft)

The gap will make the controls less effective (even if thier movement wasn't sloppy) because of an aerodynamic effect of the slot.

The potential problems are serious enough that any of or local club instructors would not be willing to have the beginner fly an airplane in that condition. (and any experienced member that brought susch sloppy hinging to the field would be awarded our "Blunder Award" at the next club meeting.)

If you are worried about the hinge gap, you can use strips of covering or clear packing tape to seal up the hinge line. This may not be necessary, since trainers generally don't develop flutter or other problems with hinge gaps.

The large gaps will also cause the controls to be less effective than they would otherwise be. You can compensate for that with larger throws of course.

If it's CA hinges, if the gap is large enough it can cause up-down movement on the hingeline, which can lead to flutter or can cause the surfaces to not center accurately enough, making the plane hard to trim out.

I'm not saying it will be a problem, I just don't know either way. To be sure, just cut the hinges and put in new ones next to the old locations. Easier than trying to use debonder.

Or you could just fly it, taking it easy and being careful. You should be able to see if it's going to be a problem with out risking a crash if you are careful with it. I've seen planes with rather large gaps fly just fine.

2 quaters ~ 1/8 inch. It could but I bet it won't matter. The fix is so easy I would suggest the repair to be safe.

Either CA or pinned hings... don't matter just cut them, trim them flush, leave whatevers left in the wood and forget about it. Put new CA hings in 1 inch from where the originals were. 5 minutes max for each surface, done. OK, maybe 30 minutes total if you count putting a new blade in your knife, cutting open the plastic baggy, uncloging your CA tip, setting the radio to your favorite station.

Mike

And there we have reality!

If it's a trainer, just seal the gap with Covering or tape. It should be fine, as the speeds of a trainer shouldn't cause flutter.

BUT on your first flight, do a few close passes and see if you can hear a low-pitch "Buzz". If you do, land it right away and re-hinge the plane.

If not, have a ball.

I was going to say the same thing as MinnFlyer. First, I recommend removing the hinges and trying again. Yes, it's a pain and will probably cause some damage, but it will be easy to repair and worth the effort in the long run.

If you aren't willing to do that, at least seal the gap with some packing tape on the underside of the control surfaces. When you put the tape in place, flex the surface to its extreme in the opposite direction as the side you're putting the tape on.

unsafe assumption...

I have seen trainers flutter off ailerons at 1/2 throttle in level flight.... with tighter hinge gaps than that.

My personal opinion is to re-hinge. Any sealing is just masking the problem. It will also be more precise and controllable if you rehinge. This is my opinion only. If you feel you must leave the hinges as they are, then by all means seal them. I wish you well on your flights.

Mark Shuman

I have this same problem on my Somethin' Extra.....I have about, well a little under almost a 1/4 in gap on the insided of the elevators.......well, I have only flew it once, and not yet, nothing has happened......Well, I HAVE sealed the TOP, and HOPE TO GOD that nothing happend.....I will be so pissed off...but I really can't say anything.....

I understand about the hassle of re-hinging...I was going to do that, but I just thought that I would just seal the TOP and see what happens.......hopefully nothing!!!

I haven't flown it yet....but maybe going this Sunday if this freakin 1 ft. 3 in of snow melts in my NORTH CAROLINA home (that's alot of snow for NC).....but I hope that I can go Sun.....

I totally agree with MinnFlyer. MAKE SURE you SEAL THE HINGE GAPS or you will probably get flutter.

3D-kid330

Sealing gaps only reduces thechance of flutter a little... the flex in the hinge line will be the factor that determines if flutter is allowed to initiate.

The sealing will reduce turbulence over the control surface slightly... and may delay flutter onset, but that's all, it won't prevent it. Once flutter starts... you have to slwo down enough to stop it. If the hinge line is too flexible, then even with the sealing, you might stall before the flutter stops.

I've had to land a plane that had an aileron fluttering at anything greater than about 1 mph above stall speed... Its not fun. (something about losing 1/4 of one wing and snapping that aileron's clevice in a mid-air messed up my model's aerodynamics...) i would imagine trying to do that with the elevator wanting to flutter at anything above stall would be a worse nightmare.

Better safe than sorry. Rehinge it.

*********
If a beginner brought that to our field... and I had my stuff with me (usually do when I know beginners will be comming...) I would personally cut the hinges... and rehinge it correctly. I've done it before...

While an 1/8th inch IS a lot of gap, I'll agree with Mike on this one. Sealing the gap with tape or covering should be enough.

All in all, the BEST solution would obviously be to re-hinge as FHHuber and others have said, but if your friend isn't comfortable with the process, seal the gap and fly it carefully.

Michael Carr, welcome to OUR world.
Dennis-

With that amount of gap, I would worry about the flexing of the hinge. Either way, the plane will fly. Just may have a short life. I would fix the hinge line first.