OK, Ive asked this question before but not sure if what I was asking was clear. so here goes - one more shot:

Ive got a Showtime 50. Ive recently changed the prop and made a couple of other changes and have renewed my interest in flying it more.

At one point, I had broken a hinge on one half of the elevator(they are split) so I repaired it the best I could at the time (2 years ago). I cut new slots next to the old hinges and installed new CA hinges. Well now that I really understand the planes alot better and am really starting to get into 3D more and more, Ive noticed that the elevator halves are not on the same verticle plane (see pic - not as noticeable in pic though). I would think that this is part of the reason for some of the times when my plane snaps to one side at high rate. When trying harriers, plane will turn to the left; yeah i could compensate but I want a good mechanical setup. I would like to use the full amount of throws available so would like to rectify the problem as Im currently trying to electronically compensate for the difference by limiting throws.

Question: Being that the entire length of the elevator half has been hinged and CA'd over its life, How would I go about repairing/re-hinging this? Ive tried using an exacto blade in areas that previously had CA hinges in place and its proven to be an extreme challenge to get everything to cut straight. Could I replace with Robart hinges? If so, would it be easy to drill through the balsa with old CA hinges and CA? Would I need to replace the trailing edges of the stab and leading edge of the elevator? What would be best here?

Sure i could move on and get another plane being that it must have hundreds of flights on it, but ive really taken this plane on as a challenge lately to get it to fly the way I always wanted it to. It was limited by the pilot at one point, but no more. I would really appreciate and help, details etc that you guys could offer.

Thank you.

It looks like you have two pushrods, so adjust them to fit equally., to the horizontal to the stabilizer. No need to rehinge if the surfaces are matched. And do not use old Ca Hinges!! if you decide to change the hinges, Trash em and use new one's.

No intention of reusing CA hinges....is that even possible? My question in regards to this is... would i have to replace the wood across the back of the horizontal stab, and leading edge of elevators, or could I accurately drill through wood which have been Ca'd and hinged in order to use robart hinge points ( for example:
http://www3.towerhobbies.com/cgi-bin...?&I=LXET54&P=7)


The problem isnt the linkage, but the alignment of the elevator surfaces across the trailing edge of the stab. Picture an imaginary line across the back, the hinge line of both elevators do not sit evenly on that line. One is higher than the other.

You are absoutly correct, the hinge line is off. I didn't see that when I posted. Thanks for the correction.

You may be able to remove the elevator and fill in the slots that may be there with epoxy, smoth it out, then slot it for pinned hinges rather than CA hinges. If you do it right, and carefully, you may be able to fix it easy enough with minimal covering removal. You can most likely remove it from the trailing edge of the wing to coat it, pressing in the epoxy to fill in gaps and old slots, smooth it out, as I said, then fit the pinned hinges in both sides.

I'm sure someone will have an alternate method, that's just my cut on it.

CGr.

Thanks CG!

After looking around im thinking Hinge points might be the way to go. Just not sure if there is enough support there in terms of wood on the leading and trailing edges. Do any of you guys install hinge points on ARFS without having to add wood stock to the control surfaces?

I'm not sure I understand your question. If you are talking repairs, then more than likely, someone has done that very thing. But, when assembling an ARF, well, there ought to be enough material there to properly hinge the control surfaces. Whatever you do, try to keep it light but strong. A tough compromise, but you can do it if you really have to. Minimize glue using the right glue for the job and wipe off any excess. Basic building rules also apply to repairs. You can be creative, and unique solutions always seem to come out of being creative. Share what you did when you decide what you will do.

Of course, it will be more difficult to do what you wish to do on the control surface because of the beveled edge.

Of course, there is always a solution called "doing nothing at all". If it ain't broke, don't fix it. Meaning, if it flys ok, then it may not need fixing


CGr.

another possible solution is remove the elevator halfs, use the elevators as plans/template and build new ones. use a slot cutter and make sure everything is exactly even and install the new parts. make sure the push rod throws are the same and the control horns provide equal leverage. the more time spent on set up will require less time spent triming or trying to compensate for an error made during set up.

or as CGr said... "if it ain't broke, don't fix it"

Before attempting to "fix" the hinge line perhaps reduce the high rate of your elevator's travel. Some planes will want to snap when applying too much elevator.
Secondly, are you sure it's not the engine's torque in a harrier that is making it turn?
Just a thought since the elevator would have minimal effect to roll or yaw an airplane.


Tom

Yeah, I was sort of thinking the same thing. The centered position of the elevator may have a minimal effect on the aircraft performance during those types of maneuvers. Again, if it isn't a problem, then it isn't broke.. yeah, yeah.. I'm repeating myself. Sorry.

You may be spending a lot of time fixing something that is being caused by something unrelated. Check it out really well before you get into that much detail in a fix.

CGr.

I certainly will look into it a little more. Thanks for the advice. Maybe Ill be able to set the elevators up a little better.

I installed robart hinge points into my mustang when I cracked a CA hinge. 2 of the 4 hinges needed to be drilled thru the old CA hinges. No problem but buy the Robarts drill jig for the hinges and use a new sharp bit and go very slowly. I would say you need the drill jig as even with the jig if you push too hard you can feel the drill bit wanting to drill either up or down of the old CA. Go slow and let the drill bit cut the old CA hinge material. I just cut the old hinge flat with the wood and drilled for the robart. I used pacer hinge glue, wet a Q-tip with some water and moisten the hole before putting the glue in. Melt some Vaseline and dip just the knuckle of the robart hinge and work it a little. You will have a very smooth operating elevator after that. If the elevator halves are in the right place vertically then mark both sides of the gap with a marking pen so the holes line up perfect. Keep in mind that the drill jig is 2 inches wide so don't mark your holes too close to the edge as you won't be able to get the jig into it. After drilling I use a cone shaped deburring tool and round out the end of the hole for the knuckle. Works great and it goes really quick. You might never use CA hinges again. Good luck.

http://www3.towerhobbies.com/cgi-bin...&I=LXET65&P=SM Hinge drill jig

http://www3.towerhobbies.com/cgi-bin...&I=LXET77&P=SM Something like this for the opening up the hole for the hinge knuckle.

http://www3.towerhobbies.com/cgi-bin...?&I=LXCX67&P=7 hinge glue, comes with a needle applicator, just wash out with water right after use. Be careful to not put too
much, if the hole is into the interior of the surface the glue will enter it, although a iron will make the dry glue
disappear.

MikeCAM YOU ARE THE MAN!!! Thank you so much for the detailed response. Really helpped me understand how to do this should I need to.

Many Thanks!!!!!

No problem. Some very good advice, leaving it could be an option but we all know what it is like to have something gnaw at you when your trying to fall asleep at night. The first time it might be a little more time consuming but after just a little practice it gets really quick. The hinges move effortlessly and you sleep better at night knowing you have a nice mechanical hinge. I put them on all my planes now and if one of my CA hinges looks iffy I replace it. Good luck and let us know how it turns out.

I do have 1 question : Are the hinge point hinges removable in any way in case of needed repairs?

They are. I have never had to replace them myself but looked into replacement before even installing them. If you do a search you can find the posts on how to do it. Basically you drill the flange off the hinge pin to get the hinge apart. Cut the hinge flat to the surface and then use the drill jig again to drill the center of the hinge. Sometimes that is enough to get the hinge out. If not I have also read of using copper tubing just a hair smaller then the hinge and cutting a piece 4 inches long. On one end you file some slots into the end just 1/16" into the tubing. 4 or 6 slots work as cutting teeth and you put that into a drill (or use by hand) and slowly cut into the hinge. As you get the majority of it out the smaller pieces should come out. If you butcher all those (and I could I'm sure then I have also read about drilling out the hinge with a bigger drill bit then the hinge but the same size as some wood dowel. You glue in the wood dowel into the hole and let dry and then use the drill jig again to redrill for the new hinge. Even more ways with some searching but after many flights on different planes I still have not had to do it. I'm sure i will some time (From a crash) but I'm not concerned about doing it.

I have also read some guys have made a removable rudder using the Robarts. They drill out the hinge pin and replace with a piece of piano wire. That way they can remove the wire and remove the rudder for transport.

I cannot convince myself that the misalignment will negatively affect the performance.

Well its just something that has been nagging me. Maybe it isnt affecting anything. I was planning on tearing the plane apart and rebuilding so this might work out if I do. I have some horns that arent prefectly aligned and some other things I want to do, so its more of a project to see what I can get out of it more than anything. Its a learning experience. I have no idea exactly, but I have HUNDREDS upon HUNDREDS of flights on this plane and i love it! Over 2 seasons and ive learned so much with it beyond my basic aerobats early on. Its like an old car you love,,,, you just do things to do them - just because. Sentimental value I guess. Almost tempted to buy a new one for the hell of it, but taking it apart and rebuilding will give me more satisfaction.

thats what I would do. I can't tell you how many "total losses" I've dug out of the trash can and rebuilt. sometimes it's not so much for the plane itself, as it is to see the final result once it breaks terra firma again.

I,ve used Robart hinge points for repairing or replacing CA hinges . I use Elmers Ultimate glue which expands into the old hinge slots and fills any gaps and imperfections in the LE and TE edge . I have also use pinned hinges with this glue in the old CA slots and it works really well.