Okay, a couple weeks ago I had a small crash that resulted in some tail damage. The horizontal stab was not damaged but the vertical stab(elevator) hit the ground and although the actual elevator was not damaged the piece of the fuse underneath it snapped off right at the nose of the elevator. When I epoxied this piece( the chunk of fuse and the elevator) back on it was square with the rudder so after it dried I never checked it again. Well I went to the field today, took off fine made the first two turns fine but when it got out directly in front of me it started some crazy stuff. It almost felt like it was turning by itself,like I didnt have control anymore but I was able to get it back and land. We were stumped and thought maybe I lost my rx for a second or two, but after we stared at it for five minutes and started really looking at it we found that the elevator was higher on one side than the other.

So for the two questions, How can I get the epoxy apart without wrecking the plane or the elevator? and how can I make this square?

any help is appreciated

thanks

Generally once something is epoxied it is permanent. You can try re-breaking the tail or cutting around things, but usually you live with the tail being out of square. I've gone through this once or twice on my own planes; you live and learn. If this was on a $1000+ airframe, I would probably remove the controls, remove some covering, and try cutting out or around the repaired area, rebuilding and restrengthening as necessary. It would be a lengthy and tedious process.

I would say live with the plane, and you will learn from now on to triple check the tail surfaces before and during the gluing process.

I thought I heard here once that certain epoxys can be softened with heat. I dont want to endanger people at our field and I dont want to consider this model a loss from such a small bit of damage.

Pretty much everything Joe said. You can cut it out under the epoxy then use shims to get it back to square. I have had the tail feathers slip while the epoxy was curing on a new build and had to do this. That always makes my day! Once epoxy cures it's pretty solid and I haven't found any way to remove it that comes out clean or easy.

To add a small detail to what's already been said.
About the only way to defeat cured epoxy is with high heat, and that obviously can cause collateral damage. I've used a soldering iron with a knife tip and won the war, but lost a battle to keep everything undamaged. As mentioned, cutting with something like an xacto saw can win the war too. Most times, how much has to be destroyed depends on how much epoxy is inside the joints you're trying to undo. When I waged my war, after it was done I decided if I ever considered doing it again, I'd saw it out and replace with scratch built replacements.

It's still unclear if the elevator is not aligned with the other elevator or not aligned with the horizontal stab in front of it (horizontal stab has the elevator attached) or if one side of the horizontal stab/elev is angled up. Just having one side of the stab with a bit of dihedral shouldn't cause anything that looked like loss of radio signal.

As noted, it takes a lot of heat to destroy epoxy.

You wrote "The horizontal stab was not damaged but the vertical stab(elevator) hit the ground..."

The horizontal stabilizer and elevator are hinged together and both are horizontal.

The control surface hinged to the vertical fin is the rudder.

Exactly what was damaged? Can you upload a picture?

basically the right side of the elevator points up and the left points down. it must have moved while drying but there wasnt any way I could clamp this area. As for looking like the rx was lost The plane was far out in front of me and when I went to make a right turn I barely started touching the stick,the plane went straight up and down and went into a dive, at this point it didnt feel like I had input. Somehow I managed to get out of it and as I was flying back towards me I tried going right again as soon as I touched the stick it did a very fast complete right roll. I started banking left and brought it past in front of me to get a look at it as soon as I wasnt holding the stick it was going hard right, I tried trimming but that didnt help much at all so I did a low circle all lefts and landed. I guess since I didnt have a problem taking off or through the first couple turns it seemed like I lost the rx. Before the repairs this plane flew like a dream and even though I havent been flying that long I know im better than what the plane was doing out there,its not like im unaware of whats going on or dont know how to fly well. I hope there is a way to fix this,I will try to get a pic.

just a thought but, have you checked the CG since the repairs? depending on where the CG was set before and how much epoxy you used it may be tail heavy now.

Yep slightly nose heavy.

This isn't what a slightly canted horizontal tail will do. It won't do anything even close to this.

You need to check for a radio problem.

post a picture if you can, I cant imagine a slightly twisted tail causing that effect in the air. I have had a plane with split elevators that the control horns were not installed equal on, want to cork screw if full elevator was pulled but other then at full pulls the plane flew fine.

if the empennage (tail area) is a little off the plane might be a little off track but is not going to fly so out of control that its hardly flyable, before you tear the tail apart, check the Center of Gravity to make sure its balanced correctly.

do a range check, making sure your reciever didn't get dammaged in the misshap, it doesn't always take a hard hit to cause problems, one reason wraping it in foam is recomended to protect against exessive vibration.

after those checks you decide to reset the tail, loosening up epoxy isn't that hard, heat gun and a exacto works well to soften the glue.

what plane is it, this will determine the best method for repairing your repair, and photos help with the best way to go about it as well.

if the tail uses stringers, thin pieces of wood along the fuse to connect the tail they can be removed with a razor saw and replaced up the fuse.

if its a slab sided fuse, meaning a piece of balsa or plywood assembled in a box structure then the repair is fairly easy,also a dremmel moto tool comes in handy for this type of work.
biggest mistake made when doing a repair in the tail section is thinking more glue is needed for the area to be stronger, it just adds weight, better off applying a patch using the least amount of glue possable epoxy isn't always necessary CA or wood glue works well and tends to be lighter if the repair is done correctly clamps and pins work well depending on access to the area.

more information would be helpfull to determine the proper course of action on repairing the airframe if needed

You didn't break the joiner wire between the two elevator halves, by chance?

Tower Trainer 40

After the crash, did you send in the rx to be checked? You also might find that a connection between a battery or switch may be damaged and you lost momentary rx. From what I see of the tail in the picture, I wouldn't think that anything there would cause flight characteristics like you discribe. I'd look towards a failure in the rx or some connection. Just my opinion.

I agree. While the horizontal stab is a bit out of alignment, it's nothing that would cause any real problems. Easily trim that out a bit. I would look at something, possibly the radio receiver as suggested.

Ken</p>

It doesn't look as bad in the pics as it does in person, also what would explain the roll? I barely started to touch the stick and start an easy turn not sharp at all when it rolled.Plus this was the fastest roll i've seen this plane do, if I do them on purpose(stick quickly all the way to one side) it easily takes twice as long. as for sending in the rx does every company offer something like this? also it wasnt a major crash, it bounced on landing(not very hard maybe 1-1/2' off the ground) but a wing tip dropped and before I could give it any input(being so low now) the plane was sideways, the spinner then touched the ground and forced the plane backwards and ended up bouncing on the elevator(kind of a cart wheel but not really vertical). it wasnt very hard at all and I have the rx and batt wrapped well and tied down tight. Could this really have ruined a rx? I mean futaba should make a product that can withstand a little abuse right?

I have had old trainers that were a bit mor off kilter then that and they were easy to trim out, that just doesn't look like the problem. I would really start going through it and be looking for something else. CG, radio, loose engine something broken??

What could make it roll faster than when you move the stick? Most certainly not a slight lean to0 the stab.

Think about what you saw. You saw a slight attempt to turn result in a roll that's faster than you cause with a normal stick movement. What makes an airplane roll normally? The ailerons. They're designed to do the deed. And trying to roll with the elevator is about the worst possible way to get a blinding fast roll. Would you guess that the ailerons SLAMMED full one direction? I'd put my money on that.

And to suddenly buck up and down? Elevators slamming up and down maybe?

Combined, it sounds like something electrical. Like a cracked circuit board or a couple of almost broken connections somewhere.

Sounds to me like the issue is not the misaligned tail. I'm sure it looks worse in person, but that should easily trim out, and probably only result in your plane not tracking straight through loops.

You receiver could have an issue. Double check that the frequency crystal didn't come loose. Double check all your control rods to make sure there is no slop nor are they binding.

I don't think the alignment is worth fixing on that plane. It's not that bad and it's only a trainer.

I wouldn't mess with a re-repair. It looks to me like it's an airworthy fix. You say it took off fine and turned fine at the beginning of the flight... If you had any serious airframe problems, you would have seen it in your take off. Especially if its gonna do a snap roll! [X(]

I'd charge up the batteries and double check all of the radio/electronic components.

check your engine mount, those tower trainers are clamp mounted and it may have come loose and is shifting in flight.
if your plane can all of a sudden roll faster, that will have little to do with the stab (which looks fine btw), unless the stab is shifting in flight (can you move it around? does it feel different than before). im guessing that your engine is flopping around so when you turn right the engine shifts right thus pulling your plane to the right more than usual.....right? [8D]

or maybe your battery is loose and shifting around in the fuse, or your wing is shifting.

did the plane fly fine for a little while then all of a sudden start acting up? or were you fighting it the instant it took off?

To get Epoxy loose use a wide flat exacto blade and a propane torch heat the blade and slowly let the blade cut it. You can also use a Soldering Iron if you have a tip small enough. to make It flat sand and build up

Heck, I have a bolt-on stab on one of my planes that, no matter what I do to straighten it out (shims, whatever) it ends up being misaligned. And, it flys just fine. Dispite that misalignment, it will loop just fine and roll with the best of the trainers (which isn't very well.. given it's a trainer).

I had an arf that I was putting together a few years back that when I epoxied the horizontal stab down, it was just fine. So, I set the thing up on a stand, made sure it was level, and that the epoxy had partially set up, then went to bed. When I got up the next morning, much to my surprise, the horizontal stab was canted to one side, lower on the left than on the right. I also noticed that there was a cat-paw image on one side, the side that was lower, of course. During the curing process, the cat had obviously either walked on it or put her paw on it, and just sat there. This cat has a habit of sitting in strange positions, usually with her butt on the ground and her front paws up on something. Well, it was enough, I guess, to cause the not-so-completely set up epoxy to flex a bit before finally setting up permanantly. The plane flew just fine.

Since RCKen suggested checking the receiver, I won't rehash that suggestion.

i'd leave that tail along. and look for a problem in the radio and or servos. that tail is out a little but didn't cause your problem.