marks90004

Hey Everyone,

When installing my aileron control horns I CA'd the screw holes, but I forgot to wait for them to dry before installing the screws in.

Now I've got these control horns on the ailerons and I don't know how to remove them.

Is there a clean way to remove the control horns and screw's without damaging the plywood block that it's CA'd to?

Campy

My Feedback: (1)

Not really.

You can try applying some heat to the immediate area. I find the tip of a soldering iron on the screw head for about 10 - 15 seconds will frequently allow you to remove the screws provided there is not an excess of CA there.

marks90004

I was afraid someone would say that. I'll give the solder iron a try.

Thanks for the help.

the-plumber

Ok, I'll bite . . . now that you've got the control horns mounted, why is it necessary to remove them ?

hookedonrc

Thanks plumber, I was wondering the same thing and you beat me to the punch.

marks90004

Well,

First, I was curious for future reference in case they get damaged and need replacement.

And second, I my plane is tailheavy. Stupid me, I did the same thing to the rudder which was set for a single control horn with a push rod.

Now I need to make it a pull pull system to get rid of the excees weight in the back.

Which means I need to replace the rudder control horn from a single to a double ended horn.

As you can see, I'm not at all a good builder. I definitely like flying more than building.

the-plumber

Ah, yes. Building error #14A.

Couple of things come to mind if you can't get the CA to release with heat.

One, cut the horn mounting block out of the flight control surface and install a new one. Not the easiest solution, of course, if you don't have the ability to fabricate new blocks.

Two (and carefully) use a Dremel cut-off wheel to grind the heads off the screws and remove the horn. Do that carefully, so you don't chop into the flight control surface. Then grind the screw stumps even with the wood. Did I mention do it carefully ? When you mount the new double horn you can offset it as needed to locate the mounting holes over clear wood.

Which brings me to building error #14B . . . you're not really using _wood screws_ to attach control horns, are you ?

If you're not using double-sided horns it is much stronger to bolt through the flight control surface and use a backing plate. If the flight control surface is tapered, install hardwood mounting blocks and drill/tap the hardwood for the correct size machine screws.

marks90004

Thanks so much for the idea's. I just bought a grinding tool for the dremel and I'll try that first. My ailerons have a tapered thickness.

The instructions on the ARF manual said to drill 1/16 holes half way through then add 2-3 drops of CA prior to installing the screws.
That's where I ran into trouble when I didn't let the CA dry prior.

I think I've committed every Building error in the book. I'm the type of person you don't want handling a powertool.
You guys could probably do a better job building an ARF with your feet than I can with my hands. But hey, I'm trying to learn.

Thanks again everyone for your advice.

PS. What's wrong with using wood screws? Just kidding Plumber. You had me rollin' when I read that.

Mastertech

My Feedback: (31)

Naw come on over to my shop and I'll teach you a complete new set of mistakes! Heck I've only been doing this for 35 years I've still plenty of airplanes to screw up yet.

jbdismukes

My Feedback: (2)

You mean there are builders out there who DON'T make misrakes?!

MinnFlyer

My Feedback: (4)

Here's a picture of the only people who don't make mistakes.

twtaylor and I should get together and compare notes, I'll bet together we could really screw something up

When I first read this, I thought you had to remove the horns to cover the plane. As far as trying to remove the horns just so you can in case you ever have to... With all due respect - What are you, NUTS?

I can't think of a single time I ever had to replace a control horn. If those things are stuck - GOOD! Just leave them like that.

If you ever have to replace them, THAT's when you should worry about it. And there's a 99.5% chance you'll never have to go there.

Also, what kind of plane is it? Where is the rudder servo located? If the servo is not in the tail, switching to a pull-pull isn't going to save that much tail weight, and unless it's a 3-d plane, you don't even have to worry about it.

Add some lead to the nose, it's really not a crime. We do it all the time.

the-plumber

Couple of things 'wrong' with wood screws in balsa, or any of the light hobby woods for that matter.

First, wood screws are tapered, and get their holding strength from deforming the wood where the taper is thicker than the pilot hole; depending on the pilot drill used, the wood can be deformed all along the length of the screw. The wood doesn't deform in one plane, i.e. away from the screw, it deforms in every direction which means that as the screw is run in the surface of the wood bulges (a very small amount, but it does bulge) which in turm may mean that the item being fastened does not make flat contact with the wood surface but rather comes to rest on a 'mound', and therein is not as stable as it would be if on a truly flat surface.

Second thing 'wrong' with wood screws in balsa is that balsa, and spruce to a lesser extent, has it's principal strengths in tension and compression, but is quite low in resistance to bending, and is abysmal in resistance to tear-out. That's why you have to harden the wood before installing treaded fasteners of any sort - they simply won't hold otherwise.

Control horns intended for attachment to balsa flight control surfaces nearly always have a backing plate, and is attached with machine screws where the screws go through the horn, the flight control surface, and the backing plate, and is locked into the backing plate. Like [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXK107&P=ML]this.[/link]

This type of control horn works on tapered flight control surfaces as well as those where the upper and lower surfaces are parallel.

Don't worry about simple building errors because you cannot possibly have made all the mistakes yet; we're still inventing dumb ways to do things.

marks90004

Well said Plumber....

I didn't know people actually use wood screws for the control surfaces. I thought that you were joking.

MinnFlyer-

You're right, I can't think of a time when I've had to replace the horns. The plane in question is a Funtana .90 and having the rudder servo using a pull-pull system at the CG rather than at the tail makes a big difference. As you know, adding lead to the nose isn't an option for 3D.

Thanks again for all your input guys.

MinnFlyer

My Feedback: (4)

I flew the Funtana with a YS 110, Rudder servo in the tail, and 2 oz of lead in the nose.

NO problem

What engine are you using?

marks90004

Saito 100. It's kinda light and definitely lower in power than the YS-110.

It balances out with the rudder servo in the tail, but thats with everything shoved into the back of the firewall.

I want a little room to play with if I feel that it's to tailheavy.

I've yet to fly it and I want to start off a little nose heavy, then move the CG back when I'm comfortable.

MinnFlyer

My Feedback: (4)

Yea, a lot of guys using Saito 100s went to a pull-pull.

THe good news is, the Funtana is unlike any other plane I've ever flown when it comes to CG. This is one plane that you don't have to worry about being tail heavy.

marks90004

Glad to hear it. I can't wait to take it up.

Just curious, is the F90 more gentle tailheavy than other planes you've flown in the same situation?

Balsa Master

or....... move the engine forwars, move the battery forward... move the radio forwars... move the servos forward... move the tank forward.... sink an ound of lead in the nose... use a heavier prop.... use a haevier nose wheel... use golden rod pushrods in tail and metal in nose... DONT CHOP IT TO PEICES although if you were to just cut a triangular peice out where the horn is it would be easy to fix that...

and thats going to save u weight?? adding 2 steel wires and an extra horn vs a horn and a steel wire... ur not gonna save hardly any weight.

marks90004

It seems moving the rudder to the CG makes a big difference on this plane.

I don't know, maybe its just this plane, but the rudder servo (1.5 ounces) has alot of leverage being 3ft away from the CG.

Don't forget, the steel wires on the pull-pull system is spread out and not concentrated on the tail.

marks90004

You seem to overlook the post where I mentioned that I had everything already shoved right behind the firewall (throttle servo, battery, receiver, and tank) and the plane is still tailheavy.

Somehow, adding more weight (lead, heavier prop) to the nose of a 3D plane is one of my last options.

Nose wheel? The Funtana 90 (as I mentioned in an earlier post was the plane in question) is a taildragger.

How much more weight do you think a double horn is compared to a single? Not much.

The Horn, it's also stuck due to the CA oozing through the holes onto the wood and horn, so cutting off the base won't do as it's held by the CA. As Plumber stated, grinding it even with the surface would probably work best.

I wasn't necessarily trying to save weight. I was trying to prevent having to add useless static weight to the nose.

Thanks for the advice though.

Stew99

I vote to stay with what you have until you are forced to change it. Add as much lead to the nose as you need for the initial flights and then start taking it out until the plane flies like you want it to. You may find it is not really as tailheavy as you thought. Only when you have established the cg position for your style of flying would I consider any kind of surgery on the plane to make it lighter.

marks90004

Thanks Stew.... that sounds like a good option. I'm basing CG points on others that have flown the funtana 90 and what they were comfortable with.

The general consensus is that the recommended CG in the manual @ 7 1/4 is too tailheavy for most.

Maybe I'll end up saving myself some time if I could fly the plane as is.

The only problem is that to get to 7 1/4 CG, I had to have the battery, throttle servo, and receiver all in the nose.

Hopefully, I could fly it at this CG. If not, I'll going to have to operate.