Jul 11, 2011, 03:33 PM
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vtdiy's Avatar
I believe your transmitter though simple, will allow you to run with ailerons on either stick. Check your instruction manual.

If you go with the onboard servo for ailerons, maybe consider just having a single aileron to simplify the hook up. This plane has massive aileron authority already.

Give it a good amount of throw, and maybe a little more up than down, if possible. This is usually achieved by angling the aileron control horn.

I fly a single aileron plane --a foamflyer SO-11 type and it works fine.
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Jul 11, 2011, 03:40 PM
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vtdiy's Avatar
If you're going fly with ailerons, I'd still give it about 2 degrees of dihedral for each wing tip.

On 18" WS:

tan (2 deg) x 9" -- that's about 5/16" for each tip.

For rudder instead, considerably more dihedral.
Jul 11, 2011, 03:55 PM
Future Pilot
astronaut's Avatar
Hmm alright. But my Tx does not allow aileron on either stick. I have the DX5e http://www.spektrumrc.com/ProdInfo/F...eUserGuide.pdf

It must have the throttle and aileron on the same stick unfortunately.

I'll give it the dihedral for sure, but very slight. Cutting out the pieces right now.
Jul 11, 2011, 04:18 PM
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vtdiy's Avatar
You'll need to soak the pieces to get the paper off for half hour. Not likely to work with just a damp cloth. Try putting in plastic bag. Use a little bit of dish detergent in hot water to help soak into the paper.
Jul 11, 2011, 04:19 PM
Future Pilot
astronaut's Avatar
Huh? I just used a sponge, and immediately peeled it off. It came off perfectly, and the foam was dry...Am I doing something wrong? Thanks!
Jul 11, 2011, 04:35 PM
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vtdiy's Avatar
Try for a 4-40 foil 4% thickness at 40% aft of leading edge.

4% thickness would mean a high point of about 1/2" high at the root when lying flat on the table, if we include the 5mm thickness of the foam. This tapers down toward the tip to almost nothing.

40% would mean the high point was about 1-3/4" back from the leading edge, at the root.

To get the camber, roll the wing half gently over a broom stick on top of a table.

When finished, slightly bend the tip trailing edge up, just a tiny amount, for washout, maybe the thickness of a Canadian dime.

To join the wings, block one half up to the 5/16" dihedral angle on a board. The edge of the root of the wing should be at the edge of the board. The shim to block up the wing tip should be taped to the board.

Take a sanding block and holding it vertically, sand the vertical dihedral angle into root. Just a touch-up so it will exactly fit when you do the same to the other wing half. Otherwise they won't meet evenly.

Use the edge of the board as a guide for your sanding block.
Last edited by vtdiy; Jul 11, 2011 at 04:49 PM.
Jul 11, 2011, 04:46 PM
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vtdiy's Avatar
Originally Posted by astronaut View Post
Huh? I just used a sponge, and immediately peeled it off. It came off perfectly, and the foam was dry...Am I doing something wrong? Thanks!
Heh, nope, you just have weaker glue in your readiboard than I do! They must be cheapenining it even more. Great news!
Jul 11, 2011, 04:47 PM
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vtdiy's Avatar
Hinging aileron and elevators: sand a 45 single bevel onto the fwd edge of the movable surface, tapering downwards and aft. The top edge should be a knife point. Put a piece of hinge tape along the top edge overlapping half its width.

Hold the surface angled downwards so the beveled face meets the aft face of the wing (or stabilizer), and attach the tape to the fixed surface. That will give it clearance to bend up and down.
Jul 11, 2011, 05:05 PM
Future Pilot
astronaut's Avatar
Wowee awesome tips! I'm almost done the basic airframe!

I'm trying to understand everything you are saying, I understand most of it though Looking up the other terms lol

Only been in this hobby for 2 months, but having a blast! Bought one plane (Champ) and have been trying to make my own since.

I'll post a pic soon!
Jul 11, 2011, 06:15 PM
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vtdiy's Avatar
Well, I have a Champ, too. Great little plane. My only RTF. Everything else I've ever owned I've built. I actually bought the Champ for the gear, which I wanted to put into an indoor model. It was actually cheaper with TX, charger, 2 batts, spare props than the gear alone for something like a Plantraco. But I haven't had the heart to tear it apart, and I haven't crashed it -- just too difficult to do.

You can't sit on it by mistake, because of the protective boxis well built. Just no real solution. So I'm stuck with a really nice little plane.
Jul 11, 2011, 06:31 PM
Future Pilot
astronaut's Avatar
Ya, the Champ is an absolute marvel! Wow, that is the exact attitude I want, "Everything else I've ever owned I've built". There's nothing compared to what one does with their own two hands.

In any case, here is the basic finished airframe. I will implement the changes you suggest tomorrow, after mulling over how I should do them best. I will make my own sander too, as all I have is sandpaper. I'll make a couple of different sizes and grains.

Currently, this airframe has a mass of 9 grams. Which I think is quite good.

Thank you vtdiy and mrexcel for all your unbelievable support so far, I truly appreciate it.
Last edited by astronaut; Jun 24, 2012 at 05:57 PM.
Jul 11, 2011, 06:31 PM
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vtdiy's Avatar
I'm wondering if you really need that thick doubler over the wing, since the wing is so thick. A piece of tape over the joint would probably be enough, besides the glue

The problem is, this design extends that doubler as a stiffener for the fuselage, which is needed to keep it from being floppy.

If you haven't already assembled things, you could maybe sand the wing doubler to taper outward to almost nothing at the joint where it stops on the wing. The center would be full thickness.

This would actually be better (tougher) than the stock design. The reason is that hard edge of the doubler, the step, is what they call a "stress riser" in engineering. It is the place where stresses are concentrated when the wing bends, because of the sharp corner. If the wing breaks, chances are that's where it will occur,just like if there were vice grips holding it there.

By tapering the doubler to a feather edge there, you are spreading out the stresses so they don't focus on one spot, or edge. This makes the wing more able to distribute the forces of an impact, and so it will break less easily. that's the theory anyway.

So, that will reduce weight and make things stronger at the same time.
Last edited by vtdiy; Jul 11, 2011 at 06:59 PM.
Jul 11, 2011, 06:33 PM
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vtdiy's Avatar
Looks great! and great weight, too! Should fly with what you have for gear.


I'd put a strip of clear packing tape under the wing, on each side from root to tip as your stiffener/wingspar -- assuming you haven't glued it all together yet. Shouldn't add much weight, but will really stiffen the wing. Probably best to do this after you have cambered it and sanded it.

Further Edit:

Sanding: do that outside. The static causes foam sanding dust to stick everywhere. The worst thing about foam. Also suggest you wear a dust mask -- the paper type with the rubber band, available at hardware stores.
Last edited by vtdiy; Jul 11, 2011 at 06:52 PM.
Jul 11, 2011, 06:57 PM
Future Pilot
astronaut's Avatar
Thanks a lot! Yep I was planning on the tape, but right now everything is just fitted together. No glue at all yet, just masking tape to hold some pieces in place temporarily.

I think that idea for sanding is excellent! It will also make it look much better IMO. I will do that for sure. I also understand your explanation too, very nicely explained.

I will shape the airfoil tomorrow, and add the finishing touches to the airframe by gluing it together with my two part epoxy and adding the packaging tape.

I have to pick up some music wire to make the control horns too.

I will try the ailerons without attaching the heavy 9g servo first, and just use the AS2000 linear one. If it works out, then that's great. I have to think of how I will make the bellcrank system though, which is why I really wanted to opt for a rotary servo instead.

Thanks again!
Jul 11, 2011, 07:11 PM
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vtdiy's Avatar
Well the wire is the pushrod. The control horn is the bit the pushrod goes into. Probably .032 wire is about rightfor a pushrod.

You can make the control horn out of a piece of nylon zip tie. Cut off a piece about 5/8" long. Drill it for some pushrod holes. You need a pretty fine drill for this and a pin vice (not an electric drill!) -- or maybe melt some holes instead using a bit of your control rod wire held in pliers, and heated over a stove flame. Not too hot -- or you'll melt too big a hole. Maybe do this with the zip tie before you cut it to length -- easier to hold, and you can move further in if you goof up the first few holes. You want a nice non-sloppy fit.

After you've made your control horns, put a slit in the foam elevator or airfoil where you want it and push it through the foam just to the other side, take it back out, apply glue, replace it, and you're done.

Hot glue (low temp type) is ideal for this, as it makes a little pad on both sides of the foam, and is really strong. epoxy will work, but tape the bottom side so it doesn't leak out because it is thinner.

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