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Old Aug 15, 2002, 12:33 AM
Tor
Registered User
Denver. Colorado
Joined Aug 2002
18 Posts
Building Tiger Moth Wing

Due to various mistakes of my first building and flying of a Tiger Moth, I am going to build another wing or possibly a new TM.

I was thinking of ordering the Wing kit for the Tiger Moth at:
http://www.horizonhobby.com

Anyone know if this includes the plastic piece that holds the lower dihedral?

One problem I had building the Tiger Moth wing, was getting the dihedral to stay at the numbers given in the instructions.

For the upper wings I sat a small weight in the center of the wings, then propped up the ends of the wing, so they were the required 38mm off the table. I then filled in the center gaps using epoxy mixed with microballons, as advised here. Unfortunatly, when the wing was dry and left to stand on it's own, I had around 25mm height on one wing, and 30mm on the other.

I again used epoxy and the plastic piece on the lower wing, and again the wing sagged to 10-15mm height less then that given in the manual.

BUT, the plane seems to fly fine.
Still if I build another wing or whole new kit, I'd like to know if there was a proper technique for getting the dihedral angle you want.


Thanks all!
Tor
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Old Aug 15, 2002, 12:37 AM
Leave me alone!
Martin Hunter's Avatar
Kamloops, BC, Canada
Joined Feb 2002
15,106 Posts
The whole design of the Tiger Moth is based on TLAR engineering. TLAR = That Looks About Right.

I'm not sure why they say 38mm, but if you've got any dihedral in there, you're fine. As you said, the plane flies good, so why worry? It's not a critical measurement. If you have less, she will self-correct and self-right ever-so-slightly more slow than if you had more, but I doubt in the real world you'd ever notice the difference.

Martin
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Old Aug 15, 2002, 12:42 AM
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Sunnyvale, CA
Joined Jun 2002
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I just got my GWS Tiger Moth Wing Tail set, p/n GWSAS2T. It did not come with the necessary dihederal brace. I am very disappointed.
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Old Aug 15, 2002, 04:46 PM
Tor
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Denver. Colorado
Joined Aug 2002
18 Posts
I am very sorry to hear that Duane.

Hope all other TM folks read this. So others don't find out the hard way as well.

Anyone have any suggestions on the best way to scratch build the missing plastic piece that holds the lower wing angle?


Tor
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Old Aug 15, 2002, 04:53 PM
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Tres Wright's Avatar
Forney, TX
Joined Mar 2002
15,165 Posts
==One problem I had building the Tiger Moth wing, was getting the dihedral to stay at the numbers given in the instructions. ==

Me too. I ended up raising the wing about 50% higher than the recommended spot, epoxiing it, letting it cure, then removed the blocking and is "sagged" to the right spot!
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Old Aug 15, 2002, 05:40 PM
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Joined Jul 2001
268 Posts
Hey fellas,

The technique I discovered to hold the wing dihedral during building the wing was very simple and effective. First I took a scrap piece of 4x6" piece of 1/8" balsa. I measured out two strips of the 38mm and two strips of the 40mm lenths and cut them out. I took a 12x36" piece of 1/4" plywood I had laying around and placed the wing I was working on on top. I marked the plywood where the edges of the wings were and then CA'd the 38mm strips at those marks, built that wing while the strips held the dihedral. Then for the next wing, I tore of the 38mm strips and CA'd the 40mm strips in their place and then built that wing . . . very simple and effective! I used 5 minute epoxy w/ baking soda and it works wonders to hold the wing dihedral instead of that silly double-sided tape in the kit. Just remember to always sand-away the paint where you use epoxy so it can "bite" into the foam and get a permanent hold.

Best of Luck,

CheeseWing
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Old Aug 15, 2002, 05:59 PM
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Perminator's Avatar
Västerås, Sweden
Joined Aug 2002
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I agree on Dreamer's TLAR theory. Don't mess around too much with GWS 38mm instructions as it WILL sag no matter how you do it. Not work all the work as you probably won't notice any difference in the end.
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Old Aug 15, 2002, 06:15 PM
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Basketcase's Avatar
St. Pete, Florida
Joined Sep 2001
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Since nobody mentioned it so far, another way to set the dihedral is install flying wires. I had the same problem with the sagging, and also thought the whole wing assembly seemed floppy.

So I reinforced the outer struts with cf rod on the front and back edges and made flying wires out of dental floss. The wires were partly for looks and partly for strength. It made a big difference in wing flex while looping or whatever.

BC

my tigermoth
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Old Aug 15, 2002, 08:14 PM
Tor
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Denver. Colorado
Joined Aug 2002
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Thanks again.

I did not know if the Flying Wires would also allow me to set the wing dihedral. That is my next 'addition' after I get it repaired from the last mishap.


Any suggestions for replacing the missing lower dihedral brace when building the Wing Kit?

Think it's ok to just use glue to fill it in, and hold it, as with building the upper wing?
Maybe some carefully placed packing tape?


Tor
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Old Aug 15, 2002, 08:38 PM
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USA, KY, Verona
Joined Nov 2001
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Easy way for me...

1. Attach the lower wing stiffener plate as stock
2. glue all the struts on, making sure to seat them in so that the full arc of the struts is glued to the wings.
3. Install the wings on the fuse.
4. glue the top wing, put a little tension on the wings (upward) and put a bit of clear packing tape on to reinforce.
Viola. Dihedral is set without having to measure a thing.

The less dihedral you have, the better the top end, and the more you have the better the turns. Adjust to suit. Thats the fun part.
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Old Aug 15, 2002, 08:49 PM
an earth bound misfit, I
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St. Pete, Florida
Joined Sep 2001
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Quote:
Originally posted by Tor
Think it's ok to just use glue to fill it in, and hold it, as with building the upper wing?
Maybe some carefully placed packing tape?
Hi Tor, that sounds like a great idea. I think it would probably work just as well. You might want to use a couple of layers.

After I broke my bottom wing right at the edge of the doubler for the forth time I added a strip of packing tape and never had any more problems with that side. (I did however fold the other side without tape.)

BC
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Old Aug 16, 2002, 12:13 AM
Tantrums Rock!
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Joined Jul 2001
268 Posts
Flying Wires

Hi Tor,

I put the Flying Wires on after I attached the two wings together and the epoxy was set overnight. The wires (kevlar thread) DEFINITELY increase the integrity of the wing structures and also enhances the way the plane looks!

- CheeseWing
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