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Restoring my Mach 1

Old 12-02-2007, 03:20 PM
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martenson
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Default Restoring my Mach 1

I just started the restoration of this freebee.
But I'm just curious abot how they covered the wings, was it usual that you covered with plywood, then glassing and then paint.
It was so easy to take the ply of and now the wing is light again.

I'm thinking of using thin balsa and cover with monocoat, is this good?

I want this bird to be light, it was so heavy, that's why I got it for free, did'nt fly that good with all that weight.

Any input would be good.

Thanks.
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Old 12-02-2007, 05:13 PM
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WEDJ
 
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Default RE: Restoring my Mach 1

Yes, 1/32 ply was an acceptable wing covering baack then. Depending on how much or little the glass was sanded/smoothed, the plane could gain a lot of weight.

We used to use 3/32 sheeting on the wings, and glass w/ 0.6 oz cloth and resin. When the cloth was applied, we would use rolls of toilet paper to soak up the excess resin. You would hold the TP with your index fingers, like a dispenser, and roll it along the fresh resin. Roll it in the direction it DOESN'T unroll, and after a few passes, get rid of the wet paper, and then keep going. Worked great.
Old 12-02-2007, 07:03 PM
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Vintage
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Default RE: Restoring my Mach 1

I have never tried using plywood for a wing covering. I always thought it added too much weight. I have always used 3/32 balsa. The only glass and resin I used was around the center section of the wing. Most cases I monokoted straight to the balsa. If painting, any good filler and primer works fine before painting. I guess the plywood cut back on hanger rash.
Old 12-02-2007, 09:16 PM
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WEDJ
 
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Default RE: Restoring my Mach 1

Actually, 1/32 ply was comparable to 3/32 balsa for weight. If you wanted to monokote, then you were done. But for paint, you needed a good, smooth base, and there's the 0.6 glass cloth for you.

Monokote vs paint - I'm not even going there. Each has its advantages, each has its detriments.
Old 12-03-2007, 03:16 AM
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martenson
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Default RE: Restoring my Mach 1

So is I stupid going to 3/32 balsa and monokote instead of ply and paint.
Remeber this was a real overweight and heavy Mach1

Now question #2 what is the best glue for attaching balsa to foam, I was thinking of Great Planes yellow wood glue.

This is my first foam balsa build, I usualy go with built up wings.

Thanks
Old 12-03-2007, 06:31 AM
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WEDJ
 
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Default RE: Restoring my Mach 1

ORIGINAL: martenson
So is I stupid going to 3/32 balsa and monokote instead of ply and paint.
Remeber this was a real overweight and heavy Mach1
Thanks
Not at all. There's no problem with either method.


ORIGINAL: martenson
Now question #2 what is the best glue for attaching balsa to foam, I was thinking of Great Planes yellow wood glue.

This is my first foam balsa build, I usualy go with built up wings.
Thanks
"best?" not going there. I would stay away from the wood glue. Do you have the foam wing cradles? If not, you will need to support the wing to avoid warps, no matter how you attach the balsa. I am familiar with two methods, epoxy and contact cement.

Epoxy - you smear it on the balsa, and squeegee as much off as you can. I used craft sticks. You want the wood to look wet, but not soakied. Then apply to foam core (in a saddle) and put the top saddle on, then weight it down with 40-50 pounds, walk away overnight. This is probably not a good method if you don't have the foam pieces the wing was cut from.

contact cement - Southern Sourgum brand comes to mind, but there are others. Apply to wood and foam, again very thinly, let dry, and press the two together. Done. The only warning is you only get one shot to put the two together, it is instant stick. Again, some sort of cradle will prevent warps.

Hope that helps.
Old 12-03-2007, 08:18 AM
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martenson
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Default RE: Restoring my Mach 1

WEDJ thanks just what I was looking for, I will try the epoxy way.

Thanks
Old 12-03-2007, 06:40 PM
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impactiq
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Default RE: Restoring my Mach 1

I would look into getting new wing cores cut and starting from scratch on the wing. Like WEDJ said..... you will have a hard time getting the wing straight with out the core saddles. A heavy plane will still fly better then a plane with a warped wing.
Old 12-03-2007, 09:02 PM
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Default RE: Restoring my Mach 1

If you decide to go the new wing core route, dbalsa.com has cores for the Mach 1.

FB
Old 12-04-2007, 03:26 AM
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martenson
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Default RE: Restoring my Mach 1

Free Bird, perfect just what i'm looking for.

Thanks
Old 12-04-2007, 07:05 AM
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KrisG
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Default RE: Restoring my Mach 1

I work with epoxy as well, and I learnt that it adds minimal weigth ( with excellent bonding) if I do it this way :

- slightly sand the core for a smooth surface. Do not forget to vacuum the core to remove all foam dust.
- put liquid pore filler on the INSIDE of the balsa skin ( to make sure the wood does not absorb any glue).
- slight sanding to make the surface smooth ( to allow a thinner layer of glue)
- put epoxy on the inside of the sheeting, and squeegee it open. Scrape with the squeegee until the whole surface looks dull ( matt) - as if there is no glue there anymore ( no gloss on the surface anywhere)
- put the skin on the foam, put a cradle under it, and a straight wooden board under that
- put the whole sandwich in the vacuum press

I usually do 1 side at a time - it only takes one hour per side ( with 30' epoxy), so I can get a wing completely sheeted in an afternoon. It is absolutely necessary to use a cradle, and I also put a wooden board under the cradle ( and everything in the vacuum bag) to keep the wing straight.

30' epoxy works great. I just leave everything in the bag for an hour or so and then sheet the other side.

In many cases, i can even work without a separate leading edge : the sheeting can just go around the "nose" of the wing. If working without a separate leading edge, first do the bottom side of the wing, sand the sheeting smoots ( no step anymore) then put the top side sheeting and overlap with the sanded border of the bottom sheeting. If you want, I can take a couple of pics of how a leading edge like that looks like.

If you would work with a glue layer this thin and just weigh it down ( no vacuum), I am practically sure that there would be places where there wil be too little contact between glue and foam for sufficient bonding. Gorilla glue would be the way to go then, as it expands and fills voids, but takes ages if you do only one side at at time, with 24 hrs time for the glue to set.

Kris
Old 12-04-2007, 02:45 PM
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martenson
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Default RE: Restoring my Mach 1

Thanks Kris

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