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Building Tips and technical articles. => Building techniques => Topic started by: Bootlegger on September 25, 2015, 11:47:42 AM

Title: thick trailing edge
Post by: Bootlegger on September 25, 2015, 11:47:42 AM

 Have some foam wings that have a 3/8" trailing edge and the  flaps will be 1/4".Will the difference make the model act/fly funny?
 I don't need to compound my problems.

        Thanks a lot... H^^
Title: Re: thick trailing edge
Post by: Mark Scarborough on September 25, 2015, 11:56:49 AM
The Impact has a 1/2 inch trailing edge,, and 3/8 flaps,,
I would say it might HELP  it fly better, not hurt it
Title: Re: thick trailing edge
Post by: David Hoover on September 25, 2015, 12:27:42 PM
The Impact has a 1/2 inch trailing edge,, and 3/8 flaps,,
I would say it might HELP  it fly better, not hurt it

However, depending on the length of the flap, 1/4" may be a little wimpy in torsion and that would not make it fly better.
Title: Re: thick trailing edge
Post by: Dennis Toth on September 26, 2015, 06:46:35 AM
For the 1/4" flap you could apply 1/2 oz fiberglass cloth with finishing resin (after wetting the cloth down scrape off as much as you can with a playing card then roll with toilet paper to remove last puddles). This gives very stiff flaps and is light weight. After that finish as normal.

Best,    DennisT
Title: Re: thick trailing edge
Post by: Avaiojet on September 26, 2015, 08:10:11 AM
For the 1/4" flap you could apply 1/2 oz fiberglass cloth with finishing resin (after wetting the cloth down scrape off as much as you can with a playing card then roll with toilet paper to remove last puddles). This gives very stiff flaps and is light weight. After that finish as normal.

Best,    DennisT

Dennis,

That's a great way of doing it.

I used resin and glass cloth on these pieces. Sig Polyester resin actually, thin enough to apply with a brush then blot with toilet paper.

Today Epoxy is preferred and is a bit thicker so spreading it as Dennis suggested is how some do it.

These parts belong to the Mig-3.

 

Title: Re: thick trailing edge
Post by: Lauri Malila on September 26, 2015, 10:37:05 AM
...and not forgetting to put the cloth with fibers running +/-45 degrees, if you want torsional stiffness.
But the 1/2oz stuff is quite gutless, I'd go for at least twice as heavy. Weight gain is zero or minimal. L
Title: Re: thick trailing edge
Post by: Avaiojet on September 26, 2015, 10:46:08 AM
...and not forgetting to put the cloth with fibers running +/-45 degrees, if you want torsional stiffness.
But the 1/2oz stuff is quite gutless, I'd go for at least twice as heavy. Weight gain is zero or minimal. L

Lauri,

I always uesd 3/4oz. I have so much of it. All our R/C pattern ships were covered in it from head to toe.
Title: Re: thick trailing edge
Post by: Target on September 26, 2015, 10:55:09 AM
If you're using cloth hinges, what I'd do is bond a same diameter aluminum tube to the LE of the flaps, then glass wrap in one piece on a 45° bias as mentioned with glass. Tubing is very torsional stiff.
R,
Chris