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Old 10-29-2007, 10:54 AM
DanH's Avatar
DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 10,452
Default Tip: Fiberglass Fabrication

I've noticed quite a few RV builders are a unsure about fabricating glass components. I thought it might be useful if they could see a part fabricated from scratch. Those who are already comfortable working with glass should probably click elsewhere now.

My RV-8 is a fastback; the raised turtledeck requires a new intersection fairing for the tail surfaces. No way the Van's fairing will fit.

First step is to develop a shape. You can use whatever works. Clay is popular. I used pour-in-place foam this time, and a few cut back chunks of an old Van's fairing. Tape off the aluminum to protect it and shape your medium as required. The Golden Rule of all composite fabrication is "Time spent getting the shape right early in the process pays large dividends in time and weight later". Do whatever it takes to get your form as perfect as possible.

Next cover the shape with plastic tape. Put a coat of wax on the tape.

Now proceed with layup. This is four plies of 9 oz crowfoot. You want crowfoot (not plain weave) or similar for this kind of shape because it forms nicely on concave or convex shapes. Get it well saturated, alternate overlaps between sides (like at the front of this part), work out air bubbles before applying the next layer. Stippling with a brush will work; I have a composite roller that I love for compacting plies and removing bubbles. In this photo I've covered the layup with saturated peel ply; it is ordinary polyester aircraft fabric left over from other projects.

Here's the cured, raw glass part, after ripping off the peel ply fabric. Because I used peel ply, the glass surface requires no sanding prior to bonding additional sections or coating with micro. Just knock off any high spots with a vixen file or coarse paper and move on to the next step.

If ya'll like this stuff I'll post further steps as I proceed.
Dan Horton
Barrett IO-390

Last edited by DanH : 10-06-2018 at 06:55 AM.
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Old 10-29-2007, 11:02 AM
gstone gstone is offline
Join Date: Aug 2006
Location: Johnson City TN
Posts: 196
Default If we like this stuff???

Thanks, Greg
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Old 10-29-2007, 01:38 PM
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pierre smith pierre smith is offline
Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,912
Default Very nice....

Yes please.....kindly do followups Dan. Where do you buy pour-in-place foam?

Rv10 Sold
46 years ag pilot/CFI
Air Tractor 502/PT-6
Building RV-12, Wings, fuse, emp complete. FWF in progress.
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Old 10-29-2007, 02:10 PM
sonex293 sonex293 is offline
Join Date: Jan 2005
Location: North Carolina
Posts: 163
Thumbs up Great!


This is a great addition!

As a fiberglass neophyte a complete listing of all items used would be most helpful! What epoxies, hardeners, flox, etc, etc, etc. This is one area that's hard to get good how-to information.

Thanks for the information! and keep it coming!

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Old 10-29-2007, 02:12 PM
DanH's Avatar
DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 10,452

<<Where do you buy pour-in-place foam?>>

Right now I'm trying the 4 lb density from:

Previously I had used clay, block foam, plaster, balsa, anything that would hold a shape. Only trick I've noted with pour-in-place foam is that you can't fool with it when you pour it. If you try to spread it or move it around in any way you wind up with varying density thoughout the cured blob. That makes it harder to sand to shape with accuracy.
Dan Horton
Barrett IO-390
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Old 10-29-2007, 02:18 PM
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flytoboat flytoboat is offline
Join Date: Dec 2006
Location: Collinsville, IL
Posts: 621
Default Another Source

Thanks for sharing this project for our training.
Also, Kitplanes magazine started a series in May 07 titled "Build Your Skills: Composites (Part 1)". It is still ongoing...
VAF #1100, EAA864
-6A bought flying
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Old 10-29-2007, 03:13 PM
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DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 10,452

<<listing of all items used would be most helpful!>>

Well, let's see now.....

My favorite general use cloth is 8.9 oz 8-harness satin weave, Wicks #7781 or Spruce #7781-60. Heavy weight, so it builds fast. "8 harness" means the weave is seven over, one under. That allows the crossed tows to shift in relation to each other. As a result, you can wrap 7781 around compound surfaces with ease.

West 105 epoxy and slow hardener (206) works fine. I keep a little fast hardener (205) around but I don't use it for layup work.

Pick up a 4' x 4' sheet of 1/2 plywood, the kind with a smooth, almost plastic finish on one face. That's your cutting board. Use a "pizza cutter" rotary fabric knife, Spruce #01-00299 or better.

General supplies: Order 3 oz and 8 oz unwaxed cups, a box of mixing sticks, and a box of latex gloves. Also order some flox, cab-o-sil (fumed silica), and micro balloons. Buy a box of cheap 1" brushes at Harbor Freight or similar.

I measure all my epoxy/hardener proportions by weight, using an old balance beam gram scale. A gram scale allow me to mix any quantity from 10 to 500 grams with perfect accuracy, meaning I don't waste expensive epoxy and I've never had a cure failure. Pumps suck (literally). You can't mix small quantities by volume with great accuracy, and a few bubbles ruins the mix ratio. Besides, scales work for proseal, structural adhesive, and any epoxy ratio.

"Real" peel-ply is nylon so it can be used in an autoclave. Polyester works for room-temp cure. Leftover fabric scraps salvaged from your biplane buddy will do fine at the basic level.

I prefer MEK for cleanup. Yeah, wear gloves.

A pair of barber's scissors (the thin pointy kind) work well for trimming wet cloth, all steel so you can wipe them with MEK for plastic handles. Spruce and Wicks sell a variety of layup rollers, stipple or ribbed. Mine is nylon, ribbed, about 2" diameter.

Composite "files" are any good grade of sandpaper glued to blocks or tubes with 3M spray-can contact adhesive. 40, 80, and 120 grits are useful.
Dan Horton
Barrett IO-390

Last edited by DanH : 07-15-2018 at 07:37 AM.
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Old 10-29-2007, 04:31 PM
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erich weaver erich weaver is offline
Join Date: Aug 2006
Location: santa barbara, CA
Posts: 1,762

More good fiberglass "how to" info here:
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Old 10-29-2007, 05:29 PM
Rivethead Rivethead is offline
Join Date: Mar 2007
Location: Corvallis Oregon.
Posts: 680

Awesome, keep up the show. It looks like you get a seamless transition from fairing to VS & HS to Fuselage sufaces. Do you use any mold release to make the fairing removable?
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Old 10-30-2007, 01:26 AM
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n468ac n468ac is offline
Join Date: Jun 2005
Location: C09 - Morris
Posts: 579

nice write up
(This post by: Christopher Checca EAA Lifetime Member #799388)

Allen Checca (father)
Christopher Checca (son)

RV-6A - N468AC
ENGINE: Lycoming 180 HP O-360-A1A
PROPELLER: Senisentch 72FM859-1-85
WEIGHT: Empty Aircraft 1152 lbs
BASED: KC09 - Morris, IL.
Flying since June 6, 2005
N468AC Web Site
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