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Another fiberglass question

SeanB

SeanB

Well Known Member
How does everyone address glassing the face of the counterweights on the elevators? I shaped the weight to follow the contour of the aluminum, but this doesn't leave a pocket to put flox into. Should I overlay cloth on the face, then try to fair it around the corners?

Thanks,

Sean Blair
COS RV-7A
:confused:


18329803454be8a971eabaa.jpg
 
and another question

One more thing...do I have to remove all the white (polyester) for the tape to bond properly, or just scuff it really well?

Thanks again,

Sean Blair
COS
RV-7A
 
Ditch the tape.....(1) tape has a selvage edge and (2) its plain weave won't lay nice on compound countours. Get some crowfoot or 8-harness satin.

Remove the polyester gel coat anywhere you wish to bond cloth.

Fill any voids with flox, lay cloth while wet.
 
Thanks

Thanks, Dan. I fortunately order crows foot at the same time. I've enjoyed your great posts on this subject. I'll study them some more before I try this.

Sean
 
I shaved about 1/16 off the face, then built up a cover with fiberglass matt and resin that caps the lead.
 
gelcoat

Dan,

You mentioned removing the gelcoat anywhere I will apply cloth. What about areas where filler, micro, etc. will be applied? Remove the gelcoat there, too? If so...it sounds like it would be best to strip the entire tip of gelcoat, then use all these materials as needed.

Thanks,
 
Yes, you will want to remove all the gelcoat. Generally, the mold is sprayed with release agent and then the gelcoat is applied over that and allowed to cure somewhat before the glass layers are applied. It's been my experience with R/C gliders that cleaning the gelcoat with solvent and scuffing it is not enough to guarantee good paint adhesion.

Clean the gelcoat first, then sand down to the glass and clean it again. For the R/C aircraft, I found that a self-etching primer got a better grip than other types; the etching agent is not so strong it will melt the glass (at least if you spray it on normally) but it apparently softens the resin enough to get a good bond. I've seen no evidence that the etch affects more than the surface; this has been used on competition F3B models with hollow bagged glass wings - the glass is structural and these ships pull incredible Gs on speed runs.
 
GELCOAT

I have had excellent results using Randolph Rand o plate epoxy primer over the gel coat. Filled some pinholes with polyester spot putty, then another coat of Randolph. I agree with removing the gelcoat for additional fiberglas but not for paint.
 
SeanB said:
Dan, You mentioned removing the gelcoat anywhere I will apply cloth.
Click to expand...

Yes.

What about areas where filler, micro, etc. will be applied? Remove the gelcoat there, too?
Click to expand...

I don't....clean, sand well, fix the surface flaws and pinholes, spray epoxy primer. Sure hope it stays on there ;)
 
Here goes!

This is my plan with the empennage tips:



Remove all the polyester gelcoat from all parts
(I've seen many not do this):confused:

Clean (acetone?)

Use aluminum rivet washers for reinforcement and glue them with E6000.

Scuff the aluminum skin approximately 1.5 inches inboard with 80 grit.

Make balsa ribs for HS and VS. Use Van's method to reinforce them. Fill recess with micro slurry.

Butter the fiberglass joggle with micro or 410 and then rivet with CS-4 blind rivets.

Scrape "oozing" material away.

Use Dan H's method to "hide the lead" on the elevators.
http://www.vansairforce.com/community/showthread.php?t=57851

Either use tape or devise strips from cloth for the transition between aluminum and fiberglass.
(Don't know if this should be one continuous strip and where to begin/end. I ordered P/N: 01-6610 from ACS...seems thick)
http://www.aircraftspruce.com/search/search.php?SRCHTXT=01-06610

Use thick plastic sheeting to sandwich strips and epoxy to wet them. Use squegee to remove excess and air bubbles.

Apply epoxy to seam of tip and skin.

Remove top of plastic sheeting and place strips on joint. Remove remaining plastic sheeting after air bubbles are removed.

Make sure strip is seated properly, then apply Peal Ply.

Let dry.

Remove peal ply.

Fair tip to skin with 410, sand, fair, sand, etc. until good.

Clean, then use Superfill to attack any pinholes.

Contact painter I plan to use. Find out the paint system they use and apply the correct primer.


Does all this sound correct?

Any suggestions otherwise before I proceed?

Everyone has been very helpful.

Thanks again.
 
Good plan

That's a good plan, except for one issue. Don't use balsa for the end cap. Balsa expands considerably if exposed to moisture. Use foam.

Don't dimple the skins. Drill then use your deburring tool to countersink the skins for the CS4-4 rivets. The head is very thin and there is plenty of skin for this.
 
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