macrafic

macrafic

Well Known Member
Van's sells both a tank sealant and a firewall sealant. Are these sandable and paintable? I'm particularly thinking of where the gear legs come through the bottom skins and where the steps go into the side skins.
 
Proseal is paintable. Not sure you will be able to sand it too well as it remains flexible.

Where your gearlegs exit the fuse should not be a factor as you will be installing gearleg fairings over this area.

With your steps, you can lay a fillet of material around the edge of the step mounting plate (if you are mounting the steps per plans) and then paint over that.

Hope this helps.
 
painless said:
Proseal is paintable. Not sure you will be able to sand it too well as it remains flexible.

Where your gearlegs exit the fuse should not be a factor as you will be installing gearleg fairings over this area.

With your steps, you can lay a fillet of material around the edge of the step mounting plate (if you are mounting the steps per plans) and then paint over that.

Hope this helps.
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Jeff is right.
Proseal is very paintable, but not sandable.
Firewall sealant is the same though it doesn't go on very smooth so I wouldn't use it for anything other than where it was needed (sealing openings in the firewall).

I disagree with not needing to seal gear leg penetrations, etc. Even with fairings over them they will still leak air. In fact at high A.O.A air actually gets forced from the wheel pants up through the gear leg fairings and into the cockpit (If the openings aren't sealed).

For openings like this I use auto body seam sealer instead of proseal. It drys quickly, and is designed to be paintable. Can be found at your friendly neighborhood auto body paint store.
 
rvbuilder2002 said:
I disagree with not needing to seal gear leg penetrations, etc. Even with fairings over them they will still leak air. In fact at high A.O.A air actually gets forced from the wheel pants up through the gear leg fairings and into the cockpit (If the openings aren't sealed).
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Agreed Scott. I guess I should have been more specific. I was basing my post purely on aesthetics. I get tunnel vision sometimes.
 
Steps

For what it's worth, when I installed my steps I put a doubler on the inside and smeared proseal on the outside between the step and skin and on the inside between the skin and the doubler.
 
sanding proseal

Proseal is sandable, just not with sandpaper.

Put rough cloth around a piece of wood and have at it.
This won't touch the aluminum, but will smooth down the cured proseal.

Jim Ayers
 
Thanks guys!!!

Rick, wondering about the doubler. I hadn't noticed on the forum that there were any issues with the installation as designed. Was your action prompted by any issues that you have heard of, of were you simply being extra cautious?
 
Doubler

Rich, my brother has been my technical go to guy during my entire build. He has a -7A (slow build) that he's been flying for over 4 years and he has 25+ years of working on "big iron".

He did this on his plane, so when he suggested it to me, I took his advise. Making the doubler was easy, doing the proseal on both the inside and outside was very messy but I'm glad I did it.
 
Those "Big Iron" guys love proseal. But I agree, prosealing parts together helps. Not only do you get the strenght from the rivets, but the proseal helps bond the parts, and at the same time keeps moisture from getting in between to start corrosion.

If you have ever worked on a pressurized airplane, the proseal the **** out of everything, and not just in the pressure vessel part of the aircraft. If you are putting parts together that you know will never need to come apart, seal it up.

Patrick
 
Back in the B1-B days we put a lot of proseal (Mil-S-8802)on exterior surfaces then sanded it smooth to meet aero requirements. Never had any trouble sanding with a jitterbug air sander.
 
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