Plenum to baffling seal

[crabandy]

I'm curious what others are using to seal their plenum to the metal baffling.

RTV would seal and be easy the first time but would have to be cut and re-applied every time the plenum is removed.
I've also thought about RTV/pro-seal/weatherstrip adhesive stuck to the plenum and molded in assembly with taped/waxed metal baffling to try and make a re-usable seal.

[civengpe]

This has been on my to do list, but honestly, I haven't seen any issues without the sealing. I just have nut plates every 6 inches or so and it forms a pretty tight seal as it it.

If you need to, Mcmaster Carr has some pretty thin, high temp gasket tape material that should work instead of pro-seal.

[BillL]

Originally Posted by crabandy

I'm curious what others are using to seal their plenum to the metal baffling.

RTV would seal and be easy the first time but would have to be cut and re-applied every time the plenum is removed.
I've also thought about RTV/pro-seal/weatherstrip adhesive stuck to the plenum and molded in assembly with taped/waxed metal baffling to try and make a re-usable seal.

I like the latter, Andy. I took some pieces of .032 and tested some fastener spacing and by fastening to a board with various screw spacings around the perimeter then pressurized the center with very low air pressure, way more than upper plenum pressure. I was thinking that they really don't deflect much, and that the air leaking was primarily due to the original mis-match. So - long winded, waxing the baffling and applying some RTV around the perimeter seems like the way to go for removability. It can look neat on the top too.

I could be all wrong, but that was/is my plan for the initial flights.

[bret]

.063 plenum here with 3/4 angle and nutplate on 2" center, wax and Ultra Black RTV. Clean and tight as a drum.

[airguy]

I'm running the James plenum with screws and nutplates on 2" centers, with a cured RTV "smear" on the aluminum for most of the way around where the fiberglass will contact, and each time I remove it I've got 4 problem areas where I apply RTV on the re-install. No problems so far.

[Weasel]

Originally Posted by airguy

I've got 4 problem areas ......... No problems so far.

could not resist

[airguy]

Originally Posted by Weasel

could not resist

Yeah, yeah...

Too busy keepin' the RV grin plastered on my face right now to tear into the plenum and rework the fiberglass again. I need the horrid memories to fade a bit (and hangar temps to drop) before I tackle that.

[Snowflake]

What about using a strip of the black baffle seal material that non-plenum guys use, and affixing that permanently to the baffles? You could use RTV/Proseal/whatever and rivets to attach one edge of the baffle seal to the baffles, and then the flange on the plenum could slide down between the free edge of the baffle seal and the baffle. Air pressure would keep the baffle seal against the inside of the plenum, and you wouldn't have to replace sealant every time you opened it?

[crabandy]

Originally Posted by Snowflake

What about using a strip of the black baffle seal material that non-plenum guys use, and affixing that permanently to the baffles? You could use RTV/Proseal/whatever and rivets to attach one edge of the baffle seal to the baffles, and then the flange on the plenum could slide down between the free edge of the baffle seal and the baffle. Air pressure would keep the baffle seal against the inside of the plenum, and you wouldn't have to replace sealant every time you opened it?

That's not a bad idea, but I would have to allow for the thickness of the material when I laid up the plenum. As it is the clearance is too tight for the baffle material. I ended up using Ultra Black stuck to the plenum and taped/waxed the baffles. I used clecos and light screw pressure to not squeeze out all the RTV, torquing down the screws for final assembly should make a nice tight reusable seal. We'll see.....