PA-22 Chin scoop baffle seal

[N2709P]

Does anyone have an idea what the dimension is between the lower chin scoop baffle metal framework and the chin cowl when installed? I am looking at a “P” seal for that area and this information would save a lot of work. This is the air dam beneath the carb.
Thank you,
N2709P

[walt.buskey]

I spent quite a bit of time with that when I re-did my baffle seals 2 years ago. I ended up using three separate pieces of McFarlane's "Special" baffle seal material, riveted to the baffle itself -- all original seal material was totally gone when I started this; nothing was left but the metal baffle itself.

It seemed to work out well in my case -- I just need to reach up in there to "flip" the seal material forward in the corners when re-installing the chin cowl. Note the overlapping angled pieces there in the corners -- my idea; don't know if that's correct, but it seems to seal quite well.

Don't have dimensions, but I think you can get the idea looking at the McFarlane seal strips. Generally, there was maybe one inch of clearance there, tapering to almost zero on he sides, but that McFarlane material easily bent outward to accommodate the gap(s). Their stuff is about 4" wide, IIRC.

PS -- do you have the usually-missing "carburetor air scoop"? (For PA-22 nose-dragger planes - but not shown in these pics -- added later.)

Here's some pics - and, apologies for the nasty-looking paint all over; that has since been remedied and looks MUCH better now!

DSC08492.jpg DSC08496.jpg DSC08513.jpg DSC08515.jpgDSC08539.jpg DSC08541.jpg DSC08672.jpg

[N2709P]

Thanks Walt! I like what you have done. The “P” seal is only about 5/8” so that will not work. It presently has the red silicon seal on it and looks like it was installed with a chainsaw and jack hammer. We have the intake scoop on her now, it was missing when we brought her home. After about 40 hours of labor, we finally have the Alaska Airforms baffles where they actually will properly fit an O-320 with a front oil cooler to my satisfaction. The Airform baffles had no provisions for the front mounted oil cooler lines (they told me a TriPacer never had a front mounted oil cooler), had a poor fit to the rear cylinders, the mating halves at the rear were poorly aligned and the rear baffles did not follow the profile contour of the rear engine case. I could/should have made a set in that time. My bad.
N2709P

[walt.buskey]

So you're the one... I remember reading about that issue with AK baffle kits in a recent thread -- and that "Tri Pacers have no front oil cooler." Oops.

I replaced one of my baffles by making my own (front left vertical), but I did spring for a new Univair baffle for the front right horizontal one. Since I have both an alternator conversion and a lightweight starter, that baffle needed to be altered to accommodate both the flexible oil cooler line and the alternator bracket; my old one had been pretty well butchered and was held together with some safety wire and a few blobs of silicone. Looks and (I suspect) works much better now.

As I mentioned, I spent a great deal of time on those baffles & seals back in 2020 (covid pandemic was good for that), so have a ton of pics that I took to document my work as I went along. If you have any other questions, please feel free to ask. I'm still a noobie and no expert... but THAT stuff I think I got right.

PS-- I must have done a pretty good job, because the owner of a totally scratch-built Super Cub thing (we called it "FrankenCub") asked me to do the front baffles & seals (behind the air intake holes) on his bird "just like you did on your plane!"

[chase]

On those, I reached my hand in; it took very little pressure from my fingers --just a touch, really-- to lift those up to contact the inside of the cowl. My assumption was that it wouldn't take too much air pressure coming in for them to "inflate" and seal against the inner surface. That McFarlane stuff is pretty flexible.

In other spots, however, I did cut slits to eliminate larger ripples/bubbles, as it took more finger pressure to lift them (and the ripple simply moved to another spot).


Moving on to the mystery duct in the chin scoop (fresh air intake for the left side of the muffler shroud), my daughter works for a fluid dynamics R&D outfit.... that has some pretty sharp machinists and some pretty fancy equipment.

Per my specs, in their spare time (and using left-over materials), they made up a scat tube stub for me to replace the patch that covered the hole on my muffler shroud. Came out great (welded on the inside!) and slips into scat tube like it was buttered. All made from 304L stainless, .065 wall thickness. Curved section matches the muffler shroud, 6" diameter.

Oughta outlast the airplane!

Attachment 17178 Attachment 17179

Want to make me a couple of these? I'm looking for this!