PA-22 Chin scoop baffle seal

[J Ryd]

Thought I'd post some pics of NOS (new old stock) of the same piece i purchased from KRN Aviation Services for $85 bucks. Not as pretty and as you can see the leather will need to be swapped out. Just for comparison for what you get to try and save a few bucks. All in all, im happy with it.20200526_193449.jpg20200526_193435.jpg

For those who might be interested -- I just received my $200 brandy-new Univair special... air scoop. Here are some decent pics of the offending -- I mean missing-- part:

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Andy, I'll take this down to the plane and fiddle with it to see how it fits; if it looks good and yours is the same (?) I'll PM you -- if yours is still available.

Now, back to the springtime house chores!

Walt

[Subsonic]

So, I'm tortured by all of this. Obviously Piper meant to seal and send some clean low density air to the intake, but having the engine cantilevered from the firewall and the nosewheel cantilevered from the firewall separately, to create some first resonant harmonic at the primary attach and a second resonant condition at the second mechanical intersection, and thus the far ends of both pendulous attachments will not be in resonance. Meaning...the front steering post will not resonate with the engine carb inlet box. At best they sort of line up and move around close to each other. so the leather hemi-circular seal gets eaten over time and leaks a lot. So what did they do? They stitched a great big large mouth bass opening over everything to drop the pressure and create a pool to drink from for the carb. Only problem is the drag it creates for the rest of the airframe. Ah, compromises...In short, I am in love with the simplistic surrender of Piper to accept well enough, so the normal people could learn to land a plane. It required a nose wheel. In my youth, I struggled to "learn to accept second best in my career, too". Words spoken to me by a very intelligent man. So, I'm gonna fly my second best plane all over the northern hemisphere.

[J Ryd]

So, I'm tortured by all of this. Obviously Piper meant to seal and send some clean low density air to the intake, but having the engine cantilevered from the firewall and the nosewheel cantilevered from the firewall separately, to create some first resonant harmonic at the primary attach and a second resonant condition at the second mechanical intersection, and thus the far ends of both pendulous attachments will not be in resonance. Meaning...the front steering post will not resonate with the engine carb inlet box. At best they sort of line up and move around close to each other. so the leather hemi-circular seal gets eaten over time and leaks a lot. So what did they do? They stitched a great big large mouth bass opening over everything to drop the pressure and create a pool to drink from for the carb. Only problem is the drag it creates for the rest of the airframe. Ah, compromises...In short, I am in love with the simplistic surrender of Piper to accept well enough, so the normal people could learn to land a plane. It required a nose wheel. In my youth, I struggled to "learn to accept second best in my career, too". Words spoken to me by a very intelligent man. So, I'm gonna fly my second best plane all over the northern hemisphere.

As Sir Watson Watt (inventor of Radar) said:
"Give them the third best, second best takes too long, the best never comes"

Some have referred to it as the "cult of the imperfect." I kinda like it! And my Tripacer!
Jan

Sent from my SM-G892A using ShortWingPipers.Org mobile app

[CamTom12]

Attachment 17163

Work on those wavy bits - they'll pass air around the engine, lowering your cooling capability.

Otherwise looks good!

[walt.buskey]

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!

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[CamTom12]

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).

Air finds the path of least resistance, I’d get that section flattened out or you may find it getting “pushed down” in flight to open a larger gap.

I’ve got the same McFarland seals, and after reworking them to flatten out some “wobbles” like that I noticed an improvement in engine temps.

Just my $0.02, good work so far!

[walt.buskey]

Thanks, Tom, I'll check that out.

In the good news department, my Univair carburetor air box scoop... seems to fit well! Was only able to get it in there after I removed the air cleaner and its housing, and man, those %$#$% screws on that housing! GRRR!! Going to have to figure something else out. Also, that housing slips very nicely inside the scoop so the scoop gets sandwiched between the air box and the filter housing.

Seemed to go in just fine (with a bit of persuasion), though I haven't yet tried putting those filter housing screws back in. Leather "gasket" thing on the scoop lined up with the nose gear perfectly, which is offset to the right about 1/2", just as the carb air box is about 1/2" to the left of plane's centerline.

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[Subsonic]

Great pictures Walt. I'm going to have to try once more to get mine to fit.

[walt.buskey]

OK, Missing carb intake air scoop is now installed!

Took the $%$# air filter housing and elongated the screw access holes in the external frame about 3/16" @ near the 11 o'clock position. That enabled me to get a 9/64" ball driver hex wrench into the hole enough to engage a #8 socket-head machine screw, around the frame tubes. Whew. MUCH easier now to get the filter housing on & off.... though it shouldn't have to come off again, if everything works....

Anyway, the only extra thing I had to do was to put a clamp across the air scoop to keep its sides pulled in & under the air filter housing as the screws were tightened (first attempt splayed the sides out).

And Voila! #13137 is now installed!

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[walt.buskey]

And now:
1) The missing 13137 is in, as well as the air filter. (Since I got oil all over the leather, I decided to keep my fancy Univair part...)
2) The missing stub on the muffler shroud is installed.
3) Chin scoop lower baffle is in -- tight fit, but it works (still have to get my hand in there and flip one flap over on top of the other).
4) The missing scat tube from the above stub to the chin scoop air intake stub... is now installed.
5) Upper part of nose gear stripped, sanded, painted (still have to do fender & fork).

Starting to put everything back together now!

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Walt