cowling differences

[narov]

Okay, probably really obvious for anyone with any sort of cub knowledge.......but why the difference in nose cowlings. Some have the round nosed airfilter below the oil cooler, and some only have what looks like a bracket airfilter. One difference I found was the bracket filter cub was a PA-18A.. Am I close or way off... maybe engine differences???
Go easy on me
Thanks,

Carlon

[SJ]

Carlon,

Apparently, you haven't read about the hazing policy around here. We don't go easy on anybody...

But seriously, good question. I was told it had to do with when they went to the 150HP engine. The older ones have the square box and the newer ones with bigger engines the round one. Although I have seen 150's with the square one.

So once again, I have proven that I can say a lot without really saying anything that you did not already know.

Welcome to supercub.org!

sj

[S2D]

Don't have my parts book here but somewhere in the late fifties they switched from square to round. early 150 HP ones came with the square also, however a lot were changed to round later on. Seaplanes required the square also, unless the STC stated otherwise. (wet paper sucks- or in this case doesn't suck.)

[M1]

The parts book shows sn 18-3771 to 18-6963 had the square bracket air filter and from 18-6964 they went to the round one. 18-6963 was made sometime in 1959. BUT there is a note that the round one is not used on sea planes.

[cubpilot2]

If my memory serve correctly the round filters arrived in 1960.
As to the seaplane usage, none are not allowed to use a paper element but the Bracket foam filter installed on the round type is all you need.
It prevents the need to find and install the old flat style.
I think the round style looks better anyway and who knows maybe a little "ram air" effect.

Question for the moment..... Major or minor alteration to switch from one style to the other. Flat to round using all original parts....... What say ya'll?

[fatcub]

Well I don't know about effectivity, but which is better? And none of this "if it comes on an -18 it must be better" stuff. If you look at it logically the round filter has physically more filter area and should flow more,,,,,but a paper element is more restrictive than a fresh foam filter..

Scott..

[Steve Pierce]

I seem to remember a thread where Jerry Burr had done some tests and found the Bracket filter more restrictive. I also seemed to remember the round filter was more restrictive or less static rpm. I don't remember what the topic was.

[narov]

ED

I would think that to switch would be a major alteration, due to the change in the engine induction system, but it is also covered by TC data (which would be approved) so just get IA to buy it off the 337 and go fly!!

Anyone else???

Carlon

[FlipFlop]

ED

I would think that to switch would be a major alteration, due to the change in the engine induction system, but it is also covered by TC data (which would be approved) so just get IA to buy it off the 337 and go fly!!

Anyone else???

Carlon

According to the local FSDO, only if the manufacturer (Piper) said it's OK, otherwise it's a major alteration...

[cubdriver]

If my memory serve correctly the round filters arrived in 1960.
As to the seaplane usage, none are not allowed to use a paper element but the Bracket foam filter installed on the round type is all you need.
It prevents the need to find and install the old flat style.
I think the round style looks better anyway and who knows maybe a little "ram air" effect.

Question for the moment..... Major or minor alteration to switch from one style to the other. Flat to round using all original parts....... What say ya'll?

I believe that is correct, so there is a 5 year span where the flat filters were factory installed on the 150 Cubs. Personally, I think the flat filters look way better, The round ones always make the Cubs look like a tired dog with it's tongue hanging out. The increased filter surface on the round one is a plus..

[Rick S]

May I tell you guys how the round air filter came into being?

My dad flew as a crop duster / spray pilot from our farm airstrip in West Texas in the late 50's, early 60's. If you've been there, you know that West Texas is a dusty place. My dad got tired of having to wash out the old-type air filters (with gasoline), oil (with a gasoline / oil mixture), then drain, let the gasoline evaporate, re-install, etc. So he and my uncle fabricated the air scoop and a bracket that would allow a small round Fram paper element filter to attach to the normal flat bracket allowing the normal flat air filter to be replaced for each annual inspection. He believed that a Piper rep saw his invention sometime at the Plainview, TX airport, and as they say "the rest is history".