Cowling split to the front, versus front being a part of the lower?

[claycookiemonster]

I see a few guys who have re-made their cowls to take the side seam up and over the front of the cowl, so the spinner and air intakes are part of the lower. The upper cowl becomes more of a "hood" like found on cars.

What are the pros and cons of this?

 

[KayS]

interesting idea, but how to remove the lower cowling with that concept?

 

[wirejock]

Cowl

Like this? Photo.
I did it so the cowl inlets would be connected to the plenum inlets.
As far as removal, my gap between cowl and spinner is 3/8" per manufacturer recommendation. The cowl inlets were trimmed back so they clear the baffle floors. The plenum slips right in with maybe 1/8" gap between cowl inlet and plenum inlet. A pair of neoprene socks slips over to seal the gap. To remove, the top cowl comes off, socks removed, then the bottom cowl can be dropped. Plenum doesn't have to come off. Sounds great bu I don't have a prop or spinner on yet. I did borrow the test spinner and it appears to be ok, but I may be in deep poo poo soon.

Pros?
Probably none for a baffled engine. Maybe a slight advantage with a plenum.
Cons?
Major modification. Lots of fiberglass work. Not for everyone. Probably difficult to remove the bottom cowl. We shall see. I also have an "A" model and three blade CS prop. The bottom of the cowl has quite a large slot covered with plates so maybe I'm ok. This should be fun.

 

[JonJay]

The standard design top cowl comes off easily by pulling the hinge pins and removing a few screws. It takes, maybe a few minutes? I’m having trouble seeing the upside to this modification.
If you have a custom plenum, makes sense.

 

[Draker]

Taking off the bottom cowl is kind of a pain. I think it would be much nicer if our cowls were split down the horizontal centerline, with a left and right cowl rather than a top and bottom one. Especially on the -A models: No more tri-gear leg getting in the way, and easier to clear the spinner. I'm sure there is a good engineering reason why airplanes have top and bottom cowls, but side by side would definitely be more convenient and probably easier to remove.

 

[scsmith]

Ryan's left and right cowl halves idea is interesting to think about, especially for -A model folks. Getting good baffle seals around the inlets would take some thought.

The ONLY reason to do the mod where the full circumference of the cooling inlets is on the bottom cowl is to facilitate a good seal to a plenum with well-shaped inlet diffuser ducts. This perfectly sealed, well-shaped inlet duct is really the only true benefit of a plenum over a well-executed set of baffles.

And of course, there are other ways to do it, such as the Sam James rings, or a similar machined ring that matches the standard inlet shape.

 

[BobTurner]

Especially on the -A models: No more tri-gear leg getting in the way, and easier to clear the spinner. .

I, and others, extended the slot for the nose gear leg another 5” forward. Much easier to remove now. Since I didn’t know about mechanical strength, and didn’t want to change cooling air flow, I put the 5” cut out piece back in, with screws/nutplates.

 

[N82VM]

Like this?

Like this guy’s cowl? https://m.youtube.com/watch?v=C1mj_5BWHAs&t=5s