Horizontal Exhaust?

[schrome]

I think this question came up on Sonerai.net not long ago but I don't remember the answers...

Has anyone tried pointing his exhaust stubs horizontally so they pierce the cowling at the parting line? Angled somewhat aftward of course.

I'm thinking less drag with the bottoms of the cheeks smooth and possibly also less effort to remove and install the cowling.

Thanks for any thoughts on the matter.

Ed
2LS

[raceair]

Ed....A possible negative to the idea is that exhaust gasses could be migrating into cracks at the canopy sides, and thru airvents.....Ed F.

[schrome]

Yeah, that occurred to me but I'm not sure about it. Could be that the prop wash mixes things up so well that there's no difference in CO infiltration. I'd hate to invest the labor and find out otherwise though!

[racegunz]

But isn't that the beauty of "experimental"? didn't the P-40 and P-51 have exhaust right out the side of the cowl? ;D

[Schmleff]

Are you talking about side exhaust?

Here is one thing to keep in mind. Exhaust gases don't leak into the thingypit, they get pulled in through any opening along the path of the exhaust. This is why my exhaust is on the bottom of the cowl cheeks, flush, blowing down and away from the airplane. All of my exhaust stays below the wing.

Exhaust gases don't leak into the c0ckpit, they get pulled in through any opening along the path of the exhaust. This is why my exhaust is on the bottom of the cowl cheeks, flush, blowing down and away from the airplane. All of my exhaust stays below the wing.

Check out these picts. The first one I am going about 210mph. Notice how had the fabric is pulled against the frame. The second pict is one on landing, about 60mph. The fabric is still sucked in. This vacuum literally pulls the exhaust in if it can find a gap.





Moving the pipes to the side will allow exhaust over the wing. It gets pulled in through not only the canopy gap, but where the aileron control tubs pass though.

Edit: hehe, the forum changes "c0ckpit" in to "thingy-pit"

[oahupilot]

well keep in mind that the s2l dumps exhaust over the top of the wing. if you want to figure out what your air flow looks like, tape some pieces of string to the skin and run the motor up. The strings will give you an idea of the flow around the area.

Or you can use a free cfd program called open foam to model the flow around the plane.

[schrome]

Wow, that's surprising! From Bernoulli's principle I would have expected the fabric to be pulled away from the frame. But then your's is so fast maybe frictional heating is tightening the fabric? :-)

I understand what you're saying about exhaust gas being drawn in through any opening, I'm just not convinced that it has fewer opportunities when it comes out the bottom. Ohau is right, it flows over the top of the wing on mine and a fringe benefit of this - if I ever try it - might be less staining on the wing.

Thanks, guys.