Updraft cooling???

[Flyingfool]

Some thing I have read about vapor lock due to heat in cowling. Or at least speculating it is best related.

I was wondering how many have tried updraft cooling. Seems like the problem would be 1) aesthetes with the method to get hot air out on top.

I wondered if someone has tried to use updraft and then have the hot air exit the rear of the cowling cheeks? Sort of like the Thorp T18. Yes heat shield for the heat exist channels rearward of the firewall would be needed. But may result in keeping the low cowl and fuel lines, carbs and gascolator cool. And or use of blast tubes to cool those key places.

 

[John B]

My Sonerai had no vapor locking problems with the short exhaust stacks. It was only after I made a set of pipes that exit out the bottom of the cowl did I experience a problem. I'm sure the vast majority of the heat was coming from the exhaust that was now within the cowl. I solved it by ceramic coating and wrapping the exhaust and eliminating the typical gascolator. I could have put the gascolator behind the firewall, but that was problematic on an already built airplane. I still have a low point drain and added an inline filter so have the features of the gascolator.

That said, updraft cooling would keep some heat out of the cowl, but in my instance I don't think it would have helped much since the heat was from the exhaust pipes which would have still been in the cowl to heat things up.

 

[Steve Stephenson]

Chucker F14 had updraft cooling. Vented out the top of the cowling.

 

[10kDA]

Steve Wittman's V-Witt has updraft cooling. The exhausts exit out the sides of the cheeks and the cheeks extend almost all the way back to the trailing edge of the wing, where the hot air exits. The carb is on top of the engine too, so vapor lock was probably not a problem. Re: gascolators - Piper Cherokees have a box around their gascolators which separates them from the hot air in the lower cowl. Some models have small vents for external air into that box. This seems like a good solution to retain a gascolator in the fuel system and keep it cool.

 

[Sb2021]

Globe Swifts have updraft cooling as well. Probably a big part of why they only look fast.

 

[Chucker]

I used updraft cooling. I chose it because the entire engine (including the fuel system and the magneto) lives in cool air. It resulted in a fairly simple installation inside the cowl with excellent access for maintenance. No blast tubes were required. The aesthetics of cooling exits on the top of the cowl may not sit well with everyone. There are photos in my gallery and in the N136DE thread.