Downdraft turns into Updraft

[Chris Zavatson]

I have data logger onboard that captures various engine compartment temps for thermal calculations. It starts recording when the master is turned on and stops when the master is turned off. For kicks, I pushed the plane into the hangar and let the recorder run for an extra hour.
What you can see is how the typical downdraft cooling system reversed and through natural convection turns into an updraft cooling system. Cool air enters the exit, rises past the engine and exits the inlet quite a bit warmer than when it started.
The oil cooler door above the accessory section was left open. The short flight went up to 8,500'.

Downdraft-Updraft Cooling-sm.jpg (254.9 KiB) Viewed 2284 times

[George Wehrung]

So I hook up a bead dryer system and that keeps the oil door open. But I do plug the cowls. So the air has to exit the oil door.


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