Seems simple enough. Just cut a rectangular hole to let the hot air out the underside of the cowling. You have the higher pressure air inside the cowling, but it seems like you would have higher pressure air under the wing too. Has anyone tried a 1/4 or 1/2 inch raised lip in front of the cut out that would, in effect, pull air down through the oil cooler and give it someplace to go? For that matter wouldn't the same principle work for the elevator tube holes, at least equalizing pressure instead of designing a seal to keep the cold out?
