Paul,

 

Very good.  Diamond has at least one aircraft that used such a flair for assistance in the exit of engine cooling air.  I used a slightly smaller but similar flair - air passing by a sharp cutoff (cowl standard exits) generally curl around the edge and make air on the other side see a smaller opening thus constraining the flow.  The external flair alters the flow so that a slight vacuum occurs and encourages the flow of exiting air at a very minor cost in drag although the more efficient flow of exit air may cancel out such drag.

 

Grayhawk

 

Posted for PAUL hershorin <paulhershorin@att.net>:

Gilles,

When I first started flying my 360 I had many heating problem, oil was 250+, cht was pushing 450 on climb out.

The first thing I did was to close the oil air from #3 to the oil cooler and I put a NACA scoop in the cowling on the

top just behind the engine baffling.  This lowered the oil temp to 210 but cht were still pushing 440.  I took the

servo off and had the flow on takeoff increases. This brought cht temps down to 415--420 and on hot days in

 south Florida, look out.  The next thing I did was the greatest and best results for oil and cht temps, and the 

simplest of all to do--I put a 3/4 inch bevel  on the bottom of the cowling to deflect the oncoming air away from

 the engine cooling exhaust air and oil and cht's temps came down an additional 35 degrees even on hot days. 

Oil temp is now always 180 to 190, cht's are 380 to 395 and egt's run 1350-1400.

 

Paul Hershorin

360  N471LA  (new prop ordered and engine is in shop--pain gear accident)  

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