Posted Tuesday, July 10, 2012 @ 08:02 AM
Hi Guys,
Those magnetos do not like to get too hot, neither does any component in the fuel system.
Adding an oil-cooler's excess heat to that already generated by combustion of a 1400cc+ engine into a small, tight cowling designed for normal flight with a 1200cc engine will always cause some kind of overheating problems.
However... I got both my magnetos overhauled as soon as I got the Fourniers, and had new coils fitted, to bypass the common issue of Fournier magneto coil breakdown due to overheating.
In Dann's case, if he can make a NACA scoop at the front of his cowling like that, and put another, separate outlet behind the oil coooler, exiting into the low-pressure air at the convex rear upper surface of his top cowling, he should get a good flow through the cooler without adversely affecting lower cowling temperatures.
The tricky bit will of course be obtaining an adequate seal between the ducting and the cowling, but ducts open at the top combined with compressible foam seals on the undersurface of the cowling should do the trick. Best of all, this does not much change the lovely flowing cowling lines, so that would probably be a very good mod.
I would love to see details when you're done Dan, and then I shall blatantly copy your design (only with your approval, of course).
I have always been concerned that the opening at the back of the oil cooler (its outlet) is robbing/diverting/by-passing much-needed air from going down through the cylinders and more importantly the heads. Your solution of using completely separate ducts for the oil cooler will completely sidestep that issue, and seems like such a good idea, I bang my head against my monitor that I didn't think of it myself!
Yours, Bob
--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV