Paul and group,
I finally have my Renesis mounted, and now I need to pursue the
cooling. I've studied Paul's articles and all the cooling threads
here, but it looks like I may have several options. I would appreciate
some help so I might have a chance of getting it as close to right as
possible!
As per the attached pix, it is obvious that the standard cowling is
far too wide (about 30", and just a little short) for this engine. I
can narrow the two bottom cowling halves without any problem, but the
fit around the prop. is still too big.
Perhaps I should just implement the best possible cooling scheme and
build a new cowling to fit. Other than overall drag, there are very
few real constraints on the size and shape of a custom cowling for
this plane. Cooling is obviously more important.
For the radiators, it looks like there are at least 2 reasonable
options. The first is to put two radiators sitting at about a 45
degree angle back, and tilted back from the top, in front of the engine
(see pic). This can support two radiators about 17x12", but does not
account for the oil cooler. I can make appropriate ducting to both of
these without too much trouble. This has been done by other Goose
builders, but with small radiators and no ducting. It seems like this
option needs quite a bit of width to work.
Another option might be to put a slightly larger, single radiator in
the front, and another radiator (or two) on the cool side of the
engine. The side looks like it could easily handle a radiator about
14x22" Notice the RX-7 oil cooler in this location on one pic. This
would have to use a 90-degree-entry style duct that fed from the front
of the cowling, beside the front radiator. The hot air could exit
either out the side of the cowling, or toward the engine. This would
give a much narrower cowling than with 2 radiators up front.
The side version could handle the stock oil cooler (5"x22") as well as
a 9x22" water radiator. However, there is another possibility for an
oil radiator if I still need more volume. Down under the rear support
bridge (see pic), there is a space that would handle about 10x14"
radiator. Air would have to be ducted down to this area, but I could
probably get a 4" diameter tube to it. It might also need a fan,
because it would get no airflow unless the plane was moving. Perhaps
an automotive-style fan and fan shroud might work? Some builders have
placed the 0-320 cooler in this location, with mixed results. No one
has used a fan.
The Goose normally ingests a lot of air through its appx. 9"x15"
intake, and sends most of it into the pylon after cooling the engine.
It exits at the rear of the pylon through 'augmentation slots'
supposedly to help deliver air to the prop. This is obviously more
intake area than is necessary just to cool the engine.
Is there a better solution than any of these ideas? I suppose the
questions boil down to: what is the smallest, most efficient way to
group water and oil radiators of certain sizes around the engine in
order to achieve the necessary cooling (240hp) with the least drag?
Your ideas and suggestions are greatly appreciated!
Thanks,
Scott Gettings
Real nice work on the motor mount Scott.
I think you are being a bit optimistic on the HP.
With only four ports and a 2.85:1 PSRU you will
be limited to about 7000 to 7500 and about 190 HP
+/- 10 HP depending on the muffler and prop. Given that, one
17" x 12" x 2" rad should work fine with a K&W truncated
well sealed diffuser vertically mounted in front of the engine.
The oil cooler can go on the plug side in a simple
K&L wedge diffuser. A Paul Lipps prop mounted close
to the rear cowl opening will enhance the air flow
through the engine compartment and the heat exchangers.
More pictures next meassge.
Paul Lamar ...No rotor no motor.
Here's what I did.
Bill Hyde
I assume it is working well Bill.
Did you fix the crash landing damage?
Paul Lamar
Hi Bill;
Have you had any problems with v-belt slippage with the side mounted
alternator?
Thanks
Cary
No slippage that I knew of. I figured if it did, that I
would add a idle tensoner.
Bill Hyde
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