Paul,

Does the wedge shaped diffuser require a trumpet shaped diffuser in front of
it, or can is it effective alone?

Sandy
Glass Goose

----------------------------------------------------------------------

It is stand alone.

BTW Here is something you might try in front of the engine.
Four cores 10" by 10" by one inch thick.
Plumbing is rather complicated however.
All four should be plumbed in parallel. Big tank on top and bottom.
It should come out to be about a one foot cube more or less.

Weld the cores to the bottom plate of the tank first.
Then weld on the top plate. The top plates will need external stiffening
ribs as 30 psi will pooch them out for sure.

I don't know where you will find a 10 inch square coolant core but oil
cooler cores might work OK for coolant. If you make it five cores one could
be the oil cooler. You might have room for six cores side by side. Less
marginal.

Paul Lamar

-----------------------------------------------------------------------

Paul,

Thanks for the folded core idea. I'll study that one. I guess it's an
understatement to say that there seems to be a lot of physics happening with
heat exchangers, some of which seem to be contradictory to this amateur. My
first concern with the folded core is the exhaust area which your book
suggests at least 10" for optimum performance. My next concern is that your
book recommends 600 to 800 ci of water cooling for the Renesis. I'm really
having trouble fitting in all the required water cooling (600-800 ci) and
oil cooling requirements (200 ci) in the space allotted. It's like trying to
put 10 pounds of "stuff" in a 7 pound bag.

My question about wedge shaped diffusers is founded in my latest two ideas
for "up front" cooling with two heat exchangers. One design with wedge
shaped diffusers on the outside of the core requiring exhaust to the inside
of the cowling (see Intakes outside 1.jpg, Intakes outside 2.jpg, and
Intakes outside exhaust.jpg attached), and the other, to put the intake
diffusers on the inside and thereby exhausting air outside the cowling (see
Intakes inside 1.jps, Intakes inside 2.jpg, Intakes inside side view.jpg,
and Intakes inside top view.jpg attached)

I'm able to fit in a 14" x 12' x 2" core on the aircraft right and a 12.5" x
12" x 2" core on the left with either design. The left one is shorter in
order to make room for the alternator and pulley (See Alternator
deconflict.jpg attached). That's a total of 636 ci of water cooling core.
While it is near impossible to get enough effective ducting beside the
engine down into the pylon for 600 ci plus water cooling cores, I can easily
get more than enough ducting down to 200ci oil cooling core (probably two
100 ci cores) (see Intakes inside duct for oil cooling area.jpg attached).
The Ducts on the inside cooling design 1 & 2(Small).jpg show a possible
cowling design for that plan. The intakes on the outside of the core cowling
would be similar.

Advantages and disadvantages of the intakes on the inside of the cores (as I
see it):
1. The exhaust may be in a high pressure area of the cowling and thereby not
get enough pressure differential.

2. I would assume since there is some frontal air exposure that louvers
would be required. I'd have to design and fab those louvers.

3. I think the louvers would make canopy design more problematic.

4. There would be plenty of exhaust area (ambient air) behind the core if #1
doesn't adversely affect it.

Advantages and disadvantages of the intakes on the outside of the cores.
1. Easier, simpler, cleaner canopy design

2. I could use fan(s) to suck air when required (I don't recall if there has
been a discussion about using fans in airplanes)

3. Both cores would exhaust into the same common area. Although a full 10"
is not available in all areas of the exhaust for each core, it is pretty
roomy (see Intakes inside duct for oil cooling area.jpg). I would like to
put intakes and 60sq ins of ducting the that same exhaust area for the oil
cooler(s) in the pylon (see ducts on the inside cooling design 1
(Small).jpg). If that adversely affects the exhaust area of the cores then
I'll have to have to move the oil cooler intakes elsewhere.

4. The cores' exhaust would flow over the engine. I assume that would reduce
engine heat build up.

What do you think?

Scott Gettings and I are also studying another plan to put one large, thick
15" x 14" core leaning back in front of the engine. The difficulties I see
is there will not be enough room to get 10" of air exhaust toward the middle
and at the top of the rad. And, then on the other side of the core there
doesn't seem to be enough room to locate a proper trumpet diffuser in order
to slow down the air before it reaches the rad face. Also, the rad is going
to have to be thicker...2.5" (yields 525ci) or 3.0" (yields 630ci). Is it
better to have 525 ci with a 2.5" core or 630 ci with a 3.0" core on a 140
mph airplane?

Wow! That's a lot of stuff. Thanks for your advice.

Sandy McNabb
Glass Goose with a Renesis

You can get away with less than 600 cubic inches if the ducting is well
done and the core is thin. People have used as little as 500 ci.

The cooling air exhaust up and out will work the best. Both scoops close
together. The wedge diffuser will insulate the core from engine heat. Also the
engine will serve to limit the flow if the cores exhausted inwards towards the
engine.

The K&W duct is too short and the back of the rad is too close to everything.
All of these ideas are OK. Making the cowl larger will certainly help.
It adds a bit of frontal area however. I'll think about these ideas some more.

---------------------------------------------------------------
If you don't mind adding a bit to the frontal area make the cowl wider.
Use two 49 square inch constant area ducts from the front of the
cowl back to two cores mounted on either side of the gear box.
The prop will help extracting the air. The cores are the same size as
the ones you suggest. Namely 12 by 16. The spinner shown is 12 inches
in diameter.

---------------------------------------------------------------------------
It is kind of easy to make the cowl wider by adding a strip in the center.
Current cowl is 28 inches wide as I recall. This one is 35 inches wide.
3.5 inches more on each side. Seven inch center strip.

The duct can be carved from styro foam and covered with duct tape to
give a smooth inside surface. The styro foam will dissolve in acetone.

Paul Lamar