Paul and Group,

Thank you very much for you book, /"How to Cool Your Wankel". /It was invaluable to me with my cooling design. You will certainly see that I tried to apply the concepts shown in the book.

I'm writing to solicit critiques on my cooling design. I'm building a Glass Goose...a composite, two place, pusher, seaplane (see Glass Goose (Small).jpg). I'm installing a Mazda Renesis four port rotary.
I'm locating the stock RX8 oil cooler five inches in front of the engine directly behind the intake (see Oil cooler location (Small).jpg).

Water cooling will be accomplished via two 16" x 12" x 2" heat exchangers located inside the pylon below the engine. I've built same dimension cardboard boxes and place them outside of the pylons just to show you where they will be located when installed on the inside on the pylon (see Heat exchanger location (Small).jpg, Heat exchanger location rear view (Small).jpg, and Heat exchanger located inside the pylon (Small).jpg).

Here is my cooling design using the principles of your book (Engine Cooling Glass Goose.jpg). I'll be flying in Texas so since my main objective is to not overheat I tended to design toward the more generous side of any envelopes....intake sizes (30% of core face), core sizes (600 to 800 ci. My design has 768 ci), etc.

And, here are my questions:

1. Have I done it right? Too much? Not enough? I'm hoping you'll be able to tell me I can use less (the intake area (see Intake area.jpg) is about 4 inches too wide for my cowling. However, proper cooling in all operations in the most important issue.

2. Seems like I've read on the site that if two heat exchangers are used they should be in series rather than parallel. Is that correct?

3. If parallel is the answer, I would like to route water hoses to the top of the right heat exchanger, out the bottom of the right heat exchanger, to the bottom of the left heat exchanger, then out the top of the left heat exchanger back to the engine. Will that work? Does a heat exchanger care which way water runs through it?

4. One of the aerodynamic issues the Glass Goose has is maintaining air flow down the side of the pylon. Current airplanes use VGs and/or turning vanes to control the air down the side of pylon. As a byproduct or advantage of this cooling design, I'm hoping that the turbulent air coming out of the cores along the pylon may help hold the air to the pylon. What do you think?

5. Do you think the prop may pull some air through the heat exchangers to help cooling on the ground? Do I need a fan in this design? Where would it go?

Do you know where I can get custom louvered grills?

Thank you very much for your consideration and comments,

Sandy McNabb


I like your drawings Sandy. Very well done.

Q2 should be in parallel.

Q4 since the top speed is  low the best idea IMHO is to position two 19 by 16 by 3/4 inch thick cores on the outside of the pylon and tilt them out to form scoops.  Real quick and easy to do. Use a boundary layer splitter plate about 1 inch out from the pylon surface.

I know this is a radical idea but it will work and has worked for other people when mounted on the bottom of the fuselage.
Check it out in my book.

Your picture of the rads mounted on the outside triggered this idea in my feeble brain :) We have gone around and around on cooling the Goose and this is the best idea anybody has come up with so far IMHO.
The drag on the aft pylon is high anyway so this will not add much more.

Q5 yes the prop will help.

I'll send some more ideas in the next message as there is no room in this one left.

We will discuss plumbing details when we come up with an acceptable solution for you.

Paul Lamar

Sorry. I made a word error in my previous posting. In question #3, it should be "If series is the answer,....."

Sandy.

No problem Sandy. Here are the best of the old ideas.
The main objection was loss of cargo room.

I'll do a 3D of the latest idea I mentioned in the message above.


Paul Lamar

Paul,
I can't remember seeing these integral oil pan engine mount designs before.
I have been agonizing over a simple design for and integral mount pan design
for the single and one of these will fit the bill nicely.

To my mind the integral approach if far better than the 2 piece approach, in
that it would be easier to fit.
Thanks
George (down under)


Sandy, The problem using the front cowl scoop is there is not enough room
along side the engine when the exhaust system, motor mounts and alternator
are mounted to get the cooling air down and back to the internally mounted
rads. Make sure you mock up the exhaust system, motor mounts and alternator
before you cast the installation in concrete.

I am still working on the new Goose 3D.

Paul Lamar

Here are the 3D's.
IMHO this is the easiest and most likely to work.
You can tilt the rads in and out to increase or decrease cooling.

BTW the area behind the engine in the pylon is ideal for an exhaust ejector
(AKA augmenter). Given the prop will chop up the noise I think you can get
away without a muffler. You will have to line the pylon with fiber frax and
thin SS.

Paul Lamar



Paul,

I'm very excited about the cooling prospects you've presented me. I've got
to admit my first reaction was, "Wow! That'll be butt ugly to put those rads
on the outside of the pylon!" However, after a little study, I think can
give the design some nice esthetics by building streamlining fiberglass
shrouds around the rads and even include turning vanes in the design which
have proven to be very beneficial for the Glass Goose's airflow down the
side of the pylon. I could also make the leading edge of the turning vanes
variable which would control the intake area for the rads...kind of a
reverse cowl flap. That maybe overdoing since the max speed for the Glass
Goose is advertise at only 140 knots. I agree the design would be very easy
to build and would seem to have very efficient cooling.  I have two
concerns: The affect of this design on the air flow down the side of the
pylon. Seems like the rads on the outside of the pylon may interrupt airflow
to the prop....then again the turbulent air it might improve it. Secondly,
your recommendation for 19" x 16" x 3/4" core only yields 228 ci of
cooling....times two rads give 456 ci of cooling which is substantially less
that the 600 to 800 ci you say is necessary for a rotary in your book. What
do you think?

I'll be out on an airline trip for the next four days, so it might be a
little while before I can get back with you.

Thanks for your help,

Sandy

Great Sandy that is the right attitude. We have been around and around with a couple of Goose builders on this problem. It is not easy squeezing in a cooling system. The best thing to do is bring the curved intake duct with the boundary layer bypass duct forward around the corner so to speak and keep the aft sides of the pylon flat. That will move the rads in at the back. The prop will do wonders to suck air through the rads, the boundary layer bypass duct as well as the exhaust ejector. The air from the oil rad will go over the engine cooling the engine and out the exhaust ejector and cool the exhaust system it self. A couple of Dodge Neon rads will work. The header tanks will have to be TIG welded up as the stock ones are plastic. I'll do a little more work on the 3D's. I think Jerry Hey may be able to do the rad work. I have not heard from Scott Gettings for awhile so he may be interested in this system as well. The RX8 alternator is pretty tricky to side mount as well we had to come up with some sort idler pulley as I recall.

Where are you? Scott is on the space coast in Florida.

Paul Lamar