Joseph M Berki wrote:
Paul,
The radiator which I need to have built is 24" X 12"
and will
sit next to
a stock Mazda oil cooler. They will be mounted in a tray under the
main
spar at an angle downward. A P51 scoop feeds this whit the
inlet under
the main gear. The aft end of the rad/cooler line up just behind
the fron
of the motor looking at it from the side.
Joe
OK I will draw it into the 3D.
Perry mentioned your engine looked a bit too far aft. How far is it
>from the e-shaft pulley to the firewall.
Paul Lamar
Joseph Berki wrote:
Paul,
It is 27" from the firewall to the bellhousing location
where the
ears are bolted. Used this location because the widest point of
the mount
is further forward than plate design making it easier to
cowl. Have you
tested the wedge duct / diffuser? I thought the Caravan episode
was a K&W
duct? Thanks
Joe
No the Caravan test was a simple wedged shaped duct. The K&W duct has
a few
problems for our use. Number one is; it is only valid for rads mounted
perpendicular to the axis of the duct. This means any tilting
of the rad becomes highly configuration sensitive and extensive
development would be required to insure uniform air flow through
the core. You could spend months with a test rig optimizing the
exact shape of the duct. Velocity taps should be used all
over the back side of the rad to insure uniform air flow.
The second major problem is the K&W is too long. In your case
it would be half the length of the fuse :)
BTW Those are real big problems with rads mounted on either
side of the PSRU in a tractor configuration. Thick or thin they
both have the same problems. Nobody is doing their homework on this.
Paul Lamar
Joseph M Berki wrote:
Paul,
I will look and see if the wedge inlet is doable. I will get
those dimensions for you also. If I tilt the tray horizontal and the wedge
shape/scoop hangs down what is the dimension of the back side
diffuser? What does the wedge inlet look like from the front/back?
I don't understand the first question.
Inlet area is 25% to 30% of the core area.
Can the scoop opening be smaller than the width of the radiator?
Yes but the inlet duct cross sections should be constant area up to where
the wedge starts.
Does it need a large area/volume like the K&W?
No. One of the wedges advantages.
That is one of the reasons I tilted it so
a plenum could be built on the back side of the firewall occupying the
space between the firewall and engine. I have some ideas for the augmenter
(incorporate the muffler into the augmenter) but there are som NACA reports
I would like to look at but I think they will not be of much help.
Joe
Joseph Berki wrote:
Paul,
The distance between the fuselage floor and the bottom of the spar
at the aft landing gear bulkhead is 12.75" , at the firewall it is
11.5". I looked at the possibility of laying the radiator down parallel to
the fuselage floor and let the wedge hang down into the air stream. The
limiting factors were the lower motor mount hard points Clearance for an
opening for cooling could be 16" max. The biggest radiator would be 10" X
24" which would mean it would have to be 3" thick. I found a NACA paper on
rectangular augmenters which would fit with the wedge in that everything
could be rectangular but I don't think it would exit the air frame correctly.
Joe
A sixteen inch wide opening would be OK but it must be about 4 or 5 inches
deep.
Does the structure look like this Long Ez? That does not give you
much room under the landing gear for an inlet duct. Do you want to
locate the inlet duct up and over the landing gear beam?
I think the biggest problem with this idea is the loss of
structural strength in the fuselage and the landing gear if you move
the inlet and inlet duct forward and above the landing gear.
BTW If I decided to design a canard airplane I would fasten the
landing gear to the spar anyway. Burt made a few structural
mistakes here and there. Particularly those silly aluminum angle
motor mount stringers only ten inches apart. Might be OK for
a Volkswagen engine. I digress.
Getting the back of the rad clear from obstructions is the next problem.
How far is the engine from the firewall?
If the air is flowing through the rad properly a 500 cubic inch core
should work fine. That means only 2 inches thick. A 3 inch core would
give a volume of 720 cubic inches. The back half of the 3" thickness
would be doing only 1/4 of the work so assuming you could get the air to
flow through the 3" core it would be much less efficient and only cool
a little bit better.
Why not move the augmentor aft under the psru?
That would give plenty of room under the engine for the rad.
Do you have a sketch of what you have in mind for the augmentor?
Paul Lamar
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