Is that a stock Mazda 2nd gen intercooler we are looking at there
Dave?
Looks like you have room to build a wedge diffuser for the top of
the
rad fed by a scoop under the prop. That should solve the water
temp problem.
Paul Lamar
Right you are, Paul. Stock 2nd gen. You are sort of right about
the
defuser. it is tight but could be made to fit. But it would be a
waste to
cover the entire rad. All that air coming out of the oil cooler
and
intercooler is already slowed down and not too warm. After all, it
is
cooling OK for flight now.
I also feel that the oil and inter cooler are probably not able to
handle
all the pressure in the diffusers and pressure is probably spilling
out the
front (if that makes sense).
My solution (after I fly off my 40 hrs) is to build a diffuser over
the last
1/4 of the rad, and feed it with cool air bled from the
difussers(like a 2"
scat tube from each). This will allow most of the original cooling
air to go
through the first 3/4 of the rad, then add a finish of cool air
right before
returning to the engine.
Add some improved insulation around the turbo and plug the few
remaining
holes in the cowl and I should be pretty close.
Adding an additional inlet would be the next step if that doesn't
work (got
to keep down that cooling drag).
I am skeptical about your idea of removing the cowl flap(& the rad
cover).
(But I will probably try it some day 'cause it probably won't make
me fall
out of the sky.) High pressure area? No doubt about it. 40% of
forward
speed, I doubt it in this case. It seems to me it should be
proportional to
the change in surface area, less the resistance encountered.
I cant remember the exact numbers, but each inlet is about 3.5 x 9
in.=
about 60 sqr in. of inlet. rad area is roughly 25x28 or 675 sqr
in.
So
assuming all the air coming in the inlet goes through the rad, it
would
still only be about a 10th the forward speed. Subtract from that
the losses
due to leakage and resistance, add some velocity for heating, and
we
are
still at less than 10% forward speed. My guess is that I would
cool
significantly worse with the cowl flap off (obviously I felt that
way or I
never would have done all that glass work I hate so much) - but it
never
hurts to try.
David Leonard
The Rotary Roster
http://members.aol.com\_ht_a\rotaryroster\index.html
Well Dave a $10 water manometer will take out all the guess work.
Paul lamar
I started using water manometers in 1965 while working on the
aerodynamics of
the Chaparral 2F road racing car. This car set lap records all over
Europe and won the Nurberg(s?) Ring and the BOAC 500 outright beating
all the
famous european race cars. About 1970 I used them to measure the
local
pressures
and velocities on the famous 1973 Trans Am Fire Bird under contract
with
Pontiac. Recently I used them on the full scale rad test unit mounted
on
top of my Dodge Caravan. With that kind of experience after awhile
you
can
look at something and tell what is going on aerodynamically . Trust
me
the air could come out of that water rad faster than you think. But
hey
don't take my word for it. Stick a pito tube down there and measure
it.
You do trust a pito tube do you not? That is where you get your
airspeed
to keep from killing your self on the base to final turn.
You are using K&M principles on the oil rad and intercooler
diffusers.
Why do you doubt them on the configuration of the rad air outlet?
Any panel within ten inches of the back side of your typical rad is
going to restrict the flow through that rad. Study these graphs
again.
I know you have seen them before. Sheeessss!!!!!
Paul Lamar
Dave has proven something that I have felt all along which is that the
rotary engine is not that difficult to cool. Early attempts ran into
trouble because of hugh cooling system design errors. But Dave is
cooling pretty efficiently with very small total inlet, using
preheated air through the radiator and with a restricted outlet.
Wow!!!! Our ace in the hole is that the oil coolers reject one-third
of the total heat. Using K&M inlet and outlet on the oil coolers
and
the radiator, together with adj. cowl flaps, should permit the
use
of a smaller radiator. Remember Ian only had 400 cu in his little
cheek rads and he did pretty good. Is there any kind of "balance" at
work between the small inlets and the restricted outlet? Remember the
little engine that could. Jerry
I agree Jerry. The size of the heat exchangers required will come down
as we learn
to control the cooling airflow better. Perry Mick is right up there
with his water
rad being exceptionally small. The red lines indicate the outlines of
an
outlet duct Perry tried at my suggestion that made it worse.
Consistent with
the K&M outlet duct guidelines. Very similar to what Dave is trying
with his
addition to the bottom of his RV6 cowl.
Paul Lamar
Perry, what is the size of your water rad area and volume? Jerry
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