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 don't get me wrong. I like your idea. It avoids the dreaded fiberglass work
by using the standard cowl openings. The only theoretical draw back I can
see right at the moment is the increased cooling air temp passing thorough
the rad is higher than ambient temperature decreasing the all important delta
T through the water rad. It needs every chance to work so the first thing is
make sure the air can get out of the rad without impediment. If this becomes the case
then the oil and intercooler should work even better. Another thing
I like about your idea is one cowl flap can control all the cooling air flow
in all three heat exchangers. I am sure you have thought about this and planed
it that way.
Paul Lamar
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