Today's Message Index:
----------------------
1. 03:22 AM - Re: Cooling diffuser (Graham Singleton)
2. 07:49 AM - Re: Cooling diffuser (Rob Housman)
3. 10:38 AM - Preliminary exhaust augmentation mockup (GLENN CROWDER)
4. 01:16 PM - Re: Perfect cooling diffuser (karelvranken)
Message 1
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| Subject: | Re: Cooling diffuser |
Ron
I will attach a pik. Problem with Europas is the gases can get sucked
into the cabin, but that could be cured I'm sure.
Graham
rparigor@suffolk.lib.ny.us wrote:
>Hello Graham
>
>"> Another way to improve cooling on the ground is exhaust extraction,
>this
>
>
>>is how the EZ boys do it. I don't think anyone has tried it yet on a Europa."
>>
>>
>
>How exact is exhaust extraction accomplished on EZ?
>
>Ron Parigoris
>
>
>
Message 2
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| Subject: | Cooling diffuser |
In re: water spray
It's been a long time since I studied heat transfer but I recall enough of
the principles (if not the details) to know that there are a couple of
conflicting factors with this proposal. On the plus side, a fine mist of
water will provide some evaporative cooling, since the phase change from
liquid to gas will remove much more heat than liquid water flowing through
the air spaces in the "radiator" (a heat exchanger in engineering speak).
Also on the plus side is the fact that heat transfer to water is more
efficient than heat transfer to air. So far, so good. The big negative
here is the impediment to air flow - put any amount of water in the spaces
where the air is supposed to flow and less air can flow resulting in less
efficient cooling. It's worth a try but I expect that spraying water will
cause coolant temperature to rise not fall.
Best regards,
Rob Housman
A070
Airframe complete
Irvine, CA
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of
rparigor@suffolk.lib.ny.us
Sent: Sunday, December 03, 2006 9:43 PM
Subject: Re: Europa-List: Cooling diffuser
Hello Graham
"> Another way to improve cooling on the ground is exhaust extraction,
this
> is how the EZ boys do it. I don't think anyone has tried it yet on a
Europa."
How exact is exhaust extraction accomplished on EZ?
How about spraying water on the radiator during extended ground operations
and temps creep high, anyone try this?
Ron Parigoris
Message 3
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| Subject: | Preliminary exhaust augmentation mockup |
I have been working on and off (mostly off) on an exhaust augmentation
system
for my EA81 powered monowheel. The idea is to use the waste heat of the
exhaust to do the cooling for you instead of using high drag ram pressure
thru the
rad. The Reno racers do this and claim it adds up to 20 mph while improving
cooling. Inlet duct areas can be dropped to almost nothing as the augmenter
creates a huge suction effect to suck cooling air thru the rad from behind.
Racers who have used this arrangement report up to 4 inches of suction. A
standard flow thru ram type duct arrangement typically only gives an inch of
pressure difference even if done well. Theoretically, one could reduce the
rad
size dramatically as a result, saving more weight and drag (maybe by half or
more).
The engine exhaust pipe will enter the duct at the big bulge and terminate
about
6 inches inside the duct. This then creates a high speed jet of exhaust
that mixes
with the back side radiator air and the mixing creates an enormous suction
on
the back side of the rad. It all fits very snug and the long oval shaped
tube tucks
in right beside the monowheel. It looks heavy but the kevlar tube is only a
pound
and the fiberglass duct is only a pound, replacing the rear duct I already
use.
I have one radical idea that I will try and that is to not use a front
difffuser duct
at all, and just let the radiator suck air from the inside of the cowling.
Hopefully,
that would be near zero cooling drag.
Ground cooling is claimed to be excellent as well, as cooling is entirely
determined
by engine rpm, not airspeed. One should be able to run WOT on the ground as
long as desired without overheating as suction is doing all the work, not
ram
pressure. Also, reports are that the long mixing tube only gets warm to the
touch.
The system should be peaches on a 912/914 powered unit as well although
you
would need a 4 into 1 type exhaust.
Glenn
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Message 4
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| Subject: | Re: Perfect cooling diffuser |
Glenn,
The duct inside isn't part of the cowling. I made it of carbon tissu, it
looks like a black hole, but be sure it is perfectly sealed on the radiator.
The radiator also is modified, no more the square block but a 4 cm thick one
of 26 cm x 15 cm = 390 cm2.
Karel Vranken.
----- Original Message -----
From: "GLENN CROWDER" <gcrowder2@hotmail.com>
Sent: Monday, December 04, 2006 2:49 AM
Subject: Re: Europa-List: Perfect cooling diffuser
>
> That looks awesome Karel!
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