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Ok, Dave, Just to enable you to keep your
promise of not making any more points, I will refrain from my crushing rebuttal
along the lines of your thin rad running out of mass flow before I run out of
DeltaT {:>)
I 'm afraid I agree with Monty's assessment of it being a
sort of snipe hunt at our level of resources and that since we are most often
fitting our cooling systems into airframes not designed for liquid cooling
everything ends up being a compromise which fortuitously works (most of the
time).
I think it was a good topic and got wrung out fairly well
- whichever side of the core you are on {::>)
Ed
----- Original Message -----
Sent: Thursday, November 15, 2007 10:14
PM
Subject: [FlyRotary] Re: Thick vs Thin
was : Diffuser Configuration Comparison
Ed Anderson Wrote:
So IF in installing the thicker core, I slow down the mass flow
through the duct by 1/2 (which I can easily do - increasing it might
be more difficult) then the air velocity through the core will be
reduced. With the velocity decreased, the air will take longer to
transverse the core. The longer the air takes to move through the core
the more heat it will absorb, the more heat the air absorbs the greater the
DeltaT of the air. The greater the deltaT of the air the more heat
will be removed even with the slower velocity and mass flow ( the drag would
also be reduced, just had to throw that one in {:>)).
Ok, I'll let you slow down the air for the thicker
RAD. But then I am going to slow the air for the thin RAD even more than
that.
Afterward, we can both make a fortune selling my new idea:
Seven-minute Ab videos!
(and maybe radiators that need no air at
all) :-)
Tracy Crook Wrote:
This
is where it starts to go badly wrong and/or misses the whole
point.
The main object of using a thick rad is to use fewer CFM
(lower
mass flow rate). If you want to assume same mass flow, there
is no
advantage (and probably a disadvantage) for a thick rad.
Ah HA! You heard it folks, right there in black
and white.
If 2.75" IS a thick rad, then I must be on your side of the
discussion all along, as my rad is 3" thick. Yet it is as wide and long
as I could reasonably fit under the cowl.
This brings me to my
final point (promise I won't make anymore points). Use the
widest-thinnest radiator you can reasonably fit under the cowl and make
appropriate ducting. I guarantee that you don't want to use the
thickest-narrowest rad you can fit. That would not cool well at all.
--
David Leonard
Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net
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