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Dear Tracy
I'm with
you what are these special flat plate rads. I have built many systems but
haven't come across these flat plate rads. I will stand corrected if
someone comes up with something. I think what everyone is talking about is a
flat plate cooler that is put in the bottom tank on rads to cool trans fluid. I
think fluidyne is using them as oil to water oil coolers. I looked into that but
didn't like the sealing system they used around the oil inlet/outlet good enough
for cars but not safe for aircraft. If anyone has anything to add to this I
would be happy to hear about it.
Regards
Ed Klepeis
----- Original Message -----
Sent: Saturday, November 24, 2007 9:39
PM
Subject: [FlyRotary] Re: Naca Report on
Radiator Thickness
OK Steve, I'll bite. Do pusher airplane builders hang their
rads out in the breeze? Do radiator companies make special flat plate
style radiators for them? What am I missing?
Tracy
On Nov 24, 2007 1:05 PM, Steve Brooks < cozy4pilot@gmail.com> wrote:
Tracy,
Maybe not relevant
for an RV, but pretty relevant if you are cooling a
pusher.
Steve
Brooks
-----Original
Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net ]On Behalf Of Tracy
Crook
Sent: Saturday, November 24, 2007 11:53 AM
To:
Rotary motors in aircraft
Subject: [FlyRotary] Re: Naca Report
on Radiator Thickness
This NACA paper discussion is interesting but has almost nothing to
do with our installations using standard automotive rads rather than the
flat plate rads in the paper. Radiator frontal area is almost
irrelavant in our installations because they are totally enclosed within a
streamlined body. Too bad, because if frontal area was a significant
factor, it would end the argument about thick vs thin :-) The thin
rad would look terrible in this respect.
Keep everything in perspective!
Note that the NACA paper indicates that the rads we use (tube &
fin type) have no application in aircraft. If that were true it
would mean all our discussions and work on installations so far have been
a total waste of time!
Tracy (should be working on RV-8)
On Nov 21, 2007 9:20 PM, Ron Springer < ron2369@sbcglobal.net> wrote:
Well,
engineering judgement tells me that your drag
increase is still too
low. Now I'll just have to prove
it by looking at that report, or
elsewhere.
Sounds like a good project for the long
holiday
weekend, or I could just work on my Cozy ... it will
be a
tough call!
> Ok, Ron, I went back and looked
at the drag aspects
> again. It looks like
> the
calculation was accurate, however, I think this
> will put it into
a
> better perspective than before.
>
> The frontal
drag at 120 mph for the 1 square foot
> radiator (using just
the
> frontal area - no drag coefficient) was
>
>
37.63 lbf/ft^2, the "internal skin" drag of the 4"
> thick
radiator was 6.7
> lbf/ft^2. The skin drag for the 1" thick
rad was
> 4.28 lbf/ft^2. So
> comparing the 6.7 with
the 4.28 was where I came up
> with the 58% increase in
>
skin drag.
>
> However, adding the frontal and
skin drag factors
> for the "total" drag, I
> get 37.62
lbf/ft^2 + 4.28 lbf/ft^2 = 40.98 lbf/ft^2
> total drag for the
1"
> rad. For the 4" rad 37.62 + 6.7 = 44.32
lbf/ft^2,
> so based on that it
> appears that the total
drag was increased by
> 41.90/44.32 = 5.5% more total
>
drag for the 4" radiator than for the 1" radiator.
> It might be a
tad bit
> less than that due to the 5% decrease in mass flow
> on the frontal area of
> the thicker
rad.
>
> At least that is the way it appears to
me.
>
> Ed
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