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Paul,
The two cores I use each have a
fin volume area of 9*10.5*3.6 = 340 in^3 (does not include side tanks). So
two give a core volume of 2*340= 680 in^3.
Your radiator would give approx (discounting 2"
total for tanks) 15*7.25*3 = 337 in^3 even with 8" and disregarding
the side tanks would only give 17*8*3 = 408 in^3.
So if we assume that the two cores represented a
minimum adequate fin core are then your radiator would have to be 60%
more efficient (408*1.6 = 652 in^3) to come close to the two cores.
My primitive cooling model indicates that with only
337 in^3, you would probably need airflow near 223 mph to provide adequate
cooling at power = 160HP. Now at a more nominal cruise say 75% =
.75*160 = 120Hp, you could probably get by with airflow at 170
MPH.
What this could mean is similar to folks using the
two cores - in that low airspeeds and high power settings exceed their cooling
capacity - however, we are generally able to get up to adequate speeds and/or
pull back the power sufficiently to come back within our cooling capacity before
overtemps get serious. So while we may overheat during take off and
initial climb, once we get up airspeed cooling appears to be adequate with the
two cores.
So assuming you could get to around 170 mph before
the overcoming the cooling inertia of your coolant mass, then by throttling back
to 120HP you might be achieve adequate cooling. However, if it took too
long to reach 170MPH then I would expect to see over heating.
Now I admit this is little better than back
of the envelope cooling model, but two cores should keep 160Hp cool at around
115 - 120MPH and that is about what people seem to be experiencing with two
cores.
So, Paul, my best opinion is that you will likely
find the 17*8*3 inch radiator inadequate for aircraft use at the power settings
we see. It might be even worst for a canard installation.
However, if anyone on the list has experience to
the contrary regarding equivalent radiator size, please jump
in.
Rusty, what was the size of your radiator and
the final determination about its adequacy?
Ed
----- Original Message -----
Sent: Wednesday, November 19, 2003 11:55
AM
Subject: [FlyRotary] radiator
Hi, fellow rotary enthusiasts.....I'm getting
ready to order a radiator for my 13b powered SQ2000 canard pusher. I
talked to Al Wick, and he has a 160 hp Subaru powered Cozy and is cooling it
very well with a radiator that is 17" x 7.25" x 3" deep. Any idea if
that size might also cool a rotary? How does that seem to compare with
two GM evaporator cores? I was told that if I can increase the height to
8 inches instead of 7.25, they can put two fans on it, as well as the built-in
Meziere EWP. I can work with the additional height of 8 inches. Just
don't want to spend $1100.00 for too small a radiator. If 17x8x3 equates to
approximately the same size as two evaporator cores like Ed Anderson is using,
I should be OK. If anyone can compare the square inches of the two, I would
sure appreciate it. Thanks in advance for any and all efforts and
recommendations. Paul Conner
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