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!

Ron

--- Ed Anderson <eanderson@carolina.rr.com> wrote:

 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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