Hi Paul...

I've been thinking about the cooling problem that has been discussed daily
since I'm been reading and following along.

In theory, using the calculations to determine the correct water and oil
cooler size, should be working.  It seems that the reason for thin cooling
vanes is to help the airflow through the cooler.  Here are a couple of ideas
I wanted to through out to help with the cooling problem.

Wider spacing between the core tubes, double to test.  This will allow more
air to pass because the boundary air around each fin is restricting air flow
through cooler.

The second idea is alignment of the airflow before and after the cooling
core.  Because the airflow is bending and changing direction, the air becomes
stagnated by internal vortices.  Try using a spiral device to help align and
rotate the air.  This device will looks like a grain auger from the side
view, but is very thin, no moving parts and will increase the velocity of
flow by aligning and rotating the airflow.

This concept could also be used on the intake to increase the velocity of air
flow to the rotor.

Rick Stitt

Bill Freeman wrote:

Rick,

Drag from alignment of flow is one of the reasons that we
are pushing for a diffuser in front of and a nozzle behind the radiator.
A diffuser converts a high velocity ambient pressure airflow into a high
pressure low velocity airflow, hopefully with good efficiency. The idea is
to have low velocity air at a high pressure at the front face of the radiator.
Since the velocity over the tubes is low and the dimension of the tube in a
flow-wise direction is very short, the boundary layer would be very thin, plus
you  intentionally destroy the boundary layer and create turbulent flow
(turning a corner can help this) to  increase your heat exchange to the air.

Since aero drag is proportional to the square of the velocity, a diffuser
that lowers the air velocity from 200 mph to 100 mph will roughly reduce
the expected drag in the radiator by a factor of 4.

After the radiator, there may be some modest gain to be had from flow
alignment vanes, altho I don't follow the 'grain auger' concept.  In any
case, diffusers and an exit nozzle are the keys to keeping the drag of
the radiator down.  And, as has been oft claimed for the P-51, you just
might do good enough to get a net thrust due to the heat added to the
air by the radiator, but I'm pretty skeptical of it working that well.

Bill

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