Jeff Spitzer wrote:

Tracy Crook wrote:

Here is my 2 cents on  radiators for aircraft.

Those radiator cubic inch specs you put out are very significant.  That is
perhaps the most important spec on the radiator itself.   OTOH,  I would
argue that THICKER radiators are the way to go on aircraft. Thinner is more
efficient if you don't care how many CFM you use to do the cooling job.
This results in the lowest rise in inlet air temp through the radiator but
you need more CFM.  More CFM used for cooling = higher drag.

Not necessarily.  Actually the thin radiator may use less CFM than the
thick one due to efficiency gains (as snipped form Paul's response) due to
greater temp difference for the given volume.  The error in your logic
comes from an unneccesary assumption that the velocity through the HX is a
constant.  On the contrary the same *mass* can move through a bigger cross
section, thinner radiator much slower and pick up the same or more heat.
This has the dual benefit of reducing the drag (thinner *and* slower) and
making more efficient use of the air.  The only downside to a big radiator
is finding someplace to put it.  In theory a bigger, thinner radiator will
always be better than a liitle, thick one in terms of cooling efficincy.
In reality airframe impact must be considered.

Jeff Spitzer

 
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