For what it's worth, I've been working on a ducted fan layout with a tractor
fan using a rotary.  The hang-up has been the problem of cooling.  To get
the power density required, it must be liquid cooled.  I've looked at all
kinds of ideas including skin radiators in the down side of the duct wall.
Because I'm going to use a relatively small diameter fan with a large center
body to OD, I've been looking at the possibility of putting intakes behind
the stators feeding through round radiators pumped by the exhaust.  Sort of
a liquid-cooled version of the SG-85 fan-pod RFB marketed in the late 70's
and early 80's.  From the write-ups on this board, I'm beginning to wonder
if a 3 or 4 stage cross flow radiator system might not work?  I don't think
it would with just ram air from the fan, but the combination of flow from
the fan and the ejector pump might just do it.  Going to have to buy your
book, Paul.  I'm going to do a mock up of the system.  Then I'll put it on
the board.  Does anyone have any ideas about how you would plumb a
cross-flow system that is round?  Or who is capable of fabricating one?  The
input power will be 150-170 hp.  Twin rotor.

George W

I don't think my book will help. It is oriented towards
cooling rotary engines in airplanes.

I would buy:
*Compact Heat Exchangers. W.M. Kays and A. L. London Kreiger Publishing
Company. Malabar Florida. 1998  ISBN 1-57524-060-2

This will be most useful for what you are doing.