<... Not that it really matters; but I do have an MS degree in engineering ....>
I think it DOES really matter.  I have enough engineering background to do a qualitative analysis of a lot of these problems, but that's only enough to eliminate the really bad ideas.  We need to quantify all this shit before we can make it work properly, and the guys with the best training are the ones who can do this chasing the least amount of foul balls.  I was suggesting that pushers seem to lend themselves better to good plenums than do tractors, and better plenums lend themselves to thicker radiators.  To the extent this is true, pushers will approach the problem a little differently than tractors.  This is obviously not rocket science, and, to coin a phrase, the devil is in the details.  My notion at this very VERY early stage is to use parallel GM evaporators in the best plenum I can build.  By the time I'm ready, you folks should have generated a lot more reliable information and my path will be much easier.

Don't think I don't appreciate all of your efforts .... Jim S.
 

Al Gietzen wrote:
We need to be careful about comparing “thick” and “thin” because it is very dependent on rad core design.  A more open matrix can be thicker for the same pressure drop; but will have a lower heat transfer per unit of volume.  Always a tradeoff.  As I recall, the P-51 had a much more open matrix than current high performance racing radiators.  It had some sort of hexagonal fin arrangement – don’t know the details.

 

Certainly the plenum design is important, but we have to work within certain constraints. We have fixed amount of dynamic head available, and we have to achieve a certain volumetric flow rate to remove the heat with a relatively limited temperature difference; all within some space constraints.  And a small area, thick rad is working against the plenum pressure recovery ratio because getting the higher pressure recovery requires a bigger expansion ratio in the plenum.

The pool of experience and analysis suggests certain ranges that we should work within.  I’ve expressed my conclusions on that before; and I didn’t just pull them out of the air.  Not that it really matters; but I do have an MS degree in engineering, and years of space nuclear power system design.  That doesn’t mean you can’t go outside those ranges, but recognize the risk, and do your testing before you try to go fly.