Sorry, Al, there was not any more to be had out of that document.  I can understand that all angles of inclination may not be equal - in heat transfer or drag, but must admit I was surprised to find that 55deg supposedly provided 30% more heat transfer and 20% less drag than one perpendicular to the air flow.  It would be interesting to find out the source of such a conclusion - I mean the graph looks like it comes from somewhere{:>)

  Ed.

Ed;

I didn’t mean to imply that they were ‘making it up’.  I can believe that that is what they actually measured. From the drawing it appears that the diffuser section is what K & W called ‘old style’; so with the rad perpendicular there may have been flow separation or whatever; IOW poor pressure recovery.  Inclining the rad increased the pressure drop, and at some point the flow stayed attached and everything worked great – you see what I’m getting at.  Too many other variables.  It’s like a one person testimonial on a health food supplement – “Oh, yeah; it cured my cancer, my athletes foot and bad breath; I swear by the stuff”.  And actual data shows it doesn’t do anything.

Al