View Single Post
  #7  
Old August 8th 07, 07:25 AM posted to rec.aviation.piloting
Morgans[_2_]
external usenet poster
 
Posts: 3,924
Default props: tractor v pusher, q tip, ducted?


"Kyle Boatright" wrote

Double? Naah. It expands, but doesn't double. Boyle's law (PV=NRT) is
based on absolute temperature, which is measured in kelvin. Kelvin is
Celsius plus 273 degrees. Guessing now, if the air temp went from 300k to
350k (or about 80F/27C to about 160F/70C) you'd see volume increase by
(350/300 -1) = 1/6th = about 17%...


OK. I have always heard the approximate rule for good cooling is double the
intake size for the exit size. Guess it doesn't transfer to expansion.
--
Jim in NC