Subject:
[FlyRotary] radiator
Hi, fellow rotary
enthusiasts.....I'm getting ready to order a radiator for my 13b powered
SQ2000 canard pusher. I talked to Al Wick, and he has a 160 hp Subaru
powered Cozy and is cooling it very well with a radiator that is 17" x 7.25" x
3" deep. Any idea if that size might also cool a rotary?
We all know that
the cooling system is the most frequent problem area in custom engine
installations. One reason is that too often it is done on the basis of
‘what worked for Joe Blow should work for me’. It’s not that I argue
with what works; it’s just that configurations are very different, and the
applications (air speeds) are different. Ducting and air flow are
probably the most variable. Right off hand, Paul, I’d guess that a 17” x
7.25” x 3” would work for roughly a continuous 100 hp climb on a 90 degree
day.
SNIP
There is
plenty of data from the racing world that suggests that a rad thickness of
about 2.5” may be optimum; 3 will be fine. The rad area times thickness
gives you volume.
Somewhere around
2.5 – 3.0 cu. in./hp will be fine for cruise. But for that climbout on a
hot day, you’re going to need more; probably around 4.
And don’t forget;
to keep the drag down you’d like to liberate that cooling air back into the
free stream at something like free stream velocity. So some of that
static pressure you recovered in the inlet duct can be used to accelerate the
air in the outlet. Outlet area should be on the order of 1.5 times inlet
area, and try to let the air out in a low pressure area.
So that ought to
get you into the ballpark, and if you do things right it will work just fine.
You can do some tuning after you get the thing flying.
Al