"We also think the original cooling system design was marginal for
desert weather."

Jerry Hey wrote:
  I will have a minimum of

800 cu in in my Tailwind  radiator.  I think it is very risky to
depend on cleaver engineering  to replace rad. cu. in. although all
the cu.in in the world will not suffice in a bad design.  Just my non
educated opinion... Jerry (backyard engineer).

. As I

recall Chuck Dunlap's rad is only about 550 cubic inches but
it is almost ideally located just behind the pusher prop under
the PSRU and a streamlined air outlet at the bottom back
of the cowl. His airplane cools fine in the very hostile
environment of southern Arizona. See the attached picture.

Paul Lamar

Mike Wills wrote:

  More clarification. I wouldnt get too hung up on core volume. As Paul
pointed out in a previous email for a conventional rad (not Pauls
cross-counterflow design) the majority of the work is done by the first

row

of tubes in the core. An 800 cu. in. radiator 20 x 20 x 2 inches thick is
probably far more rad than you need for a 180HP rotary (assuming proper
ducting). On the other hand an 800 cu in rad that is 10 x 14 x 6 inches
thick may not cool at all because you cant get any air to go through that
core. I have seen pictures of one such installation that was a total
failure in a P51 style duct.

  Chuck Dunlap was here in San Diego a couple of days ago (thanks for the
visit and the ride Chuck!). I'm not sure how big his radiator is but no

way

is it 550 cu in. I'd estimate the core at 14 x 12 x 2 for 336 cu in.
Ambient temp at Ramona was 85 degrees and I never saw coolant temp go

above

200 during our flight.

Mike Wills

Very good point Mike. Frontal area of the rad is where it is at.
If I had the room the core would be only one inch thick.

Well yes I could be wrong about that 550 ci number :-)
I will have to search back through the messages for the exact number.
Here is another shot. This one shows the rounded bottom of
the firewall to smoothly exit the cooling air.

Paul Lamar

 
Chuck wrote:

 > My core is 10.5 x 20.5 x 2.5 inches, or 538 cubic inches volume. It cools

fine below 90 degrees ambient, but keep in mind I'm probably only making
about 140 HP max. The radiator I have would be too small for a heavier ship
in hot weather. Above 90 degrees, I have to reduce throttle to give about
500 ft/min climb to keep water temp under control.

Chuck Dunlap

Done any work on the inlet scoop and duct  since I saw it at Copper State Chuck?
If not I think it could be improved in that area.

Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org