> > > >  I don't think the fans will take kindly to being spun up

when

 you are
 > > > going
 > > > > 200 mph
 > > > >  > ...Chrissi
 > >
 > > > >  Try 300 MPH because that is how fast the Lancair IV

EngineAir

 Chevy V8
 > > > goes
 > > > > with
 > > > >  electric cooling fans. Use the same kind they do. There are

at

 least
 > > > >  a half dozen flying and they have come in second two years

in a

 row in
 > > > >  the NC to OSH race at over a 300 MPH average.
 > > > >
 > > > >  Paul Lamar


 > > > If the fan switch is wired so that the fan motor brushes are
 shunted when
 > > > turned off, the fan will only turn very slowly.
 > > >
 > > > Lynn E. Hanover

 > Lynn, care to elaborate?
 > Royce

 What Lynn means is the wires going to the fan are shorted together

when

 the
 fan is off. If one wire then that wire is connected to ground when

the

 fan is off.
 This causes a magnetic drag on the motor slowing the fan down when

air is

 forced
 through the fan. I am not sure this works on solid state fan motors.

I

 suspect
 most fan motors are the old DC kind where this will work fine.

 Paul Lamar

[Todd TC. Carrico]
I thought the idea was to slow the air down before the radiator,
therefore the fans should not be seeing 200 MPH.  How slow is the air
going in a Kuchemann & Weber duct anyhow?  If It was properly done <g>.

tc

Absolutely true Todd. We just left that detail out. The 200 to 300 mph was

relative.

My guess is one fifth as fast but a lot is going to depend on
how thick the rad is and the number of fins per inch.

Perhaps Al can tell us what is going on in his test rig with his rad.
Al what was the speed of the air coming out of the blower?
What was the speed of the air coming out of the back of the rad?

Basically for pressure drops of a few inches H20, the air behaves pretty
much as incompressible so the average velocity at the face of the rad is
given by the ratio of the inlet area to face area.  Depending on the
location of the scoop entrance, you may or may not have free stream velocity
going in.

Al

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