Greetings Gentlemen,

I've been following this thread from afar and thought that I'd inject my 2
cents on this cooling issue.

One Jess Myers ( maker of the Belted Air Power PSRU ) and I have confronted
this same cooling problem here in Las Vegas, NV, where summer ramp temps can
reach 125 F.  In the '80's Jess did a considerable amount of cut-and-try
testing of various ways to cool a V8 engine using a Globe Swift as the test
vehicle while developing his PSRU.  To cut to the chase he found that if the
system cooled well on the ground at some speed over 200 mph - memory fails
here - it is as if a speed brake is deployed at this point and further
acceleration becomes difficult.  Cooling drops off as well and the engine
heats up again.

The number of fins per inch as well as their thickness contributed to the
development of what was termed at the time as an "air dam" above this speed
maximum.  The more fins/inch and/or the greater the thickness of the
radiator the better the ground cooling but the sooner the air dam formed at
speed.  Conversely, the fewer fins/inch the poorer the ground cooling and
the better the cooling at speed.

I encountered similar problems while looking for various ways to improve
cooling on a liquid cooled engine mounted on a pusher aircraft - a Varieze.
I reached a somewhat successful compromise in the form of an aluminium
radiator boosted on the ground by an electric cooling fan.  Jess was most
helpful in this area saving me from reinventing the wheel so to speak more
than once.

Hope this info is of help.  Let me know if more detail would help.

Ken Mintz
Varieze N86KM


----- Original Message -----
From: "Tracy Crook" <lors01@msn.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Monday, August 11, 2003 4:27 PM
Subject: [FlyRotary] Re: Cooling / Pressure recovery


>
> Tracy Wrote:
> >   If you DO
> > > manage to design
> > > a cooling system that will cool at full throttle on the ground, it is
> > > probably a disaster in terms of cooling drag while in-flight.
> > >
> >
> >
> >  Uughhh... I really hope you're wrong about this. Mine cools great on
the
> > ground. Define "full throttle" in terms of length of time? I've gone to
> full
> > throttle for about 8 seconds with 6 psi boost, just to test it, however
I
> > normally limit it to 0psi boost or 30" MAP. At this I've done static
> run-ups
> > for up to a minute. I've taxied around for 45 minutes at various power
> > settings and never seen more than 90C on the coolant and 85C on the oil.
> > I hope it's not a wind bag in the air.
> > S. Todd Bartrim
> > Turbo 13B RV-9Endurance
> > C-FSTB
>
> Hmmm......   You don't think 8 seconds counts as cooling do you?  : )
> By cooling, I mean that the temperature has stabalized.
> Lots of dragsters have no cooling system at all and "cool" OK for 5 - 10
> seconds.
>
> Tracy
>
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