----- Original Message -----
Sent: Tuesday, May 29, 2007 12:37
PM
Subject: [FlyRotary] Re: Cooling
Recommendations
On the other hand, since 99 % of what we do is at the eye-ball
engineering style - any examples is bound to be helpful.
Ed
What about the adjustable inlet and cowl flap interconnection being
of any help.
I can buy a lot of cooling capability and fit it into a BD-4 cowl. I
could then limit flow through the cores with a variable inlet scheme. I have
had to add pancake fans to keep temps under control when a problem occurs on
the false grid after the signal to start engines. We could just turn on the
fan and keep running. Piston cars would have to shut down and risk boiling the
fuel in the carb and flooding. We beat other cars more than once who
couldn't restart after going to operating temp and shutting down for a
while.
Once I added the biggest radiator Griffin could make I had no such
problem again and pitched the fan. But I note that just a small fan could cool
enough to allow idle speeds all afternoon. Idle is 2,200 RPM and never a drop
in the catch tank.
Lynn E. Hanover
There is no question that if you want to cool that you can do
it. One approach, as you mention, Lynn is to put a large radiator
in. I always say with enough metal and airflow it WILL COOL. But,
you also might like to minimize drag while getting adequate cooling -
depending a lot on the type of airframe, flight regime, typical environment
(South Florida vs Northen Canada) and manner of operation.
There is certainly more than one way to peel this grape that will
work. Cowl flaps can help provided that your inlet is
doing its job well -, but they can add also weight and complexity.
Same for variable inlets - perhaps more so. My personal feeling is that
if you have a very large range between your operating extremes then such
things as Cowl flaps become more necessary. But, for the RV and BD
series I personnally do not think they are necessary . At least one
individual installed cowl flaps and found them unsatisfactory in an RV.
Just did not provide as much benefit as they did downside.
So again, a lot depends on what your priorities are and what you are
willing to give up for it.
With a BD-4 you have a relative large space under the cowl which gives
options
Ed