----- Original Message -----
Sent: Thursday, July 15, 2004 6:52
PM
Subject: [FlyRotary] Re: New Scoop
Looking at John's cooling set up, it
appears that the cooler core exits are in an excellent position to
benefit from any lower pressure region that may exist at the rear
of the canard fuselage.
Its been my contention that this is one
of the reasons that at least some canard installations appear to
defy both the conventional "wisdom" and the NACA admonishment that
NACA ducts are not well suited for radiator cooling (or other uses that
produce a back pressure). That is - as in John's case -
the successful arrangement appears to minimized the back
pressure across the core and perhaps benefits from a localized area
of lower than ambient pressure.
Attached is an extract from a NACA report which
makes it clear, that at least in their opinion at the time, the NACA ducts
were not suited for radiators. But, as John and other's have shown, they
can work very effectively. So something they are doing must be
different. The only thing I can come up with is that the canard
arrangement provides the opportunity to benefit from what must be a lower
pressure area behind the fuselage as it moves through the
air.
However, in my own personal experience in
using a Naca duct in the front of my cowling (in one of my five attempts to
solve my oil cooler problem) the results were consistent with the NACA
assessment. It was not successful for me.
One of the differences is my oil cooler
was approx 10" from the firewall and did not have exit to a negative pressure
area. In fact, the pressure inside the cowl was probably slightly
positive. I don't know that would have made a difference but
seeing the success of John and others with it, I am led to believe that
having the back of your cooler cores in a lower pressure area will
enhance the probability of success in using a NACA duct.
My 0.02 worth.
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
Sent: Thursday, July 15, 2004 6:48
PM
Subject: [FlyRotary] Re: New
Scoop
>I believe that his cowling must extend down
approximately 4-5 inches to achieve that.
Nope. The cowl is
level with the fuselage floor, then curves upwards.
It's tight, but it can
be done.
John Slade (Got my EM2
.... manual)
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