Hi Darren
At this stage everything is rough and temporary so no photos are available
just yet.
The air outlet on the plane used a long "tunnel" that extends from the
firewall where it has maximum depth all the way rearwards to the main spar
where it has zero depth. I started with a flap that was hinged at the
firewall and could close off the outlet completely for drag reduction in the
glide mode but no matter what angle it deflected down in the open position
it would not allow enough air to exit. I then fitted sides to the flap so
that air could not spill around the flap satisfying the low pressure created
directly behing the flap. This improved it but was still not enough. I then
cut and hinged the flap in half (side to side) so that with the same
movement of the actuator arm I got more than double the deflection. This did
not improve anything as the smallest part of the tunnel was now at the new
hinge line and was actually a restriction.
I then cut a slot in the bottom of the cowl roughly 50mm deep and 455mm wide
to which I added a deflector lip ahead of the hole. This gave a dramatic
drop in CHTs and OT as well.
The most efficient inlet for an oil cooler that we tested is an adjustible
flap that when closed, forms part of the cowl skin but when open presents a
thin lip to the incoming air that "slices off " a strip of the air as it
slips over the surface of the cowl. This duct was positioned on the
underside of the cowl to one side and half way between spinner and firewall.
The inside walls form a divergent duct of which the walls diverge an an
angle not exceeding 7deg. This is the most efficient way to slow the air
down and get pressure recovery without creating turbulence. The rear wall of
the duct is the cooler.
I hope that the above helps somebody to avoid a lot of headaches one day.
Regards
Dene Collett
Avlec Projects cc
Port Elizabeth
South Africa
- Original Message -
From: "Darren Crompton" <kr.2s.dar...@gmail.com>
To: "KRnet" <kr...@mylist.net>
Sent: Tuesday, December 22, 2009 2:06 PM
Subject: Re: KR> COOLING ISSUES SORTED
Hi Dene,
Sounds interesting. Can you talk more about the outlet position and what
area is working for you? Some photos of this and the oil cooler scoop would
be great to see too.
Cheers
--
Darren Crompton
