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
