REFLECTOR: Nose OIl cooler scoop flaw

[Scott Derrick]

Al, I think your right, I'm going to make a couple more flights getting
the mixture map correct and if the oil temps stay above 200 with 60%
power. I can't see how fixing that entry could anything but improve the
positive pressure side of the cooler.

I'm supposed to do a triangular run at full throttle and give him the
numbers. I would expect it in the 85-90 range for pitch, 68 inch
diameter. From what I understand he doesn't really change the pitch or
helix as he calls it. He changes the blades airfoil which changes the
lift of the blade.

I was thrilled that he is willing to apply a credit. He's more than fair.

Scott

Al Gietzen wrote:
>
> Scott;
>
> I think you’re right, it’s sort of a half NACA, half ram, half (bleep)
> scoop. I know it’s tough to cut into a nice paint job, but that may be
> your best solution. It is in a relatively high pressure area which is
> good, but a NACA scoop is not optimal anyway for something a
> restrictive as fairly dense core heat exchanger.
>
> I’d smooth out (and forget the NACA shape) the entrance, and maybe
> pull out the entrance lip a bit to give an opening about ¼ of the face
> area of the cooler – maybe a touch more. Basically as you said; a
> submerged ram scoop. It will be ingesting the boundary layer which is
> going to trip some turbulence in the duct, but the BL is still quite
> thin that close to the nose. Make a smooth expansion into the duct.
>
> Just my thoughts.
>
> BTW, what pitch is Catto shooting for with the new prop? I can see
> where trying to re-do a pitch of 105 (or whatever it was) down to
> maybe 85 - 90 would be tough, and still maintain the right blade
> profile. Great that he’ll give you credit on your prop.
>
> Good luck,
>
> Al
>
> >
>
> > I know, its not a NACA. It looks kinduv like one if you stand far enough
>
> > back, its really a flush mounted RAM scoop made to look like a NACA if
>
> > you squint your eyes real tight.
>
> >
>
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