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From: "George Lendich" <lendich@aanet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-4080409@logan.com>
Subject: Re: [FlyRotary] Re: Scoops
Date: Wed, 13 Jan 2010 09:06:40 +1000
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Tony,
Everyone has a go at explaining the trumpet shape of the inlet duct - why 
should I be any different.
I like what Ed and Ernest have said and I don't know if it can be classified 
as an airfoil but it does similar things, as it acts to hold the airflow to 
the walls of the duct - hopefully eliminating any possible eddies/ 
reversals, that restrict free flow into/ through the radiator.
Everything is in the design shape and length available. Limited length tends 
to warrant a different design - like wedge shape, as it's nearly as good.
When you look at a trumpet shape and ( in you mind) bend it to one side, you 
end up with something similar to a wedge shape.
I think the P51's design was for a vertical radiator, however later tests 
have shown that rad fins at a significant degree ( I would have to check my 
notes) the air becomes turbulent going through the radiator fins, and 
therefore is more efficient at removing heat. What I'm saying you could set 
the Rad at an angle and reduce the height of the overall ducting required.
Hope that helps.
George ( down under)

>> Tony
>>
> Tony, why your depiction leaves out is the big blockage to free airflow, 
> otherwise known as the radiator.  If that airflow was in a free stream, it 
> would do exactly as your curly lines depict.  But it isn't in a free 
> stream.  It has that radiator spanning the whole area, blocking the air's 
> progression, and pushing it to the side.  It is the pressure at the center 
> of the radiator acting to push air to the side that keeps the flow 
> laminar.
>
>
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