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Message-ID: <380C28518A5D4AC9B4489DF5601E263C@george>
From: "George Lendich" <lendich@optusnet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-3206778@logan.com>
Subject: Re: [FlyRotary] Radiator size
Date: Fri, 10 Oct 2008 09:37:31 +1000
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Giff,
RULE OF THUMB
My notes say 3 to 3.5 cu inches to each hp.
( some smaller reciprocating engines can use 2 cu inches to each hp, but 
wouldn't recommend it for a rotary).

30% frontal area entrance to radiator.

No incursions causing exit restrictions for at least 6inches behind the 
radiator. Unless it's a designed . Augmentation is also good.

Exit area 1.4 times inlet area.

For example Mazda 13B producing 200 hp
Rad Core area = 600 cu inches
Inlet area = 60 cu inches
Exit area = 84 cu inches

If using cowl flaps to regulate exit air, Cruise =  48 cu inches or 80% of 
inlet area.

If using  AN fittings use AN16 or 1" to limit any restriction.

Care must be made to the shape of the inlet plenum i.e. trumpet or wedge 
shaped, to maintain maximum inlet efficiency, by converting velocity (of the 
air) to density. Pressure directly in front of the Rad can be up to 80% of 
dynamic pressure - if designed right.

HTH
George (down under)


>I am trying to get a rule of thumb for required radiator size.
> I would like to know the engine HP and the size of the radiator, in order 
> to
> determine the cubic inches of radiator required for each horsepower.
>
> Giff Marr
>
>
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