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Date: Fri, 09 Mar 2012 11:10:50 -0500
From: Ernest Christley <echristley@att.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Engine cooling
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Tracy wrote:
> Sanity check:
>=20
> 1) Requirement: Radiator surface required is 1.5 sq in of surface area
> per cubic inch of the engine. For example: LS1 V8 Chevrolet =3D 350 cu =
in
> x 1.5 =3D 525 sq in of radiator surface area required. For this purpose=
,
> this applies only to the surface area of the radiator that the air flow=

> first makes contact with.=20
>=20
>=20
> 2) Requirement: Minimum of 3.0 cu in of cooling volume per HP produced.=

> For example: We only utilize up to 300 HP of an LS1 for aircraft use.
> Using a dual radiator configuration with two radiators measuring 15=94 =
x
> 18=94 x 2.25=94 thick =3D the total cooling volume is 1215 cu in.=20
> Therefore, our cooling volume to HP ratio: 1215 cu in cooling volume =F7=

> 300 HP =3D 4.05 cu in per HP. With this formula, we have been able to
> maintain climb out temperatures of around 200=B0F and 190=B0F at cruise=
 on
> a 100=B0F day. With a cooling system like this, we could taxi from Hous=
ton
> to Dallas with no overheating problems.
>=20
> Is it just me or is the math here bogus?
>=20

He's got dual radiators that add up to 540in^2 of surface and 1215in^3 of=
 volume.  The math is right.
What doesn't add up to me, is that he says you can get by with 3in^3/hp, =
but then demonstrates that 4in^3/hp is just
adequate on a reasonably hot day.  I would not take issue with the math, =
just his definition of what constitutes "minimum".