X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-lb0-f180.google.com ([209.85.217.180] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTPS id 5435472 for flyrotary@lancaironline.net; Fri, 09 Mar 2012 14:43:05 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.217.180; envelope-from=rwstracy@gmail.com Received: by lbon10 with SMTP id n10so386081lbo.25 for ; Fri, 09 Mar 2012 11:42:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=Bcug8N5pvw4kjzhxGz7sPJ4k5ZANVJNtr0cSRYA49Vc=; b=Z95Pe9jKqUKCEB8XOVoFP9eJbVj9eANS0nymCJOgkdUJ7uMFg60tZgj0lhW0PWsfbG Wxk1YHwnZJnEPbxODAF3MTrGB6Xbfx8vpA/NM8qN8QKVPHYg8dB6YMKWtmEmaAXMPHS4 pg9DdpC5Sn9bl/zPEgC5Y+8dj2WsE96I+uKClmFXOMQ+NH+4dXbi6iG6oLm2x1A5Iny/ o0F2skcV7oYeXSUbQtiqYRO3RCFsVrz28MP3MCbq65Jw1d60yQDbVztM2aaf27XP8f/D HbyvElj39mcObOaZHfJmcXwCdJgBlJ3kEB1P7LSiy8HMq08Q41xUOwMZ242wShOpnjEV 1swA== MIME-Version: 1.0 Received: by 10.152.162.72 with SMTP id xy8mr2584110lab.32.1331322147553; Fri, 09 Mar 2012 11:42:27 -0800 (PST) Received: by 10.112.94.179 with HTTP; Fri, 9 Mar 2012 11:42:27 -0800 (PST) In-Reply-To: References: Date: Fri, 9 Mar 2012 14:42:27 -0500 Message-ID: Subject: Re: [FlyRotary] Re: Engine cooling From: Tracy To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=f46d04426e92afc1ad04bad497e0 --f46d04426e92afc1ad04bad497e0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Ah, I missed the detail of having 2 rads. It was the odd definition of "radiator surface area" that got me off track. Guess that means face area. If the designers of the P51 had used his formula, the rad core would have measured about 5 feet square and would not have fit in the airplane. But I do agree with his basic rule of thumb on rad core volume. 3 CI per HP is a reasonable target. Tracy On Fri, Mar 9, 2012 at 11:10 AM, Ernest Christley wrote= : > Tracy wrote: > > Sanity check: > > > > 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. > > > > > > 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. > > 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. > > > > Is it just me or is the math here bogus? > > > > 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". > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > --f46d04426e92afc1ad04bad497e0 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Ah,=A0 I missed the detail of having 2 rads.=A0 It was the odd definition o= f "radiator surface area"=A0 that got me off track.=A0=A0 Guess t= hat means face area.=A0 If the designers of the P51 had used his formula, t= he rad core would have measured about 5 feet square and would not have fit = in the airplane.=A0=A0 But I do agree with his basic rule of thumb on rad c= ore volume.=A0 3 CI per HP is a reasonable target.

Tracy

On Fri, Mar 9, 2012 at 11:10 AM= , Ernest Christley <echristley@att.net> wrote:
Tracy wrote:
> Sanity check:
>
> 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 purpos= e,
> this applies only to the surface area of the radiator that the air flo= w
> first makes contact with.
>
>
> 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.<= br> > 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.
> 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<= br> > maintain climb out temperatures of around 200=B0F and 190=B0F at cruis= e on
> a 100=B0F day. With a cooling system like this, we could taxi from Hou= ston
> to Dallas with no overheating problems.
>
> Is it just me or is the math here bogus?
>

He's got dual radiators that add up to 540in^2 of surface and 1215in^3 = of volume. =A0The 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. =A0I would not take issue with the math, = just his definition of what constitutes "minimum".


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Homepage: =A0http:/= /www.flyrotary.com/
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