Sender: <marv@lancaironline.net> (Marvin Kaye)
To: flyrotary
Date: Sat, 29 Mar 2003 11:15:40 -0500
Message-ID: <redirect-2091891@logan.com>
From: <daveleonard@cox.net>
Subject: Re: [FlyRotary] Re: Thick vs Thin
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> I don't think I agree Dave, the flow of the air past the fins, etc.
> influences the heat transfer coefficient. So the efficacy of the transfer
> from metal to air is affected by the speed of the air flowing past the
> surface. I maintain that you cannot separate the DRAG phenomina from the
> heat transfer properties of the exchangers, they are interlinked. You also
> have a space constraint to work with.
> 
> The heat transfer is affected by the design of the radiator (fins, flow
> rate, thickness, etc.). Having a low drag radiator that doesn't cool won't
> serve my needs.
> 
> Bill Schertz
> 

In the sense that higher speed airflow will cause turbulent air instead of possibly laminar flow you are correct - but I don't think you could design an aircraft radiator to flow laminar air if you spent you life trying, let alone do it without trying.  

You are also right that for a GIVEN rad, increasing the air velosity will increase the mass of air and thus the cooling.  But read my earlier post closely.  By expanding the surface area of the rad, the SAME mass of air can pass through the SAME volume of rad and absorb the SAME amount of heat, but at a slower velosity.

EVERYONE needs less drag, unless you are referring the weight of a paycheck :-)

Tracy - I haven't read a rebut to my previous post.

Dave Leonard