Mailing List flyrotary@lancaironline.net Message #19889
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Cooling Chart Was [FlyRotary] Re: rule of thumb and RV-3 sizes- was Cooling Inlet Areas/Bernie's RV9
Date: Thu, 7 Apr 2005 12:16:31 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
  Jerry;

Like most things; it’s a tradeoff.  Generally more cooling air flow equals more drag.  Somewhere in there one would hope there is an optimum; but everyone’s criteria for trading configuration needs for drag reduction is different.  The attached chart shows radiator cooling drag as a function of area (actually height for a given width, but same idea) for a fixed amount of heat rejection.  Larger area gives less drag, and vice-versa.

Sorry, best quality I could achieve scanning a scan, and keeping a manageable file size.

Al

 Al, Interesting chart. 

Not certain I am interpreting it correctly, though.  Not certain what the X axis is related to is this the height you mention?

It appears to show that the thicker radiators produce less drag overall than the thinner radiator.  Is this for equivalent core volume or core area? Its my understanding that for the same cooling core volume the smaller surface face core will produce the less drag, is this what that is showing or the opposite?  Sorry to be slow today, I'll blame it on leaning over my Aerostars engine bay for 7 hours yesterday replacing a water pump - aches and a restless nights sleep.{:>{

By the way, I order some of those B9EQV spark plugs you mentioned to  see if they reduce the SAG interval compared to the stock plugs.

Ed A.


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