Mailing List flyrotary@lancaironline.net Message #55247
From: Ernest Christley <echristley@nc.rr.com>
Subject: Re: [FlyRotary] Re: Blower design
Date: Tue, 31 May 2011 16:31:42 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Pat Panzera wrote:
Here's more info that was sent to me:




Hi Pat,

As you might already know, the stock cooling fan gets discussed (sometimes cussed) quite a bit in Corvair car circles.  Chevy did tests on the fans, so the HP use isn't a guess, it's documented - you do have to extrapolate the curve, but at 3400, it takes about 7 HP to drive the fan.

The later magnesium fans were made to help keep the belt on during enthusiastic driving of a stick shift car, the earlier fans actually flow a little more air per HP.  The later fan does use a little less HP total, but it also flows less air, the fan design suffered a bit so it could be a cast rather than a built up assembly.

More info on my site at:

http://autoxer.skiblack.com/fan.html

Hope that helps.

Not to be glib, but...not really.
Talking about Hp requirements without stating head pressure and flow in the same sentence tells you very little.  Up at 18,000ft, it won't take nearly as much power to drive any fan for a given rpm.  Dunk that sucker in a pool of water and spin it up to 6000rpm, and THEN take a reading Hp requirements.  The numbers Chevy give, and what all the Corvair guys are quoting, are with a very low restriction output section.  They are basically quoting full flow numbers.  The numbers we're interested in will be much closer to the static pressure, no-flow end of the scale.
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