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Date: Thu, 10 Jun 2004 10:30:16 -0400
From: "ericruttan@chartermi.net" <ericruttan@chartermi.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Pop off
References: <list-146411@logan.com>
In-Reply-To: <list-146411@logan.com>
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How can altitude not make a difference?
Springs are always relative devices.  ALWAYS.

If you got a one inch hole with a spring that resists 10# of boost at sea 
level.  The means that it can only resist 10psi DIFFERENCE.

At sea level (atmosphere ~14PSI) you go to MAP ~24PSI of boost, your ok. 
MAP 25 and the spring opens.

At 20K ft the spring will be open at over 14PSI MAP (atmosphere ~5PSI).

Big difference.

Now this example highlights extreme cases.  It might be fine in a 
traditional home builders mission, perhaps at low altitudes.  The reduced 
MAP at altitude might not matter to most people.

But altitude makes a difference in this device.

marc wrote:
> Common in turbo normalized aircraft installations. Look at the T337P. Go
> to RAM's website. Altitude makes no difference in this device, just
> absolute manifold pressure.
> 
>  
> 
> Marc Wiese
> 
>  
> 
> -----Original Message-----
> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
> Behalf Of John Slade
> Sent: Tuesday, June 01, 2004 8:57 AM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Re: Pop off
> 
>  
> 
> I've been thinking about the POV, and wondering how it'll behave at
> altitude.
> 
> If the air is pushing against a spring, perhaps the ambient pressure
> behind the spring wont make much difference. Has anyone tested the
> behavior of a POV at altitude. Seems to me that it would hold back
> pressure, even in a vacuum.
> 
> John (popping off to the hangar to remove cowl and investigate the last
> flight)
> 
>  
> 
>