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From: "William" <wschertz@ispwest.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-148113@logan.com>
Subject: Re: [FlyRotary] Re: Pop off
Date: Thu, 10 Jun 2004 22:32:47 -0500
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The only problem I see right off is the friction of the piston.
Bill Schertz
KIS Cruiser # 4045
----- Original Message ----- 
From: "Marvin Kaye" <marv@lancaironline.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Thursday, June 10, 2004 9:07 PM
Subject: [FlyRotary] Re: Pop off


> Hey guys,
>
> We've been talking about these pop-off valves as safety devices for some
time,
> but the problem always seems to be that the available crop of these things
> will only work at sea level.  This is an obvious shortcoming for airplane
> applications, as the MAP will always be decreasing with altitude.
>
> I've been kicking around some ideas for awhile and came up with a little
> drawing of one of these things that, I think, addresses the problem.  See
the
> attached picture.
>
> My thinking is that if you create a chamber where you carry around your
sea
> level altitude with you, close it off with a piston, the exposed side of
which
> is open to the atmosphere, then as your altitude increases the piston
should
> move down an amount equal to the change in atmospheric pressure.  It then
> applies the required additional force to our spring and keeps a steady
20psi
> of force on the valve at the bottom.  (This would be the equivalent of 40"
hg
> MAP, but you could make it be whatever you want by changing the spring
rate.)
>  As you can see, the exposed sides of both the movable piston and the
valve
> are seeing atmospheric pressure... in this example drawing the piston and
> valve's areas are both one square inch, just to keep things simple.
>
> Now, for the $64,000 question... what's wrong with this?  If it won't
work,
> why not?  What do we change to make it work?  This can't be that hard.
>  Suggestions????........
>
>       <Marv>
>


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