Steve;

 

Attached is scan of the pressure/speed graph.  I scaled it and compressed as .jpg to get the size down to transmit here; if it is not sufficiently clear let me know and I’ll send larger file direct to you.

 

Note that what I was talking about is simpler than the EAA article – I’m only looking at the airspeed, not the altimeter which requires knowing local pressure, etc.  The air speed is only differential pressure; so for this you can size your manometer to read up to about 20-25 inches.

 

A pressure vs altitude chart can be found on the internet; e.g., http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html. You can convert to inches H20 knowing there are 407.2 in. H20 in a standard atmosphere of 14.7 psi, or 29.92” HG.

 

Have fun,

 

Al

 

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Steve Thomas
Sent: Sunday, January 17, 2010 8:59 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Pitot/Static & Transponder Cert.

 

Al,

 

Yes, please, send the graph of in. of water vs. airspeed.  Is there a graph of in. of water to altitude?  I have a how-to from EAA that goes through all of the calculations here: