[Info-vax] OT: Aircraft pitot tubes and clustering.

[Paul Sture]

In article <D4idneHzH_l3lLDWnZ2dnUVZ_rSdnZ2d at earthlink.com>,
 "John Reagan" <johnrreagan at earthlink.net> wrote:

> "JF Mezei" <jfmezei.spamnot at vaxination.ca> wrote in message 
> news:00e4e770$0$6712$c3e8da3 at news.astraweb.com...
> 
> >
> > Which is why there should be sources of speed which are independent from
> > air pressure. The problem is that other sources of speed (GPS which
> > gives ground speed, and inertial systems which calculate speed based on
> > acceleration) do not give "air speed".
> >
> > Air speed is critical to determine if you are flying of falling out of
> > the sky.
> >
> 
> And it just isn't air speed.  It is air density as well.  Lighter air gives 
> less lift.  So altitude helps determine density but different air masses 
> have different densities at the same altitude.  It all factors into the 
> pressure readings from the pitot tubes.
> 

Yep. On a trip to a small airstrip (well a football field really - they 
took the goalposts down for us) in Africa we waited until it got dark 
and therefore cooler before attempting a take off. I could have sworn we 
brushed the tree tops on the way up.

-- 
Paul Sture