Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Tue, 18 Jun 2002 14:19:53 -0400
Message-ID: <redirect-1480651@logan.com>
From: "Greg Nelson" <gnelson@gt.rr.com>
References: <list-1480158@logan.com>
Subject: Re: [LML] Re: stalls
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<<High altitudes and high temperature = low drag and longer rollouts. That's
yet another reason to really know where those speeds are, not estimates

There are truly many scenarios wherein it is important to be informed of
potential  for stall and spin.  Consider these:  rain, snow, ice, frost,
bugs and just plain dirt all cause loss of lift in the wings as well as
increased drag on our airplane fuselages.  Varying loads within the airplane
of passengers, baggage and fuel all cause changes in cg.  Air traffic,
weather, vectoring, approach and takeoff, ordinary and emergency flight
maneuvers all dictate changes in attitude in our super slick, high
performance airplanes that are sometimes dirty, fly in rain and at varying
extremes of flying weights and loadings.  Our planes are usually flown by
rank amateur pilots getting 50 to 150 hours per year.  We fly into airports
and landing strips that are sometimes a challenge to experts -in weather, at
night, in crosswinds, uneven terrain and unfamiliar surroundings.

Each of these conditions and hundreds of others beg for an AOA-type of
instrument.  The AOA offers the pilot information that no other instrument,
or combination of instruments, offers.  Not even experience can offer the
same types of safety margins that the AOA offers though there is no
substitute for experience (and good judgment) in piloting.  For example, an
experienced pilot must continually guess at his stall speed when facing a
forced landing while sitting next to a 250 pound passenger and heavy in
baggage and fuel but low header tank fuel in air chop or crosswinds.  The
air chop and crosswinds alone cause continuously varying stall speeds and
approach attitudes.

A properly calibrated AOA is not infallible and can be tricked.  Ice, for
instance, will change the airfoil shape and therefore its efficiency
rendering AOA information unreliable (can also plug the ports of both the
pitot and AOA).  Still, the AOA or RLI devises (and there are others) equip
a pilot mightily.  Stop worrying about lift; get yours today!