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From: ths@lanl.ARPA
Newsgroups: net.aviation
Subject: Trick Question and Others
Message-ID: <31026@lanl.ARPA>
Date: Tue, 24-Sep-85 11:39:41 EDT
Article-I.D.: lanl.31026
Posted: Tue Sep 24 11:39:41 1985
Date-Received: Sat, 28-Sep-85 06:23:04 EDT
Distribution: net
Organization: Los Alamos National Laboratory
Lines: 33

Well I sure received a bunch of replies to my question about what causes an
airplane to climb in a constant airspeed ascent.  I also added some fuel to
the fire when I used the term "all fources are equal" instead of "all
forces are in equalibrium".  The "trick" in the question is simply that few
text books for the private and commercial pilot discuss this aspect of
flight.  It has only been in recent years that Jeppesen has paid more
attention to the drag curve, but they still don't adequately explain the
relationship of the four forces.

I received a number of interesting explanations ( and a few unfriendly
comments) but the bottom line is the "the vertical component of thrust" as
explained so effectively by Oscar Strohacker.

Going on the Cessna flap (no pun intended), the official statement by
Cessna was that with 40 degrees of flap at gross weight, the aircraft had
little if any ability to climb.  This situation tended to get some pilots
into trouble during a go-around or if the flaps became inoperative in the
fully extended position.  The Cessna flap is so effective that reducing the
travel to 30 degrees did not significantly degrade the landing performance
which was outstanding to begin with.  I believe only the 172 has the notice
in the handbook about "avoiding" slips with full flaps extended.  It does not
actually "prohibit" slips.

With respect to "dropping the nose" in lieu of slipping with full flaps,
this can be used effectively. HOWEVER, my experience with Many Many pilots
is that they arrive in the flare with an excess of 10 knots or greater
airspeed.  If they were trying to execute or demonstrate a short field
landing they will then try to force the airplane onto the runway resulting
in wheelbarrowing and/or porposing.  My suggestion is to use the most
appropriate technique and if you grossly misjudged, demonstrate a full-flap
go-around.

Ted


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