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From: dbp@dataio.UUCP (Dave Pellerin)
Newsgroups: net.aviation
Subject: Re: Acrobatics (Really How Things Fly)
Message-ID: <726@dataio.UUCP>
Date: Tue, 23-Jul-85 10:24:02 EDT
Article-I.D.: dataio.726
Posted: Tue Jul 23 10:24:02 1985
Date-Received: Thu, 25-Jul-85 21:53:37 EDT
Reply-To: dbp@dataio.UUCP (Dave Pellerin)
Distribution: net
Organization: The Boneless Chicken Farm
Lines: 28
Keywords: Say What??

>
>>2) ....describing the differential airflow... how this creates lift. 
>>OK; so how does a plane fly inverted? ...
>>Will Martin
>>
>Common misconception, differential airflow causes lift. Basic laws of
>physics will tell you "action = reaction" Lift is caused by the acceleration 
>of a mass of air downward, period. The airfoil is just an efficient way
>of doing this. A lot of aerobatic planes have symetrical wings with zero
>dihedral and get lift purely from angle of attack. Hope this helps.
>		Tom ihnp4!cbnap!tel

Sorry, lift is created by two factors; increased air velocity over the
upper surface, and the so-called "action = reaction" lift.  The first
factor accounts for (in normal aircraft) about 80% of the lift produced.

"Action = reaction", where air is deflected downward, accounts for only
20% of the total.  If Newton's law were the only factor, the perfect
airfoil would probably be a flat plate!  Most asymetrical airfoils will
produce a significant amount of lift at slightly negative angles of attack.

A "symetrical" airfoil becomes quite asymetrical with a little angle of
attack.  Dihedral has little or no affect on lift, it only provides yaw
stability.


		Dave Pellerin
	..uw-beaver!entropy!dataio!dbp