From: "Scott Dahlgren" <dahlgren@itsnet.com>
To: "___Lancair list" <lancair.list@olsusa.com>
Subject: flaperons
Date: Thu, 24 Dec 1998 00:06:32 -0700
Message-ID: <NBBBIPBKBOKGEELJMONFGEHMCDAA.dahlgren@itsnet.com>
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Marv,

Here are the main pro's and cons of flaperons:

pro's:
-easy construction
-lighter weight

cons:
-lower ultimate lift (yes, it's lower!)
-more stall/spin prone

to the eye you would get more lift, but the lift you gain is at the end of
the wing. as all wings lift elliptically,  the % of lift carried by the ends
of the wings is almost insignificant (5% for both control surface areas
would be optimistic). this is why the wing tip extensions have no spar, they
just make the main wing carry more load but they themselves carry very
little. with flaperons the flap and control surface share the same total
amount of deflection, so deflection is limited to ensure you never exceed
the control limit and stall the tip section which could (likely) give you a
nasty spin. this ends up giving you a significant loss of total lift
compared to a separate flap/control system, which has higher lift can better
control, but is more complex and heavy.

if you want more lift, continue the flap under the belly of the aircraft
like is done on aircraft such as the AR-5. that will make the lift more
effective, and efficient since that is the area where most of the lift
happens. I am sealing the junction between my flap and the fuselage fillet
to improve lift. remember though, if you lower the stall speed too much you
will need larger control surfaces all around or you will crash at low speed.

hope this helps,

Scott