Message-ID: <19991214070215.5638.qmail@web111.yahoomail.com>
Date: Mon, 13 Dec 1999 23:02:15 -0800 (PST)
From: BILL HANNAHAN <wfhannahan@yahoo.com>
Subject: CG Issues
To: MAIL LANCAIR <lancair.list@olsusa.com>
Mime-Version: 1.0

          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> 
>>


When the 320 was designed they lengthened and enlarged
the tail for the larger engines and props. They also
moved the battery back for CG purposes.  

I have been flying a 360 with the long Hartzel prop
since 92 (1300hrs).  I made it as simple and light as
possible (1010 lbs.) with the standard parts, and it
is quite nose heavy with no baggage, which is good.

A longer engine mount will add square inches of wetted
surface area increasing parasitic drag. More
importantly it adds those square inches well forward
of the CG and moves the prop disk forward.  From a
stability standpoint both of these changes cancel out
square inches at the tail reducing pitch and yaw
stability margins.

If you want to move the CG forward move the battery up
behind the seat and save a little weight on cables. If
you want to save a lot of weight and make a big CG
change delete the passenger rudder pedals and install
the battery on the back of the fire wall.

Does your passenger need rudder pedals?  Yes if you
are building a trainer, otherwise no.  It flies great
with the stick, the pedals are only required when
weight is on the gear.

When my passengers get in and realize there are no
pedals they usually enquire about my health and ask
what they are supposed to do if I have the ‘BIG ONE’. 
The answer is,

1	Find an airport with a long wide smooth hard surface
runway.
2	Set up a long shallow stabilized final at 85-90 mph
with the gear up and 20 degrees of flap.
3	Don’t move a muscle, don’t try to save the engine
and prop, just fly it onto the runway gear up, it will
be the safest landing you ever make.

Why is a gear up landing safer?  Because lots of bad
things can happen when the gear is down.  A tire can
blow and jerk you off the runway at high speed.  A
brake can lock up and jerk you off the runway at high
speed. A gear leg can collapse and jerk you off the
runway at high speed.  Your passenger can bounce it
off the nose gear and get into a big PIO.  With the
gear up your passenger only lands once, he can’t get
the nose up to make it fly again.  Your beautiful
airplane is transformed into an expensive hockey puck
which slides to a stop along a reasonably short and
straight line.

In seven years only one passenger has landed on the
first try without help.  The average passenger trying
to land on the gear under the stress of an emergency
will most likely PIO, stall/spin.

Don’t try this on grass. A metal prop may dig in and
flip the airplane. Wood props will shatter, but if the
ground is soft or uneven some other part of the plane
may gouge into the soil resulting in the dreaded
sudden stop.  Sudden stops are not likely on hard
surface runways unless the angle of incidence is
substantial.

Keep building, it’s an amazing airplane and still
great fun to fly.

BILL HANNAHAN
WFHANNAHAN@YAHOO.COM

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
LML website:   http://www.olsusa.com/Users/Mkaye/maillist.html
Builders' Bookstore:   http://www.buildersbooks.com/lancair
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>