Mailing List lml@lancaironline.net Message #24232
From: Cary Wigington <tclwig@sbcglobal.net>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: CG and Gross Weight
Date: Mon, 21 Jun 2004 08:55:31 -0400
To: <lml@lancaironline.net>
Marv,

From reading your postings, it looks like you have given a lot of thought to
avoidance of CG problems with your plane.  I believe that you have moved the
battery forward and have placed the hydraulic pump on the firewall.  I am
unable to post on the bulletin board, but would really like to know what
others have experienced.

Attached are the CG calculations I have run based upon CG calculations in
the Cafe Foundation test of the 320 (Sport Aviation, February 1999.)  At my
weight and my wife's hopeful weight, we appear to be within the CG envelope
regardless of loading.  The rub is we will be at least 100 lbs. over gross.
I am assuming gross weight at 1800 pounds per the CAFE article, but I
thought the design weight was to be 1650 pounds.

I have wetted the outer wing to gain fuel capacity, and I like the idea of a
header tank (gravity fuel feed is a nice redundancy).    That may have been
a mistake.  Operating out of Dallas Addison (642' msl) and a 7,000 runway
isn't a problem in most likelihood, but I am curious as to what other 320
owners have experienced.

So, my issues are as follows:

1.  Exceeding gross weight - in the real world, what happens?  What is the
correct gross weight number?

2.  What is the effect on CG by moving the hydraulic pump and battery
forward (estimates or calculations)?

3.  The CAFE plane doesn't appear to have had a header tank.  Do you know
the CG numbers for running the header tank?

4.  Does the bigger tail have any effect on CG (the CAFE plane had the
extended engine mount and the small tail)?

5.  Do wingtip extensions add to the payload numbers?

Most of us understand what the term "Experimental" means, but I would really
like to have a better feel for whether I should complete this plane or move
to something else (a four seat or Legacy).  I would really like to stick
with this plane.  I have factory new O-320 and too much time and money
invested.

As always, I really appreciate your help.

Cary Wigington
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