Date: Fri, 19 May 2000 06:54:03 -0400
From: Dr Michael A Fopp <70734.101@compuserve.com>
Subject: Re: lancair.list V1 #35 - CG Problems
Sender: Dr Michael A Fopp <70734.101@compuserve.com>
To: "lancair.list@olsusa.com" <lancair.list@olsusa.com>
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Hi Every one!

As many of you know I have built a Lancair with both the long and the short
engine mounts so I have data on both.  If you place the hydraulic power
pack behind the baggage bulkhead you are in for trouble.  The best place
for it is behind the passenger seat and I posted photos of such an
installation a few years ago but can send new ones if it helps.  The
variable is the battery and this can be placed in a number of positions
forward of the cg and (in my case) behind the left seat - photos also
available.  The larger tail affects the cg quite considerably and if you
have this and the short engine mount (as I did first time round) you MUST
move the pump as above.

Retrofitting the longer engine mount is not difficult but is a real chore. 
It took me about 200 hours and I will write up something about my repairs
for LNN when I have time.  The problem is the really bad mouldings that
Lancair use for the cowlings.  The first time was bad enough but to get
another, longer set, and find that they had merely extended the original
aberrations was a bit of a pain.  In my case I had real cooling problems
with the short mount and cowlings so I made some changes to the new
cowlings.  The change in cg announced by Lancair last year (bringing it
forward to 11% MAC) mean that I have a comfortable cg range which is
impossible to breach at the aft end unless you overload the
baggage/hatshelf areas.  It is possible to get it too far forward with a
light pilot and full header/empty wings - an unlikely event.

I have employed a professional Test Pilot to carry out 5 hours of testing
on my 320.  He is entirely satisfied with its handling at MTOW of 1785 lbs
and fully aft cg.  However, he would not approve it under FAR23 for IFR
because of a particular trait which I don't yet understand.  I will report
more fully on the testing, particularly of the extended wingtips when I
have time.  The cg issue is something to sort during the building process
and, because of my regular visits to Australia (where they have done
extensive professional testing of the type) I was aware of the gear pump
location problem from the beginning.  I would recommend ALL builders to
move the pump to behind the seat, open up a panel in the seatback and thus
make it better for the cg and for installation/maintenance.  In my case the
battery was good behind the other seat and if I had put it further forward
I would have had to move it back when the longer mount went on.

If you can, fit the longer mount.  The aircraft looks sweeter, handles
better, has less cg problems, engine cools better, exhaust pipes are 3"
away from the underside,  and there is much more room to work on the engine
accessory case.  The downside is, in my case, the top cowling fouled the
top of the mount and I had to put a "power bulge" in it, the air intake
holes are still not symmetrical so you have to cut one of them away and
re-fit it and the airscoop retrofit is a real pain because Lancair produce
it out of different, thinner, material.

Finally, the new nose leg (self centering etc) is a dream and I have not
had any sign of shimmy.  If you have not had your's serviced by the factory
for a couple of years, send it back at the first opportunity for all the
mods to be incorporated.

I have almost finished the 5 hours of testing with the Test Pilot and
should start my own Lancair trips shortly.  Regrettably my nose gear
incident last year has cost me my trans-atlantic expedition to invade the
USA in 2000, so I will not be over with G-FOPP this year.

Michael

 Dr Michael A Fopp 
 michael_fopp@compuserve.com
 Signed at 11:51 on 19-May-00
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LML website:   http://www.olsusa.com/Users/Mkaye/maillist.html
LML Builders' Bookstore:   http://www.buildersbooks.com/lancair

Please send your photos and drawings to marvkaye@olsusa.com.
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