I would have thought that since the tailplanes are providing a downforce
throughout the flight regime, that the optimum CG position for minimising
drag is when the CG is at the fully aft CG limit. At this point the wings
are producing the least amount of excess lift (and hence drag) to counteract
the tailplane downforce. However, I don't know how great the effect is in
reality.
By playing around with your loading on a flight by flight basis, you can
move the CG around a bit, although it is generally easier to move the CG aft
(eg put more baggage in the baggage bay), than forward (means putting
baggage on your passenger's lap!).
I have a fairly aft empty CG, and have to watch loading quite carefully,
especially when flying solo (eg if solo, bags go on passenger seat, rather
than in baggage bay).
One thing though is that with a fully aft CG the controls do feel quite a
lot more sensitive, and some people have said that landing is a little
harder, especially with a crosswind.
Hope this helps.
David
GBWJH
-----Original Message-----
From: owner-europa@aztec.houxou.com
Subject: Best CG location
Hi Folks,
When I did my weight and balance I ballasted such that typically I am in the
mid-range of the envelope (60" - just aft actually) with just me on board
and
half fuel. When I take-off I set 1 division down trim on the MAC scale and
the airplane just rises off by itself which is most satisfying.
In the cruise however I find I have to use almost full downtrim. When I land
the trim ends up about two divisions of up trim.
Anybody else find this? Is the center of lift aft of the mid-range as shown
on the CG envelope? as I'm assuming that if airplane CG matches center of
lift then trim should be neutral.
With two up I find I don't need quite so much nose down trim in the cruise
which I guess is to be expected but its still quite forward.
Any comments on optimum CG position for least drag from the tailplane and
tabs would be appreciated.
Oh, and by the way, Christine and I are expecting a baby in September!
Regards
Martin Tuck
N152MT
Wichita, Kansas
|