Andreas Maurer wrote:
On 14 Jan 2004 20:15:24 -0700, (Mark James Boyd)
wrote:

Just imagine what forces your movable weight will exert under a g load
different than 1? For example, when you are flying through a vertical
gust?

I'd imagine it will behave the same as an attached one pound ballast
weight on the upper part of the rudder of the glider used to
balance the rudder. Perhaps I'm missing your point here...


This is precisely the cause why your idea cannot work - and why the
pilot of a hang glider is hanging so far *below* his wing.


Now this a very interesting point. Whether the weight is above
or below the C.G. seems to also have an effect. Thank you
Andreas...

The biggest safety feature would be ensuring the weight didn't
come loose during a critical phase of flight (near the ground)
and your supplementary "weight" cables don't hinder
the original controls in any way...

A weight right in the tail which moves maybe 3 feet forward
when the auxiliary stick is moved might do it. Hmmm...


Have you ever thought about what is regarded as the most important
invention of the Wright brothers?
You name it - aerodynamical control around all three axes.

It seems this weight shift idea is just a very fine refinement.
It's intention is to reduce that tiny bit of additional
drag caused by moving surfaces or trim. I agree this is
not anywhere near "the most important invention," but just a
fun winter mind-teaser.

There's a good cause why there was never such a system that ever
worked on an aircraft, although thousands of designers have tried it
in the pas 120 years.

Well, it has worked to improve the efficiency in cruise of
modern jet airliners, and has helped my fuel efficiency in
my 172 across the country, but perhaps, as you point out, not
as a primary control (for pitch in these cases). Except for
ultralights and powered parachutes (which have a low hanging weight)
we don't see it used in modern aircraft.
Perhaps you are right, the standard glider design
(with no low hanging weight) doesn't lend itself well
to this means of control...

Andreas

Thanks for your thoughts!

Mark