"T o d d P a t t i s t" wrote in message
...
"bumper" wrote:

It went into an unstable phugoid oscillation with each dive being steeper
than the previous. I chickened out and stopped the "test" early on after
my
ears got pinned back - - and I was in a closed cockpit (g).

I did not have spoilers or gear out.

I have always done this with the brakes out. It's always
entered phugoid oscillations, but not so bad that I felt the
aircraft was in any danger. I must admit that sometimes,
they seemed to be getting more severe, but in the 8 -
10,000' I've had to play with, I've always been limited by
the need to land, not by the need to protect the glider from
itself. I'm reasonably confident that with 8,000' or less
of cloud to descend through, it would protect itself better
than I could.

Any high performance glider will have an undamped phugoid - they're just too
good at converting airspeed into altitude and vice versa. Opening the
spoilers and lowering the gear with help with damping. Experiments with any
particular glider are recomended.


I have yet to try the "hold a magnetic compass heading of
south with rudder only" method or the "fly constant GPS
heading" method to compare. The latter two are difficult to
practice realistically in a single seat aircraft without
being contaminated/influenced by the visual horizon.
--
I've practiced the south compass heading trick from the back seat of a Duo
Discus and it works surprisingly well particularly when combined with GPS
ground track data. I just used smooth, coordinated control inputs to hold
the south heading. However, I've had a LOT of IFR experience in single
engine light aircraft. Even so, I'd still want at least a T&B if I had to
try it in IMC.

Bill Daniels