Chris Rollings wrote in message ...
Under JAR 22 (Glider Certification Rules), a glider
is required to have postive (or at least neutral) longitudinal
stability. Put simply, if you move the nose up (or
down) a bit and then leave it alone, it should tend
to move back towards where it started from, or at least
stay where it is, not continue to pitch further up
(or down).

It is quite possible (easy in most cases) to learn
to handle a glider that does not have this stability,
but it requires CONSTANT vigilance on the part of the
pilot. A failure in concentration of only one or two
seconds can result in a massive divergence of the flight
path with catastrophic consequences.

Both my ASW 19 and my ASW 28 exhibit positive pitch stability for
small disturbances when aero towed on the cg hook. Both gliders will
fly hands off on aerotow for several seconds and will return to the
trimmed pitch attitude following small upsets.

You tests on kiting used very large pitch upsets and they were
determined to be unrecoverable. Was any testing done to determine the
largest recoverable pitch upset?

Now that most gliders in UK have both aerotow and CG hooks, is there
any intention to repeat the test series to compare the characteristics
of the same glider with each hook?


Andy