"JC" JRC at visi dot com wrote in message
...

In the spin the Puch's nose will go beyond vertical. You can really
notice this when flying from the backseat. (The Blanik L-13 will do
this also.)


(What follows is part of my standard pre-flight briefing to students before
teaching spins -the pro's can ignore if they wish.)

Various gliders may in fact go past the vertical with respect to the ground
but there is more to it. Most of us have the mental picture of a spin entry
sequence as if the glider stops all its forward motion at the stall and
thereafter proceeds straight down in the spin. With a bit of thought, this
is seen as wrong.

In fact, the glider carries substantial forward motion through the stall and
into the spin. The result of this is that the path of the gliders center of
gravity traces an arc that transitions from level flight to vertical in the
spin. (Imagine the path of a Badminton birdie.) Usually, the first full
turn or two of autorotation is in this arc so that, at the 180 degree
points, the glider is somewhat inverted with respect to the ground. To the
pilot, this appears as if the spin is asymmetrical as the glider first goes
past the vertical and then rotates to a more nose-up attitude.

This may well be the source of a lot of the, "Wow, that glider spins funny",
or "It tries to go flat in the spin", type of statements. If the pilot
holds the glider in the spin, the path will become vertical and, from the
perspective of the pilot, will appear to spin symmetrically. With some
gliders, I have seen this take two or more turns.

If the recovery is attempted at the first 180 degree point, the glider will
reach a higher airspeed in the dive recovery and burn more altitude. A
better technique is to apply anti-spin controls at a point that will stop
the rotation at the 360 degree point. The difference in altitude loss can
be substantial.

The higher the airspeed at which the stall break occurs, and the faster the
glider snaps into the spin, the more pronounced this effect appears.

Bill Daniels