Sandy Stevenson wrote:
I've been looking for an expalantion of the aerodynamics of how an aircraft
gets into a spiral dive.

"In the process of learning gliding turns, a beginner may fail to
control the tendencies to overbank and to dive. The bank may approach
the vertical and the nose of the glider may fall more than 45 degress
below the the horizon; of course, speed will increase rapidly."
-Page 18, The Joy of Soaring by Carle Conway

"Sometimes the elevator is unable to keep the wing stalled beyond the
incipient stage of the spin. In this case, as the nose and wing drop,
the wing will unstall and the speed will increase with the glider in a
spiral dive."
-Page 127, Gliding, Sixth Edition, by Derek Piggott

but I
don't yet
understand how it comes about that adding back pressure increases one's
airspeed.

"If the pilot then pulls the stick back in a mistaken effort to slow
the glider or to bring its nose back up to the horizon, the glider will
simply turn faster and the spiral will continue to steepen. The
resulting increase in the angle of attack and airspeed could overload
the wing to the point of structural failure."
-Page 18, The Joy of Soaring by Carle Conway (paragraph following that
quoted previously from Conway)

"..., during the spiral dive you will learn that the effect of backward
motion on the control stick will not raise the nose of the glider (and
consequently is useless in trying to recover from the dive). This is
because the steep bank means that any increase in angle of attack of
the wing will generate more lifting force inward--tightening the
turn--than it will upward. Tightening the turn only results in greater
loads, airspeed, and sink rate, and eventually could lead to failure of
the glider."
-Page 76, Learning to Fly Gliders by Bob Wander

If someone could point me to a good explanation of what's going on
aerdynamically
when an aircraft is in a spiral dive, I'd appreciate it.