"John Harper" wrote in message news:1060020100.727307@sj-nntpcache-5...
Did my first accelerated spins yesterday (in a Grob). Woohoo.
Unfortunately my stomach wasn't wild about them, so I only
did a couple. But I did get to thinking about the aerodynamics
of them (maybe as a way to forget my nausea!), and I had a
couple of questions which I wondered if anyone here can answer.............


Two modes of spinning that inhibit (if not totally block) your ability
to recover are Accelerated, and Flat. It is always best to take the
spin out of these modes and back to a normal un-accelerated, not flat
spin before recovering.

Accelerated spins, as you have seen, rotate much faster than
un-accelerated spins. Available rudder on a given aircraft may not be
sufficient to cancel yaw in this situation. Once the spin is
converted to a normal (un-accelerated) spin (stick back in the case of
an upright, positive spin), normal recovery methods can be used.

Upright positive flat spins are technically "unrecoverable" (without
first converting them to normal spins) in many aircraft. A standard
tail configuration with the horizontal stab and elevator located below
the rudder, does not allow sufficient airflow to get to the rudder for
normal operation in these spins. This means that the rudder will
loose much of its effectiveness in a flat spin. Since the flat spin
also rotates faster and has a larger yaw component, the rudder will
probably be nearly useless while the spin is flat. The correct
proceedure requires power be set to idle, hold the stick back so there
will not be acceleration, and roll aileron into the direction of spin
to return to a normal spin condition. Once this has been accomplished
the spin can be stopped normally. The faster rotation rate (inertia)
will still slow the recovery somewhat.


Dave Swartz
Fort Lauderdale, Florida
http://www.FlightFantastic.US