Don Johnstone wrote:
At 21:12 01 March 2006, Marc Ramsey wrote:
Stefan wrote:
Chuck Griswold wrote:

Why would you use tail
ballast to instruct
aerobatics?
You wouldn't have guessed it: To do simple erect spins.

I am aware that some pilots claim to have been able
to spin the 21
without the tail ballast. I'm not among them.
Technique that has worked for me in just about every
21 or 103 I've
tried it (and I weigh 95 kg or so):

Establish a stable slip, nose slightly higher than
normal, for purposes
of this discussion, left wing down. Apply full left
rudder, at same
time move stick fully right and back. No need to jerk
the controls,
quick smooth movements are all that is needed. You
might have to play
with the slip angle a bit...

Yep that will work as will sitting a Grob 103 on the
stall buffet and applying full left rudder and full
right aileron and stick back. Will not work to the
right very well because of the asymetric nature of
the Grob rudder and the most you will get from either
technique is half a turn unless the front cockpit weight
is very low. The initial pitch down and roll can be
very dramatic but after that it is very benign.



There is a pretty good web site on this topic at
http://ocglider.com/Grob_spin_avis.htm
worth a look.