You have to be really careful with that. The worst thing that can happen in such
a recovery attempt is that you cross over from a positive spin into an inverted
spin. You will then think you are using recovery rudder but will have in-spin
rudder and will not recover from the spin. A good friend of mine died in just
such a situation, so be very careful with that.

Guenther
---------------------------------------------------
Dr. Guenther Eichhorn |
ADS Project Scientist | Phone: 617-495-7260
http://ads.harvard.edu | Fax: 617-496-7577
Smithsonian Astrophysical Observatory
60 Garden Street, MS-83, Cambridge, MA 02138, USA


In article 1060020100.727307@sj-nntpcache-5,
"John Harper" writes:
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.

We recovered by un-accelerating the spin (stick slowly back) then
a normal recovery. Even so it was pretty eye-popping and stomach
churning.

What would happen if you put in full anti-spin rudder while in a
stable accelerated spin? There seem to be four possibilities:

-- rudder stall
-- rudder/vertical stab falls off (shades of AA587)
-- the yaw is enough to break the spin (unstall the downgoing wing).
But the yaw will rotate the airplane in the vertical plane, so now the
nose will be pointing horizontally (or at least not nose down) with
some random bank angle (-180 - +180) when suddenly both wings
start flying again. This would really be the unusual attitude recovery
from Hell since you could really be absolutely anywhere and massively
disorientated with it.
-- the yaw isn't enough to break the spin (gentle rudder application).
This seems the most intriguing of all. Since you have airspeed, the rudder
will cause continuing yaw - I guess flattening the spin somewhat. But now
you have full anti-spin rudder which means that recovery options are
limited! Presumably recovery would be: full pro-spin rudder, stick back
to flatten the spin, then normal recovery - if you have any altitude
left.

Anyway I'd appreciate any comments from people who've tried any of
this - of course I'll be asking my instructor next time I see him too.

Thanks,

John
of all