Spot on Ian. The rules for the Air Cadets in the UK,
RAF rules, prohibit intentional spinning below 2500ft
in a glider. If you are still spinning you abandon
at this height and to my mind this is one of the most
sensible rules the AC have. Even that might be cutting
it a bit fine depending on how easy it is to actually
get out of the glider.


At 20:00 14 January 2005, Ian Strachan wrote:
In article , Andrew Warbrick
writes

snip

I won't let a spin demo go beyond the incipient stage
below 1500', but then, I'm a wimp.

Dear Andrew,

You are not a wimp, you are sensible and alive. And
so are your
students.

Having flown many spins in a military training environment,
there was
always a 'golden rule' on recovery heights. Heights
for spin entry and
minimum heights for recovery were always such that
if recovery had not
taken place, there was sufficient height to bale out
or eject as
appropriate. I speak of the fully-developed spin, of
course. Bale-out
heights were, to my recollection, something like 4000
ft for a Harvard
and Jet Provost and no less than 12000 ft for a Hunter.
I recall a
Hunter spin bottom out once at 6000 ft but passing
12 it was recovering
so the crew stuck with it. They started at 35k, by
the way!

It is this simple safety rule that some parts of the
gliding world seem
to have forgotten. An instructional cult seems to
have grown up in some
places that seems to think that low level spinning
is an absolute
necessity to teach student pilots of the dangers.
I instructed in
gliders for 35 years and IMHO, it is not necessary.
Recovery from
fully-developed spins can be taught at a safe height
just as in other
branches of aviation. There is nothing 'macho' about
spinning too low,
just a failure to understand the dynamics of the manoeuvre
and the
possible dangers not only to the instructor but to
the innocent student.

In any case, the emphasis in instruction should be
on quick recovery at
the wing-drop or incipient stage before the spin has
developed fully.
THAT should be practised very regularly and full multi-turn
spins only
rarely to show what can happen if the correct actions
are not taken
early enough.

I have even heard it said by some instructors that
deliberate low level
spinning is required because the student must experience
the visual
'ground rush' that he/she would get in a real situation
of an
inadvertent spin at low level. This is a good way
to an early grave,
particularly if something happens in one of these low
level spins such
as control failure, rudder cable slackness, or even
as simple as
someone's foot trapped the wrong side of a rudder pedal.

Also, spins are not regular reliable manoeuvres with
streamlined stable
airflow, they are complex interactions between turbulent
(stalled)
airflow, significant control moments and inertia/gyroscopic
effects.
Occasionally, for no particular reason other than statistics,
a spin
will go deeper into the stall (high alpha) than normal,
and recovery
will be delayed. Think of this before continuing a
deliberate
fully-developed spin below the height above the hard
stuff at which it
would be possible to bale out if the recovery were
to go wrong.

There are old pilots and there are bold pilots, but
there are few old,
bold, pilots. An aviation truism, I think. Me, I'm
old but still here
and enjoying cross country soaring!

--
Ian Strachan