Elevator power.
I may have missed the comment , but has anyone experienced
insufficient pitch down authority with full forward stick?
Our club had an incident in very rough conditions.
A PIK20B , belly hook, flown by a very experienced pilot,
was forced to release as a snatch caused an uncontrollable
pitchup. CG position not known, but the pilot was not large.
I did a calculation ( 30 years ago) to see if this was plausible
and indeed, if the CG was is near the aft limit with a PIK 20,
the transient pitchup couple in a snatch can probably overpower
full nose down elevator, thus initiating kiting.
There a re probably many other sailplanes susceptable to
this near the aft CG limit.
John firth

At 14:46 22 February 2014, Chris Rollings wrote:
At 14:28 22 February 2014, wrote:
On Saturday, February 22, 2014 1:58:28 AM UTC-6, GC wrote:
On 22/02/2014 16:17, Alan wrote:
=20
=20
=20
...You don't get kiting if you fly normal "high" tow behind the
towplan=
e,
=20
if you remain in control.
=20

=20
If you don't remain in control, starting from low tow is not
going
t=
o
=20
make a lot of difference.
=20
=20
=20
Experience (tens of thousands of aerotows) shows there is a
enormous=20
=20
difference. The inadequate control and time to go from high tow to=20
=20
kiting is orders of magnitude different from that required to g
from=20
=20
low tow to kiting. In fact, I've never heard of that eve
happening.=20
=20
Even with low time students. Kiting from high tow, however, is=20
=20
apparently so common as to need a whole new system of electronic=20
=20
whizzbangery and gallons of bandwidth to stop.
=20
=20
=20
If the tug has just lifted off, being in low tow sounds a bit
diffic=
ult,
=20
but that would be a particularly hazardous time.
=20
=20
=20
Yes. Liftoff is a time to be wary and we train accordingly.=20
=20
Nevertheless, all I can say is that low tow has prevented kiting=20
=20
accidents for many years. But don't take my word for it, keep this=20
=20
ridiculous discussion going with another screwball idea fo
pivoting,=20
=20
autoswivelling, pitch-sensing, stick-following nonsense.
=20
=20
=20
If the issue is serious - as it was in Australia - flying low to
will=20
=20
solve it. If it isn't - see my previous post.
=20
=20
=20
GC
=20
=20
=20

=20

=20
As for automatic methods to mitigate the problem, perhaps the
soluti=
on
=20
is not to modify tow planes, but to modify gliders. If the glider
is
=20
in a very high pitch attitude on tow, it might be a good time to
automa=
tically
=20
release.
=20

=20
Another modification might be to attach the tow rope to the top
of
t=
he glider.
=20
This would cause the tow force to pitch the glider down.
=20

=20

=20
Is this more of a problem when folks try to tow a slow glider
like
a=
2-33 at
=20
high speeds?
=20

=20
Alan
=20

GC is making his point for low tows very convincingly - why is he
immediate=
ly being ripped, Chris? Preparing and steering into low tow at a safe
alti=
tude, say 300',

If you wait 'till 300 feet the majority of the risk of a fatal kitin
incident is already behind you, once past 400 feet there is just abou
enough height for the tow pilot to recover.

means to mentally and then practically pushing the stick
fo=
rward and then holding in the low tow position. That's the opposite
maneuv=
er of what's leading to kiting. Drifting upwards takes you into the
prop
w=
ash and again, it takes forward stick pressure to move into the saf
spot.
=
That feedback mechanism is correctly maintaining the intended safe spot
wh=
ile in the normal tow position only visual cues are being used.
I think I'll give the low tow a try, if ever that polar vortex over
Chicago=
makes like tree...
Herb


I've been aware of the Australian preference for low tow and the reason
for it for over 30 years. My own flight testing and experience lead me t
believe that it does not significantly reduce the probability of a kitin
accident.