The point is not 'does a Cof G hook cause a glider
to pitch up on tow'. The point is that if something
(an accidental pilot input, or a gust not corrected
for immediately because the pilot in momentarily distracted)
causes the glider to pitch up, will it carry on pitching
further up of its own accord, stay it the attitude
it has reached, or start to pitch back down of its
own accord? If the first of those three, how easy
is it to stop it pitching up? In the tests on the
Ka8, it seemed to me to be (almost?) impossible to
stop it, once the pitch angle exceeded about 30 degrees.


Don't know about most of the other types mentioned
in this thread. I've flown most of them, but even
I didn't include 'simulated tug upset whilst aerotowing
on C of G hook' in my normal type conversion exercises
- I think I would have found it hard to get a tow after
a while if I had.

Chris Rollings

At 00:00 08 January 2004, Mike Borgelt wrote:
On Tue, 6 Jan 2004 18:39:17 -0000, 'W.J. \(Bill\) Dean
\(U.K.\).'
wrote:

There have been several fatal 'aerotow upset' accidents
in the U.K. where
it seems certain that towing on a hook intended for
winch launching was a
factor.

These include:
Lasham new year 1963/4 Auster towing a Ka 6cr or Skylark
2 (I forget which),
Tug at Aboyne towing a Ka 6e,
Tugs (Super Cubs) towing K 18s at Portmoak and Dunstable
(within a few
months of each other), this led to the tests by Chris
Rollings, Verdun Luck
and Brian Spreckley at Booker see
http://www.glidingmagazine.com/ListF...Dtl.asp?id=327
.

Will that do, or how many others do you need?

So that is 4 in 40 years.

I think we've managed to kill that many towplane pilots
in Aus in the
last 15 in mid airs. At least one, maybe more would
have had a good
chance of survival if he had had a parachute. Something
that still
isn't required here.

The common link with the upsets mentioned seems to
be high wing wooden
gliders of low wing loading with deep fuselages. These
may be prone to
pitch up.

How long were the ropes in these situations?

Were there other circumstances that contributed?

Could they have been compensated for?

Any glider which launches well on a cable using the
aft launching hook, will
do the same behind a tug maybe killing the tug pilot
in the process. If
you really think that the glider pilot can control
or stop this process once
it starts, READ THE ARTICLE LINKED ABOVE; I suggest
that the pilots who
conducted those tests were more experienced, more current
and just plain
better than you.

You are suggesting that on a winch launch with much
higher loads in
the cable that these gliders are not controllable in
pitch?

To my certain knowledge it is possible to fit a forward
hook for aerotow to
the ASW 15, 17, ASK 18, ASW 19, 20, and 22 and the
Pegase; the ASK 21 and 23
and I think later types were fitted with it as standard.
I don't know of
any examples of these in club (as distinct from private
owner) use which
have not been modified.

I once owned an ASW20B. The GFA required the nose hook
to be fitted.
The Scheicher factory job on this was pitiful. Nobody
who bought
gliders from this batch of 6 put up with it. The releases
were taken
out and glassed over. When finishing the area it became
apparent that
the skin had been distorted by the additional release
bulkheads.
I don't ever recall the 20B having the slightest tendency
to pitch up
on aerotow on the belly release.

I have no aversion to properly engineered nose hooks
like in
Glasflugel and Schempp gliders but poorly designed
retrofits are a bad
idea particularly when no testing has been done on
that particular
type to see if indeed the 'solution' is effective
or even necessary.

The BGA considers 150 foot ropes acceptable. I consider
these
dangerously short, 200 feet is more like it with around
240 to 260
being much better.

Now consider this::

The world's politicians and bureaucrats are forever
looking for ways
to meddle in our lives to keep themselves in jobs.
If we place
requirements on our own operations (Like compulsory
nose releases)that
are not firmly founded in proper testing and rational
analysis we
weaken our case in resisting the idiot requirements
that come in a
never ending stream from these people.

I've yet to meet anyone who has flown on a 250 foot
rope who hasn't
admitted it was easier than on shorter ropes. When
I aerotow I want to
go soaring for maybe several hours and maybe the enviroment
on the
ground was stressful due to heat, humidity etc. I really
don't need a
5 minute adrenaline thrill to begin a cross country.
I would like
tows to be a non event. Longer ropes and tow pilots
who don't try to
thermal or do other sudden manouevers all aid in this.

The scariest tow I ever had was in my Salto (with nose
release) behind
a tow pilot who was not paying attention and who pulled
back hard on
leaving the ground as we encountered a gust leaving
me dangling low
from the end of the rope with decreasing airspeed.
Followed by a hard
push just as I was climbing slowly back up into station(low
tow)
leaving me very high followed by another hard pull
which put me very
low again wherupon I released and did a 180 back to
the strip.
Probably my shortest ever aerotow flight, closest to
disaster and on
the 130 foot or so ropes that were fashionable at the
time. I never
ever want to do this again. It was 30 years ago and
I remember it
clearly.
A rope twice as long likely would have made this a
non event.

The surprisingly easy tows were at Minden in an ASW20(belly
release)
through the rotor behind a 182. Long rope, no problem
at all.

Mike Borgelt