Keep your hand off the release handle during aero tows!

At 20:08 06 October 2013, John Galloway wrote:
At 15:34 06 October 2013, Bill D wrote:
On Sunday, October 6, 2013 2:53:16 AM UTC-6, Don
Johnstone wrote:


http://www.aaib.gov.uk/cms_resources.cfm?
file=3D/Schempp-Hirth%20Nimbus-3=
%20glider%20G-EENN%2006-13.pdf

There are so many bonehead screw-up's in this report it
makes one want to
c=
ry.

A few:

1. Not staging the glider so it points exactly at the winch.
2. A VERY long, slow, wobbly takeoff roll despite a 15kt
headwind
component=
..
3. A failure of the launch crew to stop the launch when a wing
went down.
4. Not releasing when it was clear the ground roll wasn't
precisely normal.

A dry Nimbus 3 launching into a 15 knot wind would likely
have aileron
cont=
rol BEFORE the roll began and should have been airborne in
around one
secon=
d after rolling about a glider length. Obvious point: Once
airborne,
there=
's no danger of dragging a wing.

At least you Brits are good at writing accident reports.


This tragic accident happened to one of my club colleagues.
With reference to the comments above:

1) There is nothing in the AAIB report to suggest that the glider
was not pointing at the winch. It was situated 30m from the
position that the cables had been drawn to and so the cable
would have been pulled over to the glider. It may have been
better to point the glider away from the winch and somewhat
towards the line of the cable. (Better still to have minimized
the bow in the cable by positioning the glider closer to the cable
and pulling the cable as straight as possible.)

2)There is nothing in the report to suggest "a very long, slow,
wobbly takeoff roll". I can report from personal experience of
many launches from the winch and professional winch-driver
involved that this is a very powerful rapidly accelerating winch.
The AAIB report makes direct reference to the fact that the
winch was operated correctly according to the manufacturer.
The cable released at 4 seconds from the start of the launch
with the glider already airborne and unrecoverable so that
leaves no time for a takeoff roll as characterised above.

3) There is no suggestion in the AAIB report of a "failure" by the
ground crew to stop the launch. This point is specifically
addressed:

"On this occasion both the wing holder and the launch signaller
saw the wing touch the ground but events then developed
quickly, so it is unlikely that either of them had time to consider
and make a ‘stop’ signal. Therefore, the responsibility to
release the cable would have to rest with the pilot"

4) Agreed - to release the cable as soon as the wing cannot be
kept level is vital.

John Galloway

All John says is absolutely correct. The sad fact is that this type of
accident occurs on a fairly regular basis and as yet no one has come up
with a plausible cause. What is clear that the wing drop is a symptom and
requires that the glider is released very early which is why the hand
should be on the release. A similar accident happened at my club a month
back involving a Discus, in that case the pilot was unhurt but the glider
was written off.
What is clear is that once the glider starts to yaw nothing on this earth
is going to stop it except contact with the ground so early release, to
mitigate the inevitable accident, is essential.

Not a single instructor, check pilot or examiner I flew with in England and Germany ever suggested/required holding the release on a winch launch. I was always told to keep my hand close, but not wrapped around the knob.

Worked well every time.

On Sunday, October 6, 2013 4:54:35 PM UTC-6, Terry Pitts wrote:
Not a single instructor, check pilot or examiner I flew with in England and Germany ever suggested/required holding the release on a winch launch. I was always told to keep my hand close, but not wrapped around the knob.



Worked well every time.

I think "touching but not gripping" is the best advice.

On Sunday, October 6, 2013 4:05:57 PM UTC-6, Don Johnstone wrote:

All John says is absolutely correct. The sad fact is that this type of

accident occurs on a fairly regular basis and as yet no one has come up

with a plausible cause. What is clear that the wing drop is a symptom and

requires that the glider is released very early which is why the hand

should be on the release. A similar accident happened at my club a month

back involving a Discus, in that case the pilot was unhurt but the glider

was written off.

What is clear is that once the glider starts to yaw nothing on this earth

is going to stop it except contact with the ground so early release, to

mitigate the inevitable accident, is essential.



The sad fact is the UK hasn't figured out the cause - everyone else has.

At 16:52 08 October 2013, Bill D wrote:
On Sunday, October 6, 2013 4:05:57 PM UTC-6, Don
Johnstone wrote:

All John says is absolutely correct. The sad fact is that this
type of
Which is? Come on, lets hear it Bill! BTW it is not always
possible to launch straight into wind due to the layout of some
glider sites. Wing drops are usually caused by gusts, which are
usually not predictable. The only safe way of dealing with them
is to release as soon as the wing starts to drop and before it
touches the ground. Releasing under tension often requires a
good firm pull, so a good firm grip on the release knob (or an
extension cable if necessary) is essential.

Derek Copeland


accident occurs on a fairly regular basis and as yet no one
has come up

with a plausible cause. What is clear that the wing drop is a
symptom and

requires that the glider is released very early which is why
the hand

should be on the release. A similar accident happened at my
club a month

back involving a Discus, in that case the pilot was unhurt but
the glider

was written off.

What is clear is that once the glider starts to yaw nothing on
this earth

is going to stop it except contact with the ground so early
release, to

mitigate the inevitable accident, is essential.



The sad fact is the UK hasn't figured out the cause - everyone
else has.

Bill,

I have watched this tread with some interest. Just for the record, what
authority are you on the subject? I find it very interesting that you are
so dismissive of the hours of research done by trained professionals who
have considerable amount of date and past cases to work with.

If this is your humble opinion, look after yourself, but keep your opinions
to yourself. If how ever you are some sort of authority in the subject, I
will bow to your superior judgement.

Regards,

Justin


At 16:52 08 October 2013, Bill D wrote:
On Sunday, October 6, 2013 4:05:57 PM UTC-6, Don Johnstone wrote:

All John says is absolutely correct. The sad fact is that this type of

accident occurs on a fairly regular basis and as yet no one has come up

with a plausible cause. What is clear that the wing drop is a symptom
and

requires that the glider is released very early which is why the hand

should be on the release. A similar accident happened at my club a
month

back involving a Discus, in that case the pilot was unhurt but the
glider

was written off.

What is clear is that once the glider starts to yaw nothing on this
earth

is going to stop it except contact with the ground so early release, to

mitigate the inevitable accident, is essential.



The sad fact is the UK hasn't figured out the cause - everyone else has.

Time for pogo sticks.

The idea of launching a glider by having someone run the wing originated with wooden gliders and quite low speeds for stall and aileron effectiveness. Those speeds have gradually crept up through the years, to the point that really nobody can run the wing of a modern glider, with waterballast, and anything less than 10 mph straight down the runway, to the point of aileron effectiveness. Mostly we hope that the wing runner lets go, with the aircraft in balanced position, and it picks up speed faster than one wing drops. That often isn't true.

For airtows the results are usually just some scraped gel coat; sometimes a collision with a runway light, and occasionally a ground loop. There have been accidents where wing down gliders hurt bystanders, the Tonopah 15 m nationals being the one I remember best.

Clearly, for winching, wing-down events are much more serious.

The answer: either retractable or disposable pogo sticks on the wingtips, or mid-wing. Something that keeps the wings level to 25 mph and then either drops off or retracts into the wing.

Reading the UK Nimbus 3 report, it would seem that a video link between winch driver and launch point would be a good idea, and quite cheap with current technology. It would cut a crucial second or so out of the abort-the-launch loop

John Cochrane

JC wrote:
The answer: either retractable or disposable pogo sticks on the wingtips, or mid-wing. Something that keeps the wings level to 25 mph and then either drops off or retracts into the wing.

Along this line, many self-launchers have small in-line skate wheels on the wingtips so they can start with the wing already touching the runway. Perhaps a simple retrofit could save your gel-coat (or your life).
As for dropable pogo sticks, hang gliders that aerotow often use a 3 wheeled launch cart(with a wide stance)to keep the wing level until it flies away from the cart. No one wants to lift their sailplane into a cart so this won't work for us. :-)

On Wednesday, October 9, 2013 12:53:26 PM UTC-4, Soartech wrote:
Along this line, many self-launchers have small in-line
skate wheels on the wingtips so they can start with the
wing already touching the runway. Perhaps a simple retrofit
could save your gel-coat (or your life).

Without a steerable tail-wheel and enough tail weight to make
it actually steer, tip wheels merely avoid scraping the wingtip
finish as you ground-loop.

As some who have observed interesting Whale take-offs can attest ;-)

OTH, as it has a proper steerable tail-wheel, I normally
take off without a wing-tip runner in Antares...

Wingtip wheels would help airtow wing drops -- and encourage a lot more toughing it out and waiting for the wing to come up. Especially with water, and double especially with half water, they're not ideal. I'm not a winch expert, but I assume wingtip wheels would be of little help in those accidents..


John Cochrane