Nimbus 4DT accident 31 July 2000 in Spain.

On Tue, 5 Jul 2005 10:27:40 UTC, "Bert Willing"
wrote:

I take of with my ASW20 on a black link. And it's not the winch driver who
decides about this.

If that is the correct link for the glider, then fine. If it's not,
and I were either launch marshall or winch driver, then I can assure
you that I, personally, would have nothing to do with launching you.

The correct weak link for an ASH-25, as specified by the designer and
manufacturer, is brown, 850dN.

Ian


--

On Tue, 5 Jul 2005 10:54:57 UTC, Bill Gribble
wrote:

As far as character is concerned, I'm pretty certain the last time I
launched an ASH25 (as signaller, at least) it was on a black link. Or it
would have been if that was what the pilot had asked for.

Would you launch a K8 on a black link if the pilot requested it? In
the old days, would you have signalled "all out" to the winch driver
if the pilot requested it and despite open brakes? Would you launch a
glider with a faulty back-release if the pilot said "Oh, that's OK,
just launch me."

I don't think /anyone/ on an airfield is entitled to overlook a clear
safety risk of this sort.

Ian

The book says it should be red. And as long as I'm operating my private
ship, it's me who is responsible for which weak link I ask for. Launch
marshals may comment on that, but not decide. Winch drivers are told which
glider is on the other side of the rope, and when they should start to pull.

I have seen (from the ground) quite a couple of critical situations
resulting from fatigued weak link breakage, and I prefer to watch angle of
attack and speed, and pull the knob myself if necessary. And even if the
book doesn't like it, that even works while being launched into thermals or
Mistral rotors.

--
Bert Willing

ASW20 "TW"


"Ian Johnston" a écrit dans le message de news:
dzZo7CxomoOm-pn2-DhT3lGVC8vpw@localhost...
On Tue, 5 Jul 2005 10:27:40 UTC, "Bert Willing"
wrote:

I take of with my ASW20 on a black link. And it's not the winch driver
who
decides about this.

If that is the correct link for the glider, then fine. If it's not,
and I were either launch marshall or winch driver, then I can assure
you that I, personally, would have nothing to do with launching you.

The correct weak link for an ASH-25, as specified by the designer and
manufacturer, is brown, 850dN.

Ian


--

Is there any commonly known way to test a weak
link non-destructively (other than launching a glider)?

At 13:06 05 July 2005, Bert Willing wrote:
The book says it should be red. And as long as I'm
operating my private
ship, it's me who is responsible for which weak link
I ask for. Launch
marshals may comment on that, but not decide. Winch
drivers are told which
glider is on the other side of the rope, and when they
should start to pull.

I have seen (from the ground) quite a couple of critical
situations
resulting from fatigued weak link breakage, and I prefer
to watch angle of
attack and speed, and pull the knob myself if necessary.
And even if the
book doesn't like it, that even works while being launched
into thermals or
Mistral rotors.

--
Bert Willing

ASW20 'TW'


'Ian Johnston' a écrit dans le message de news:
dzZo7CxomoOm-pn2-DhT3lGVC8vpw@localhost...
On Tue, 5 Jul 2005 10:27:40 UTC, 'Bert Willing'
wrote:

I take of with my ASW20 on a black link. And it's
not the winch driver
who
decides about this.

If that is the correct link for the glider, then fine.
If it's not,
and I were either launch marshall or winch driver,
then I can assure
you that I, personally, would have nothing to do with
launching you.

The correct weak link for an ASH-25, as specified
by the designer and
manufacturer, is brown, 850dN.

Ian


--




Mark J. Boyd

On Tue, 5 Jul 2005 12:45:41 UTC, "Bert Willing"
wrote:

The book says it should be red.

Which is 750dN, and you are launching with black, which is 1000dN.
That 250dN (33%) extra probably represents around 50 - 75% overload at
the wing fuselage junction. With all due respect, that's an insane
risk to take. Would you fly your glider with a cockpit load or ballast
250kg above the maximum permitted? Would your insurance company let
you? Would your national aviation authority let you?

And as long as I'm operating my private
ship, it's me who is responsible for which weak link I ask for.

Indeed, but as long as you are being launched by other people it is
their responsibility to assess your request and, if it's unsafe,
refuse it, just as it would be their duty to refuse to launch you if
you were drunk, or if your airbrakes were open.

Launch
marshals may comment on that, but not decide.

On the contrary, I believe that launch marshalls /should/ decide.
Nobody should be complicit in dangerous behaviour of this sort.

I have seen (from the ground) quite a couple of critical situations
resulting from fatigued weak link breakage, and I prefer to watch angle of
attack and speed, and pull the knob myself if necessary.

Well good luck - and here's hoping that by the time you pull the knob
the hook (and wheel on an ASW20?) isn't on its way to the ground along
with sundry control connections. That's if a good unexpected bump on
the way up hasn't taken your wings off.

Ian

First of all, if the weak link breaks, the overload would be 33% (I don't
know what you do to get 50-75%).
Secondly, the point is not to get the weak link breaking at all. As long as
you stay within the limits of max winch tow speed, the overload is zero.
You might be not aware, but there is a good number of clubs who don't use
any weak links _at all_ (or launch marshalls...).

And I stand my point - it is my responsability to deal with my security, my
insurance and my legal authorities. Good luck? Go tell that to those who had
an accident initiated by a weak link failure. After 25 years of flying, I
still have to learn about a case of structural overload during winch launch.
However, I can accept that if I don't fly my glider, that I am imposed to
the owner's rules.

--
Bert Willing

ASW20 "TW"


"Ian Johnston" a écrit dans le message de news:
dzZo7CxomoOm-pn2-8g13dep07KYM@localhost...
On Tue, 5 Jul 2005 12:45:41 UTC, "Bert Willing"
wrote:

The book says it should be red.

Which is 750dN, and you are launching with black, which is 1000dN.
That 250dN (33%) extra probably represents around 50 - 75% overload at
the wing fuselage junction. With all due respect, that's an insane
risk to take. Would you fly your glider with a cockpit load or ballast
250kg above the maximum permitted? Would your insurance company let
you? Would your national aviation authority let you?

And as long as I'm operating my private
ship, it's me who is responsible for which weak link I ask for.

Indeed, but as long as you are being launched by other people it is
their responsibility to assess your request and, if it's unsafe,
refuse it, just as it would be their duty to refuse to launch you if
you were drunk, or if your airbrakes were open.

Launch
marshals may comment on that, but not decide.

On the contrary, I believe that launch marshalls /should/ decide.
Nobody should be complicit in dangerous behaviour of this sort.

I have seen (from the ground) quite a couple of critical situations
resulting from fatigued weak link breakage, and I prefer to watch angle
of
attack and speed, and pull the knob myself if necessary.

Well good luck - and here's hoping that by the time you pull the knob
the hook (and wheel on an ASW20?) isn't on its way to the ground along
with sundry control connections. That's if a good unexpected bump on
the way up hasn't taken your wings off.

Ian

On Tue, 5 Jul 2005 15:59:24 UTC, M B
wrote:

Is there any commonly known way to test a weak
link non-destructively (other than launching a glider)?

The Tost system uses two in parallel, one slightly longer than the
other. Whoever hooks up the glider should always check that both links
are intact and that only one is taking the load.

Ian

--

Ian Johnston wrote:

On Tue, 5 Jul 2005 15:59:24 UTC, M B
wrote:

Is there any commonly known way to test a weak
link non-destructively (other than launching a glider)?

The Tost system uses two in parallel, one slightly longer than the
other. Whoever hooks up the glider should always check that both links
are intact and that only one is taking the load.

Ian

--
We've gone to using a single TOST weak link. Over the years, the metal
sleeve gets dented, making inspection suspect without a time consuming
disassembly. A few times the links part without any warning that perhaps
the first may have failed previously. We have also had both fail at the
same time when going through a sharp wind gradient. We replaced both and
broke both on the very next launch through this sharp gradient. At the
price of the weak links, consuming one at a time, rather than two, just
makes more sense.

NDT would work if you jigged up an accurate test bed. I would be more
concerned with rope weak links used in aerotowing than TOST weak links if I
wanted to test something. From many years of observation I'm pretty
confident that the TOST links perform as expected.

Frank

Bert Willing wrote:

First of all, if the weak link breaks, the overload would be 33% (I don't
know what you do to get 50-75%).
Secondly, the point is not to get the weak link breaking at all. As long
as you stay within the limits of max winch tow speed, the overload is
zero. You might be not aware, but there is a good number of clubs who
don't use any weak links _at all_ (or launch marshalls...).

And I stand my point - it is my responsability to deal with my security,
my insurance and my legal authorities. Good luck? Go tell that to those
who had an accident initiated by a weak link failure. After 25 years of
flying, I still have to learn about a case of structural overload during
winch launch. However, I can accept that if I don't fly my glider, that I
am imposed to the owner's rules.

Interesting. I find it odd that German rules, which are often clearly more
strict than other soaring environs, would allow this departure.

Frank

On Tue, 5 Jul 2005 16:35:18 UTC, "Bert Willing"
wrote:

First of all, if the weak link breaks, the overload would be 33% (I don't
know what you do to get 50-75%).

I said already. The overload on the aircraft as a whole is 33%,
However, that's a lot more than 1.3G structurally, because at 1.3G
much of the applied load is on, and then balanced by, the wings.

Secondly, the point is not to get the weak link breaking at all. As long as
you stay within the limits of max winch tow speed, the overload is zero.

Except you can stay within that limit with 250dN load more on the
winch hook and the wing attachments than the designers of the aircraft
thought safe.

Would you fly with 250kg of unofficial extra ballast in the fuselage?

You might be not aware, but there is a good number of clubs who don't use
any weak links _at all_ (or launch marshalls...).

Then they are idiots.

Ian