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Nimbus 4DT accident 31 July 2000 in Spain.



 
 
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  #211  
Old July 6th 05, 12:15 PM
Andreas Maurer
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On 5 Jul 2005 21:16:28 GMT, "Ian Johnston"
wrote:


As Bert already stated: As long as you stay within the safe speed
range, there is no way to exceed the stress limits of the glider -
simply there isn't enough lift available.


Um, must check, but am pretty sure angle of attack influences lift as
well...


Indeed... but if you stay within the allowed speed range, you'll get a
stall if you pull too hard instead of overstressing the glider.


Besides: I've never seen an ASW-20 break a weak link on my home
airfield. We were using the blue ones for the 20.


So why would anyone fly with a 33% over strength link?


Ask Bert - he's got his reasons!


Unless the glider hits a gust, or the pilot pulls back too hard, or
the throttle of the winch suddenly shoots open or ...


Nope.
Either of these cases results either in a stall (pulling back too
hard) or overspeed... but does not lead to overstress. If you leave
the safe speed range, you pull the release... problem solved
immediately.


It's been ages since I did a winch launch in an SF34 and I really
can't remember much about it, but surely in that case the manufacturer
should be approached about changing the link officially, and issuing a
strengthening modification if required?


Indeed... but nothing has happened.

I wonder if Centrair changed this on the Alliance 34? I must check the
handbook - we have one at my current (all aerotow!) club.


Please do - I'd be interested if it's different for the Alliance 34.




Bye
Andreas
  #212  
Old July 7th 05, 11:22 PM
W.J. \(Bill\) Dean \(U.K.\).
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TOST WEAK LINKS.

The BGA now recommend as follows:

"The weak-link assembly incorporates a link to suit the glider being
launched (see Appendix E) and this remains with the parachute assembly.
(At some sites, a selection of weak-links, suitable for launching each of
the glider types in the club’s fleet, may remain permanently attached to the
parachute assembly. This is convenient, but calls for extra care in
ensuring that the correct link is chosen for each launch.)

"N.B. The Tost weak-link system is designed for use either with a single
link or with double links. If the double-link system is employed, it is
essential that the links are of different design (the main link having round
holes and the reserve link having slotted holes). Using two weak links,
each of the same design doubles the breaking load and renders the whole
assembly ineffective. Because of the risk of assembling two weak links
incorrectly, the single-link assembly is recommended as the more foolproof
system."

This is a quote from the BGA Winch Operators Manual , page 20,
http://www.gliding.co.uk/forms/clubm...t/winchops.pdf .

This recommendation was made after an Olympia 463 had structural failure
while being winch launched, and the pilot was killed. It was found that
there was weakness in the wings due to water ingress while in the trailer,
and a double strength weak link had been used; it was not established which
was the critical factor.

This accident was on 13th July 1996, BGA Ref: 79/96, AAIB Ref: EW/C96/7/5.

W.J. (Bill) Dean (U.K.)
Remove "ic" to reply.


"Ian Johnston" wrote in message
news:dzZo7CxomoOm-pn2-1IU6gvmrdIOd@localhost...

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




  #213  
Old July 11th 05, 01:29 PM
Mark Newton
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In article ,
"Bert Willing" wrote:

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.


With all due respect, Bert, if a weak link breakage creates a "critical"
situation, then the pilot has a training issue which needs to be
resolved. Sounds like some cable break practice is in order.

A launch isn't supposed to be a hazardous maneuver. If there's -any-
stage during the launch where someone wouldn't be comfortable with
the cable breaking, they need to find an instructor and get some
remedial training.

- mark
  #214  
Old July 11th 05, 01:58 PM
Bert Willing
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With all due respect from my side, I am well trained to aborted launches, to
high-speed passes below 20ft along a runway, and to circeling inverted.
However, each of these situations presents an elevated risk as the margin
for errors is reduced.

Now if you think that an aborted winch launch does not represent an elevated
risk - keep on dreaming.

--
Bert Willing

ASW20 "TW"


"Mark Newton" a écrit dans le message de
news: ...
In article ,
"Bert Willing" wrote:

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.


With all due respect, Bert, if a weak link breakage creates a "critical"
situation, then the pilot has a training issue which needs to be
resolved. Sounds like some cable break practice is in order.

A launch isn't supposed to be a hazardous maneuver. If there's -any-
stage during the launch where someone wouldn't be comfortable with
the cable breaking, they need to find an instructor and get some
remedial training.

- mark



  #215  
Old July 11th 05, 02:37 PM
Bill Daniels
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Bert, if you mean that the consequences of mishandling the controls is
higher during a aborted launch, I agree. However, that risk is more than
adequately managed through training. I feel confident that no unmanageable
situation will arise that will hurt me or my students as long as they fly
the way they were taught.

I can't say that about air tow. While all the risks involved in winch
launch are manageable, situations beyond my control can happen with air tow.

Bill Daniels


"Bert Willing" wrote in
message ...
With all due respect from my side, I am well trained to aborted launches,

to
high-speed passes below 20ft along a runway, and to circeling inverted.
However, each of these situations presents an elevated risk as the margin
for errors is reduced.

Now if you think that an aborted winch launch does not represent an

elevated
risk - keep on dreaming.

--
Bert Willing

ASW20 "TW"


"Mark Newton" a écrit dans le message de
news: ...
In article ,
"Bert Willing" wrote:

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.


With all due respect, Bert, if a weak link breakage creates a "critical"
situation, then the pilot has a training issue which needs to be
resolved. Sounds like some cable break practice is in order.

A launch isn't supposed to be a hazardous maneuver. If there's -any-
stage during the launch where someone wouldn't be comfortable with
the cable breaking, they need to find an instructor and get some
remedial training.

- mark




  #216  
Old July 11th 05, 02:45 PM
Mark Newton
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Posts: n/a
Default

In article ,
"Bert Willing" wrote:

With all due respect from my side, I am well trained to aborted launches, to
high-speed passes below 20ft along a runway, and to circeling inverted.
However, each of these situations presents an elevated risk as the margin
for errors is reduced.

Now if you think that an aborted winch launch does not represent an elevated
risk - keep on dreaming.


You didn't say "elevated risk". You said "critical situation," which
means something completely different to "elevated risk."

You are now pretending you didn't say that for the sole purpose of
taking umbrage at my comments, which you would have me believe are
wrong.

They are not wrong, and I stand by my comments. Perhaps if you
stood by yours instead of redefining the language you used we'd be able
to walk away from this without any disagreement.

- mark



"Mark Newton" a écrit dans le message de
news: ...
In article ,
"Bert Willing" wrote:

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.


With all due respect, Bert, if a weak link breakage creates a "critical"
situation, then the pilot has a training issue which needs to be
resolved. Sounds like some cable break practice is in order.

A launch isn't supposed to be a hazardous maneuver. If there's -any-
stage during the launch where someone wouldn't be comfortable with
the cable breaking, they need to find an instructor and get some
remedial training.

  #217  
Old July 11th 05, 03:08 PM
Bert Willing
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From an elevated risk, you have critical situations more easily happening.
Being well trained for interruptions is to my mind mandatory for anybody who
wants to make winch launching.

--
Bert Willing

ASW20 "TW"


"Mark Newton" a écrit dans le message de
news: ...
In article ,
"Bert Willing" wrote:

With all due respect from my side, I am well trained to aborted launches,
to
high-speed passes below 20ft along a runway, and to circeling inverted.
However, each of these situations presents an elevated risk as the margin
for errors is reduced.

Now if you think that an aborted winch launch does not represent an
elevated
risk - keep on dreaming.


You didn't say "elevated risk". You said "critical situation," which
means something completely different to "elevated risk."

You are now pretending you didn't say that for the sole purpose of
taking umbrage at my comments, which you would have me believe are
wrong.

They are not wrong, and I stand by my comments. Perhaps if you
stood by yours instead of redefining the language you used we'd be able
to walk away from this without any disagreement.

- mark



"Mark Newton" a écrit dans le message de
news:
...
In article ,
"Bert Willing" wrote:

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.

With all due respect, Bert, if a weak link breakage creates a
"critical"
situation, then the pilot has a training issue which needs to be
resolved. Sounds like some cable break practice is in order.

A launch isn't supposed to be a hazardous maneuver. If there's -any-
stage during the launch where someone wouldn't be comfortable with
the cable breaking, they need to find an instructor and get some
remedial training.



  #218  
Old July 11th 05, 03:13 PM
Don Johnstone
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A couple of points. After the first launch a weak link
is no longer at it's design strength, this reduces
with every launch. After 20 launches check the hole
in the centre of the tost weak link you will find it
is slightly oval and if you run your fingers along
the edges you will feel a depression. Unfortunately
many weak link 'holders' do not allow this check to
be made easily. A weak link will eventually break just
through 'normal' use if it is not replaced.

Up to the point at which the cable is at an angle of
more than 60 deg to the ground it is best if the cable
is released under full tension and the result dealt
with as a launch failure. What should be avoided is
lowering the nose early in the launch and pulling the
release especially if the launch is fast. It is very
easy for the parachute to open and fly and glider catch
up with it in those circumstances. I have seen the
cable wrapped round the wing when a pilot lowered the
nose because he was going to enter cloud and then pulled
the release. It should always be the other way round.
Lowering the nose when the glider is directly over
the winch, at the top of the climb is fine.

At 12:48 11 July 2005, Mark Newton wrote:
In article ,
'Bert Willing' wrote:

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.


With all due respect, Bert, if a weak link breakage
creates a 'critical'
situation, then the pilot has a training issue which
needs to be
resolved. Sounds like some cable break practice is
in order.

A launch isn't supposed to be a hazardous maneuver.
If there's -any-
stage during the launch where someone wouldn't be comfortable
with
the cable breaking, they need to find an instructor
and get some
remedial training.

- mark




 




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