wings came off

[hinterland]

In French Alps last week end..

http://www.ledauphine.com/isere-sud/2010/09/20/coupe-icare-un-planeur-se-disloque-en-plein-vol

[Berry[_2_]]

In article >,
"hinterland" > wrote:

> http://www.ledauphine.com/isere-sud/2010/09/20/coupe-icare-un-planeur-se-dislo
> que-en-plein-vol

What sort of glider was that? Wings looked sort of like an Lo-100, but
the fuselage looked like a pod-and-boom affair. One of the wings
appeared to chop off the tailboom as the fuselage was tumbling.

Good thing it was equipped with a ballistic chute. I think it might have
been hard to get out of with it tumbling like that and not too high
either.

[Markus Graeber]

It was the new Archaeopteryx high tech hang glider/microlift glider
(http://www.ruppert-composite.ch/english/index.html):

L/D 28:1, VNE 130 kph, + 5.3 g/- 2.65 g, and, as demonstrated, a
balistic recovery chute :-) Very interesting concept that puts it
between a hang glider and a full fledged glider as we know it.

The pilot was doing acro, after some spinning he was coming out of his
second loop and must have pulled a little too hard on the stick during
recovery... Here a better view of the sequence of events:

http://www.youtube.com/watch?v=AgOR5PLTn84

Markus

On Sep 20, 5:11*pm, Berry > wrote:
> In article >,
>
> *"hinterland" > wrote:
> >http://www.ledauphine.com/isere-sud/2010/09/20/coupe-icare-un-planeur...
> > que-en-plein-vol
>
> What sort of glider was that? Wings looked sort of like an Lo-100, but
> the fuselage looked like a pod-and-boom affair. One of the wings
> appeared to chop off the tailboom as the fuselage was tumbling.
>
> Good thing it was equipped with a ballistic chute. I think it might have
> been hard to get out of with it tumbling like that and not too high
> either.

[Mike the Strike]

On Sep 20, 3:11*pm, Berry > wrote:
> In article >,
>
> *"hinterland" > wrote:
> >http://www.ledauphine.com/isere-sud/2010/09/20/coupe-icare-un-planeur...
> > que-en-plein-vol
>
> What sort of glider was that? Wings looked sort of like an Lo-100, but
> the fuselage looked like a pod-and-boom affair. One of the wings
> appeared to chop off the tailboom as the fuselage was tumbling.
>
> Good thing it was equipped with a ballistic chute. I think it might have
> been hard to get out of with it tumbling like that and not too high
> either.

Since Coupe Icare is primarily a hang-glider/paraglider event, I think
it is safe to assume that this was an ultralight, possibly foot-
launched aircraft.

No doubt we will be further enlightened by our European colleagues in
due course.

Mike

Mike

[Martin Gregorie[_5_]]

On Mon, 20 Sep 2010 15:46:19 -0700, Mike the Strike wrote:

> No doubt we will be further enlightened by our European colleagues in
> due course.
>
Here you go: http://www.ruppert-composite.ch/english/


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Mike the Strike]

On Sep 20, 3:46*pm, Mike the Strike > wrote:
> On Sep 20, 3:11*pm, Berry > wrote:
>
> > In article >,
>
> > *"hinterland" > wrote:
> > >http://www.ledauphine.com/isere-sud/2010/09/20/coupe-icare-un-planeur....
> > > que-en-plein-vol
>
> > What sort of glider was that? Wings looked sort of like an Lo-100, but
> > the fuselage looked like a pod-and-boom affair. One of the wings
> > appeared to chop off the tailboom as the fuselage was tumbling.
>
> > Good thing it was equipped with a ballistic chute. I think it might have
> > been hard to get out of with it tumbling like that and not too high
> > either.
>
> Since Coupe Icare is primarily a hang-glider/paraglider event, I think
> it is safe to assume that this was an ultralight, possibly foot-
> launched aircraft.
>
> No doubt we will be further enlightened by our European colleagues in
> due course.
>
> Mike
>
> Mike

Indeed it was an Archaeopteryx - the schedule had two of them flying
there. Good photos and video on their website:

http://www.ruppert-composite.ch/english/index.html

Hope that their naming it after an extinct Jurassic flying dinosaur
didn't jinx it!

Mike

[Westbender]

On Sep 20, 5:42*pm, Markus Graeber > wrote:
> It was the new Archaeopteryx high tech hang glider/microlift glider
> (http://www.ruppert-composite.ch/english/index.html):
>
> L/D 28:1, VNE 130 kph, + 5.3 g/- 2.65 g, and, as demonstrated, a
> balistic recovery chute :-) *Very interesting concept that puts it
> between a hang glider and a full fledged glider as we know it.
>
> The pilot was doing acro, after some spinning he was coming out of his
> second loop and must have pulled a little too hard on the stick during
> recovery... Here a better view of the sequence of events:
>
> http://www.youtube.com/watch?v=AgOR5PLTn84
>
> Markus
>
> On Sep 20, 5:11*pm, Berry > wrote:
>
>
>
> > In article >,
>
> > *"hinterland" > wrote:
> > >http://www.ledauphine.com/isere-sud/2010/09/20/coupe-icare-un-planeur....
> > > que-en-plein-vol
>
> > What sort of glider was that? Wings looked sort of like an Lo-100, but
> > the fuselage looked like a pod-and-boom affair. One of the wings
> > appeared to chop off the tailboom as the fuselage was tumbling.
>
> > Good thing it was equipped with a ballistic chute. I think it might have
> > been hard to get out of with it tumbling like that and not too high
> > either.- Hide quoted text -
>
> - Show quoted text -

Looks to me like the first loop would have been pulling more G's than
the second. Higher speed, harder pull. Perhaps the damage was done on
the first one.

[Berry[_2_]]

In article
>,
Mike the Strike > wrote:

> On Sep 20, 3:11*pm, Berry > wrote:
> > In article >,
> >
> > *"hinterland" > wrote:
> > >http://www.ledauphine.com/isere-sud/2010/09/20/coupe-icare-un-planeur...
> > > que-en-plein-vol
> >
> > What sort of glider was that? Wings looked sort of like an Lo-100, but
> > the fuselage looked like a pod-and-boom affair. One of the wings
> > appeared to chop off the tailboom as the fuselage was tumbling.
> >
> > Good thing it was equipped with a ballistic chute. I think it might have
> > been hard to get out of with it tumbling like that and not too high
> > either.
>
> Since Coupe Icare is primarily a hang-glider/paraglider event, I think
> it is safe to assume that this was an ultralight, possibly foot-
> launched aircraft.
>
> No doubt we will be further enlightened by our European colleagues in
> due course.
>
> Mike
>
> Mike

Ah, I see now. Thanks.

Pretty little machine. Must be great fun to soar those microlift
machines. Not so good for aerobatics, apparently.

Hey, make these gliders cheap enough and we'll have a new "extreme
sport" with competitors vying to produce the most spectacular in-flight
breakup.

[Bart[_4_]]

On Sep 21, 11:05*am, Berry > wrote:
> Hey, make these gliders cheap enough and we'll have a new "extreme
> sport" *with competitors vying to produce the most spectacular in-flight
> breakup.

If they use weak links instead of spar pins, the aircraft could even
be reused!

B.

[sisu1a]

> If they use weak links instead of spar pins, the aircraft could even
> be reused!


Shear humor! :o

[Ramy]

On Sep 21, 11:21*am, sisu1a > wrote:
> > If they use weak links instead of spar pins, the aircraft could even
> > be reused!
>
> Shear humor! *:o

Another video showing the deployment:
http://www.youtube.com/watch?v=-j5N9SJjuU4&feature=player_embedded#
It took only 6 seconds from breakup to full canopy!! Try this with a
conventional backpack chute...
Another proof of the value of integrated ballistic chute.

Ramy

[Larry Goddard]

"Westbender" > wrote in message
:

> On Sep 20, 5:42*pm, Markus Graeber > wrote:
> > It was the new Archaeopteryx high tech hang glider/microlift glider
> > (http://www.ruppert-composite.ch/english/index.html):
> >
> > L/D 28:1, VNE 130 kph, + 5.3 g/- 2.65 g, and, as demonstrated, a
> > balistic recovery chute :-) *Very interesting concept that puts it
> > between a hang glider and a full fledged glider as we know it.
> >
> > The pilot was doing acro, after some spinning he was coming out of his
> > second loop and must have pulled a little too hard on the stick during
> > recovery... Here a better view of the sequence of events:
> >
> > http://www.youtube.com/watch?v=AgOR5PLTn84
> >
> > Markus
> >
> > On Sep 20, 5:11*pm, Berry > wrote:
> >
> >
> >
> > > In article >,
> >
> > > *"hinterland" > wrote:
> > > >http://www.ledauphine.com/isere-sud/2010/09/20/coupe-icare-un-planeur...
> > > > que-en-plein-vol
> >
> > > What sort of glider was that? Wings looked sort of like an Lo-100, but
> > > the fuselage looked like a pod-and-boom affair. One of the wings
> > > appeared to chop off the tailboom as the fuselage was tumbling.
> >
> > > Good thing it was equipped with a ballistic chute. I think it might have
> > > been hard to get out of with it tumbling like that and not too high
> > > either.- Hide quoted text -
> >
> > - Show quoted text -
>
> Looks to me like the first loop would have been pulling more G's than
> the second. Higher speed, harder pull. Perhaps the damage was done on
> the first one.

Before the loops, I noticed that he did a rather significant negative
pushover.... Wonder if that might have weakened something...

Larry

[tienshanman]

In French Alps last week end..

http://www.ledauphine.com/isere-sud/2010/09/20/coupe-icare-un-planeur-se-disloque-en-plein-vol

This embarrassing aerial crack up is not a very good advertisement for any glider, but especially not for an UL that sells for $85,000.....(basic glider + fairing for enclosed cockpit) http://www.ruppert-composite.ch/downloads/preisliste2010.pdf

[John Smith]

tienshanman wrote:
> This embarrassing aerial crack up is not a very good advertisement for
> any glider, but especially not for an UL that sells for

You can break *any* aircraft by pulling too many Gs.

[Bruce Hoult]

On Sep 22, 7:33*pm, John Smith > wrote:
> tienshanman wrote:
> > This embarrassing aerial crack up is not a very good advertisement for
> > any glider, but especially not for an UL that sells for
>
> You can break *any* aircraft by pulling too many Gs.

It's got to be especially tricky when you've only got a 70 knot Vne to
work with.

We think we have to be careful when we're in a glider with only a 108
or 119 knot Vne!

[Don Johnstone[_4_]]

At 07:33 22 September 2010, John Smith wrote:
>tienshanman wrote:
>> This embarrassing aerial crack up is not a very good advertisement for
>> any glider, but especially not for an UL that sells for
>
>You can break *any* aircraft by pulling too many Gs.

I think you might find that most of the modern gliders we fly are capable
of withstanding more "G" than the human body can take.
Overstressing a modern glider is unlikely to result in a catastrophic
failure unless there is already damage.
Remember the placarded limits have nothing to do with the design limits of
the glider. Most are placarded to +3.5 and -1 which was an arbitary figure
set by the LBA. Most gliders of the type we now fly exceed this level.
That is not to say that people should fly outside the placarded limits.

[Derek C]

On Sep 21, 8:51*pm, "Larry Goddard" > wrote:
> "Westbender" > wrote in message
>
> :
>
>
>
>
>
> > On Sep 20, 5:42*pm, Markus Graeber > wrote:
> > > It was the new Archaeopteryx high tech hang glider/microlift glider
> > > (http://www.ruppert-composite.ch/english/index.html):
>
> > > L/D 28:1, VNE 130 kph, + 5.3 g/- 2.65 g, and, as demonstrated, a
> > > balistic recovery chute :-) *Very interesting concept that puts it
> > > between a hang glider and a full fledged glider as we know it.
>
> > > The pilot was doing acro, after some spinning he was coming out of his
> > > second loop and must have pulled a little too hard on the stick during
> > > recovery... Here a better view of the sequence of events:
>
> > >http://www.youtube.com/watch?v=AgOR5PLTn84
>
> > > Markus
>
> > > On Sep 20, 5:11*pm, Berry > wrote:
>
> > > > In article >,
>
> > > > *"hinterland" > wrote:
> > > > >http://www.ledauphine.com/isere-sud/2010/09/20/coupe-icare-un-planeur...
> > > > > que-en-plein-vol
>
> > > > What sort of glider was that? Wings looked sort of like an Lo-100, but
> > > > the fuselage looked like a pod-and-boom affair. One of the wings
> > > > appeared to chop off the tailboom as the fuselage was tumbling.
>
> > > > Good thing it was equipped with a ballistic chute. I think it might have
> > > > been hard to get out of with it tumbling like that and not too high
> > > > either.- Hide quoted text -
>
> > > - Show quoted text -
>
> > Looks to me like the first loop would have been pulling more G's than
> > the second. Higher speed, harder pull. Perhaps the damage was done on
> > the first one.
>
> Before the loops, I noticed that he did a rather significant negative
> pushover.... Wonder if that might have weakened something...
>
> Larry- Hide quoted text -
>
> - Show quoted text -


Just looked like a normal push over to gain speed for an aerobatic
manouevre to me. This is a foot launched glider, so must be much more
lightly built than a normal glider.

Derek C

[kirk.stant]

On Sep 22, 6:05*am, Don Johnstone > wrote:
> At 07:33 22 September 2010, John Smith wrote:
>
> >tienshanman wrote:
> >> This embarrassing aerial crack up is not a very good advertisement for
> >> any glider, but especially not for an UL that sells for
>
> >You can break *any* aircraft by pulling too many Gs.
>
> I think you might find that most of the modern gliders we fly are capable
> of withstanding more "G" than the human body can take.
> Overstressing a modern glider is unlikely to result in a catastrophic
> failure unless there is already damage.
> Remember the placarded limits have nothing to do with the design limits of
> the glider. Most are placarded to +3.5 and -1 which was an arbitary figure
> set by the LBA. Most gliders of the type we now fly exceed this level.
> That is not to say that people should fly outside the placarded limits.

Curious statement. Cite, please? Humans can take a lot of Gs,
especially when reclined - I've done over 9 g instantaneous in a Swift
and sustained 9 g for 20 some odd seconds in a centrifuge and wouldn't
want to try it in my LS6!

I'm pretty sure a hard pull at VNE in just about any glider (Swift or
Fox excepted, maybe) has a good chance of causing catastrophic
failure.

Kirk

[Don Johnstone[_4_]]

At 12:29 22 September 2010, kirk.stant wrote:
>On Sep 22, 6:05=A0am, Don Johnstone wrote:
>> At 07:33 22 September 2010, John Smith wrote:
>>
>> >tienshanman wrote:
>> >> This embarrassing aerial crack up is not a very good advertisement
>for
>> >> any glider, but especially not for an UL that sells for
>>
>> >You can break *any* aircraft by pulling too many Gs.
>>
>> I think you might find that most of the modern gliders we fly are
>capable
>> of withstanding more "G" than the human body can take.
>> Overstressing a modern glider is unlikely to result in a catastrophic
>> failure unless there is already damage.
>> Remember the placarded limits have nothing to do with the design
limits
>o=
>f
>> the glider. Most are placarded to +3.5 and -1 which was an arbitary
>figur=
>e
>> set by the LBA. Most gliders of the type we now fly exceed this level.
>> That is not to say that people should fly outside the placarded
limits.
>
>Curious statement. Cite, please? Humans can take a lot of Gs,
>especially when reclined - I've done over 9 g instantaneous in a Swift
>and sustained 9 g for 20 some odd seconds in a centrifuge and wouldn't
>want to try it in my LS6!
>
>I'm pretty sure a hard pull at VNE in just about any glider (Swift or
>Fox excepted, maybe) has a good chance of causing catastrophic
>failure.
>
>Kirk


Prevalence of G-induced loss of consciousness (G-LOC)in the United
Kingdom Royal Air Force (RAF) was found to be 19.3% in 1987. With the
introduction of the Typhoon, a fourth generation aircraft, the prevalence
of G-LOC has been re-assessed to determine the effectiveness of current G
tolerance training. Method: A survey was sent to 4018 RAF aircrew,
irrespective of their current role. Information was requested on G-LOC,
role and aircraft type, experience, and attitudes toward G-LOC prevention.
Results: Responses were received from 2259 (56.2%) individuals, 882 (39%)
of whom were current fast jet aircrew. At least one episode of G-LOC was
reported by 20.1% of all respondents. In front line aircraft, prevalence
of G-LOC among the 882 fast jet aircrew who responded was 6%. In the whole
group, G-LOC was reported most commonly in aircrew under training (70.9%),
and was most prevalent in training aircraft (77.4% of G-LOC events). At
the time of the G-LOC, 64% of aircrew had less than 100 h total flying
time. G-LOC was reported most frequently between +5 to +5.9 Gz, and
“push-pull” maneuvers were associated with 31.3% of G-LOC events.

G-LOC was reported most frequently between +5 to +5.9 Gz.

Studies have shown that prone positioning has little effect, the only
remedy is a G suit and training, not often found in gliders.
The USAF require F16 pilots to demonstrate an ability to withstand a
maximum of 9 Gz and this can only be achieved through training and the
wearing of a G suit.

I am left wondering how sufficient acceleration could be maintained in a
LS6 to load the aircraft, in controlled flight, to sustain 9 G or indeed
more than 6G, ignoring that the pilot is going to become rapidly
unconsious if it were to be achieved. I am at a loss to understand why
anyone would want to do that anyway.

[150flivver]

On Sep 22, 8:54*am, Don Johnstone > wrote:
> At 12:29 22 September 2010, kirk.stant wrote:
>
>
>
> >On Sep 22, 6:05=A0am, Don Johnstone *wrote:
> >> At 07:33 22 September 2010, John Smith wrote:
>
> >> >tienshanman wrote:
> >> >> This embarrassing aerial crack up is not a very good advertisement
> >for
> >> >> any glider, but especially not for an UL that sells for
>
> >> >You can break *any* aircraft by pulling too many Gs.
>
> >> I think you might find that most of the modern gliders we fly are
> >capable
> >> of withstanding more "G" than the human body can take.
> >> Overstressing a modern glider is unlikely to result in a catastrophic
> >> failure unless there is already damage.
> >> Remember the placarded limits have nothing to do with the design
> limits
> >o=
> >f
> >> the glider. Most are placarded to +3.5 and -1 which was an arbitary
> >figur=
> >e
> >> set by the LBA. Most gliders of the type we now fly exceed this level.
> >> That is not to say that people should fly outside the placarded
> limits.
>
> >Curious statement. *Cite, please? *Humans can take a lot of Gs,
> >especially when reclined - I've done over 9 g instantaneous in a Swift
> >and sustained 9 g for 20 some odd seconds in a centrifuge and wouldn't
> >want to try it in my LS6!
>
> >I'm pretty sure a hard pull at VNE in just about any glider (Swift or
> >Fox excepted, maybe) has a good chance of causing catastrophic
> >failure.
>
> >Kirk
>
> *Prevalence of G-induced loss of consciousness (G-LOC)in the United
> Kingdom Royal Air Force (RAF) was found to be 19.3% in 1987. With the
> introduction of the Typhoon, a fourth generation aircraft, the prevalence
> of G-LOC has been re-assessed to determine the effectiveness of current G
> tolerance training. *Method: *A survey was sent to 4018 RAF aircrew,
> irrespective of their current role. Information was requested on G-LOC,
> role and aircraft type, experience, and attitudes toward G-LOC prevention..
> *Results: *Responses were received from 2259 (56.2%) individuals, 882 (39%)
> of whom were current fast jet aircrew. At least one episode of G-LOC was
> reported by 20.1% of all respondents. In front line aircraft, prevalence
> of G-LOC among the 882 fast jet aircrew who responded was 6%. In the whole
> group, G-LOC was reported most commonly in aircrew under training (70.9%),
> and was most prevalent in training aircraft (77.4% of G-LOC events). At
> the time of the G-LOC, 64% of aircrew had less than 100 h total flying
> time. G-LOC was reported most frequently between +5 to +5.9 Gz, and
> “push-pull” maneuvers were associated with 31.3% of G-LOC events. *
>
> G-LOC was reported most frequently between +5 to +5.9 Gz.
>
> Studies have shown that prone positioning has little effect, the only
> remedy is a G suit and training, not often found in gliders.
> The USAF require F16 pilots to demonstrate an ability to withstand a
> maximum of 9 Gz and this can only be achieved through training and the
> wearing of a G suit.
>
> I am left wondering how sufficient acceleration could be maintained in a
> LS6 to load the aircraft, in controlled flight, to sustain 9 G or indeed
> more than 6G, ignoring that the pilot is going to become rapidly
> unconsious if it were to be achieved. I am at a loss to understand why
> anyone would want to do that anyway.

G-LOC and structural deformity are two different issues. You can
snatch the stick and pull an instantaneous g-load that will snap the
wings off before your body reacts and you g-loc.

[sisu1a]

> I'm pretty sure a hard pull at VNE in just about any glider (Swift or
> Fox excepted, maybe) has a good chance of causing catastrophic
> failure.

Pretty sure a hard pull at VA+ is all that is needed...

-Paul

[John Smith]

Don Johnstone wrote:
> I think you might find that most of the modern gliders we fly are capable
> of withstanding more "G" than the human body can take.
> Overstressing a modern glider is unlikely to result in a catastrophic
> failure unless there is already damage.

If you want to go up and verify this in real, then please be so kind and
do so without an innocent passenger on board!

Modern gliders tend to be certified to JAR-22. Non-acro gliders are
certified in the utility category which means a max. load factor of
+5.3G at maneuvre speed and +4G at Vne. Safety factor ist 1.5 (for a new
glider, probably less for a worn-out one!). Since gliders tend to be
constructed to the minimum requirements, because more strength means
more material, hence more cost and less payload, both not desirable,
chances are you will break a glider when pulling 8G at Vne. 8G are
perfectly standable (albeit for most peoole not enjoyable).

BTW, for aero-reated gliders, JAR-22 requires a load factor of 7G at
Vne. Earlier certified gliders are rated for less, only few gliders
(Swift, Fox) are rated for a higher load factor.

[John Smith]

Don Johnstone wrote:
[lots of yadda yadda snipped]
> G-LOC was reported most frequently between +5 to +5.9 Gz.

You completely forgot to mention the time factor. G-Loc needs at least 4
seconds to occur. No glider aerobatic maneuvre will give you a high G
load of more than 4 seconds, it's simply not possible, energeticwise.
(Except with a spiral, of course.)

Read for example: http://aeromedical.org/Articles/g-loc.html

[Bob Kuykendall]

On Sep 22, 6:54*am, Don Johnstone > wrote:

> Studies have shown that prone positioning has little effect...

Prone, as in a Horton? Yes, that would be as expected.

As for the rest, many small aircraft have been shed of their wings in
circumstances where the only possible explanation was deliberate
though injudicious pilot input. So I don't think anybody should doubt
that it is well within the realm of possibility.

Thanks, Bob K.

[Andor Holtsmark[_2_]]

Max. g is not a structural issue with several modern gliders. Other design
requirements result in a structure that by far surpasses the certification
requirements.

Andor

[cernauta]

On Wed, 22 Sep 2010 17:30:25 +0200, John Smith
> wrote:


>Modern gliders tend to be certified to JAR-22. Non-acro gliders are
>certified in the utility category which means a max. load factor of
>+5.3G at maneuvre speed and +4G at Vne. Safety factor ist 1.5 (for a new
>glider, probably less for a worn-out one!).


>chances are you will break a glider when pulling 8G at Vne. 8G are
>perfectly standable (albeit for most peoole not enjoyable).

Should I read 6G, I guess.

aldo

[kirk.stant]

On Sep 22, 8:54*am, Don Johnstone > wrote:

> *Prevalence of G-induced loss of consciousness (G-LOC)in the United
> Kingdom Royal Air Force (RAF) was found to be 19.3% in 1987. With the
> introduction of the Typhoon, a fourth generation aircraft, the prevalence
> of G-LOC has been re-assessed to determine the effectiveness of current G
> tolerance training. *Method: *A survey was sent to 4018 RAF aircrew,
> irrespective of their current role. Information was requested on G-LOC,
> role and aircraft type, experience, and attitudes toward G-LOC prevention..
> *Results: *Responses were received from 2259 (56.2%) individuals, 882 (39%)
> of whom were current fast jet aircrew. At least one episode of G-LOC was
> reported by 20.1% of all respondents. In front line aircraft, prevalence
> of G-LOC among the 882 fast jet aircrew who responded was 6%. In the whole
> group, G-LOC was reported most commonly in aircrew under training (70.9%),
> and was most prevalent in training aircraft (77.4% of G-LOC events). At
> the time of the G-LOC, 64% of aircrew had less than 100 h total flying
> time. G-LOC was reported most frequently between +5 to +5.9 Gz, and
> “push-pull” maneuvers were associated with 31.3% of G-LOC events. *
>
> G-LOC was reported most frequently between +5 to +5.9 Gz.
>
> Studies have shown that prone positioning has little effect, the only
> remedy is a G suit and training, not often found in gliders.
> The USAF require F16 pilots to demonstrate an ability to withstand a
> maximum of 9 Gz and this can only be achieved through training and the
> wearing of a G suit.
>
> I am left wondering how sufficient acceleration could be maintained in a
> LS6 to load the aircraft, in controlled flight, to sustain 9 G or indeed
> more than 6G, ignoring that the pilot is going to become rapidly
> unconsious if it were to be achieved. I am at a loss to understand why
> anyone would want to do that anyway.- Hide quoted text -
>
> - Show quoted text -

At the time (many years ago) I was active and current in F-4s, and we
had to undergo centrifuge training to identify G-LOC causes and
prevention. Centrifuge was with a G-suit, and gradually ramped up to
determine relaxed G tolerance, G-tolerance with proper straining
maneuver and G-suit, and time of useful consciousness at 9 Gs while
performing a tracking exercise in the centrifuge (simple video game
type thing). At the time (I was in my late 30s, smoked, partied, NOT
a marathon runner!), I could function at 4 to 5 Gs relaxed, 6 Gs with
simple straining, and 20 - 30 seconds at 9 Gs with everything working
(tight G-suit, straining, breathing, etc). 9 Gs is rough, and the
penalty of any relaxation was immediate GLOC (fun to watch the "fit"
skinny non-smoking runners pass out at 8 Gs!).

I'm surprised about the comment that position had little effect - that
goes counter to my experience and to the physiology of G-effects on
the human body. Bloody boffins, probably asked the wrong questions...

The thing about G-LOC is that it is not so much a matter of the peak G
load, but is more a function of the rate of onset of the Gs. If you
are expecting the Gs, then you can prepare; but a snatch pull to 5 Gs
when not expecting it (which happened frequently when you were in the
back seat of an F-4, for example, looking in the radar or checking 6)
could definitely put you in a world of hurts!

But Gs is like any physical activity - you have to do it a lot to
maintain your acclimitization. I enjoy acro up to 3-4 gs nowadays,
but would not like to try 5 sustained anymore! Fortunately, glider
acro is not only low peak but also short sustained Gs.

My LS6 has a pretty small elevator but at redline is real sensitive in
pitch, I think the instantaneous G that could be generated with a hard
pull would not be good for the airframe, to say the least! And it's
the instantaneous G that is what is going to break the wings, not the
sustained G (which is always going to be low in a glider).

Cheers,

Kirk

[John Smith]

cernauta wrote:
> On Wed, 22 Sep 2010 17:30:25 +0200, John Smith
> > wrote:
>
>
>> Modern gliders tend to be certified to JAR-22. Non-acro gliders are
>> certified in the utility category which means a max. load factor of
>> +5.3G at maneuvre speed and +4G at Vne. Safety factor ist 1.5 (for a new
>> glider, probably less for a worn-out one!).
>
>
>> chances are you will break a glider when pulling 8G at Vne. 8G are
>> perfectly standable (albeit for most peoole not enjoyable).
>
> Should I read 6G, I guess.

Of course, my mistake. I had it correct, then reviewed it, mixed up the
Gs at Va and Vne and "corrected" it. Oh well.

[Don Johnstone[_4_]]

At 21:33 22 September 2010, John Smith wrote:
>cernauta wrote:
>> On Wed, 22 Sep 2010 17:30:25 +0200, John Smith
>> wrote:
>>
>>
>>> Modern gliders tend to be certified to JAR-22. Non-acro gliders are
>>> certified in the utility category which means a max. load factor of
>>> +5.3G at maneuvre speed and +4G at Vne. Safety factor ist 1.5 (for a
>new
>>> glider, probably less for a worn-out one!).
>>
>>
>>> chances are you will break a glider when pulling 8G at Vne. 8G are
>>> perfectly standable (albeit for most peoole not enjoyable).
>>
>> Should I read 6G, I guess.
>
>Of course, my mistake. I had it correct, then reviewed it, mixed up the
>Gs at Va and Vne and "corrected" it. Oh well.

I think we are getting a little away from the point. The original
proposition that pulling G in any glider would result in failure. I
suggested that catostropic failure would not necessarily occur in many
gliders. The certified load factors do not necessarily indicate the actual
load factor that an airframe can sustain. The RAF bought 100 Grob Acros, 99
went into service and 1 went to Slingsby for testing on a rig. It was as
the result of this testing that the spigot problem was indentified. After
the airframe had been tested beyond the expected life by a considerable
margin Slingsbys were asked to apply loads sufficient to break the
airframe. They were unable to do so, and after breaking the rig several
times trying, gave up.

[Bob Kuykendall]

On Sep 22, 4:06*pm, Don Johnstone > wrote:

> ...The RAF bought 100 Grob Acros, 99 went into service and 1 went to
> Slingsby for testing on a rig...

We should be cautious about confusing anecdote with data. The testing
of one relatively conservatively-designed trainer doesn't tell us much
about the strength of the average sport or racing sailplane.

It may be that this one example tells us more about Slingsby's welding
than about Grob's composites.

Thanks, Bob K.

[Mike the Strike]

.....and none of it may bear any resemblance to the current accident.

The design of an ultralight foot-launched sailplane obviously
introduces more compromises than conventional designs. Looking at the
manufacturer's website videos shows that the rigging of the wings
seems very different from modern sailplanes, which typically use
overlapping spars. What would worry me, though, is that after one
wing separated, the second wing and tailplane rapidly followed, then
the tail boom. The glider basically disintegrated.

Mike

[John Smith]

Don Johnstone wrote:
> I think we are getting a little away from the point. The original
> proposition that pulling G in any glider would result in failure. I
> suggested that catostropic failure would not necessarily occur in many
> gliders.

It all depends on how many Gs you pull.

[John Smith]

Mike the Strike wrote:
> What would worry me, though, is that after one wing separated,
> the second wing and tailplane rapidly followed, thenthe tail boom.

I would assume that after one wing has separated, it couldn't matter
less whether the seond wing follows or not.

According to Rupport Composite, the Archaeopteryx is designed for a
maximum maneuver load of 4 g at 85 km/h. The pilot himself confirmed
that he had exceeded the allowed load by flying too fast and pulling too
hard.
Source:
http://www.ruppert-composite.ch/531251969e0bf2b07/5312519dfb06c0c01.html
(German only).

[Bob Whelan[_3_]]

On 9/22/2010 6:13 PM, Bob Kuykendall wrote:
>
On Sep 22, 4:06 pm, Don > wrote:
>
>> ...The RAF bought 100 Grob Acros, 99 went into service and 1 went to
>> Slingsby for testing on a rig...
>
> We should be cautious about confusing anecdote with data. The testing
> of one relatively conservatively-designed trainer doesn't tell us much
> about the strength of the average sport or racing sailplane.

Kinda-sorta related, I'll bet big bux sailplane designers (and maybe even the
JAR/FAA design criteria folks) carefully tweak their design limits to whatever
materials they're using for primary structure, too.

The 1.5 ultimate/limit load factor ratio has historical roots in the metal world.

Early glass-glider designers quickly realized the relative floppiness of 'pure
fiberglass structures' meant stiffness needed to be explicitly addressed when
it came to wing structure, hence - in spar breakage terms - 'glass gliders'
tend to be 'overstrength' simply because it's necessary in order to obtain a
useably high Vne while avoiding flutter. (How well your metal pushrods will
work/stand-up at max-load-deflections is of course a tale in itself. Joe Test
Pilot, anyone?)

Carbon fiber primary wing structure meant designers could back away from
'stiffness-influenced overstrength structures' since carbon fiber structures
(pound for pound) are so much stiffer than their fiberglass equivalents.

Is any of this relevant to the real world of Joe Pilot? Is the Pope Catholic?

Regards,
Bob W.

[Grider Pirate]

(How well your metal pushrods will
> work/stand-up at max-load-deflections is of course a tale in itself. Joe Test
> Pilot, anyone?)
Which reminds me that I've wondered WHY they're still using metal
pushrods in carbon wings, instead of pultruded carbon tubing pushrods.
Perhaps because we still don't trust the bond between a carbon tube
and the metal fitting?

[Dave Nadler]

On Sep 23, 5:56*pm, Grider Pirate > wrote:
> (How well your metal pushrods will> work/stand-up at max-load-deflections is of course a tale in itself. Joe Test
> > Pilot, anyone?)
>
> Which reminds me that I've wondered WHY they're still using metal
> pushrods in carbon wings, instead of pultruded carbon tubing pushrods.
> Perhaps because we still don't trust the bond between a carbon tube
> and the metal fitting?

Cost. Open class gliders are often out of rig ;-)
Dick Butler has used carbon tubes in Concordia.

Best Regards, Dave

[Bob Kuykendall]

On Sep 23, 2:56*pm, Grider Pirate > wrote:

> Which reminds me that I've wondered WHY they're still using metal
> pushrods in carbon wings, instead of pultruded carbon tubing pushrods.
> Perhaps because we still don't trust the bond between a carbon tube
> and the metal fitting?

Dave nailed it: cost, as in cost per unit stiffness. Carbon might be
stiffer per unit mass and per unit volume, but is painful in terms of
stiffness per unit paycheck.

Stan Hall wrote a great article on this that describes how Euler's law
of column buckling shows that strength cancels out of the equation; it
is dominated by the stiffness. So once you decide to use aluminum, it
pretty much doesn't matter what aluminum you use. No need for 7075-T6
or even 2024-T3, good old 6061-T6 will do just fine so that's what I
(and most European makers) use. The article is in the highly-
recommended _Collected Works of Stan Hall, Vol 1_.

Your other point is quite valid as well. Establishing a reliable high-
strength bond between a carbon fiber tube and its end features is
still a bit exotic. I've seen it done, but it's just not something I
want to do and trust my life to.

Thanks, Bob K.

[John Smith]

Dave Nadler wrote:
>> Which reminds me that I've wondered WHY they're still using metal
>> pushrods in carbon wings, instead of pultruded carbon tubing pushrods.

> Cost.

I would rather say: high cost vs. zero benefit.

[bumper[_3_]]

On Sep 23, 3:45*pm, John Smith > wrote:
> Dave Nadleur wrote:
> >> Which reminds me that I've wondered WHY they're still using metal
> >> pushrods in carbon wings, instead of pultruded carbon tubing pushrods.
> > Cost.
>
> I would rather say: high cost vs. zero benefit.

There are exceptions. Early Stemme S10-VT's used aluminum push rods
for the spoilers, which had the over center for locking the spoilers
closed in the spoiler box. Problems occurred with the differential
thermal expansion between the aluminum rods and CF wings. In cold
temperatures the spoilers could unlock without pilot input. Changing
the push rods to carbon fiber solved the problem and CF rods are used
for spoilers on Stemmes now.

bumper
MKIV and QV
Minden