Plane wings

[[email protected]]

I have heard talk about that under stress testing of airplanes (eg. big
Boing machines), they bend the wings so much that they touch each
otherover the airplane?
Has anybody seen such photos, or is this just a lie?

[Jim Macklin]

Not quite that far, but there is an article with a picture
at
http://hsc.csu.edu.au/engineering_studies/aero_eng/3056/corrosion.html


--
James H. Macklin
ATP,CFI,A&P

--
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But government sees it as an obstacle to be overcome.
some support
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See http://www.fija.org/ more about your rights and duties.


> wrote in message
oups.com...
|I have heard talk about that under stress testing of
airplanes (eg. big
| Boing machines), they bend the wings so much that they
touch each
| otherover the airplane?
| Has anybody seen such photos, or is this just a lie?
|

[Robert M. Gary]

You can see it fail during stress testing of the 777 in the video
http://www.amazon.com/exec/obidos/tg/detail/-/B00000FBL5/103-8305603-9180642?v=glance

The wing tips certainly aren't close to touching each other but its
still amazing to watch. When it breaks, it makes some noise.

-Robert

[Vic7]

I have heard talk about that under stress testing of airplanes (eg. big
Boing machines), they bend the wings so much that they touch each
otherover the airplane?
Has anybody seen such photos, or is this just a lie?


Not a lie that they perform this test, although as previously pointed out, the spar fails long before the wing-tips meet. I remember seeing a PBS/History/Discover channel program about the initial production of the B777. They had impressive footage of the destructive load testing of the wings. IIRC they failed at a 40-something degree deflection.

I've have also seen footage on the web site of one of the German sailplane manufacturers (A. Schleicher, Schempp-Hirth, or Glaser Dirks, perhaps) of the destructive test of a new wing design with a carbon fiber spar. That was very impressive and violent.

V7

[Skywise]

Vic7 > wrote in
:

>
> Wrote:
>> I have heard talk about that under stress testing of airplanes (eg. big
>> Boing machines), they bend the wings so much that they touch each
>> otherover the airplane?
>> Has anybody seen such photos, or is this just a lie?
>
>
> Not a lie that they perform this test, although as previously pointed
> out, the spar fails long before the wing-tips meet. I remember seeing
> a PBS/History/Discover channel program about the initial production of
> the B777. They had impressive footage of the destructive load testing
> of the wings. IIRC they failed at a 40-something degree deflection.
>
> I've have also seen footage on the web site of one of the German
> sailplane manufacturers (A. Schleicher, Schempp-Hirth, or Glaser Dirks,
> perhaps) of the destructive test of a new wing design with a carbon
> fiber spar. That was very impressive and violent.
>
> V7

I've seen these tests as well. Something to keep in mind though is
that these are static loads. That is, the loads are applied slowly
until the wing fails. Dynamic loads are another matter entirely.
If the wing fails a static load at 40 degrees, it'd probably still
break if it was deflected to a lesser degree quickly, like within
seconds.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html
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Sed quis custodiet ipsos Custodes?

[Capt. Geoffrey Thorpe]

"Vic7" > wrote in message
...
>
>...
> I've have also seen footage on the web site of one of the German
> sailplane manufacturers (A. Schleicher, Schempp-Hirth, or Glaser Dirks,
> perhaps) of the destructive test of a new wing design with a carbon
> fiber spar. That was very impressive and violent.
>

Testing to Destruction
of the DG-1000 Wing

Camera-inside: normal: 4,88 MB
http://www.dg-download.de/Videos/bruchversuch-i-s.mpg

high-speed: 23,5 MB http://www.dg-download.de/Videos/bruchversuch-i.mpg


Camera-outside: high-speed 26,3 MB
http://www.dg-download.de/Videos/bruchversuch-a.mpg


--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
Spell checking is left as an excercise for the reader.

[Stubby]

What is the point of that extreme testing?


Capt. Geoffrey Thorpe wrote:
> "Vic7" > wrote in message
> ...
>> ...
>> I've have also seen footage on the web site of one of the German
>> sailplane manufacturers (A. Schleicher, Schempp-Hirth, or Glaser Dirks,
>> perhaps) of the destructive test of a new wing design with a carbon
>> fiber spar. That was very impressive and violent.
>>
>
> Testing to Destruction
> of the DG-1000 Wing
>
> Camera-inside: normal: 4,88 MB
> http://www.dg-download.de/Videos/bruchversuch-i-s.mpg
>
> high-speed: 23,5 MB http://www.dg-download.de/Videos/bruchversuch-i.mpg
>
>
> Camera-outside: high-speed 26,3 MB
> http://www.dg-download.de/Videos/bruchversuch-a.mpg
>
>
> --
> Geoff
> The Sea Hawk at Wow Way d0t Com
> remove spaces and make the obvious substitutions to reply by mail
> Spell checking is left as an excercise for the reader.
>
>

[Matt Whiting]

Stubby wrote:
> What is the point of that extreme testing?

To confirm the design calculaions and assumptions before placing human
life at risk.


Matt

[Stubby]

Matt Whiting wrote:
> Stubby wrote:
>> What is the point of that extreme testing?
>
> To confirm the design calculaions and assumptions before placing human
> life at risk.

Is it even possible to operate an airframe in a way that will produce
wing-bending of that degree? If so, I believe human life will have
already been in risk long before. It's unrealistic and I believe the
value of "accelerated testing" was debunked about 30 years ago.

[Stefan]

Stubby wrote:

> Is it even possible to operate an airframe in a way that will produce
> wing-bending of that degree?

Yes.

In the break test, wings must withstand the rated G load multiplied with
a safety fator of 1.5. Gliders are usually rated for 5.4 G (or some
such), which causes impressive wing bending. IIRC, the wing in the DG
video broke when it reached the factor 1.7, which made the manufactorer
somewhat unhappy, because it proved that the wing had been designed too
strong, which means too heavy and too expensive. They have corrected
that now.

Stefan

[Morgans]

"Stubby" > wrote in message
. ..
>
>
> Matt Whiting wrote:
> > Stubby wrote:
> >> What is the point of that extreme testing?
> >
> > To confirm the design calculaions and assumptions before placing human
> > life at risk.
>
> Is it even possible to operate an airframe in a way that will produce
> wing-bending of that degree? If so, I believe human life will have
> already been in risk long before.

True, but people do accidently wander into thuderstormsm and it would be
nice to come out the other side with the wings still attached.

>It's unrealistic and I believe the
> value of "accelerated testing" was debunked about 30 years ago.

That is news to me. Someone better tell the big aircraft manufacturers
about that, as well as the big auto makers. They ALL participate in
accelerated testing.
--
Jim in NC

[Matt Whiting]

Stubby wrote:

>
>
> Matt Whiting wrote:
>
>> Stubby wrote:
>>
>>> What is the point of that extreme testing?
>>
>>
>> To confirm the design calculaions and assumptions before placing human
>> life at risk.
>
>
> Is it even possible to operate an airframe in a way that will produce
> wing-bending of that degree? If so, I believe human life will have
> already been in risk long before. It's unrealistic and I believe the
> value of "accelerated testing" was debunked about 30 years ago.

Generally, the answer is yes. I don't know what G loading the test was
at when the wing broke, but at typical cruise speeds, a very abrupt
control input or very strong wind gust can generate loads that exceed
the design limits of the airplane.

Your second sentence makes no sense. No structure is 100% safe.

This isn't accelerated testing, this was simply a load test to failure.


Matt

[Robert M. Gary]

My favorite was the tail skid test. Apparently some airline pilots are
quite ham-fisted and are known to over rotate on take off, dragging the
tail on the ground. The test is that the plane can still take off under
the drag of the tail sliding on the ground. It was pretty awesome to
watch this thing draggin its butt down the runway!!

-Robert


Roy Smith wrote:
> In article om>,
> Robert M. Gary > wrote:
> One of the other fun tests was the maximum effort braking test. They
> take a real production 777 (not yet certified), load it up, and go
> barrelling down the runway at full speed, then slam on the brakes for
> an emergency stop. Tires pop, and the brake drums are glowing red
> hot, but the plane comes to a safe stop. Part of the certification
> test is that the wheels have to withstand this for a certain amount of
> time without catching fire. The fire & rescue guys are all standing
> around with fire hoses counting down the time on their watches until
> they're allowed to turn on the water to cool things off. Wait too
> long, and you risk destroying a perfectly good airplane. Jump in too
> soon, and you invalidate the test.

[Big John]

Stubby

Was flying a F2H3 (Banshee) and dive bombing. Dropped and pulled it in
to 6 G's for recovery. 'G' suit was inflated to max and I was grunting
like a stuck pig to stay awake when I hit the jet wash of the bird
ahead of me. G meter went to over 14 G's but bird stayed together
thank god.

Flew home very straight and level and when parked ground crew found
loose rivets all over the bird.

Sure glad they built some extra into that bird and used at least the
1.5 criteria as I was near the ultimate.

Just another day at the office :o)

Big John
```````````````````````````````````````````````

On Sat, 18 Feb 2006 12:12:44 -0500, Stubby
> wrote:

>
>
>Matt Whiting wrote:
>> Stubby wrote:
>>> What is the point of that extreme testing?
>>
>> To confirm the design calculaions and assumptions before placing human
>> life at risk.
>
>Is it even possible to operate an airframe in a way that will produce
>wing-bending of that degree? If so, I believe human life will have
>already been in risk long before. It's unrealistic and I believe the
>value of "accelerated testing" was debunked about 30 years ago.

[[email protected]]

>>>>My favorite was the tail skid test. Apparently some airline pilots are
quite ham-fisted and are known to over rotate on take off, dragging the

tail on the ground. The test is that the plane can still take off under

the drag of the tail sliding on the ground. It was pretty awesome to
watch this thing draggin its butt down the runway!! <<<<

That's the Vmu test (minimum unstick speed) or the minimum airspeed the
plane will fly with. Naturally it requires a high AOA so they attach
blocks to the skid on the tail and watch the sparks fly. Not sure if
it's because of ham-fisted pilots; I think it's just part of normal
certification.

[nrp]

This ultimate test isn't done on a virgin airframe. Rather it is done
after the prototype airframe has been subjected to a very extensive
random fatigue spectrum using typically a hundred or more hydraulic
actuators, which simulates the design life inputs to the airframe.

This fatgue test will include taxi loads, ground-air-ground loads,
pressurizations, power up and power down, turbulence - the whole gamat
of what an airframe sees in its life. This test may go on for years to
verify the desiign life of the airframe. During the fatigue test,
cracks will be encountered in the test airframe, and a fix will be
engineered to repair the crack, and the test continues. Meanwhile
later production airframe versions are put in service, but the
operators are careful to follow the service and crack etc history and
the repair of each airframe to make sure they do not get ahead of the
lab test airframe.

It is important in fatigue testing (whether cars or airplanes) to
maintain some semblance of the randomness of the loading, otherwise the
test specimen will give a wildly optimistic picture of the fatigue
life. The ground-air-ground cycles have to be randomly interspersed
with flight loads and pressurizations etc for an accurate test. Hence
this is a big test facility involving a lot of people.

The ultimate test is done after the design fatigue life has been
reached in the lab. I suspect much champagne is popped when it reaches
150%. The Airbus A-380 just had its very recent ultimate test (per
Wall Street Journal) and only made something less than 150% so there
wasn't much champagne popped after that one.

This system broke down in the case of the DC-10 at Chicago because a
very damaging prying load was input to the engine mount through a jury
rigged maintenance procedure that of course was not anticipated in the
fatigue test.

I'm not an expert in this, maybe others posters are. I know Boeing is
very good at predicting the fatigue life of structures.

[Matt Whiting]

nrp wrote:

> I'm not an expert in this,

Yes, that is apparent.

Matt

[[email protected]]

Airbus A380 test wing breaks just below ultimate load target
Flight International 02/16/06

The wing of the Airbus A380 static test specimen suffered a structural
failure below the ultimate load target during trials in Toulouse
earlier this week, but Airbus is confident that it will not need to
modify production aircraft.

The airframer has been running load trials on a full scale A380 static
test specimen in Toulouse since late 2004 (pictured below). After
completing "limit load" tests (ie the maximum loads likely to
experienced by the aircraft during normal service), progressively
greater loads have been applied to the specimen towards the required
1.5 times the limit load. Engineers develop finite element models (FEM)
to calculate the load requirements.

"The failure occurred last Tuesday between 1.45 and 1.5 times the limit
load at a point between the inboard and outboard engines," says Airbus
executive vice president engineering Alain Garcia. "This is within 3%
of the 1.5 target, which shows the accuracy of the FEM." He adds that
the ultimate load trial is an "extremely severe test during which a
wing deflection of 7.4m (24.3ft) was recorded".

The European Aviation Safety Agency (EASA) says that the maximum
loading conditions are defined in the A380 certification basis. "The
aircraft structure is analysed and tested to demonstrate that the
structure can withstand the maximum loads, including a factor of safety
of 1.5. This process is ongoing and will be completed before type
certification."

However Garcia says that the failure of the wing below the 1.5 target
will require "essentially no modifications" to production aircraft:
"This static test airframe has the first set of wings built, and we
have refined the structural design for subsequent aircraft due to
increased weights etc. We will use this calibration of the FEM to prove
the adequacy of the structure on production aircraft."

EASA says that it is aware of the structural failure but "cannot make a
statement about the specific failure as it has not been officially
briefed by Airbus on what the cause was, and the certification process
is ongoing".

Garcia says that the FEM calculations had already established that the
A380's wing had "no margin at ultimate load. We had a weight saving
programme and `played the game' to achieve ultimate load." However in
earlier briefings, Airbus structural engineers had stated that it
planned to carry out "a residual strength and margin research test" in
2006 after completing ultimate load trials.

The results gleaned from the static testing will be extrapolated for
the future aircraft developments over the next 40 to 50 years says
Garcia. "It is normal to refine and strengthen the structure of new
heavier or longer range variants," he says.

[lynn]

Before purchasing the B-747 for AF ONE, Boeing had to do a highspeed
heavy weight abort. The aircraft stopped. The brakes eventually caught
fire and they let it cook for about 12 minutes. Result was the
fuselage was entact and never really threatened during the 12 minutes.
The damaged parts were replaced and the aircraft was flown again.
There are films of the event. Our part 121 carrier shows the film in
recurrent training.

Evacuation tests require all the evacuatees to be out of the aircraft
in 90 seconds or less. This is done in darkered conditions, with some
exits blocked. FAR PArt 121-291
<http://www.flightsimaviation.com/data/FARS/part_121-291.html> will
give the details and criteria for a evacuation certification.

[Stubby]

I'm not familiar with that plane, but why did you exceed its ratings?
14 Gs is a lot and I'm not surprised there were some loose rivits but I
am surprised you survived without damage to your body!



Big John wrote:
> Stubby
>
> Was flying a F2H3 (Banshee) and dive bombing. Dropped and pulled it in
> to 6 G's for recovery. 'G' suit was inflated to max and I was grunting
> like a stuck pig to stay awake when I hit the jet wash of the bird
> ahead of me. G meter went to over 14 G's but bird stayed together
> thank god.
>
> Flew home very straight and level and when parked ground crew found
> loose rivets all over the bird.
>
> Sure glad they built some extra into that bird and used at least the
> 1.5 criteria as I was near the ultimate.
>
> Just another day at the office :o)
>
> Big John
> ```````````````````````````````````````````````
>
> On Sat, 18 Feb 2006 12:12:44 -0500, Stubby
> > wrote:
>
>>
>> Matt Whiting wrote:
>>> Stubby wrote:
>>>> What is the point of that extreme testing?
>>> To confirm the design calculaions and assumptions before placing human
>>> life at risk.
>> Is it even possible to operate an airframe in a way that will produce
>> wing-bending of that degree? If so, I believe human life will have
>> already been in risk long before. It's unrealistic and I believe the
>> value of "accelerated testing" was debunked about 30 years ago.
>

[.Blueskies.]

"Stubby" > wrote in message ...
> I'm not familiar with that plane, but why did you exceed its ratings? 14 Gs is a lot and I'm not surprised there were
> some loose rivits but I am surprised you survived without damage to your body!
>
>

I think the 150% is the limit where the structure will return to the original form. Beyond that and deformation occurs.
Sounds like the Banshee can take a brief 14 g load and deform, but still stay together. Glad you made it through Big
John!

[Dave Doe]

In article >, William.Plummer-
says...
>
>
> Big John wrote:
> > Stubby
> >
> > Was flying a F2H3 (Banshee) and dive bombing. Dropped and pulled it in
> > to 6 G's for recovery. 'G' suit was inflated to max and I was grunting
> > like a stuck pig to stay awake when I hit the jet wash of the bird
> > ahead of me. G meter went to over 14 G's but bird stayed together
> > thank god.
> >
> > Flew home very straight and level and when parked ground crew found
> > loose rivets all over the bird.
> >
> > Sure glad they built some extra into that bird and used at least the
> > 1.5 criteria as I was near the ultimate.
> >
> > Just another day at the office :o)
> >
> > Big John
> > ```````````````````````````````````````````````
> >
> > On Sat, 18 Feb 2006 12:12:44 -0500, Stubby
> > > wrote:
> >
> >>
> >> Matt Whiting wrote:
> >>> Stubby wrote:
> >>>> What is the point of that extreme testing?
> >>> To confirm the design calculaions and assumptions before placing human
> >>> life at risk.
> >> Is it even possible to operate an airframe in a way that will produce
> >> wing-bending of that degree? If so, I believe human life will have
> >> already been in risk long before. It's unrealistic and I believe the
> >> value of "accelerated testing" was debunked about 30 years ago.
> >
> I'm not familiar with that plane, but why did you exceed its ratings?
> 14 Gs is a lot and I'm not surprised there were some loose rivits but I
> am surprised you survived without damage to your body!

Watching Discovery the other night, about the dude that did the "brake"
tests - in a rocket powered sled. Performed these tests several times
(the madman!) - I think the G forces were about 30G - some possibly
above that. De-acceleration, from memory, was about 3 seconds - so a
bit of time there too!

The body can take big G loadings, so long as it's the time that loading
is experienced is very short.

--
Duncan

[Bob Moore]

".Blueskies." wrote
> I think the 150% is the limit where the structure will return to the
> original form. Beyond that and deformation occurs.

Nope...100% is the 'Limit Load', 150% is the 'Ultimate Load'.

Below the Limit Load, no permanent deformation or breakage
will occur.

Between the Limit Load and Ultimate Load, permanent deformation
may occur, but no breakage.

Above the Ultimate Load, the structure may break.

Bob Moore

[.Blueskies.]

"Bob Moore" > wrote in message 22...
> ".Blueskies." wrote
>> I think the 150% is the limit where the structure will return to the
>> original form. Beyond that and deformation occurs.
>
> Nope...100% is the 'Limit Load', 150% is the 'Ultimate Load'.
>
> Below the Limit Load, no permanent deformation or breakage
> will occur.
>
> Between the Limit Load and Ultimate Load, permanent deformation
> may occur, but no breakage.
>
> Above the Ultimate Load, the structure may break.
>
> Bob Moore
>

Thanks!

[Kevin]

Vic7 wrote:
>
> Not a lie that they perform this test, although as previously pointed
> out, the spar fails long before the wing-tips meet. I remember seeing
> a PBS/History/Discover channel program about the initial production of
> the B777. They had impressive footage of the destructive load testing
> of the wings. IIRC they failed at a 40-something degree deflection.

I saw that footage too, it was amazing to watch. They were simultaneously
pulling both wingtips upwards with the rest of the fuselage anchored to
the floor. The tips were being pulled pretty slowly, perhaps a centimeter
or two per second, the motion was barely visible. The hangar was very
quiet as the wings bent more and more, then all of a sudden, the wings
snapped very violently and suddenly. Amazing to see.

Kevin.