Plane wings

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 quite that far, but there is an article with a picture
at
http://hsc.csu.edu.au/engineering_st...corrosion.html


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

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
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?
|

You can see it fail during stress testing of the 777 in the video
http://www.amazon.com/exec/obidos/tg...80642?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

Originally Posted by

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

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
Quake "predictions": http://www.skywise711.com/quakes/EQDB/index.html
Sed quis custodiet ipsos Custodes?

"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.

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.

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

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


Matt

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.

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