787 Wing Flex Test

Approximately 25 feet of deflection at the tips, 150% load. This was NOT a break test.
Note the deflection in the picture. No need for winglets on this one.
(Note: Enclosed information from public sources)
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That's incredible

 

Just install some linkage to make them do that up and down and you can get rid of those big round things underneath that make so much noise.

 

Yeah, but does the -tail- stay on?



Oh wait....you said Boeing...all is well.

 

I saw the B-52 at 35 feet but then it had a wing span of 285 feet.
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OOPS! My finger made an error. That 285 foot wing span should be 185 feet for the B-52

 

I think if they let go it'll take off!

 

Wow- Wonder what the equivalent "g"s were for that much deflection? That is going to be one tough airliner. Like a cockroach, or carbonroach, more accurately.

Taz
Terry Phillips

 

When did development on the 787 start? I was in a mechanical engineering class back in 2003 and they showed a video of an airplane going through a wing flex test, it was incredible.

 

Maximum design load limit is 2.5g so at 150% those wings were at 3.8g (at max gross weight)

 

I think back to the 707 " Gander Dive" when the PAA 707-120 dove from 33000 feet to approximately 6000, exceeded M 1.0 , and made a pullout that put a permanent 2 deg. more dihedral in the wings. Stories were that it flew better after the dive than it did before. True fact is that there wasn't ONE fuel leak after the deflection. It lost many access panels and secondary sheet metal panels especially in the upper surface wing to body fairing filet that was crushed from the deflecting wing and center section. Boeing knows how to build wings.
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That was probably the 777 test you saw. It was shown in engineering courses many places. The development of the 787 started in the early 00s.

 

They didn't have a completely assembled A/P fuselage and wings until 2007.

 

Wow, what a coincidence I stumbled upon this thread... Back in February, I took a week vacation up in Seattle with my wife. On one of the last days, we visited the Boeing "Museum of Flight", and I was fortunate enough to happen to be in their mock control tower when a 787 test mule was on approach. I only took my 20mm lens with me that day to the museum expecting to only need to capture planes up close and indoors, so I've had to crop this photo to get the plane to fill the frame. Needless to say, the thing that jumped out at me first and stuck with me in my mind when I told friends & family about the sighting was how much flex there was in the wings. You can see that a little bit here in the picture, particularly with respect to the right (starboard?) wing that is clearly above the level of the horizontal stabilizer.

Sorry if my terminology is a little off - I'm not a pilot, I just love planes. Maybe some day...
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Great job, good comments, good observations. No apologies needed for terminology. Nice picture.
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That is one of the more remarkable stories I have read about aviation, and I have read a lot!

Amazing!!!

 

I was working on the program at the time and it amazed everyone. I have the report someplace in my junk and also an article that Aviation Week published. I imagine that it is on the web someplace also. The airplane was put on auto pilot and the captain went aft to chat with the VP of PAA Atlantic Operations. The captain noticed an increase in wind noise and also noticed that he saw sky out of the window when he should have seen water. The G forces were building as he clawed his way back to the flight deck to discover that the airplane was in a diving spiral. The auto pilot had disengaged and the co-pilot had somehow become incapacitated. After recovering, he and the captain pulled on the yokes until they pulled out at 6000 feet. The airplane exceeded Mach 1 and reached the yield point on the structure. I can't remember the figures but I might be able to look them up. I believe that the horizontal tail had to be replaced as well as most of the access panels and the upper wing to body fillet.
I think that the most amazing incident was with another PAA 707-321 when the number 4 engine threw a turbine disc up into the outboard wing and ignited the fuel in it. As the structure began to fail, the wing began to twist and flop and acting like a huge aileron so the captain rolled the airplane back and forth until he twisted it off at the outboard / inboard wing joint. He then put some aileron trim into it and flew it back to SFO to a safe landing. I have some in flight photos of that someplace too.
I could go on about several more incidents but I think that I have blabbed too much already.
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I think you'll find that most of us disagree with that!

 

Not trying to fish, I simply don't want to hog the mike.

 

Not at all -- I, for one, would love to hear more of these stories!

 

Seconded. A new thread, perhaps?

 

Make with the stories please!

 

Okay. Give me a week or two and I'll make up some more. Really, Terry Phillips, Russ Turner, and many more guys have done much more important stuff.

 

Agreed.

 

Regarding the " 707 upset" (as some wags call it) I should have mentioned the cause since the airplane was just cruising along at FL350. It was steadily burning off fuel and the result was a steady increase in speed that was not monitored. The airplane was reaching critical Mach with the center of pressure moving aft and the nose dropping. The copilot , working on some kind of paperwork never noticed that the breaker had popped on the auto pilot and it had disengaged. As one of my friends put it " It ran amuck with Mach Tuck." Please realize that I'm digging into a 51 year old event and I apologize for any errors in terms and figures. The other suspect in this over-speed phenomenon was the 720 B with the JT3D's. It was capable of quickly reaching critical Mach if it wasn't watched.
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