Ever Wonder How They Test Aircraft Wings?

By Tuesday March 30, 2010


Click pic to embiggen

This is the Boeing 787 Dreamliner being tested.



20 Comments
  1. UncDon says:
    3/30/2010 at 7:01 pm

    Without the link, I would’ve captioned it, “Mankind Finally Invents Flapping-Wing Airliner”.

    Reply
  2. bobbo, int'l pastry chef and Red Baron says:
    3/30/2010 at 7:28 pm

    “Another concern arises from the risk of lightning strikes.[129] The 787 fuselage’s composite could have as much as 1,000 times the electrical resistance of aluminum, increasing the risk of damage during a lightning strike.[130] Boeing has stated that the 787′s lightning protection will meet FAA requirements.[124] FAA management is planning to relax some lightning strike requirements, which will help the 787.[131]” /// Well, this is just like dating women isn’t it? If she doesn’t meet your standards, lower your standards.

    The B-52 was the best a/c for demonstrating wing flap. You can still watch them take off with the wings dragging on the runway as they get faster. You know they are about to take off when the wing starts to fly and the wing tip arcs up about 12 feet and starts to support the weight of the plane. I can see a bungee cord doing that, put not a series of welded and riveted metal parts.

    “The Plane, the Plane!!!!!”

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  3. Bubba Ray says:
    3/30/2010 at 8:42 pm

    Bobbo said, “I can see a bungee cord doing that, put not a series of welded and riveted metal parts.”

    Metal is flexible, especially aluminum. I’ve had some engineering problems with the large telescopes we build, tube flexure is a very bad problem, as mirror collimation needs to stay within fractions of 1/1000 of an arcsecond.

    That’s why tube truss design and materials are so important, and weight is not a large factor. Weight affects mount design, which also cannot flex. That’s why large telescopes look so overbuilt.

    However, in an aircraft, weight is also a paramount factor in design and execution. A little flexure in the wing structure as a tradeoff for weight is acceptable.

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  4. Sea Lawyer says:
    3/30/2010 at 8:59 pm

    Red Baron Bobbo – haha, love it!

    Reply
  5. LDA says:
    3/30/2010 at 9:05 pm

    Cool pic. Makes me feel safer, until I remember the video of the wing snapping, but I guess that is the point of the stress test.

    Reply
  6. sargasso says:
    3/30/2010 at 9:21 pm

    I saw a very similar test on a plane in the 1960′s. It is called failure mode analysis. Not very fashionable among young engineers, but essential when there is no existent failure model for a design. The Apollo project was almost entirely failure mode research. “Let’s try to kill these guys”. I love Boeing, they’re not old fashioned, just very, very American in their philosophy of design. My guess is, they are using a pre-stressed multi-modal wing design, maybe 16 element, so strong that passenger bones will break before the wings fall off. Airbus, by comparison, is a computer science company.

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  7. bobbo, int'l pastry chef and Red Baron says:
    3/31/2010 at 1:58 am

    #3–Bubba==well, thats kinda my point, “A little flexure in the wing structure”====I’m talking 12 Friggen Feet–and thats just half the arc from a normal take off. Get at altitude with some turbulence and you got plus/minus 12 feet===aka===”This beast is flapping its wings” ((and in the background—”We’re all gonna die!!!!))

    You don’t see that in a 182.

    Reply
  8. soundwash says:
    3/31/2010 at 3:34 am

    people are only learning about this now?

    how about we stop futzin around, chuck the wings, go all nonconducting composite skin, charge/dump positive ions out the front/leading edge and negative ions out the back, (like the B2) -tune some field coils to nullify local gravity…

    ..and start the producing the craft we were supposed to be flyingdecades ago ffs..

    sheesh.

    -s

    Reply
  9. Eric says:
    3/31/2010 at 4:05 am

    I saw a documentary a few years back about the 777. The wing test is basically a stretch it ’til it breaks test. It took days for them to run the test and when one of the wings finally broke it was nearly vertical. The noise echoed through the hangar for several seconds.

    Reply
  10. Cap'nKangaroo says:
    3/31/2010 at 5:32 am

    Isn’t engineering the most fun!

    Reply
  11. Nobody says:
    3/31/2010 at 5:49 am

    @# 6 sargasso
    All commercial aircraft have the wings tested to 150%
    ps The 787 wings are designed and built by Mitsubishi not Boeing

    Reply
  12. Guyver says:
    3/31/2010 at 10:41 am

    2, Bobbo, Ever consider that the reason for the FAA lowering their standards is due to those standards assuming every aircraft flown will be all-aluminum? The standards would be higher since the aircraft would be more conductive. The 787 may be the first commercial aircraft to make significant use of composites, but the military has been doing this sort of thing for ages. Also, could you explain how lightning prefers to strike the path of most resistance as you’re implying? Last I checked, it’s always been the path of least resistance. :)

    9, Eric, Sounds like a very slow break test. The one I observed took less than an hour.

    11, Nobody, The 787 is completely designed by Boeing. Boeing has outsourced the construction of parts to foreign companies in order to barter for the sale of this plane overseas (like they did with the 747 and 777). Regardless, the wings and other parts are Boeing-designed.

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  13. bobbo, pragmatic scientist and existential wag says:
    3/31/2010 at 11:47 am

    #12–Guyver==no I never considered that. Took the quoted material very much at face value.

    So, lets read it again to the point you raise.

    Seems that the “Standard” at issue is not conductivity as you suggest but just the opposite==”LACK of conductivity or resistance. The implication is that a plane made of composites if it is hit by lightning will more likely be damaged by the lightning than would be an aluminum airplance because the resistance to the electron flow is higher. More heat? More electrical pulsing?? Who knows?

    I guess it comes down to just exactly what the “standard” in question really is.

    but good to know that new airplane designs don’t have to meet standards, new airplane designs simply require changes to the standards. Are you comfortable with that given the nature of your (our) ignorance of the subject at hand???

    I know every time I have lowered my standards regarding the women I date, I have always regretted it. I assume airplanes are no different. Choose your ride carefully.

    Reply
  14. Bubba Ray says:
    3/31/2010 at 1:24 pm

    #7, Bobbo, “You don’t see that in a 182,” no, and a Cessna 182 doesn’t have a wingspan of 185 feet. It’s only 36 feet. You can’t have the B52 design in a B52 made of steel to not flex in a wingspan of 185 feet. Geez.

    Reply
  15. bobbo, I see dead people says:
    3/31/2010 at 1:42 pm

    OK Bubba–once more with feeling: Have you ever watched a wing flap thru 24 feet of arc?

    The B-52 must have the most flapping fixed wing design there is. Never saw that amount of flexure in any other plane. I think it fair that I remark and relate to “the Mostest” thing on a b-52 without some metallurgist guy pooh poohing me with physics.

    Now,I must say I did see a telescope get tired and just droop down on the ground when it got tired looking all day long, but it was a Mickey Mouse cartoon. Not sure of the physics at play there.

    Reply
  16. Guyver says:
    3/31/2010 at 2:17 pm

    13, Bobbo, It’s probably more accurate to say the standards are being changed to be more realistic with the alternative materials.

    I wouldn’t get stuck in first gear and assume standards are being “lowered”.

    Again, the military uses a lot of composites for their aircraft and Boeing is also a military contractor. The magnitude of composites used in commercial is a first, but not for military. If there were some real problems, the military industry would have discovered these problems in great numbers a long time ago.

    That being said, it doesn’t hurt to be cautious if you’d rather someone else beta-test as a passenger on your behalf. :)

    Reply
  17. Bubba Ray says:
    3/31/2010 at 2:48 pm

    bobbo, I see dead people said, on March 31st, 2010 at 1:42 pm, “OK Bubba–once more with feeling: Have you ever watched a wing flap thru 24 feet of arc?”

    Yes, I have. My cousin was a B-52 driver. That may seem like a lot of flexure, but there has never been a B-52 downed due to wing failure. 24 feet in 185 feet of wing full of gas and engines isn’t that big a deal.

    How about the SR-71 Blackbird that just leaks like a sieve on the ground because it isn’t up to operating temp.?

    The wings on my Citabria don’t flex, they’re made of spruce and very short length, but if they were 185 feet long, they’d snap like a toothpick. The B-52 wing flexes only 13 percent, no big deal.

    Learn some engineering, then get back to me. The B-52 is a beautiful aircraft, and has been in service since the 50′s. The wing flexure doesn’t seem like any kind of problem, especially on a 50 year old airplane. Ever flown in a 787?

    Reply
  18. GetSmart says:
    3/31/2010 at 5:38 pm

    If you look out your window on a 787 and see the wing in that posture you’re probably already bleeding from the nose and ears because of “G” forces. Something would certainly be very, very wrong.
    As to the susceptibility of carbon composites vs. aluminum to the effects of lightning, “The military does it.” is not the best argument. They will gladly trade off safety for performance they need in a war machine.

    Reply
  19. Sea Lawyer says:
    3/31/2010 at 8:11 pm

    #18, They will gladly trade off safety for performance they need in a war machine.

    The funny thing is that the military follows significantly higher safety and maintenance regimes than does commercial aviation. The military will ground an entire fleet of aircraft before a commercial airline would ever be required to, since airlines that can’t carry passengers tend to go out of business; the military doesn’t have that worry.

    Reply
  20. GetSmart says:
    4/1/2010 at 6:24 pm

    #19 Sea Lawyer: The Air Force is less worried about lightning than enemy radar. Sure, in peace time they’ll stop and fix a problem. In a wartime combat scenario, they’ll fly the mission anyway if it’s necessary. The F-105 Starfighter was a killer jet interceptor back in the day. Especially during takeoffs and landings, or with a pilot new to the airframe. It’s scarcely the only example.

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