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This photo of Allegiant Air flight 331 got me wondering: how much weight would a typical airliner's wings be able to hold?

Aside: Apparently these folks didn't realise that if they smell gas in the cabin, they probably shouldn't decide to go out of the emergency exits and stand ON TOP OF ITS TANKS! God forbid one of them gets nervous and lights a smoke!

My question is basically: how much weight are airliner wings required to hold $\div$ the average passenger weight? Theoretically how many people? :)

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    $\begingroup$ Just an aside. You can drop a lit cigarette on jet fuel. It won't ignite. $\endgroup$ – Simon Jun 15 '15 at 5:07
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    $\begingroup$ @Simon what about fumes? $\endgroup$ – PTwr Jun 15 '15 at 7:03
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    $\begingroup$ No problem in the open air. I've tried it with Jet-A1 and Avtur. You have to try really hard to get a jet fuel fire. You could stand on that wing smoking all day with no problem. It would be risky during refuelling but otherwise, it;s OK (NB. I am not suggesting anything - just pointing out that jet fuel is not explosively flammable as suggested by Hollywood and the media). Note to interested readers. Do not try this with Avpin :) $\endgroup$ – Simon Jun 15 '15 at 7:56
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    $\begingroup$ As many as you like, as long as they mind the NO STEP signs! :) $\endgroup$ – Pavel Jun 15 '15 at 8:06
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    $\begingroup$ Shouldn't the wings be able to hold the weight of the entire aircraft? That's what they're designed for after all. $\endgroup$ – Ajedi32 Jun 15 '15 at 13:21
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Disregarding the fact that the wing load vector on a passenger jet usually points up, not down, the wings will usually bear most of the load for the entire aircraft. The MTOW for an MD-80 is 63,500 kg. If an "average" passenger is 80 kg, then that is 800 passengers. Obviously that is going to be greater than the number of passengers on the flight, because those wings had already lifted those passengers (and the rest of the plane) into the air in the first place.

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    $\begingroup$ That is also at 1 G. The wing can lift some multiple more of this. $\endgroup$ – user3309 Jun 15 '15 at 0:27
  • $\begingroup$ Indeed. I'm making some major simplifying assumptions here. $\endgroup$ – Greg Hewgill Jun 15 '15 at 0:27
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    $\begingroup$ Transport aircraft have to be able to withstand -1G to +2.5G. The -1G is most interesting here, because passengers standing on the wing are causing bending moment in the same direction as if they were in cabin during negative-G manoeuvre (nobody flies airliners inverted, but negative G is sometimes encountered in heavy turbulence). $\endgroup$ – Jan Hudec Jun 15 '15 at 5:31
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    $\begingroup$ @JanHudec: In this case you need to subtract the wing's own dry weight twice plus that of fuel inside once, because gravity is pointing the wrong way for the -1g case. But this should leave enough margin. $\endgroup$ – Peter Kämpf Jun 15 '15 at 6:21
  • $\begingroup$ @TUMBLEWEED Yes, it's always good for the wings to be able to create more than 1G of lift. Otherwise, taking off (or entering a climb, or decreasing descent rate) becomes very problematic. :) $\endgroup$ – reirab Jun 15 '15 at 15:38
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The specific numbers will vary by aircraft type and model, but from an empty dry wing, you can add thousands of pounds of fuel to each wing. Then on a winter night, add several pounds of ice/snow to every square foot of the wing's surface, which can easily remain there for hours or days. Granted, this is all weight that is on the wing rather than on the fuselage, but as was pointed out, these wings support over 50 tons of aircraft weight at cruise and can handle over double that at a sustained G load, so these are pretty stout structures. A couple dozen people just isn't that big a load for a structure that can handle loads WELL over an order of magnitude greater on a fairly routine basis.

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Each aircraft has its own design for how much it weight it has to hold on the wing. This is incorporated when an airliner goes through certification (I believe it needs to carry 3 times it's design load for 5 seconds, but I may be wrong in that).

Some airplanes are required to hold lots of weight on the wings, not only from the forces of flight, but also by the possibility of evacuations. According to Wikipedia, aircraft such as the Boeing 747 can hold 740 kg/m2. With a wing area of 525 m2, this means that the wings can hold 388 500 kg. Assuming each passenger is about 100 kilograms, that means you can hold 3885 people on the wing at once. That is, of course, if you can manage to fit them all in that gaggle without slipping off. It'd be pretty tough getting 5 people in a square metre, would it not?

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    $\begingroup$ Over 1000 people on EACH WING? Where'd they all come from? Triple economy class seating??? That's actually a good illustration to compare wing capacity with aircraft capacity. $\endgroup$ – Ralph J Jun 15 '15 at 0:52
  • $\begingroup$ Sorry! Not 1940, but 3885 (How'd you screw that up Zin)! Let just say that we stacked people on top of each other and hope they were skinny noodles, and hoped for the best as well. :) $\endgroup$ – Zizouz212 Jun 15 '15 at 1:00
  • $\begingroup$ If I were an airline stockholder, the ability to stuff 2x3885 pax into a cabin, and not being allowed by administrations would haunt me all my life. We need less regulations. $\endgroup$ – mins Jun 15 '15 at 5:30
  • $\begingroup$ @mins it's only a matter of time.. $\endgroup$ – Raystafarian Jun 15 '15 at 9:00
  • $\begingroup$ @mins Well... the plane does have to hold a bit more than just passengers. Itself and the fuel, for example. Passengers are usually actually a relatively small percentage of the overall weight of an airliner, especially in the case of jets designed for long-hauls, like the 747. The fuel alone weighs (a lot) more than the pax. For a 747-400ER, the empty weight plus a full fuel load is 382,334 kg... and the MTOW is only 412,775 kg. In the case of a full fuel load, that leaves only 7.4% of the MTOW for pax+cargo. $\endgroup$ – reirab Jun 15 '15 at 15:11
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Everyone pointed out that the total weight won't be a practical limitation. But what may be the limit is the local pressure on the wing skin. Aerodynamic forces are nicely distributed over the wing area. Not so with shoes. A small lady on high heels may do enough damage to ground the aircraft :) Not to mention that some people may start wandering on flaps and other "no step" areas, which may also cause structural damage.

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