PPRuNe Forums - Can wings snap off if empty?

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- - Can wings snap off if empty? (https://www.pprune.org/tech-log/619664-can-wings-snap-off-if-empty.html)

Quote:

Originally Posted by VinRouge (Post 10427194)

some aircraft such as the herc have a ZFW that changes due to airdrop. Once the load is used, the excess fuel can then be burned as recovery fuel. Often on result missions, you have to plan on rtb without completing the drop so then the fuel becomes unusable.

Ah, OK.
I take the point about refuelling, or airdrop missions.
I thought the OP was asking if this applied to all cargo, and possibly PAX config.

Quote:

Originally Posted by VinRouge (Post 10427194)

So if I understood that right. If you do not drop a load from fuselage you have to keep fuel in wings?

Quote:

So if I understood that right. If you do not drop a load from fuselage you have to keep fuel in wings?

That's right. It's all about reducing the wing bending moment. :ok:

Quote:

Originally Posted by FCeng84 (Post 10426921)

Thanks for the kind words.

As load factor increases, ailerons and outboard spoilers trailing edge up (dumps some outboard lift) and at the same time inboard spoilers down (if, up - preserves inboard lift). The challenge is what this does to longitudinal center of lift and pitching moment on a swept wing airplane and how to manage to preserve acceptable maneuver response from the pilot's point of view.

Thank you for your replies. Interestingly, you answered the question I MEANT to ask but couldn't form. :) If you need to use wing mechanisms to reduce wing load, what do you use to actually steer the aircraft? It must be one heck of a task for a computer AND the computer programmer to implement an algorhythm (no idea how to spell that) that will both preserve the wing from over bending and at the same time will make sure the plane flies where the pilot commanded.

Another thought suddenly got caught in my neuron nets. I remember reading that on Airbus A310 they removed the outboard ailerons because, after flying A300, they realized those were "unnecessary". I wonder if they simply added them as, let's call them, "wing load controlling devices".

A number of aircraft I'm familiar with use the ailerons for more than one task. Some blended the functions mechanically others via software. It's not that complicated and many model flyers do the same thing particularly in high performance gliders. Google "snap flap" on DLGs for example where the wing trailing edge device is used for pitch trim as well as Roll, High lift and High drag(lift dump). All the functions are mixed in the transmitter in that case.

As for empty wings snapping off!
I flew Tankers and it never happened to me even when landing on fumes! We did have strict rules about how much centre tank fuel we could load and how we considered that fuel in the mass and balance calculations.