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I am actually trying to understand which option is going to be a more relaible for the wing-fuselage attachment. Should I choose a connection between the flanges of the spars within the wing to the internal structure of the fuselage, or I should go with the attachment of webs of the spars within wing to the fuselage? What most of the aircrafts opt for, and does it depend on what aircraft category it belongs to (like commercial/fighter/cargo etc).

If any answers are provided, it would be appreciated to back it up with reasons.

(Does aircrafts also connect the wing skin to the fuselage skin? If yes, then what kind of aircrafts do that and why).

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  • $\begingroup$ Do you understand what the web is supposed to do? And what the spar is supposed to do? $\endgroup$
    – DKNguyen
    Nov 9, 2021 at 15:00
  • $\begingroup$ Yes. spar webs carry the shear loads while spar flanges carry the bending loads. But I saw some aircraft designs where connections were made between the spar webs and fuselage, while some had connections with spar flanges and fuselage. So I don't know why are they going for different options. $\endgroup$ Nov 9, 2021 at 15:01
  • $\begingroup$ You are asking whether the fuselage should mount to the spar or the shear web right? $\endgroup$
    – DKNguyen
    Nov 9, 2021 at 15:01
  • $\begingroup$ I just know what kind of loads each carry. But from the connection point of view, I don't know which one makes sense and why. $\endgroup$ Nov 9, 2021 at 15:03
  • $\begingroup$ Oh, I think I know what you're getting at. The spar is what you need to connect to since that is supposed to be what carries the bending load, but sometimes you just can't because it's too thin. Nowhere to grab onto. In cases like that , the web is reinforced near the root to transmit forces to the spar. Like a foam wing with thin carbon spar caps. And yes, stressed skin designs exist. $\endgroup$
    – DKNguyen
    Nov 9, 2021 at 15:05

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It seems your asking about lightweight airplanes like Cessna 172 or Cherokee Warrior etc. The big airplanes structure is hardly reducible to members as simple as spar or its web and flange.

Cessna 150 and 172, 180, and some others have two pipe stub outs that attach to the fasteners connected to the continued pipe built in the fuselage on top of the cockpit.

They are only compression, tension member of a truss whose diagonal strut is attached mid-wing to the landing gear.

Cherokee has its spar continue under the fuselage and attached to special brackets on the two sides with flanges and web both connected.

Every design has been calculated and tested not just for bending moment and shear but any complex combination of twist and torque and vibration and unsymmetrical loading.

As for the skin, I don't know about the new composite carbon fiber skins but the classic aluminum, that I repaired myself (as an emergency, I am a PPL pilot), is mostly simple sheets of aluminum riveted or screwed to the frame and they are designed to have seams at convenient places so as not creat parasite stresses due to wind or vibration. The Cessna is a monocoque structure meaning the skin is the structure. Below is a figure of a Cessna 172.

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Cessna 172

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