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We can evaluate how thick walls are by looking at door or window frames, however that isn't representative of an aircraft fuselage, which appears to be very thin:

enter image description here
Airbus A350 XWB forward fuselage, source

  • How thick (thin!) is the fuselage?
  • Do some areas have a thicker skin for some reason?
  • What about glass, doors, wings, floors, and other elements than the walls?

(I'm talking about the aircraft skin itself, not stringers or other structural stiffeners.)

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    $\begingroup$ It is really quite thin and fragile too. You see the red robotic arms? They are equipped with load sensors and once the load is exceeded they go into floating mode with an alarm sounding and those green lights that you see everywhere go into orange or red failure mode. It is a rather bad idea to temporarily disable these sensors when testing the software to compute the robot arm movements and mess up and then you can easily distort a part of the fuselage (insurances can be a nice feature) $\endgroup$ – PlasmaHH Nov 10 '17 at 9:57
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    $\begingroup$ You can't evaluate the thickness of a building's walls by examining the door or window openings. Like aircraft walls, building walls are composite structures. Masonry walls have inner and outer leaves with an insulated void, timber-framed walls often have an outer shell of fairly thin siding. You are asking about the thickness of those outer skins, not of the structural elements or the whole. $\endgroup$ – RedGrittyBrick Nov 10 '17 at 10:37
  • $\begingroup$ Imagine an aluminum pop can - blow it up to the size of a 737 fuselage and the aircraft skin will be about half to a quarter of the thickness of the pop can wall thickness. $\endgroup$ – J... Nov 10 '17 at 19:38
  • $\begingroup$ @mins No, that's not even close. Maybe I wasn't clear. If you scaled a standard 355mL beverage can proportionally to a cylinder of diameter equal to the fuselage of something like a B737 (imagine exactly a pop can the size of an aircraft), you would find that the pop can would have a wall thickness several times (2-4) thicker than the aircraft. This is just to give a sense of scale with respect to something you might handle in your everyday life. $\endgroup$ – J... Nov 10 '17 at 20:12
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    $\begingroup$ @mins If I had time, I could probably answer a lot of them, at least for Airbus A340/A380/A400M, but you know, life and kids and stuff... $\endgroup$ – PlasmaHH Nov 10 '17 at 22:26
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The skin on the wings also tends to be a bit thicker, as well as being composed of different materials and finishes.

MD/DC, Airbus, and Boeing have aluminum skin roughly an 1/8th inch thick that is backed with a sealed fiberglass coating which provides the skin with strength and flexibility. The underbellies have slightly thicker skin and so do areas subjected to high wind.

Areas like the APU intake and gear doors have significantly thicker skin up to a 1/4 inch.

Airbus Gear Door

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  • $\begingroup$ That image is misleading. It does not show a solid slab, but a hollow box section. $\endgroup$ – Hobbes Feb 15 at 9:56
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From whats written here

f100 skin is 1.0 - 1.4mm

b747 skin is 1.8 - 2.2mm

a320 skin is about 1.1mm

According this article on the 757

...Although Boeing specified that the skin in that area of the fuselage must be 0.039in (0.99mm) thick...

Some interesting info here as well.

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  • $\begingroup$ Have any figures for composite fuselages? $\endgroup$ – Nick T Nov 10 '17 at 20:20
  • $\begingroup$ @NickT I have come across a few things on that topic. I think that might be a great question all to its self as composite skins are much different than metal skinned aircraft. $\endgroup$ – Dave Nov 10 '17 at 20:25
  • $\begingroup$ The first source (forum) also states: "More recent commercial a/c have fuselage skins that are quite a bit thinner than 1/4 inch". I would prefer figures to be supported by technical documents (if possible). The A350 fuselage is 50% composites. $\endgroup$ – mins Nov 10 '17 at 22:08
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Just a couple of mm thick, about 2-3 is enough. The fuselage barrel gets its strength from the large diameter: bending moments of the fuselage (and wing) get translated into tension and compression loads in the skin. The aircraft skin is the main load bearing structure.

from a sales site for I-beams

It's the same principle as that for I-beams:they are that shape because the top and bottom plates carry the useful load, the middle bit is basically mainly there to keep them apart. If a beam is required for more load, increasing the distance between top and bottom has a quadratic effect on load level reduction. And the same principle that nature applies to bird bones: they are hollow, because the outer bit is the most effective.

The stringers and other structural helpers are mainly there to help keep the skin in shape, prevent buckling etc. Some older and/or smaller wings use a single, I-beam type spar for absorbing the ebnding moment, but most effective is the wing box shape: front spar, rear spar, top skin, bottom skin. It resists torsion best and reduces flutter, it also keeps the skin in better shape.

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The fuselage skin varies in thickness depending on the section, physical features, structural loading, etc. but is between about 2-4mm in thickness for pressurized aircraft and roughly half that value for unpressurized airplanes.

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  • $\begingroup$ Actually it even varies along a single panel. In this movie (from a german children television show) it can be seen that the panels of an A320 are actually etched to different thickness depending on the proximity to stringers or windows: youtu.be/M83SZfATzfs?t=251 $\endgroup$ – dronus Jun 17 at 19:47
  • $\begingroup$ Yes areas of the skin can have doublers in sections determined to have high stress concentrations such as around windows, doors, spars, frames, etc. The thickness of the skin as well as all other structural members is determined by iterative stress analysis during design. $\endgroup$ – Carlo Felicione Jun 18 at 16:52
  • $\begingroup$ Well I don't would call this doublers, as actually there is nothing joined or attached, just the whole skin is etched down to three or more different thickness levels depending on the location. So the answer is much more complicated than one thickness value... $\endgroup$ – dronus Jul 5 at 14:59

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