9
$\begingroup$

How much of the dry mass of a typical airliner (let's say a Boeing 737 or Airbus A320, if a particular model is needed) consists of rivets used in assembling the plane?

$\endgroup$
4
  • $\begingroup$ Could you unaccept my answer? I'm not confident it's correct and like I'd to delete it pending some more research. $\endgroup$
    – Chris
    Dec 24, 2023 at 18:52
  • $\begingroup$ @Chris sure, I unaccepted it. $\endgroup$
    – Someone
    Dec 24, 2023 at 19:06
  • 1
    $\begingroup$ A similar question with a slightly different answer would be the weight caused by the addition of rivets. There is some overlap of material where it is riveted together which adds slightly to the weight compared to using larger non-riveted sections. Partly countering this is the rivets replace a (very) small part of the material. Further complicating that question would be taking into consideration having to use thicker material to make larger sections possible. But still it's interesting to think if you could hypothetically "3D print" a hull, how much less would it weigh than riveted sections $\endgroup$ Dec 25, 2023 at 19:15
  • $\begingroup$ German Karlsruhe Tech managed to build a 4 mm thick wall concrete kart body on a prestressed concrete plate (see Indian concrete magazine), at a density of 2.6 gr/ cc, It isn't bad $\endgroup$
    – Urquiola
    Dec 26, 2023 at 20:13

1 Answer 1

2
$\begingroup$

$\def\cm{\rm cm}$ I cannot find authoritative answers. But we can do some ballpark estimates. This is an image of an A320 fuselage. Making a lot of assumptions, but one hopes that they will more or less balance out. I would say that separation between rivets is around $1.5\cm$ (using a window height of $36\cm$ to compare). The spars seem to be separated by about $50\cm$, with rivets all around. The fuselage diameter is 395cm, which gives us a circumference of $395\times 3.14 = 1240 \cm$. The length of the fuselage is $3757\cm$, which gives us $3757/50 = 75$ spars. That gives us $$\tag1 75 \times 1240\cm \times\frac1{1.5\cm} = 62,000 $$ rivets for the spars. There are also seem to be rivets along the fuselage, separated by 15cm. This would give us $$\tag2 \frac{1240\cm}{15\cm}\times \frac{3757\cm}{1.5\cm}= 207,000. $$ A crude estimate looking at the windows gives me $200$ rivets per window, with $88$ windows, so $$\tag3 88\times 200 = 17,600. $$ I cannot find a good enough picture of the wing, but based on this one I will assume the same rivet density as in the fuselage. The surface are of the fuselage is $1240\cm\times 3757\cm = 4,658,680 \cm^2$, and we estimated (from $(1)$ and $(2)$) $269,000$ rivets, so $$ \frac{269,000{\rm\ rivets}}{4,658,680\cm^2}= 0.06 \frac{{\rm\ rivets}}{\cm^2}. $$ The wing area of the A320 is $1,226,000 \cm^2$. Doubling this because we want to also count the underside, we get $$\tag4 2\times 1,226,000 \cm^2 \times 0.06 \frac{{\rm\ rivets}}{\cm^2} = 70,791 \ \rm rivets. $$ We are ignoring the other surfaces, but let us assume that the contribution is not that significant. We get a total of $$ (1)+(2)+(3)+(4)= 357,391 \ \rm rivets. $$ This number looks coherent with sources that mention 3 million rivets for a 747 or A380, which weight around 10 times as much as the A320.

As for the weight of a rivet, this article mentions about $300$ rivets in $0.25\ \rm lbs$ bag. That's $$ \frac{0.25\ \rm lbs}{300\ \rm rivets}\times \frac{\rm kg}{0.454\rm lbs} = 3.78 \times 10^{-4}\frac{\rm kg}{\rm rivet}. $$ This gives us a total rivet weight of $$\tag5 3.78 \times 10^{-4}\frac{\rm kg}{\rm rivet}\times 357,391 \ \rm rivets = 135\rm kg. $$ The empty weight of an A320 varies according to variants, but one source I found says $42,220\ \rm kg$. This gives the proportion as $$ \frac{135}{42220} = 0.003, $$ or $3/1000$.

$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .