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For a university project, I'm working on optimisation of a Falcon-9-like launch vehicle, and one element of that is varying expansion ratios of the engines. This will impact on the engine mass, but to calculate that I'd need the thickness (or mass per unit area) of the engine bell of a Merlin or comparable engine, and I'm struggling to find any sources.

Edit: it's been pointed out that my question lacked specifics, I was after the typical wall thickness of a regeneratively cooled nozzle - as opposed to radiatively cooled like Merlin Vac, and not including support structures or external piping

Talisker
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    It varies enormously engine-to-engine. I believe it also varies with different parts of the nozzle; someone (I forget who) on this site claimed the very large nozzle expansion of the Merlin vacuum engine gets down to 1/64" thickness at the end, and you can see quite a bit of flexing happening in videos of Falcon second-stage burns. https://space.stackexchange.com/questions/22789/did-i-see-the-formosat-5-f9-2nd-stage-nozzle-vibrate-at-about-2hz-at-seco-1/22790#22790 – Russell Borogove Apr 10 '20 at 17:32
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    SpaceX once fixed a crack at the end of a nozzle by trimming it with a tin snips. So they can get pretty thin. https://naturallyfundamental.com/spacex-tin-snips-rocket-fix/ – Greg Apr 10 '20 at 21:25

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At the exit plane the Space Shuttle Main Engine (SSME) nozzle was about 2 inches thick. This was a regeneratively cooled nozzle built up of tubing with a manifold encircling the exit.

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Source: SSME Orientation (annotation mine)

Three SSME nozzles in the engine shop at KSC and a closeup.

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Source: personal photos

Organic Marble
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