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Some American rocket engines have TCA's (thrust chamber assemblies) built after a certain scheme:

A combustion chamber, including part of the nozzle, made of several dozens of stainless steel tubes running alongside the exhaust gas, brazed together (also referred to as longitudinal tubewall chamber) plus sometimes an nozzle extension.

However, one thing that left me baffled is: How were these tubes brought into a proper shape to be made into a nozzle? As the cross-section of the combustion chamber varies, so has the tubing, and as seen in Hazel and Huang below, the cross-section may not even remain circular.

Hazel and Huang make a comment about the manufacturing of these tubes here in their book, but unfortunately, details are left out.

NASA SP-8087 also describes the process, but again, no details.

What I'd like to know is: Do we have video footage / images or a more detailed description of this manufacturing process and/or the tooling that was used in it? One source which I'm unfortunately not able to recall claimed that this process was very difficult and prone to failure, thus for each engine they wanted to build an order was placed for three times the tubes necessary, all of them had their performance estimated by undergoing flow-tests and two thirds with the worst performance were simply discarded.

Edit: This is a question specifically regarding the manufacturing process of stainless steel tubing with varying cross-section.

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  • $\begingroup$ I don't think it's correct that the tubes get mashed into square-ish shapes. I think it's more that they get brazed together at the points where the circles touch. I'm out of town right now but when I get back, I have some pictures I took of the actual tubes in the SSME, and unless I'm misremembering, they are round. BTW, I am not the down voter and I'm baffled as to why this got downvoted. $\endgroup$ Aug 5 at 23:12
  • $\begingroup$ Check out this picture of the inside of an F-1. You can see the tubes are still round. cdn.arstechnica.net/wp-content/uploads/2013/04/… $\endgroup$ Aug 5 at 23:26
  • $\begingroup$ "All american rocket engines I know of": I think only the RL-10 and RS-25E are still built that way, and Rocketdyne's experimenting with a 3D printed thrust chamber for the RL-10, while the RS-25E only uses it because development of a more modern channel wall version got cut. Modern practice is to use milled or 3D printed channel walls. $\endgroup$ Aug 6 at 0:27
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    $\begingroup$ Related question with informative comments and answer: space.stackexchange.com/q/30588/6944 $\endgroup$ Aug 6 at 0:33
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    $\begingroup$ @OrganicMarble I should have stated that I don't really know about how modern engines are made, I always was more interrested in the 'retro' side of things, primarily anything that took place in the 60s. Also, whoever downvoted probably believed that I didn't read up on the related question you sent me, but I have already read it and it did not really satisfy me, which is why I wanted to ask this in the first place. This question is specifically regarding the manufacturing process. $\endgroup$
    – Darkcoucou
    Aug 6 at 8:31

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