Hacker News Reader

Comment by WalterBright | Hacker News Reader

The sheets of stainless steel appear to have separated at the joints. This says the sheets are stronger than the joints, meaning they're overweight :-)

View on HN

They're experimenting with 3mm steel instead of 4mm steel. A test tank they've built already passed an initial pressure test on 26 Jan.

One Starship requires 15 rings, a nosecone, a bottom and tanks. If they would all move from 4mm to 3mm then that would save a lot of weight. About 7-10 tonnes according to [1].

[1]: https://forum.nasaspaceflight.com/index.php?topic=52701.160

Wow, that could be a really big deal in terms of maximum payload.

I was thinking something similar myself (more on weld quality, "welds should be as strong as the rest of the material"), but then I realized that this doesn't matter, and having an unoptimized test vehicle a week earlier is always going to be the better option for SpaceX.

1. Is it light enough to fly?

2. Is it strong enough to not cause a failure?

#shipit

A static weld is usually stronger than the base metal under static conditions (i.e. not undergoing dynamic shock loading). Welds are created at 3000 degrees C with 50-100C metal right next to it. By the time a weld cools there are always captive stresses, meaning during a failure the weld is the most brittle part. This can be alleviated with pre and post weld heat treatment, but there are always stresses built into a weld.

wouldn't it be common to rip right next to stiffer the joints if they where the hardest part too?

Reply on news.ycombinator.com