[jodrellblank]

> "China is doing R&D on a partial-vacuum train (basically Musk's hyperloop thing) with a target of 1,243 mph"

When the vacuum fails - mechanical failure, human error, natural disaster, attack - air is going to rush into the tube. The speed of sound is how fast air molecules move, so train doing 1243mph might hit into a wall of air coming the other way at 767mph for a 2000mph collision. Don't think "wind isn't that fast", think vacuum implosion[1][2]. The weight of 60+ miles of atmosphere pushing down trying to force air into the tunnel. The principle that moves atmospheric steam engines. The train will then be blown backwards into the train coming behind it for another 1000mph+ collision.

This will be the Hindenburg of the Hyperloop.

[1] https://www.youtube.com/shorts/j-s5Ut5cm50

[2] https://www.youtube.com/shorts/if9xxrRouRY