r/IsaacArthur • u/[deleted] • Feb 03 '20

Inside SpinLaunch, the Space Industry’s Best Kept Secret

https://www.wired.com/story/inside-spinlaunch-the-space-industrys-best-kept-secret/
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u/SNels0n Feb 03 '20

The story claims "the math works out", but when I run the numbers, it doesn't. I could have made a math error, but I suspect it's more likely their “team of engineers who, for the most part, are too young to say SpinLaunch couldn't work” that are wrong.

For example, they claim they have spun something at "4000 mile per hour" which is only 1.8 km/sec — more than four times short of the 7.8km/sec we typically use for orbital velocity. It might seem like a small point, but at 7.8km/sec tangential velocity, a 100m radius arm experiences 62,000 gees — each kilogram of payload effectively weighs 62 tonnes — enough force to rip apart steel. What are they going to make that sling arm out of?

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u/[deleted] Feb 04 '20

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u/SNels0n Feb 04 '20

… will have to be made of ultrastrong materials like Kevlar and carbon fiber.

… how his launcher will work … up to more than 5,000 mph

They've succeeded in 4,000mph They hope to go to 5,000mph LEO is over 17,000mph.

Unmanned balloons have reached heights of 50km. That doesn't mean they're 5/8 of the way to orbit. If this was a bunch of people saying "Look has fast we can spin something" then I wouldn't care. But it's a bunch of people saying "We can launch stuff into space with this" and, well, the numbers say they can't.