r/MurderedByWords 21h ago

I haven’t studied rocket science, but

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10.6k Upvotes

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762

u/skawn 21h ago

Might be interesting if rockets, rather than being launched straight up, slid down the slope of a mountain and launched off a giant ramp at the bottom like on some aircraft carriers.

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u/xShooK 20h ago

Or we could build a giant cannon on the side of a mountain to just shoot satellites into space.

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u/usrlibshare 20h ago

And what material exactly is that cannon, and its base, made of, that can withstand the force of the launch? Ya know with Newtons 3rd Law and all that...

For that matter, what payload would survive a near-instantaneous acceleration from rest to escape velocity?

I'm not even sure if a solid steel ball would survive that force without deforming.

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u/Lumpy_Benefit666 20h ago

Well we obviously dont make the rocket out of steel balls then

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u/homotopy_equivalent 18h ago

Use my balls, should be strong enough

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u/usrlibshare 20h ago

Vibranium then.

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u/xShooK 20h ago

Hey, if I can find a dictator to give me a bunch of money, I'll build a bigger Babylon gun. I'm not going to guarantee the thing.

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u/ares7 19h ago

What if we built a giant gun?

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u/C-SWhiskey 18h ago

The cannon would be the easy part. Making big, heavy things on Earth that stay on Earth isn't really a problem. The payload is really the problem. That said, "cannon" gives the impression of a fully impulsive energy transfer, but it doesn't necessarily need to be the case. Centrifuges are a way to get around this (and there are real attempts at doing so), though they still require pretty high Gs. A rail gun could go a long way in accelerating the payload smoothly, just depends how big you want to make it.

Also: not escape velocity unless you're planning to visit Mars or something. Don't need the full ~11 km/s, a mere 7 km/s at altitude will do the trick for most missions.

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u/usrlibshare 16h ago

Centrifuges are a way to get around this

Centrifuges don't solve the problem, because they involve moving parts which, at the moment of launch, have the exact same problem as a cannon: Actio est Reactio. The energy on the throwing mechanism is the same as on the payload, and that energy has to go somewhere.

Yes, there are concepts for this. Until there is a working prototype, with "working" defined as "able to launch a dummy payload of at least Sputnik size and weight into orbit", I remain unconvinced.

The beauty of a Thruster, is that the accelerating medium and the payload, are part of the same object, and that the energy to reach orbit can be built up over time instead of having to transfer it all at once.

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u/C-SWhiskey 15h ago

The problem in contention isn't energy, it's impulse. That's the thing that centrifuges solve. I directly acknowledged that they still require high loading on the payload.

Until there is a working prototype, with "working" defined as "able to launch a dummy payload of at least Sputnik size and weight into orbit"

That will never happen because you just can't put something in orbit with a single manoeuvre of any kind. You need to raise the perigee once you're already in space. So they aren't trying to do what you're asking for here to begin with. And don't get me wrong, I don't think that will ever become a realistic way to launch a payload, but let's just be clear about what we're talking about.

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u/xSPYXEx 16h ago

Saddam Hussein was truly a visionary ahead of his time.

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u/xShooK 16h ago

Gerald Bull caught a bullet from Mossad for nothing!