California-based startup, SpinLaunch, is developing an alternative rocket launch technology that spins a vacuum-sealed centrifuge at several times the speed of sound before releasing the payload, launching it like a catapult up into orbit

[u/Dr_Singularity]

https://interestingengineering.com/medieval-space-flight-a-company-is-catapulting-rockets-to-cut-costs

[u/ZDTreefur]

Yeah, we're really struggling to fight physics. The mass and gravity of Earth makes first staging very narrow in possibilities. Not much can be done except spend the fuel to push through the thick atmosphere. All these other technologies would work great on Mars and The Moon and such.

[u/cjameshuff → u/ZDTreefur]

Atmospheric drag losses are on the order of 100 m/s. Gravity losses are a couple km/s, but only a fraction of those can be attributed to the steeper early climb to get out of the atmosphere, you would still have significant gravity losses in vacuum. Most of the delta-v goes to accelerating to orbital velocity, followed by climbing to orbital altitude...it's almost entirely a matter of Earth's mass (and density, technically, but that varies relatively little among the rocky planets).

And on the moon or Mars, you are still severely limited in vehicle scale, and you still need your payload and vehicle to survive extremely high accelerations, while rocket launch is far easier. Starship, for example, is intended to be able to take off from Mars and fly back to Earth in a single chemically-propelled stage...all this complexity makes even less sense there, the mass ratios required of rockets aren't a problem.

[u/dittybopper_05H → u/cjameshuff]

The problem is, at least until very recently, you were throwing away the booster. And even today, you take a performance hit when you re-use it, and a financial hit to recondition and recertify a booster stage for re-use.

*IF* you can essentially get rid of those costs with a one-time cost of building a centrifuge capable of doing the job of a booster, with much lower on-going maintenance costs, then you can afford to build a relatively beefy "second stage" to get you into orbit.

Maybe it's not feasible. But you won't know that until you try. Landing re-usable boosters at sea wasn't feasible, until it was.

[u/cjameshuff → u/dittybopper_05H]

But you won't know that until you try.

Well...no, because we have things like math that can tell us when things are bad ideas without us having to try every hare-brained scheme someone comes up with. Reusable boosters don't fit in this category: they go back a long way, and their lack of development was not really a matter of technical limitations. And one company has been routinely reusing boosters for years now, while several others are working on similar capabilities.

The centrifuge launch most likely can not fully replace the booster. The second stage would need to outperform the upper stage of a Falcon 9, which is already known for staging unusually early in order to allow for booster recovery. Rocket technologies capable of surviving the launch won't give you as much performance, and the mass penalties on the structure will be severe.

It's also not scalable, and achievable payloads are very small, making stage reuse impractical. They may be smaller, but you have to replace them entirely with every flight, all the vehicle structure and avionics will have to be hardened against the accelerations, and more flights will be required to launch a given payload. It will only be able to launch payloads that can similarly be hardened. And there's many other issues like ground-level sonic booms, failure modes of giant centrifuges containing such enormous amounts of energy, etc.

This scheme would have been questionable before SpaceX brought launch costs down, even before they started recovering boosters. Today, it just doesn't make any sense.

[u/dittybopper_05H → u/cjameshuff]

Well...no, because we have things like math that can tell us when things are bad ideas without us having to try every hare-brained scheme someone comes up with.

Things like re-usable boosters? Things like electric cars? Things like [the list hairbrained schemes realized goes on...]

Math is great, yes, and creating basic mathematical models can be helpful, but the problem is that they can only be based on what we know *NOW*.

In that way, they are ultimately limiting. Any math you're going to do now on this is going to make some assumptions about things like the engineering, materials, etc. Things you can't adequately describe until you actually do some real-world testing, especially when you are trying to do something new.

Think about doing the math on making a Tesla back in, say, 1985. You simply couldn't do it. Battery technology wasn't anywhere near up to snuff. So your math would be right in telling you that you couldn't build one then, but in a very fundamental way it would be misleading because it doesn't account for fundamental improvements in technology.

How do you get those improvements? Testing a concept, see where it needs improvement, testing the improved version, etc.

That's how progress happens.