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Giant catapult sends satellites into space

spinlaunch.com

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Re: Giant catapult sends satellites into space

#31

Post by fcq »

Manuel_D wrote: post #8

There's some pretty fundamental problems with spin launch. Atmospheric drag is greatest at sea level, and drops as altitude increases. A traditional lift vehicle is traveling slowest during the early parts of its ascent, and starts reaching high velocity once it's cleared the thicker parts of the atmosphere. In contrast, spin launch is at its highest velocity (before the rocket engine ignites) right after it's releas…

I wonder what would be the technical challenges of a railgun powered rocket/capsule to launch small payloads to space, technically the remaining concern would be the G force from the acceleration.

Re: Giant catapult sends satellites into space

#32

Post by rdtsc »

The recent news items about them have the "someone please buy us" desperation vibe to them. It was an exciting startup 10 years ago or so, then everything went quiet, then all of the sudden there were some items in the news but nothing really substantial - "we hit orbit" or something like that. Just a nebulous "Oh, there Spinlaunch, remember us?"

Re: Giant catapult sends satellites into space

#33

Post by ballooney »

As I said here a few years ago, I support this sort of company. VCs are basically stupid, especially for companies that are more complicated than gluing javascript together, and so it’s only just and right that some actual engineers have some fun in the desert for a few years at their expense, and get some experience putting ambitious, if ultimately silly, machines and prototypes together quickly and scrappily for a few years. Then when spinlaunch goes bust, which of course it will as its idea makes zero sense from an engineering pov, there will be a bunch of hardened and experienced engineers who can go and work for people with more of a clue and do something useful. It’s like a well funded extra-curricular student project.

Re: Giant catapult sends satellites into space

#34

Post by bloopernova »

MadnessASAP wrote: post #30
bloopernova wrote: post #17

Accelerating in a huge vacuum chamber seems pretty difficult to achieve, and wouldn't there be a huge shock to the vehicle as it hits a wall of dense air? How much of a difference would a low pressure chamber make, I wonder? Maybe you could build the circular accelerator then a much longer exit pipe that runs up the side of a mountain. Although that sounds way, way easier said than done! But if your exit air pressure…

Well actually.... Even if you place the exit at higher altitude with lower pressure, without a seal you'll still end up with higher pressure at the base. Just like you do in open air, the weight of the air column pushing down increases the pressure.

Good point!

If the launch vehicle can accelerate well enough in low pressure instead of vacuum then maybe you could "just in time" depressurize segments of the tube. Although that's still getting perilously close to the magical airlock concept.

Apologies for rambling, this is fascinating.

Re: Giant catapult sends satellites into space

#36

Post by wkat4242 »

Manuel_D wrote: post #8

There's some pretty fundamental problems with spin launch. Atmospheric drag is greatest at sea level, and drops as altitude increases. A traditional lift vehicle is traveling slowest during the early parts of its ascent, and starts reaching high velocity once it's cleared the thicker parts of the atmosphere. In contrast, spin launch is at its highest velocity (before the rocket engine ignites) right after it's releas…

I don't see how this will work. You need to launch through the entire atmosphere and still end up with orbital velocity. The only acceleration happens at the beginning so you must launch at speeds much higher than orbital speeds. Which in turn means heating will be insanely high as your highest speed is going to be at the highest drag. The satellite will heat up a lot more than one simply re-entering. Meaning a totally different design or a bulky fairing. Because sats aren't made to withstand that kind of heat. Also yes the forces will be extreme. They seem to be going for the fairing, but how does that reenter then?

I just don't see this happening tbh.

Besides, with spacex and reusability launch capacity is already more available and cheap enough than humanity needs.

Re: Giant catapult sends satellites into space

#37

Post by Animats »

petee wrote: post #27
ARandomerDude wrote: post #19

From what I can tell looking at SpinLaunch's website and web search, they were founded in 2014, "launched" a couple projectiles in atmosphere, had a leadership change in 2022, and have been pretty quiet since then. Unless I've missed something, the headline "Giant catapult sends satellites into space" is not true. To date, they have not put anything into orbit and the company appears to be on life support.

From what I could find they have only reached 1/10th of the Karman line. I also think its a red flag that they do not have actual press releases or data, just a list of any random website that wrote a story about them.

SpinLaunch built a prototype back in 2022 that can throw stuff up to suborbital altitudes. The big version was supposed to be done by now. They had a lot of trouble finding a launch site. Hawaii didn't like it. Alaska didn't like it. Australia was discussed but nothing happened.[1]

This might be useful if there were space stations that needed large, frequent deliveries of fuel, air, and water.

[1] https://thespacebucket.com/what-happened-to-spinlaunch-its-p...

Re: Giant catapult sends satellites into space

#38

Post by XorNot »

fcq wrote: post #31
Manuel_D wrote: post #8

There's some pretty fundamental problems with spin launch. Atmospheric drag is greatest at sea level, and drops as altitude increases. A traditional lift vehicle is traveling slowest during the early parts of its ascent, and starts reaching high velocity once it's cleared the thicker parts of the atmosphere. In contrast, spin launch is at its highest velocity (before the rocket engine ignites) right after it's releas…

I wonder what would be the technical challenges of a railgun powered rocket/capsule to launch small payloads to space, technically the remaining concern would be the G force from the acceleration.

Railguns have always suffered from rail degradation.

Basically even if you build a suitably large one, you might get as few as 1 shots from the structure before having to replace the entire rail.

Re: Giant catapult sends satellites into space

#39

Post by stevage »

wkat4242 wrote: post #36
Manuel_D wrote: post #8

There's some pretty fundamental problems with spin launch. Atmospheric drag is greatest at sea level, and drops as altitude increases. A traditional lift vehicle is traveling slowest during the early parts of its ascent, and starts reaching high velocity once it's cleared the thicker parts of the atmosphere. In contrast, spin launch is at its highest velocity (before the rocket engine ignites) right after it's releas…

I don't see how this will work. You need to launch through the entire atmosphere and still end up with orbital velocity. The only acceleration happens at the beginning so you must launch at speeds much higher than orbital speeds. Which in turn means heating will be insanely high as your highest speed is going to be at the highest drag. The satellite will heat up a lot more than one simply re-entering. Meaning a total…

You're missing the fact there's a second stage.
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