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 released, so it's going to bleed off a lot of speed before it reaches the upper atmosphere.
Second, spinning exerts very heavy lateral Gs on the vehicle and load. This is not typical for space launch payloads, which are usually only designed to withstand vertical Gs. When the catapult releases the payload, atmospheric drag is going to put heavy vertical Gs on the payload. So a payload delivered through spin launch is going to have to withstand both lateral and vertical Gs.
Its an interesting concept, but I'm not sure if the advantages of this approach outweigh the disadvantages.
I do see a future use case for spin launchers based in vacuum, say, on the moon. Or maybe on Mars where atmosphere is much thinner.
I could see it being a great option for getting bulk goods into space. Fuel, water, food, spools of wire or powders for additive manufacturing, structural components, etc. Depends on what is cost effective. The difficult part would be catching the payloads.
It would probably be an even better option on lower gravity lower atmosphere celestial bodies.
When you have low gravity and little atmosphere, I can't imagine many scenarios where a spin launcher would be a better fit than a mass driver. One of the biggest problems with a mass driver on Earth is that you need to do it in a vacuum over a huge area, which isn't a problem with - say - launching from the moon. The spin launch approach makes some sense on Earth, given that you only have to build a (relatively) small vacuum chamber and a very well-timed airlock to let the payload get into the atmosphere.
But the counterweight issues, extreme G forces during spin-up, etc make it kind of a non-starter in my mind for other bodies; I'd love to hear arguments for it vs simple mass drivers off Earth.
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.
It is not possible to go into orbit from a single speed boost at the surface, even without an atmosphere, because the "orbit" would still contain the starting point. In other words, the orbit would intersect with the surface of Earth. (Well, unless you go all the way to escape velocity.) To fix this, an additional "apogee kick" is needed.
The Spinlaunch concept is to get a small rocket + payload to 60 km altitude. Then the rocket would fire and actually put the payload in orbit.
The catapult would only provide up to 2 km/s out of the ~ 10 km/s or so required to get to orbit. Saving those 2 km/s of rocket delta-v could be significant, because rocket size goes up exponentially with delta-v.
SpacePort America, SpinLaunch's New Mexico test flight facility, is at ~5000' above sea level. If drag is a serious limitation, they could potentially see additional gains by relocating their launch facilities to a city in e.g. Peru. My understanding is the atmospheric density is about 25% lower above 12K feet compared to sea level and about 15% lower than at 5K feet and there are a handful of places with road networks that go that high
> spin launch is going to have to withstand both lateral and vertical Gs.
I wonder if there is a trick to rotate the craft between disconnection and hitting the atmosphere so that the forces are in the same direction for both?
You would have to do the rotation in the short straight section in the vacuum chamber after it is released from the centrifuge. The craft is traveling extremely fast at this point and you only have maybe 50m or less to do the rotation. I think doing a 90 degree rotation in this timespan (25ms or so, because you’re traveling at 2km/s) would need extreme rotational acceleration which wouldn’t be much gentler on the craft, and you would need some system that can actually achieve this rotation in this short time.
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.
The railgun "solution" occurred to me too. Is the rail degradation a failure of materials science? Or are the materials that would be required for this so theoretical at this point to be science fiction rather than science?
There's nothing fundamentally impossible AFAIK - i.e. the rail itself doesn't have to do anything it can't, but you need the surface to survive enough shots to make it worthwhile.
For an actual weapon, this is potentially worth it at a pretty low number since the weapon itself will be pretty small. For a rocket accelerator sled this is going to be more of a problem (but like, conversely you could consider ideas like re-surfacing the rails in place since your turn around isn't fast).
You got the basic physics, but don't you think they have considered these issues? It's why this is interesting at all : despite the very obvious difficulties they think this has a case.
First time i saw this i thought it must be people who do actually know their stuff. But then they realized it can not be done and decided to have fun while scamming investors.
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 released, so it's going to bleed off a lot of speed before it reaches the upper atmosphere.
Second, spinning exerts very heavy lateral Gs on the vehicle and load. This is not typical for space launch payloads, which are usually only designed to withstand vertical Gs. When the catapult releases the payload, atmospheric drag is going to put heavy vertical Gs on the payload. So a payload delivered through spin launch is going to have to withstand both lateral and vertical Gs.
Its an interesting concept, but I'm not sure if the advantages of this approach outweigh the disadvantages.
I do see a future use case for spin launchers based in vacuum, say, on the moon. Or maybe on Mars where atmosphere is much thinner.