I heard about this and it's a great idea if it works. It's not totally fuel free as the throwing pay gets it mostly out of the atmosphere and there is a small rocket (last stage for a normal rocket) that puts the payload in the right place.
It's even far from fuel free, to reach Low Earth Orbit a rocket needs between 9.3 and 10km/s of delta-v.
According to the video the system is launching the rocket at mach 6, which is equivalent to 2km/s.
So the system is providing only 1/5 of the energy needed to get to orbit. It's good but I'm not sure it is worth the drawback of having to handle the huge acceleration.
On the other hand the same system on the moon would provide enough energy to reach orbit, it would just need a small amount of propellant to circularize.
Or by increasing slightly the speed of the system it could even send stuff straight to earth with no propellant.
20% of the delta-v is not the same as 20% of the energy or fuel. The early stage when the rocket is the heaviest and down in the thickest atmosphere is by far the most fuel-expensive.
The idea of throwing something into space isn't anything new, tbh I've always kinda wondered why no one has spent more time developing it.
Edit: I wonder how many Gs the rocket experiences while spinning, and if a human could theoretically survive it long enough to get thrown into space. I can see it now: rockets becoming luxury space vehicles for rich people while the spin launch is how poor people commute to the space dock.
The projectile experiences wicked g-forces when it is being spun up: around 10,000 times the force of gravity. This is enough to tear the skin and muscle off a human being. This means SpinLaunch will not be going into the astronaut business. They also won’t be able to drive large satellites into orbit. The projected weight limit for the system would be payloads of about 440 pounds. That is a lot less than something like the Hubble Space Telescope weighs. -- source
...if a human could theoretically survive it long enough to get thrown into space.
The answer is 'no'. This thing would spin all the blood out of your body, and then when it actually launches you, your body would get shattered by the shock, and then shattered again a millisecond later as your spacecraft plows into the atmosphere at a few mach number.
Strange that a bunch of aerospace and mechanical engineers believe it is, and have tested the math, yet some random person who probably doesn't even work on STEM believes they have the better idea.
I can't tell if you genuinely think you're smarter than these people or if this is just the classic "space craft are stupid!" Rhetoric that's become popular since Musk started SpaceX.
You don't need to be Stephen Hawkings to understand that the bottleneck is not in the launch sling but in the satellite themselves. The idea is in the same league as the space elevator; sure you can do it, but is it better than rockets?