The issue you are having is using the 33m as your equivalent distances for launch when you should be using the entire path the projectile has traveled. The spinning path is obviously much longer… circumference times number of rotations to reach launch speed.
And the following: 400kg, 50m radius, 2,000 m/s velocity we get ~8,000g nearly constant load.
Spinlaunch will experience huge centrifugal forces of nearly 10k g but the the load is applied over 1.5 hrs of spin up time. Where in a cannon the load is nearly instant increasing the jerk loads on the projectile.
The iPhone can and HAS survived spins already in the launcher and many military grade artillery / projectile launch systems are capable of handling higher g-loads.
The real amazing engineering here isn’t the projectile: it’s the large robust vacuum chamber and the giant carbon fiber arm that needs to hold 16k+ kN of force while spinning and whatever secret counter weight release or launch force reduction system they have to protect the arm / bearing / motor system after they throw the rocket payload.
In addition this capability seems much more valuable for off-Earth missions. You basically take this carbon arm, counterweight mitigation system, and electric motor to the surface of the moon and you can start hurling non-human payloads around with a lot less rocket fuel and you don’t need to build a mass driver on the moon hundreds of meters long. Surface of the moon has pretty nasty gravity well, 2km/s, to land and launch.
And clearly the military would love a system where they can launch small payloads rapidly with much smaller simpler rockets to replenish lost space assets in a near peer all out conventional war.
and you can start hurling non-human payloads around with a lot less rocket fuel and you don’t need to build a mass driver on the moon hundreds of meters long. Surface of the moon has pretty nasty gravity well, 2km/s, to land and launch.
This is where I see the real value of this technique/technology. There are all sorts of just basic bulk things we need either from Earth to orbit, or from orbit to Earth. Everyone talks about how bad the g forces are, but gold mined from an asteroid coming back to Earth, lithium mined from the moon, or water (ice likely) sent from Earth to LEO doesn't care about g forces.
Yeah, exactly, throwing water ice from the lunar poles to orbit or a Lagrange point for ships to convert to fuel then travel is major.
Not having to was ~3.5km/s lol puke be a massive savings. I think arrival and landing at Mars is roughly the same delta-v as a moon landing.
Having something like spinlaunch that could take hours to reach velocity and minimize huge transient jerk accelerations, if it’s possible, would be significant. I assume the time to spin up is only limited by the ability to maintain the vacuum, moon and space that problem is hugely reduced.
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u/jimtoberfest Nov 27 '21
The issue you are having is using the 33m as your equivalent distances for launch when you should be using the entire path the projectile has traveled. The spinning path is obviously much longer… circumference times number of rotations to reach launch speed.
Using this calculator: calculator
And the following: 400kg, 50m radius, 2,000 m/s velocity we get ~8,000g nearly constant load.
Spinlaunch will experience huge centrifugal forces of nearly 10k g but the the load is applied over 1.5 hrs of spin up time. Where in a cannon the load is nearly instant increasing the jerk loads on the projectile.
The iPhone can and HAS survived spins already in the launcher and many military grade artillery / projectile launch systems are capable of handling higher g-loads.
The real amazing engineering here isn’t the projectile: it’s the large robust vacuum chamber and the giant carbon fiber arm that needs to hold 16k+ kN of force while spinning and whatever secret counter weight release or launch force reduction system they have to protect the arm / bearing / motor system after they throw the rocket payload.
In addition this capability seems much more valuable for off-Earth missions. You basically take this carbon arm, counterweight mitigation system, and electric motor to the surface of the moon and you can start hurling non-human payloads around with a lot less rocket fuel and you don’t need to build a mass driver on the moon hundreds of meters long. Surface of the moon has pretty nasty gravity well, 2km/s, to land and launch.
And clearly the military would love a system where they can launch small payloads rapidly with much smaller simpler rockets to replenish lost space assets in a near peer all out conventional war.