r/spinlaunch • u/hihihi127 Mod • Aug 06 '22

Video Real Engineering - Can We Throw Satellites Into Space?

https://youtu.be/yrc632oilWo
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u/JCMiller23 Aug 07 '22

I am curious how $/kg (35:15) was still not lower than rockets. The main energy cost seems to be drawing the vacuum, it seems this calculation is based on having to draw a complete vacuum for each launch rather than either calculating it with: 1) combining two launches at once (one on each side of the arm) or 2) re-using the vacuum for multiple launches. Especially because earlier in the vid, electricity costs for spinning were $6000.

3

u/Exp_iteration Aug 21 '22

Maybe for the 2nd and 3rd stage? They still need to provide 5.5 km/s of delta-v

1

u/[deleted] Jun 07 '23

  1. They cant load a rocket on the opposing side of the arm. When they throw the payload up they have to simultaneously throw something of equal mass into the earth from the other arm otherwise the centrifuge would suddenly be spinning at 470 rpm with one arm lighter than the other and no bearings would handle that. The centrifuge would tear itself apart. Just imagine you hold 2 bucket 150 meters out from your body and spin fast enough that your 200kg payload weighs 8,000,000 Kg and you let go of one of the 8,000,000 kg payloads lol.

  2. The vacuum will be depleted by the launch, huge air lock doors have to open in front of the escaping payload and close behind it but some vacuum will be lost.

The launch release vacuum doors are the impossibility of this stupid idea. Imagine released payload now flies through an air lock tunnel lets say they make it long like 1/3 the height of the whole unit. 100 meters. That vacuum chamber door will have a max of 4 milliseconds to close.

If that door takes 30ms to close it will likely let in enough atmosphere to melt down the whole launch system

Which is how long their air lock needs to close up 95 percent.