is this really more efficient than just launching the rocket normally with chemicals?

the article doesn't really go into detail but alludes to the answer to my question being "yes".

I guess the idea is:

you can spin a smaller rocket which requires energy EnergySml. Alternatively you could have a larger rocket which requires EnergyLrg to get out of the atmosphere.

So EnergySml + Fuel in rocket to leave atmosphere << EnergyLrg (which is launch + leave atmosphere)?

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other questions I had were:

- wouldn't the rocket being spun have to be heavier than the equivalently sized chemical rocket because it has to be able to survive being flung around in a centrifuge?