As I understand it the initial motion of the rocket launch is the most energy intensive. Why is there not some propulsion method (electromagnetic or old skool motors) that assist with pushing the spacecraft up. This would also reduce the fuel load?
Basically, why do we not slingshot the craft up and let the onboard fuel take it the rest of the way once it’s got some momentum, even if it’s the first 100 meters?
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The energy requirement would be insane and not reduce fuel all that much
The vast majority of the energy isn’t used for going up, its for going sideways because the rocket needs to get up to 8000 m/s to keep its payload in orbit.
If you wanted to give a Falcon 9 a boost over the first 100 meters so you double its acceleration during that time you would need a launch stand that’s 30% taller than the rocket (F9 is only 70 meters tall) and it would need to push upwards with 770 tons of force. That’s feasible but generally we’d just call that another stage of the rocket as you’d need the power from 9 Merlin engines to pull that off and give you the 760 MJ of energy.
While this would result in some energy savings it adds yet another point of failure, added cost and complexity to a launch, and helps the payload by maybe 1-2%. This is pretty similar to launching off a mountain, it could help but its wayyy less convenient.
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