Uhhh
Can someone tell me what velocity you need to launch an object at in order to reach orbit? And what accelerative forces you need in order to achieve that?
How big is this railgun? How are they handling heat from atmospheric friction? You have the same problem going up too quickly as you get coming down too quickly.
The Delta-V (change in velocity) to reach the ISS (400km) in Low Earth Orbit (LEO) is 9.4km/s. This is the absolute minimum so it doesn’t include things like drag or other inefficiencies. Getting to space takes only about 1.4km/s, just about all the rest of that delta-v is used to accelerate the spaceship to 7.6km/s. This is about the minimum speed, altitude, and delta-v to get into orbit and stay there. Going much lower than the ISS will have your orbit decay too much to stay in orbit for more than weeks or months. I think it would take about 8000m/s to orbit right at 100km but your orbit would decay really quickly at that altitude, you would only get a few hours of orbiting.
I think I answered you below about why you can’t to orbit using only a railgun.
Edit: Going from earth orbit to other places doesn’t take as much delta-v as you might think. Going from earth orbit to lunar orbit only takes about 3km/s and going from earth orbit to mars orbit takes 5.7km/s.
You’d still need engines and fuel onboard, or you couldn’t circularize the orbit. The idea is more just get something out of the atmosphere with something that doesn’t itself have to be dragged along for the ride, then do the rest of it once you don’t have atmospheric drag and you aren’t fighting directly against gravity anymore.
It’s kind of the same as the idea of “what if the first stage was a big air-breathing plane that just, like, flew really high and really fast?” that keeps cropping up, just finding a way to make the first part of the process less absurdly expensive.
But no matter what you can’t put something into orbit with a single input of velocity unless that was enough to remove it from the Earth’s sphere of influence entirely, because you can’t make the lowest point in an orbit higher than the point you’re currently at.
What if the interior of the railgun accelerator was all a vacuum and the exit point was really really really really tall? So that impact with atmosphere at the exit of the gun was lower.
