# how to get around a centrifugal force gravity ship

Lets say you had a really big space ship that uses the ramjet method to collect hydrogen. It can only generate gravity in a ring spinning around the collection cone. This means there's nothing in the center of the ship. My question is how do you get out of the ring into the other areas? Would it have to be a timed thing where you stay in this isolated room that the computer will slide out at the right time into the weightless area? That's the best I can do. If you can provide diagrams I would appreciate it.

• Does the ramjet operate all the time? If so, it will be accelerating. Acceleration is the equivalent of gravity. Or do you need centrifugal gravity during the spaceship's cruise phase, when the ramjet has shut down & it's reached its maximum velocity. – a4android Aug 30 '20 at 9:04
• If there's nothing in the center of the ship - other than fusing hydrogen, of course - why would you want to get there? – jamesqf Aug 30 '20 at 16:27

### You climb a ladder / stairwell / elevator.

Here's a map of the space craft from the perspective of people inside it, using colour codes.

And here's an outside view of the ship with the same colours:

You can stay on ground level and walk around, or you can take an elevator up to the zero-g engine room and then back down to the other side.

The engine room does rotate in zero g, but so does everything inside, including air and people.

If you're engine room needs to be stationary relative to the suroundings for some reason (and I can't think of any good reasons for this to be the case - navigation and propulsion can handle this rotation fine.), then you're better off rotating the engine room within a solid cylinder rather than have the elevators rotate around a stationary centrepoint. Eg the red circle is on bearings, everything else is one solid structure

Docking on the axis of rotation requires you fly very slowly and match the spin, and is the easiest to do, however you can only have one docking port (assuming engine is the other side).

Docking can also occur by pulling up at a constant force which matches the gravity. Eg if the station is simulating 50% gravity at ground level, a 0.5g pull up manoeuvre would match the ground trajectory, and you could dock on the ring, and walk up stairs to the main level. Downside is you need to use fuel to dock. This is pretty tricky to do by hand without training but a computer could automate it quite efficiently.

2001 A Space Odissey gives a good example of how to transfer between distant sectors of a ring ship.

• When you want to move to a different sector, you can move along the circumference.
• If you want to quickly reach a distant sector or want to leave the ship for the outside, you reach a sector where one of the arms is connected and then move along the arm toward the center (from where you can move outside) and then along another arm for reaching the other end.

Mind that in any case you want to avoid docking anything like a transfer vessel to the outer ring: it would cause a significant disturbance to the momentum of inertia and consequently disturb the rotation. It is way better to have docking and undocking happening close to the rotation axis of the whole ensemble.

• The question clearly states no center. I'm not sure if this answer is usable. I would say that a path could exist against the collection cone in the middle however, making your answer valid. – Trioxidane Aug 30 '20 at 6:39

You catch a train. Along the centrifugal ring there is a rail carriage. It sits on the exterior of the ring.

To use it, an astronaut walks down the main corridor in the centrifugal ring. Enters the carriage, unlocks it from the structure of the ring proper and now the carriage is driven along its own railway in the opposite direction to the motion of the ring. It will soon come to rest with respect to the main body of the spaceship.

It can be driven to whichever area your astronaut wants to access. The carriage will stop there and locks itself onto the structure of the spaceship. The astronaut exits through a door in the carriage. (Probably, opposite the door where they entered in the first place.)

Now the astronaut can access anywhere in the rest of the spaceship. The usual corridors and doors will make the rest of accessing the spaceship easy.

The carriage can be used to return the astronaut the ring section by simply speeding up to match the velocity of the ring. This is apart from positioning itself to enter whatever part of the ring itself.

Note: The doors to the carriage will be effectively airlocks -- for the sake of safety.