A Question Of Maneuverability In Space... Max Versus Limited

[Spacescifi]

In video games like Elite dangerous, all vessels can do pitch, yaw, roll, forward, backward,  up and down and even lateral thrust.

 

I am of the opinion that IRL spaceships often get by with less for the simple reason that they do not need full maneuverability.

 

I honestly think pitch, yaw, roll, up and down and forwards with side thrust is good enough.

Reverse thrusters would likely be weaker than main engines, and I suppose the main reason to or have them is if your main engine is poor st throttling down it's thrust (rather true with any rocket of good thrust nowadays).

 

On the other hand, if you have a scifi drive with both high thrust and great throttling I argue that you do not need reverse thrusters at all. You can maneuver like players do in the Asteroids game just fine, and if doing doing rendezvous just fly above or below to slow on aproach to avoid blasting rendezvous ship or station with exhaust. Afterward use up and down thrusters to line up, use side thrust if needed, and and let a docking port extend to attach. Done.

 

What do you think?

 

Both for scifi and real ife?

Edited January 27, 2022 by Spacescifi

[kerbiloid]

Elite has a non-Newtonian physics (except FFE) and overpowered fuel.

[RealKerbal3x]

In typical sci-fi, spacecraft basically fly like aircraft. They can pretty much fly in any direction they choose, and they slow down/stop if their engines are disabled.

IRL spacecraft are a lot more limited. Changing trajectory is possible, but unless you have some sort of far-future torch drive, a maneuver like a 90° turn - something that a TIE fighter pilot wouldn't think twice about - is out of the question.

Of course, real spacecraft can orient themselves any way they want, but that doesn't necessarily mean they're heading in that direction.

If we had spacecraft that could just point and go, space exploration would be a lot simpler. But we have to deal with orbital mechanics.

[wumpus]

Oddly enough, there exists a space game which closely models both newtonian physics is reasonably close to current (and near future) tech.  I'm sure there is a link to it on this site.

[KSK]

1 hour ago, wumpus said:

Oddly enough, there exists a space game which closely models both newtonian physics is reasonably close to current (and near future) tech.  I'm sure there is a link to it on this site.

You mean

https://iss-sim.spacex.com

I’m drawing a blank otherwise. :p

More seriously - have a go at the linked ‘game’ @Spacescifi- it’s not particularly difficult but it is a nice demonstration of why reverse thrusters are good to have.

 

[EnderKid2]

You'd still want the full array of RCS thrusters because when doing maneuvering close to other things, you don't want to be swinging your spacecraft around a lot.

[Nuke]

i like full 6dof on ships that need to dock. on most probes i usually get away without it.  i have, on  occasion, docked ships without any thrusters except the main engine, sometimes to things that are spinning. goods thing ksp docking ports have strong magnets. warships would have large lateral thrust capability to dodge incoming projectiles. in almost all situations the main engine is still going to give you the best acceleration. 

i once did a probe with 3 ion thrusters and no reaction wheels, you could get 2 axis control with variable thrust. i later found that if you angle out 2 of the thrusters slightly, you could get rough 3-axis control. but this made the probe squirrely during burns (moving the com towards the straight thruster helped somewhat). i remade the design with 4 thrusters and that turned out to be a lot better. 

the cheatiness of ksp's reaction wheels has made me wonder if you can get 3 axis control out of just 2 thrusters. im not sure if reaction wheels can exchange momentum between axes, if they can then moving the momentum to the one axis with control authority for detorque might work. but then again im not sure if that is physically possible. 

[Shpaget]

IRL, it's entirely mission specific. Take JWST for example. It, not only, can not go in reverse because there are no forward facing* thrusters, but is not allowed to turn around and come back.

*forward being the big eye side