What do I need RCS thrusters for?

[Kerbonaut257]

Guys. I need ideas of why I need to use RCS ports and docking. I rarely do missions that require either. Help me!

[Gaarst]

Build a space station?

[__Ultimatum]

They can help maneuver you spacecraft and they allow for precise movement for maneuvers and docking. You can move your ship around without having to point in one direction and fire the engine then point the other way and slow down. 

[eddiew]

Two big ones stand out:

- Orbital lab. Depending on your settings, it may be overkill, it may be useless, but if you want to max science income for whatever reason, this is how.

- Orbital fuel caches. I do this regularly on larger worlds like Duna, Tylo, Laythe and Vall. Carrying more fuel than you need for the present operation is inefficient, so the ability to leave say 10 tons of fuel in orbit with your transfer stage, descend, get your science, and ascend again can leave you with a lander that is a lot more than 10 tons lighter. Examples in spoiler.

Spoiler

 

 

[Red Iron Crown]

Moved to Gameplay Questions.

[WanderingKid]

2 hours ago, Kerbonaut257 said:

Guys. I need ideas of why I need to use RCS ports and docking. I rarely do missions that require either. Help me!

If you don't need them, then you don't.  A similar question would be: "I'm not landing on the planet, why should I bring a drill?"

If you're looking for ideas as to why you might want to START using them, that's a different concern.   They're typically needed for docking, rendezvous, control of very large ships, and as lightweight thrusters on places like Gilly.  They also make for easier orbital adjustments on interplanetary journeys for large ships so you don't have to turn the monster around a few times.

[Aegolius13]

I try to avoid them when possible.  If you use the "point both ships at target" docking method, they're often not needed for docking.  But can still be useful on bigger ships.

Front facing thrusters are helpful for slowing down, without requiring you to flip your ship around and fire main engines.

[JAFO]

If you have some need to make particularly precise orbits or maneuvers, they come in very handy for fine-tuning your Ap or Pe. Simpler and more controllable than just using the thrust limiter on your main engine.

[Capt. Hunt]

And docking in orbit is extremely useful as well, if you build your ship in orbit, you don't need to launch it all in one piece from Kerbin, you may need more launches, but they'll be significantly smaller and an order of magnitude cheaper.  The same goes for the return trip, launching from the mun is much easier if your lander isn't hauling all the fuel it needs to return to Kerbin.

[DD_bwest]

rcs makes docking easier..

docking is good when you want to plan a mission to a planetary body that involves multiple landings.   very easy to land in every biome for either of the 2 moons in a single launch.   and the other day i manged to do that for Eeloo lol over 20k science from 1 launch lol

[Vaporized Steel]

@Kerbonaut257 You may want to read this http://wiki.kerbalspaceprogram.com/wiki/Reaction_Control_System

...If you haven't already...

 

 

[bewing]

I do tons of docking, but I never use RCS. If you can live without it, then live without it. Eliminating RCS reduces your cost, your part count, and eliminates whole tech nodes out of your R&D tree that you don't need to activate.

[JohnnyPanzer]

I love your attitude! "Guys, I'm not using this feature, help me come up with missions that would require me to do so". That is a perfect example of the pioneer spirit! 

My suggestion: try to assemble a truly huge station in orbit, without each part having it's own dedicated engine. You will quickly find a use for RCS.

[Foxster]

I very, very rarely need RCS. 

I used to use it for, say, Eve return missions. It's the one place that it is not practical for me to build a lander that can make it back to Kerbin. Once the lander was back in orbit, the mothership needed to dock and that is hard enough without trying with no RCS.   

These days though I don't even do that. I make landers completely disposable and EVA the crewman over to the mothership. 

[Clipperride]

As the above answers show, it's very much a matter of personal preference.  I wouldn't dream of building a ship that needed to dock with another without RCS.  Ive also found them very handy for making fine adjustments to the final orbits of relay satellites that form part of a constellation.

Although you dont need them now, don't forget them entirely as they may help make future missions that bit easier.

[Red Iron Crown]

If you ever try Realism Overhaul you'll find RCS systems go from "occasionally useful luxury" to "absolute necessity". In stock I almost always have more monoprop than I need, in RO I can never have enough RCS fuel. It's just so useful, for fine-tuning orbits without using up engine restarts, for ullage, and for attitude control since reaction wheels are not up to the chore.

[Kerbonaut257]

3 hours ago, Red Iron Crown said:

If you ever try Realism Overhaul you'll find RCS systems go from "occasionally useful luxury" to "absolute necessity". In stock I almost always have more monoprop than I need, in RO I can never have enough RCS fuel. It's just so useful, for fine-tuning orbits without using up engine restarts, for ullage, and for attitude control since reaction wheels are not up to the chore.

I'm considering imposing a rule upon myself that I can't use RCS wheels except 1 wheel of each size in each stack. Just straight up have to use RCS thrusters for all attitude adjustments on larger craft. I think that may be kinda fun

[Red Iron Crown]

5 minutes ago, Kerbonaut257 said:

I'm considering imposing a rule upon myself that I can't use RCS wheels except 1 wheel of each size in each stack. Just straight up have to use RCS thrusters for all attitude adjustments on larger craft. I think that may be kinda fun

I've started disabling them altogether in stockish installs. RCS for maneuvering is more fun and challenging.

[Kerbonaut257]

1 minute ago, Red Iron Crown said:

I've started disabling them altogether in stockish installs. RCS for maneuvering is more fun and challenging.

It's not a bad idea. Though I didn't like RP0/RO, stock definitely IS pretty easy. Especially with all the mods I have. #monoprop life

[Tyko]

with CommNet and relay sats RCS is a great way to manage the orbits of lightweight satellites. I had a lot of fun setting up sets of 3 relays satellites in equidistant orbits around Mun and Minmus. The sats only had RCS and it was a (relative) breeze to get highly accurate orbits.

[NSEP]

RCS provides linear movement. Reaction wheels cant do that.

[Temeter]

Docking. And if I got them, then they are very usefull for finetuning rendezvous with crafts or planets.

[Capt. Hunt]

While several people here claim they can dock without RCS, it is still much safer to do so with it.  RCS thrusters are the only engines in the game that won't impart a force on anything that happens to be in the thrust cone. If you fire your main engine to decelerate during a docking maneuver and you're within 20-30 meters of the target, you will impart a force on it.  Docking with RCS allows more fine controls without harming the receiving craft.  Sure you can put a screw in a wall with a sledge hammer, but isn't it still better to use a Phillips head screwdriver?

Edited October 22, 2016 by Capt. Hunt