What do you use RCS for?

[Slam_Jones]

Used to use it on a few landers, til I realized just how inefficient they are for that.

Now I mainly use em for docking.

[Duxwing]

I almost never use RCS because docking with main engines is easy: rendezvous, approach at high and then low velocity, stop, align docking ports, and dock at low velocity. RCS nevertheless eases docking and enables it for large payloads.

-Duxwing

[merendel]

95% of the time I use RCS for docking only. I do ocasionaly use RCS for fine tuning a burn thats particularly sensitive but thats normaly a situation where I already had the jets for docking and its easier than trying to turn around and thrust limit. Very rarely will I use RCS for rotation or stability on larger ships. Useing it for stability normaly only happens during launch when I cant stuff enough reaction wheels and fins on a craft to keep it sable on the way up. Turning happens when I've got a massive craft and I dont want to stuff dozens of reaction wheels intoto it to make it turn in a reasonable timeframe. Both can sometimes happen if I'm trying to push a space potato around and couldnt line up well enough on the COM.

I've deorbited once or twice off them but it was never a planed thing. they were out of fuel situations that just happend to have monoprop and thrusters from earlier in the mission. May as well use the mono prop instead of geting out and pushing.

[ArmchairGravy]

Docking, landing on Gilly, and fine-tuning burns are the reasons I use RCS.

[Commander Zoom]

Earlier today (and many times before), I used RCS to make fine adjustments to my interplanetary encounters. A little goes a long way, when you're in solar orbit.

And also for turning those big rigs, of course, and docking/rendezvous maneuvers.

I've sometimes used it for deorbiting spent stages, etc - particularly if there's no regular fuel left in 'em (because I pumped it all out into another craft).

[Overland]

RCS thrusters used to be used as emergency braking systems on the first few generations of my locomotives..the single direction type pointing forward.. back in the days where they were mostly passenger based bullet trains rather than present day freight locomotives

ive since done away with them when the transition from jet propelled was made to dedicated turbine electric generation for the bogeys

as such putting a train into dynamic braking via the reverser and giving engine power reverses the bogeys giving an easier way to manage speed on the sometimes near vertical mountain sides rather than the hairy 60+ ms and sudden braking when the wagons got skittish

they still do have thier uses though

the rcs tanks modded to hold fuel make great fake air tanks

and of course RCS in the traditional way is great for when im launching an outpost station thats big on functions but not so much aerodynanics..

generally firing constantly intune with the SAS to keep a station on course and to prevent...um

lithobraking

which for me means the sudden stop when you hit kerbin mountaim sides

[T.A.P.O.R.]

I selected all.

For some of my craft, torque alone can't do the job efficiently.

Also I am a bad pilot, so I need all of the help I can get.

[Vivian_Science]

There is another thing I use it for that I don't think many people do. I use it to help particularly stubborn aeroplanes take off.

[TheMoonRover]

Deorbiting - when I run out of fuel I use the RCS. This usually only happens in early career (or early science mode)

Docking - although sometimes I like the challenge of trying to dock without RCS (or just forget it), I generally use it.

Low grav landing - I always used the same RCS lander for Gilly, Bop, Pol and Minmus from 0.19 to 0.22, although I've since started using small ion landers for those. I remember taking a science lab to Gilly in First Contract. After entering Gilly's SOI I jettisoned the transfer stage, leaving only an ion engine for propulsion. It was slow but effective. I once managed a rather heavy landing on Duna using an RCS powered lander and one small parachute (before the O-10 engine was added)

Turning/reorienting - sometimes, but usually in early career when there're no batteries or solar panels to power the reaction wheels.

Stability control - likewise^

Edited March 21, 2015 by TheMoonRover
typo

[Francois424]

I use it all the time. To me this is a very important part of all my ships.

At one point I used the liquid fuel RCS and I loved them better! Less of them for same force = less part count... until I noticed it caused asymmetric consumption of fuel between my different boosters (a fatal problem with almost all launches, and not fixed with a both-way fuel line)

So back to regular RCS.

Edited March 21, 2015 by Francois424

[mrclucks]

Docking and directional control when I don't have SAS in the best of positions

This whole 'fine tuning' orbits idea is genius!!

[celem]

Everything.

Since I play RSS/RO I need it for attitude control.

I use it as an ullage system for EngineIgnitor and cryogenic fuels (when re-orienting doesnt generate enough centrifugal I thrust for 10-15 seconds with them to settle the propellants. Remember when using RCS as an engine that it has 2 modes controlled by CAPS. It generates more thrust in coarse mode. It burns both ways without needing to reorientate which is great for finetuning).

OMS for Remote Tech relays. Fine tuning intercept burns/circularising/precise orbit adjustment in every version/config of the game. Docking (Assembly Tugs). Deorbit. Seperation. And of course, low grav landers. For that matter, high grav atmospheric landers with chutes for soft-landing jets (did RSS Mars with RCS and chutes).

RCS is the swiss army knife of spacecraft control. Torque can go jump off a bridge, I deleted all torque producing parts.

edit: oh, ive also burned it in futuristic ion stuff thanks to KSPInterstellar

Edited March 22, 2015 by celem

[Xannari Ferrows]

Every one of these, if I have the available leeway.

[FleshJeb]

Huffing. It makes my voice all squeaky.

[kzauner]

I checked all options.

Crap, missing option: Fine tuning orbits. Any others I missed?

Yes: Propulsion. Especially on very small probes (satellite contracts, for example). I just add 1-2 extra linear ports so I get some extra push in prograde-direction. The sats do everything on Monopropellant: circularisation-burn, transfer & injectionburn. For many crafts the O-10 is just overpowered.

cu

Clemens.

[pincushionman]

Landing -- but NOT as the landing engine! See, I'm crap at zeroing my lateral velocity using the main engines - too easy to get the ship flipped around the wrong way and get confused. So I get close, then I flip the camera to look down such that IJKL are consistent with the screen direction, and RCS out the remaining lat with those keys while using the main engine to control the rest of the descent with the throttle.

[Newt]

I use it for all of those, sometimes. I have also done all of those without it.

[khyron42]

I've used it for all of those at various times - plus for finishing orbit insertion, in one small spaceplane design.

[celem]

Huffing. It makes my voice all squeaky.

Heh, made me chuckle.

For those who have never used the RealFuels mod. Helium is a historical monopropellant, though low performance beside stuff like hydrazine.

[amorymeltzer]

Any others I missed?

As an action group 'cause upgrading the VAB is like the last thing I do. RCS just means "open the solar panels" as far as I'm concerned!

[Madrias]

I've used RCS for a lot of things, actually.

Deorbit: Both planned (RCS used when fuel remained) and unplanned (Ran out of Oxidizer with a periapsis too high to aerobrake).

Docking: Always. I don't care how much torque you've got, you need something to push you sideways.

Low Grav Landing: Not so much as the primary landing engine, but as delta-V assistance once 90% of the descent velocity is eaten up by the main engine, then the last 20 meters or so is all RCS.

Course Corrections (turning/reorienting): Yep. SAS torque is good for small vehicles, but once you've got your Jool-Class mothership moving around, you need something to move you around.

Stability Control: On occasion, but yes. Once you're high enough up that your control surfaces are lacking authority, but your main engines are still pushing some thrust, you need something to give you some direction.

And now for things not mentioned in the main list.

Rover Propulsion: Landing gear, a few girders, a cockpit, and some SAS thrusters. Instant Kerbaled Rover.

Action Group: Anyone who's played Career mode knows this one. I need something to open solar panels.

Low Gravity Main Stage: Four O-10 engines around the Rockomax RCS can with your remaining rocket pieces on top. Leave your landing crap behind and power up.

Takeoff-Boosters: O-10 engines, some RCS fuel, and up you go with even your heaviest planes.

Satellite Adjustment Systems: Using your RCS to adjust the orbits of your satellites when they're now in the way of your debris field.

[wolfedg]

Typically I use it for the usual things you use it for namely orienting my spacecraft. However I have been known to invent uses for it like on this jet that uses rcs for pushbacks from the gate and refueling stations.

[Mandelbrot]

Should've added ullage to the poll!

[Sampa]

for me, mostly docking purposes. However, if a ship is large enough, I will require RCS to reorient it.

[Aragosnat]

All of the above.