Talk:Reaction control system

Location of thrusters on space capsules

 * I randomly came to this article and started to read through it, and found much of it to need improvement, both content-wise and style-wise. I went through this section and made numerous changes, and I think it is now more readable. Many things can still be improved, however, and I think the entire article should have a rewrite. There is much more to talk about than the placement of RCS on various spacecraft (which is likely contained in specific articles regarding those craft); a section that says "for placement on Apollo click here," "Mercury click here," etc would be fine. The article also needs to talk about the chemicals used in the various RCS systems, their thrust output, design changes/problems, etc. It's also unsettling that the article doesn't have one single citation in it. I'll come back to this at a later time, and make some of these changes. 100DashSix 03:22, 22 July 2006 (UTC)

Not JUST for Spacecraft!!!
RCS Thrusters are also used on Ocean-Going ships (Cruise Ships, etc) to aid in stationkeeping and docking / undocking procedures. More and more ships are incorporating RCS thrusters in order to break away from needing Pilot Boats in some of the larger ports.

Although I have no Documented Articles to support this other than 1st hand observation aboard Carnival, NCL and Dolphin Cruise Lines, I'm confident that someone on staff can find something to verify this. [Grin]

Rob-J, MFI 22:17, 17 May 2007 (UTC)


 * They're thrusters, but not RCS thrusters. Ships use thruster propellers, in a small tube crossing from one side of the bow (or sometimes, stern) to the other, to provide side force for maneuvering (particularly, for skidding the ship sideways).  But they aren't rockets like RCS thrusters are.  Georgewilliamherbert 22:33, 17 May 2007 (UTC)

Yup... My bad... What I was thinking of was more along the lines of Azimuth thrusters

I was not aware that RCSs were actually small "firing" Rockets, as opposed to being a "compressed gas" delivery system (using the action/reaction of expelling the compressed gasses). Perhaps that might be worth adding to the Article. Rob-J, MFI 22:23, 19 May 2007 (UTC)

No mentions of TCS?
The RCS should be broken down into its two components for maneuvering in spaceflight. In particular, vehicles that must perform docking maneuvers have the RCS broken into two seperate modes and completely seperate controls: RCS mode (in this case Rotational Control System) that performs rotational maneuvers of the X, Y, and Z axis and TCS (Translational Control System) that will move the craft laterally along the X, Y, and Z axis. In other words, RCS affects the orientation of the craft without affecting position while TCS changes the position without affecting the orientation. Rendezvous and docking would be virtually impossible without translational control. —Preceding unsigned comment added by 198.31.184.166 (talk) 18:22, August 29, 2007 (UTC)

The reason is that on most spacecraft the samme jets are used for translation and rotation. Different combinations produce different thrusts and/or torques. If you look at the Shuttle RCS, for example, there are no pure translations, amd the only pure couples are about roll. The autopilot fires several jets simultaneously to achieve commanded forces and torques. —Preceding unsigned comment added by 192.80.95.242 (talk) 17:57, 27 March 2008 (UTC)

Fuel refills?
I'm confused by little chance in the sentence, Because spacecraft only contain a finite amount of fuel and there is little chance to refill them.... Is there any chance? Has there ever been a spacecraft which could do an in-flight refuel? -- RoySmith (talk) 21:01, 10 May 2009 (UTC)


 * Yes. The Soviet space stations, starting around Salyut 7, and definitely Mir and the Russian ISS modules.  Progress supply vehicles are routinely equipped to do a fuel transfer to the station.  Georgewilliamherbert (talk) 22:40, 10 May 2009 (UTC)
 * OK, thanks for the explanation. -- RoySmith (talk) 00:17, 11 May 2009 (UTC)

Removed incorrect statement about Mercury and Gemini's RCS thrusters.
For Mercury and Gemini, the section "Location of thrusters on space capsules" originally claimed:

These thrusters were only used after the re-entry rockets or other modules were jettisoned, and were used for re-entry orientation, not translation.

That's simply not true, and I've replaced the statement with a simpler one saying the thrusters were only used for orientation, which is correct. At least for Mercury, the thrusters were used throughout the flight following capsule separation from the booster. They served both to reorient the spacecraft and to maintain stable orientation, and they were vital to ensure that the retrorockets were fired in the proper direction.

--Colin Douglas Howell (talk) 04:43, 18 May 2009 (UTC)

Improvement of introduction
Critics:


 * "A reaction control system (RCS) is a subsystem of a spacecraft whose purpose is attitude control and steering by the use of thrusters".

Attitude and Orbit control


 * "An RCS system is capable of providing small amounts of thrust in any desired direction or combination of directions".

Why all directions? Most three-axis stabilized spacecraft can for example not make thrusts in radial direction. For out-of-plane maneuvers it is enough to be able to make burns in one of the two directions orthogonal to the orbital plane.


 * "An RCS is also capable of providing torque to allow control of rotation (pitch, yaw, and roll).".

Not necessarily! Some spacecraft are spin stabilized! Some three-axis stabilized spacecraft use magnetic torquers!


 * "This is in contrast to a spacecraft's main engine, which is only capable of providing thrust in one direction, but is much more powerful.".

Many spacecraft has no "main engine" at all! The author must be thinking of one special design with one "main engine, which is only capable of providing thrust in one direction"

Conclusion:

The introduction should be improved/re-written!

Stamcose (talk) 14:34, 30 July 2011 (UTC)


 * You're absolutely correct about that last sentence, and I've removed it. It wasn't even correct; sometimes the main engine doesn't only point in one engine, but is mounted on a gimbal (e.g. the Apollo service module).JustinTime55 (talk) 16:12, 18 March 2013 (UTC)

A couple of points

 * The article seems to make no mention of the fuels used. These were generally hypergolics, or monopropellant hydrogen peroxide in the case of the Project Mercury spacecraft.
 * The Mercury and Gemini descriptions are very inaccurate, and contain WP:OR. Mercury, to my knowledge had no RCS thrusters, or at least not all of them, in its "forward compartment"; at least the roll jets were located much farther aft. Gemini's forward thrusters were a separate system used only for reentry; the main system (OAMS was located in the aft adapter section. The statement about only small translation thrusters being needed because of its "low mass" is completely fallacious OR; large amounts of thrust aren't necessarily required for delta-v changes, which themselves are frequently small for modest orbit changes. What really counts is the amount of propellant available. JustinTime55 (talk) 16:39, 12 April 2013 (UTC)

Article scope: vertical-landing aircraft
I reverted mention of the Rolls-Royce Thrust Measuring Rig (which should probably be mentioned at Lunar Landing Research Vehicle, BTW). VTOL and STOVL aircraft use vectored engine thrust for attitude control, but that's really not quite the same as an RCS as we define it here (also, I don't think real-world usage of the term is necessarily there.) Do we want to expand the scope of this article, which was intended for spacecraft? JustinTime55 (talk) 15:26, 7 April 2015 (UTC)