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Maneuvering with Reaction Control System (RCS) Thrusters


Reaction Control System

Background of RCS

Reaction Control Systems rely on Newton's Third Law which states: "Every action must have an equal and opposite reaction." Positively and negatively charged particles are separated. Using a set of magnetic fields, these particles are accelerated to the direction opposite the direction the vessel or other body is trying to reach. Due to the impulse of these particles as they're expelled, a force acts on the body in the opposite direction, equal to the force with which the particles are expelled. As a result, the body is accelerated in this direction.

Reaction Control Systems Also rely on Newton's First Law which states: "A body in motion tends to stay in motion unless acted on by an outside force." In Space, there is no Outside Force (friction) to act against a vessel to slow it down, therefore, in order to stop a vessel's trajectory, "braking" is done by applying thrusters opposite of those used to set the vessel in motion. For example, if the Aft Thrusters were fired to propel the vessel forward, the Forward Thrusters must be applied in order to slow, or answer the "All Stop" command.


LM RCS.jpg
Lunar Module RCS Circa: 1969

Shuttle front RCS.jpg
OV (shuttle) RCS Circa 20th/21st C.

24th C. Thruster Module
Typical Saucer Section Placement
Empok Nor's Thrusters

Thrusters (aka: Maneuvering Thrusters) are used by starships and other spacecraft to make precise movements at very slow speeds in lieu of primary impulse or warp engine use. Thrusters are low-power reaction control jets that may be used for fine positional and attitudinal control, including station-keeping. They are typically used in docking maneuvers.

Thruster Location

Galaxy Class RCS.gif
The Green Circles Indicate Typical RCS Placement
Depending on the starship type, the system consists of a number of thrusters mostly located around the perimeter of the Saucer Section.

RCS Thruster Maneuvering

Xy Axis.gif XYZ Coordinates.jpg XYZ Axis.gif

X = Straight Forward & backward; Y = Port & Starboard; Z = Straight Up & Down

To Move:

  • Forward - all Aft Facing Thrusters would activate
  • Reverse - all Fore Facing Thrusters would activate

  • Side Slip to Port - All Starboard Thrusters would activate
  • Side Slip to Starboard - All Port Thrusters would activate

  • Straight Up - All Ventral Thrusters would activate
  • Straight Down - All Dorsal Thrusters would activate

  • To Pivot Left - Fore Starboard & Aft Port Thrusters would activate.
  • To Pivot Right - Fore Port & Aft Starboard Thrusters would activate.

  • To Roll Left - Dorsal Port & Ventral Starboard Thrusters would activate.
  • To Roll Right - Dorsal Starboard & Ventral Port Thrusters would activate.

You might never need to do a Banked turn using only Reaction Control Thrusters... But if you wanted to, say... to maneuver through an Asteroid Field... the flowing could be done:

  • Banked Turn to Left
    • All Aft Facing Thrusters would activate.
    • Dorsal Port & Ventral Starboard Thrusters would activate.
  • Banked Turn to Right
    • All Aft Facing Thrusters would activate.
    • Dorsal Starboard & Ventral Port Thrusters would activate.

(More to come)

The Mutara Nebula Incident

Phenomena like the Mutara Nebula decrease the ability of a spaceship to utilize sensors.

Mutara2.jpg Mutara3.jpg
Kirk orders the Enterprise into the Nebula, where he can even the odds against a "Superior" opponent.
Mutara4.jpg Mutara5.jpg
The Enterprise was able to spot Reliant and get off a few quick disabling shots. Reliant tried to fire torpedoes, but could not lock onto Enterprise, which had already changed course.
Mutara6.jpg Nebula7.jpg
When Spock realizes that Khan is using 2 Dimentional tactics & strategy, Kirk orders a course of "Z -10000 Meters", allowing Reliant to pass overhead. Kirk then orders a return to original course to pop up behind the Reliant and

fire, completely disabling it, defeating Khan.

Return to Navigation


  1. Star Trek: The Next Generation Technical Manual, pgs 87 & 88
  2. Federation Data-bank
  3. Babelfish Translation To assist in translating Federation Database Information.
  4. WIkipedia: Reaction Control System (Graphics)
  5. CAD Lesson 3 (Graphics)
  6. Whatever else I can find and scavenge

Rob Johnson, IC 2004-2007
15 May 2007

Cbs-para2.jpg Star Trek®,, Star Trek: The Next Generation®, Star Trek: Deep Space Nine®, Star Trek: Voyager®, and Enterprise® are registered trademarks of CBS Paramount Television & Viacom. All material found on these pages are for promotional purposes only. No infringements on their copyright is intended. These are Star Trek Fan Pages.

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