Reaction control system

Reaction control system

A reaction control system, abbreviated RCS, is a subsystem of a spacecraft. Its purpose is attitude control and steering. An RCS system is capable of providing small amounts of thrust in any desired direction or combination of directions. An RCS is also capable of providing torque to allow control of rotation (pitch, yaw, and roll). This is contrast to a spacecraft's main engine, which is only capable of providing thrust in one direction, but is much more powerful.

RCS systems often use combinations of large and smaller (vernier) thrusters, to allow different levels of response from the combination.

Reaction control systems are used:

* for attitude control during re-entry;
* for stationkeeping in orbit;
* for close maneuvering during docking procedures;
* for control of orientation, or 'pointing the nose' of the craft;
* as a backup means of de-orbiting.

Because spacecraft only contain a finite amount of fuel and there is little chance to refill them, some alternative reaction control systems have been developed so that fuel can be conserved. For stationkeeping, some spacecraft (particularly those in geosynchronous orbit) use high-specific impulse engines such as arcjets, ion thrusters, or Hall effect thrusters. To control orientation, a few spacecraft use momentum wheels which spin to control rotational rates on the vehicle.

Location of thrusters on space capsules

The placement of the translation thrusters (which are used to alter the spacecraft's velocity) has one important requirement that the placement of the orientation thrusters (which are used to rotate and orient the spacecraft) does not: if the direction of thrust of the translation thrusters does not pass through the center of mass of the spacecraft (when tracked backward from the nozzle) the spacecraft will rotate--an unwanted side effect. Current and past spacecraft are not operated by automatically firing the orientation thrusters to counteract this rotation because such a system might fail, so manual re-orientation is required afterward. Because of these constraints, translation thrusters can generally be placed in fewer locations than orientation thrusters.Fact|date=February 2007

Two Apollo spacecraft (the Service Module and the Lunar Module) had translation thrusters grouped into external blocks of four, which served to translate and orient the spacecraft. Other designs used separate sets of thrusters for these two tasks.

The Mercury and Gemini spacecraft each had groupings of two nozzles inserted into their forward compartments, with slots cut out from which the exhaust could escape. These thrusters were only used after the re-entry rockets or other modules were jettisoned, and were used for re-entry orientation, not translation. (Indeed, the Mercury spacecraft had no separate capacity for translation at all.) Similarly, the command modules of both the Apollo and Soyuz spacecraft have their thrusters ungrouped.

A pair of translation thrusters are located at the rear of both the Gemini and Soyuz spacecraft; the counter-acting thrusters are similarly paired in the middle of each spacecraft (near the center of mass) pointing outwards and forward. These act in pairs to prevent the spacecraft from rotating. The thrusters for the lateral directions are mounted close to the center of mass of each of these spacecraft as well, but Gemini has only one engine for each of the directions while Soyuz again uses a pair.

None of these engines is intended for orientation. For that purpose, both Gemini and Soyuz have engines at the extreme rear of the spacecraft. Here Soyuz uses engines only one-tenth the power of the others.Fact|date=February 2007

Gemini, due to its relatively low mass, was able to change its orbit using its thrusters, and did not require an engine (unlike its heavier descendants).

Finally, Soyuz has a thruster at the rear of the spacecraft that points parallel to each solar panel. This thruster is used for orientation, but has the unique application of keeping the spacecraft's solar panels pointing towards the sun. Without this thruster, a computer system would have to keep the panels properly aligned, wasting electricity.Fact|date=February 2007 The spin is dampened by a counterpart thruster on the other side.

Location of thrusters on spaceplanes

The suborbital X-15 and a companion training aerospacecraft, the NF-104 AST, which would travel to an altitude that rendered their aircraft controls unusable, established the basic locations for thrusters on winged vehicles not intended to rendezvous in space; that is, those that only have orientation thrusters. Those for pitch and yaw are located in the nose, forward of the cockpit, and replace a standard radar system. Those for roll are located at the wingtips. The X-20, which would have gone into orbit, continued this pattern.

Unlike these, the Space Shuttle has many more thrusters, for it does rendezvous in orbit. No nozzles are on the underside of the craft, which would have pierced the heat shield. The rearward-facing thrusters are located in the OMS pods mounted at the tail.

External links

* [http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts-rcs.html Space Shuttle RCS]
* [http://www.jetaerospace.org/Thruster/ Jet Aerospace: Mono-fuel RCS thruster]


Wikimedia Foundation. 2010.

См. также в других словарях:

  • Reaction Control System — RCS Triebwerke in der Nase des Space Shuttles Das Reaction Control System (RCS) dient der Steuerung eines Raumfahrzeugs außerhalb der dichten Atmosphäre mit Lageregelungstriebwerken, da hier aerodynamische Steuerflächen, wie sie bei Flugzeugen… …   Deutsch Wikipedia

  • Reaction Control System — Les propulseurs RCS sur le module lunaire Apollo. Les propulseurs RCS sur l …   Wikipédia en Français

  • Control system (disambiguation) — A control system is a device or set of devices to manage, command, direct or regulate the behavior of other devices or systems. A control mechanism is a process used by a control system. Control system may refer to: Contents 1 General control… …   Wikipedia

  • Attitude control system — In spaceflight, the attitude control system (ACS) or attitude determination and control (ADAC) system of a spacecraft consists of equipment to measure, report and change the orientation of the vehicle. [cite web… …   Wikipedia

  • Traction control system — A traction control system (TCS), also known as Anti Slip Regulation (ASR), on current production vehicles, are typically (but not necessarily) electro hydraulic systems, designed to prevent loss of traction of the driven road wheels, and… …   Wikipedia

  • Fire-control system — Note: the term fire control may also refer to means of stopping a fire, such as sprinkler systems. A fire control system is a computer, often mechanical, which is designed to assist a weapon system in hitting its target. It performs the same task …   Wikipedia

  • Reaction wheel — A momentum/reaction wheel comprising a high accuracy Conical Earth Sensor to maintain a satellite s precise attitude A reaction wheel is a type of flywheel used primarily by spacecr …   Wikipedia

  • Control moment gyroscope — A control momentum gyroscope (CMG) is an attitude control device generally used in spacecraft attitude control systems. A CMG consists of a spinning rotor and one or more motorized gimbals that tilt the rotor’s angular momentum. As the rotor… …   Wikipedia

  • Control variable — For the notion of a controlled variable, see independent variable. The term control variable has different meanings, depending on the area/place in which it is used. The control variable is something that is constant and unchanged in an… …   Wikipedia

  • system — An orderly, interconnected, complex arrangement of parts. See accumulator system air filtration system air injection reaction system air system alarm system anti dive system anti lock brake system anti noise system …   Dictionary of automotive terms


Поделиться ссылкой на выделенное

Прямая ссылка:
Нажмите правой клавишей мыши и выберите «Копировать ссылку»