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Questions tagged [rcs]

Reaction Control Systems, small thrusters to control attitude and occasionally translation of a spacecraft.

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Does Starship perform a launch tower avoidance maneuver?

Does Starship perform a launch tower avoidance maneuver? If yes, is this accomplished using gimbaled raptor engines or RCS rockets? How far laterally is the Starship axis shifted by this maneuver and ...
Woody's user avatar
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3 votes
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65 views

Righting JAXA's SLIM Lunar lander using RCS

The SLIM lander was supposed to roll onto the side as part of the landing process but ended flamey end up. Which has impacted the ability of the vehicle to collect solar power, and probably other ...
GremlinWranger's user avatar
17 votes
1 answer
2k views

Why does the Psyche Spacecraft use cold gas thrusters?

In a recent article on SpaceNews they write [There exist] nitrogen cold-gas thrusters that orient the spacecraft. This seems like an odd choice for me, considering it is a multi year mission that ...
Hans's user avatar
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2 votes
0 answers
107 views

Help with designing nozzle geometry for compressed air thruster

I am designing a compressed air thruster with a conical nozzle geometry. The general design consists of a compressed air tank, pneumatic tubing, and then the actual chamber with the nozzle. The ...
Kyle's user avatar
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12 votes
2 answers
1k views

What does "reaction" in "reaction control system" and "reaction wheel" refer to?

I have a basic understanding of how RCS and reaction wheels work, but I can't figure out what "reaction" refers to in their names. Is it referring to how a craft's attitude "reacts"...
JAK Zero's user avatar
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1 vote
1 answer
452 views

Where and how many RCS thrusters are installed on Starship?

Starship from SpaceX will soon launch. During the 10 km test it used RCS thrusters to flip itself in the right position. On the website it mentions how important it is to use air friction to slow down ...
The Rocket fan's user avatar
1 vote
1 answer
90 views

What happens when an RCS thruster fails to fire?

Let's imagine a UDMH/N2O4 thruster (like on a Soyuz) has an issue where the oxidizer valve/line freezes solid, blocking the flow. What happens with the fuel? The propellants are pressure fed with a ...
Innovine's user avatar
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1 vote
1 answer
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What is the propellant consumption rate for Soyuz?

At what rate does a Soyuz propulsion system (KDTU-80) consume it's propellants? I am interested in the mass consumption rate of both the main engine (e.g. an s5.80) and a single DPO thruster. Please ...
Innovine's user avatar
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3 votes
0 answers
123 views

Reaction control system testing

How are RCS (reaction control systems) for Launch vehicles usually tested? After going through some literatures, I came across two different testing schemes, Leans more towards testing the Cold gas ...
nik's user avatar
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2 votes
0 answers
190 views

RCS thruster temperature

How fast does an RCS thruster heat up if it's fired continuously? Will it stabilize at a maximum temperature? Does it need to be shut off before it melts itself? What would that temperature be if so? ...
Innovine's user avatar
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3 votes
2 answers
350 views

Soyuz thruster placement

I notice that the Soyuz uses two high-thrust thrusters to translate in one direction along an axis, however some of the thrusters are located at a slight angle on either side of this axis, rather than ...
Innovine's user avatar
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3 votes
1 answer
338 views

Are the (relatively) new "all electric" satellite buses like the Boeing 702SP really all-electric? Are RCS and momentum unloading done with ions?

This answer to Can ion Thrusters be used for Reaction Control System? got me thinking about the new "all-electric" class of commercial satellite buses. Question: Are the (relatively) new &...
uhoh's user avatar
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2 votes
1 answer
482 views

Can ion Thrusters be used for Reaction Control System?

As RCS (Reaction Control System) mainly required less thrust than regular rocket engine can ion Thrusters be used for attitude determination in spacecraft(Orion, Dragon), satellites or even during ...
Mukul Hatekar's user avatar
8 votes
1 answer
959 views

Why were the apollo CM RCS thrusters all placed in only one half of the module?

All the apollo CM RCS thrusters for pitch, roll, and yaw control were placed only in the upper half of the capsule (as seen in the image below). Why is that? (I think I read somewhere that it was due ...
RNG's user avatar
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3 votes
1 answer
195 views

Attitude control of rockets with RD-107 engines

This question is specifically about the Soviet engine RD-107, (although it can be generalized) a version of which was clustered in Soviet rocket 8K71 which launched their "Sputnik". Each ...
Niranjan's user avatar
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7 votes
2 answers
755 views

"Re-entry" vs "Reaction" in RCS

Reading through the Wikipedia (not known for being the bastion of all truth but usually a decent starting point) article for Gemini 8, I came across this passage (emphasis mine): The astronauts ...
Freddie R's user avatar
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6 votes
1 answer
306 views

RCS jet select algorithms (e.g. in space shuttle)?

I'm looking for a clear description of RCS jet selection logic. The space shuttle, for instance, had tens of RCS thrusters, only three of which would be called to fire at a time given a 3D attitude ...
user avatar
1 vote
2 answers
336 views

Dragon RCS: Four controlled degrees of freedom... or six?

Would Dragon's RCS clusters allow it to translate cleanly left-right and backward-forward, like a crab? Or are they meant only for roll/pitch/yaw control + longitudinal (up/down) translation, like an ...
user avatar
4 votes
0 answers
312 views

Falcon 9 cold gas thrusters: why in line with grid fins?

The cold gas thrusters of the Falcon 9 are right in line with the grid fins. The grid fins deploy immediately after MECO and stay deployed while the cold gas thrusters fire. And it seems the expelled ...
user avatar
28 votes
3 answers
7k views

Could the Columbia crew have survived if the RCS had not been depleted?

I ask this question because of a comment made by John Connolly, NASA engineer and director of the International Space University. To quote Connolly, "..when he (Rick Husband) saw that the RCS was ...
Ashley's user avatar
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4 votes
2 answers
1k views

Calculating mass expelled from cold gas thrusters

Consider a cold gas thruster rated at 1 lbf per firing. The thruster is on-off: there is no throttling, so when it fires it's at a constant full thrust. Assume the gas is nitrogen, and that it has a ...
user avatar
2 votes
0 answers
59 views

Does the Falcon 9 stage 1 have cold gas thrusters near the bottom?

I've seen the cold gas thruster pods on the interstage of Falcon 9, and I know that stage 2 has them too, even if there seem to be zero pictures of them on the web (they're the only means of roll ...
user avatar
3 votes
0 answers
117 views

Is steam a good gas to use for a small RCS thruster on a small rocket?

Is steam a reasonable tradeoff from other hot/cryogenic gases in order to have safety and have it easily obtainable? Thanks
Not_Shark's user avatar
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1 vote
0 answers
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Falcon 9 CGT Force?

Curious how much force the Falcon 9 cold gas thrusters produce for steering? I've seen numbers in the range of 25--100 lbf, but not sure where in this range (or outside it) the Falcon 9 falls. If you ...
user avatar
2 votes
1 answer
282 views

Options for (high-thrust) RCS with Isp beyond that of chemical?

There are a number of potential options for high-performance engines in the future: nuclear pulse propulsion, NTR, gas-core NTR, nuclear electrothermal, and potentially even fusion rockets. However, ...
ikrase's user avatar
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3 votes
0 answers
94 views

Where are Falcon 9 1st stage GN2 tanks located?

Is nitrogen propellant for the two cold gas thrusters pods contained in the interstage? The view we have from the B5-B1050 recovery shows several small COPV(s) pic1 Here you can see where the cold gas ...
redshiftseven's user avatar
2 votes
0 answers
628 views

Details on Starship's Reaction Control System thrusters

Recent renderings of the proposed lunar starship has stirred speculation about what those 12 small landing engines are, half way up the space ship. In guessing they may be the same engines being ...
Johnny Robinson's user avatar
0 votes
1 answer
383 views

Bipropellant RCS systems: Do they go together with docking? Or with manned spaceflight?

In a recent discussion, I asked about using a certain bipropellant system for RCS thrusters (I was actually thinking about it as fuel for an MMU jetpack or the "scooter" commonly imagined in science ...
ikrase's user avatar
  • 8,883
22 votes
3 answers
3k views

How dangerous are RCS thrusters?

How dangerous are RCS thrusters, in a vacuum, to A. other spacecraft, especially when docking, and B. astronauts in EVA suits? How far away do you have to be to be safe / do RCS thrusters need to be ...
ikrase's user avatar
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1 vote
1 answer
368 views

RCS or Reaction Wheel for a 30kg cubesat

I am working on the design of a cubesat, it weighs approximately 30 kg and I am doing the Navigation and Guide Control system. I was wondering if I had some blueprint for some RCS or Reaction Wheels ...
Valentino Zaffrani's user avatar
2 votes
1 answer
142 views

Is there an alternate term to "fired" for the Reaction Control System?

Do the astronauts use any word, other than "fired" when referring to the use of the Reaction Control System for attitude control or translation?
Bob516's user avatar
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9 votes
1 answer
167 views

During the MSL (Curiosity) Mars atmosphere entry, when was the last time the Reaction Control System used?

I understand that the Mars Scientific Laboratory used its Reaction Control System during its entry into the planet's atmosphere. At what altitude was the RCS last used? "Seven Minutes of Terror" ...
Bob516's user avatar
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27 votes
2 answers
3k views

Why aren't RCS openings an issue for spacecraft heat shields?

A spacecraft which needs to both maneuver and enter the atmosphere needs both a reaction control system and a thermal protection system (aka heat shield). As the heat shield needs to be on the outer ...
DrSheldon's user avatar
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7 votes
1 answer
303 views

Apollo SM RCS specific impulse?

What is the specific impulse of the RCS thrusters on the Apollo Service Module? This document cites 281 seconds for the LM's RCS thrusters, but I cannot find similar specs for the SM.
space_voyager's user avatar
5 votes
2 answers
202 views

Apollo CSM RCS maximum number of simultaneously active engines?

Reading the RCS subsystem manual, it seems like each RCS quad of the Apollo SM consisted of four hypergolic engines. Am I correct in saying that all four engines of each of the four quads could be ...
space_voyager's user avatar
7 votes
1 answer
357 views

Apollo CSM mass, inertia and RCS parameters?

Is there a document specifying the total mass, the 3-by-3 inertia tensor of the Apollo CSM assembly, as well as the geometry of the service module and command module RCS assemblies (in other words, ...
space_voyager's user avatar
2 votes
1 answer
720 views

What are the limitations of monopropellant RCS thrusters in a re-useable spacecraft?

I understand the disadvantage of monopropellant is mainly dependent on the life of the catalyst. There is a possibility of catalyst failure due to it being subjected to catalytic poison and catalytic ...
user28833's user avatar
  • 499
2 votes
1 answer
79 views

What lateral and rotational accelerations can a spacecraft achieve?

I've found information like the Space Shuttle Orbiter has so many thrusters each generating so much force to maneuver "with redundancy" in orbit. But without knowing something like how many thrusters ...
Greg's user avatar
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5 votes
2 answers
1k views

Is it possible to use RCS instead of gimbal to control first stage attitude?

Questions like this one emphazise the role of gimbal to control the attitude of the first stage. But once in orbit, satellites usually uses reaction control systems. Is it possible to use RCS to ...
Manu H's user avatar
  • 3,790
7 votes
2 answers
404 views

Why does candidate optimal group computation produce strange results when thrusters are too close together?

I have two thruster configurations I'm testing. One is almost symmetric about its center-of-gravity (it's a little bottom-heavy, but the thrusters themselves are the same fore and aft). The other has ...
Translunar's user avatar
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14 votes
2 answers
6k views

Was the Space Shuttle ever rotated to induce artificial gravity?

The Space Shuttle was a fairly compact transportation vehicle in terms of the amount of space available for astronauts to move around. Did they ever attempt to roll a Space Shuttle to induce ...
user avatar
4 votes
1 answer
438 views

Could Vostok 1 deorbit on its cold gas thrusters?

Citing the Wikipedia article: The orbit's perigee and apogee had been selected to cause reentry due to orbital decay within 10 days (the limit of the life support system function) in the event of ...
SF.'s user avatar
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16 votes
4 answers
3k views

What is the minimum number of RCS thrusters capable of stabilizing a satellite against an arbitrary rotation?

In case of a very specific rotation, even one suffices, but it must be located just right for that specific axis of rotation, and if you want to rotate the satellite, it can do so in that specific ...
SF.'s user avatar
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