Questions tagged [rcs]

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

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13
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3answers
2k 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 ...
8
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1answer
606 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 ...
3
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1answer
94 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 ...
6
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1answer
104 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 ...
6
votes
1answer
574 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 ...
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2answers
110 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 ...
3
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0answers
46 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 ...
28
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3answers
6k 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 ...
4
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2answers
539 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 ...
2
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0answers
30 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 ...
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0answers
79 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
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0answers
24 views

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 ...
2
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1answer
117 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, ...
3
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0answers
62 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 ...
2
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0answers
345 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 ...
0
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1answer
191 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 ...
22
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2answers
2k 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 ...
8
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1answer
137 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" ...
1
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1answer
205 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 ...
2
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1answer
124 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?
27
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2answers
2k 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 ...
7
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1answer
215 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.
5
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2answers
149 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 ...
7
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1answer
157 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, ...
3
votes
1answer
352 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 ...
2
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1answer
63 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 ...
5
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2answers
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 ...
7
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2answers
265 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 ...
13
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2answers
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 ...
4
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1answer
364 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 ...