Questions tagged [flight-control]
Systems and software used to control a space craft's trajectory.
74 questions
17
votes
1
answer
2k
views
How are rockets able to keep their centers of mass in line with thrusters?
How can the thrusters of a rocket keep in line with its center of mass seemingly perfectly to not exert any torque and rotate the rocket? For torque to not be exerted, the force vector must align with ...
- 553
5
votes
2
answers
1k
views
Is the set of software and hardware of modern attitude control systems exhaustive?
In the book ADCS - Spacecraft Attitude Determination and Control on page 426 there is a diagram of the JWST ACS. Next I attach a reproduction of it from the book.
The diagram shows the main soft- and ...
- 383
3
votes
0
answers
84
views
What online courses teach you hands on AOCS GNC?
I am looking for online courses that teach you "attitude and orbit determination and control systems" and "guidance navigation and control" with a focus on satellites or space ...
8
votes
1
answer
223
views
Understanding and breaking down pointing requirements
“< 1 deg, 3σ total angle pointing stability” - What does the 3sigma indicate? Does this mean that 99.7% of the total pointing error (which I assume is computed via a sim), is within 1 deg? If it ...
1
vote
1
answer
137
views
Gas generator exhaust for roll control
Can the exhaust from the turbopump of a rocket engine be used for roll control if a rocket only has 1 engine?
Did the falcon 1 rocket control roll this way?
- 29
6
votes
0
answers
121
views
Looking for Apollo Flight Control Hardware Blueprints (such as RHC, THC and COAS)
I've been looking to build replicas of Apollo flight control hardware such as RHC, THC, ACA, TTCA and COAS, and am looking for detailed engineering drawings that show dimensions and internal ...
- 191
1
vote
1
answer
268
views
The Boeing Big Onion - Why not use the atmospheric engines on landing?
https://www.aerospaceprojectsreview.com/blog/?p=1325
In relation the the Boeing "Big Onion" SSTO LV, I was doing some brief digging on it's flight profile.
(See the awesome Hazegrayart ...
- 1,189
2
votes
0
answers
93
views
Hohmann Transfer - Adaptive Guidance Law
Is there an equivalent adaptive guidance law for the Hohmann transfer as there is with the initial ascent profile for a rocket launch (e.g. Powered Explicit Guidance)?
This is for a personal project - ...
- 71
13
votes
2
answers
2k
views
What caused the jitter in the DART video as it approached Dimorphos?
If you look at the series of images DART took as it approached Dimorphos, the asteroid jumps around a bit as you approach. Does this mean small corrections were being made right up till near the end? ...
- 11.6k
10
votes
2
answers
3k
views
What does the Ariane 5 rocket use to turn?
I noticed that the Ariane 5 does not have wings. It also does not have RCS thrusters except for sometimes with its payload, but that is not being used during liftoff. I tried to find some methods it ...
- 6,836
4
votes
0
answers
100
views
+100
Please explain a way of calculation of Lagrange multiplier in algorithm of low thrust transfer
In David Vallado's book 'Fundamental of Astrodynamics and Applications', chapter 6.7. ("Continuous-Thrust Transfers") there is an algorithm #47: Low Thrust Transfer. In this algorithm a ...
- 391
3
votes
0
answers
71
views
Will JWST be handed over from Arianespace/ESA/CNES to NASA at some point the way Cape Canaveral handed over missions to Houston?
Will JWST be handed over from Arianespace/ESA/CNES to NASA at some point the way Cape Canaveral handed over missions to Houston?
JWST has its own propulsion and communication system. Presumably the ...
- 151k
2
votes
1
answer
125
views
Identifying attitude control mode in GNC software?
Launch vehicles will generally have multiple multiple attitude control modes.
At launch, the engine-gimballing thrust-vectoring system is in charge.
In orbit, the reaction control system is (at least ...
user39728
6
votes
1
answer
155
views
Exact condition for hold-down release?
I've read the space-shuttle hold-down clamps would be released once all engines registered 90% of nominal thrust.
But would this be sufficient condition to open the hold-down clamps and release the ...
user39728
5
votes
2
answers
132
views
Space missions that employed separate flight software development teams?
A recent question "Back up plan to use LOX-RP1 for Apollo mission" has an answer stating
Another example is that some spacecraft have a backup flight software system written by a group of ...
- 10.1k
3
votes
1
answer
124
views
How was it commanded to Ingenuity to fly to 10 ft and land again?
Since Mars is multiple light minutes away from Earth, Ingenuity can't be controlled remotely like any drone. Was there a command given to Ingenuity to at a certain time rise to 10 feet and then land ...
- 633
8
votes
1
answer
454
views
How did the pilot lockout on Vostok 1 work?
The entire mission would be controlled by either automatic systems or by ground control. This was because medical staff and spacecraft engineers were unsure how a human might react to weightlessness, ...
- 48.3k
4
votes
0
answers
150
views
During space shuttle reentry, why was the sign of GALR based on mach number rather than directly on alpha?
(My apologies if this should go in Aviation.SE instead - I'm not quite certain where questions regarding the behaviour of the shuttle's flight controls during reentry should go.)
For flight in ...
- 4,187
2
votes
0
answers
54
views
Trim controls for Apollo RCS systems?
Did any of the Apollo-era spacecraft have any method of trimming the RCS jets? Due to variable mass placement (fuel tanks and sublimators emptying, astronauts moving, item stowage, location of moon ...
- 4,655
3
votes
0
answers
115
views
Trying to modify a JPL guidance algorithm for the Mars Sky Crane and Mars 2020
I've been trying to implement a modification to the JPL guidance law that was used (or very similar to what was used) for the powered descent portion of the MSL mission and I'm struggling to figure ...
- 31
3
votes
0
answers
131
views
What are the implications of North Korean black and white patterns on missiles?
Black and white patterns on rockets were originally intended as roll patterns. They helped as a visual back-up for acceleration sensors measuring the roll, as discussed in this previous question What ...
- 1,134
7
votes
3
answers
327
views
Can ten (or more) rockets be used together to launch one massive object?
With computer flight controls where they are today, what would stop us from building a relatively large space station on earth, but then using 10 or 20 or even 100 falcon heavy or Starship or SLS ...
- 335
3
votes
0
answers
123
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
- 485
4
votes
1
answer
1k
views
How powerful do cold gas thrusters normally get?
Modern rockets like the Falcon 9 use cold gas thrusters for steering on landing approach when the engines are dead.
Cold gas thrusters are common in smaller satellites and spacecraft, which way a ...
user36480
5
votes
1
answer
76
views
Attitude and orbit detection systems for solar sails
When a solar sailing craft is successfully getting force from solar photon pressure, that force applies a small torque to the craft because the center of pressure is never perfectly aligned with the ...
- 163
2
votes
2
answers
147
views
Efficiency in Space Capsule Docking Process
I'm watching the first operational Crew Dragon Capsule proceed through the regimented, and VERY careful International Space Station (ISS) docking process, which was turned on after pausing another ...
- 555
4
votes
1
answer
312
views
Can the grid fins affect the rotation of the Falcon 9 descent?
Can the grid fins control the rotation of the Falcon 9 on descent?
How would they have to be positioned to stop the rotation?
If used to rotate the ship, then how they would they have to be positioned ...
- 2,690
3
votes
0
answers
189
views
Rocket Engine - Actuator in Loop Simulations
For Actuator-In-Loop simulations, why are the rocket engine nozzles along with the thrust vector control assembly (including the actuators) kept inverted on a platform like in the attached image or as ...
- 101
2
votes
1
answer
167
views
Knowing when to stop burning
Navigating in orbit usually relies on firing engines for some amount of time to achieve a specific velocity. This answer, for example, mentions "closed-loop guidance" for the ISS boosting.
...
- 365
5
votes
2
answers
1k
views
How do Falcon 9 grid fins deploy?
Is it aerodynamic drag that flaps the grid fins open? Or is there a controlled mechanism for it? Pictures show the grid fins connect through a small link to something inside the rotating trunnion arm--...
user36480
2
votes
1
answer
138
views
Who or what performs the throttle up?
During a Falcon 9 launch you hear the commands 'throttle up' and 'throttle down'. Who or what performs 'throttle up' and 'throttle down' (i.e. astronaut or computer)?
- 21
2
votes
0
answers
133
views
How did omission of command to Huygens lander not get caught by anybody at ESA nor anybody at JPL? Procedures in place to avoid in future?
In this answer to Prior to putting spacecraft on a trajectory going a significant fraction of the speed of light, would some things need to be tested on Earth? I wrote:
As far as communications is ...
- 151k
12
votes
3
answers
2k
views
How does “space weather” cause reaction wheel failure?
Failure of reaction wheels often causes premature mission ending or failure to achieve the goal because spacecrafts are no longer able to maintain orientation and have to rely on chemical propellants. ...
- 2,341
2
votes
0
answers
203
views
Why were hot-stick downmoding to CSS, and the ability to use CSS for some control axes but not others, disabled during space-shuttle powered flight?
During ascent, if need be, a space shuttle’s flight controls could be switched from the normal, automatic control mode over to manual1 control (known as control-stick steering, or CSS), allowing the ...
- 4,187
4
votes
4
answers
1k
views
High altitude stage separation
Normally, at high altitude above Earth's surface, there are stage separation of a rocket. If we consider unmanned rockets, at high altitudes, how does human operators of a rocket who are here on Earth ...
- 341
13
votes
1
answer
1k
views
Could the Apollo Lunar Module be flown to a landing without the LEM Guidance Computer?
Inspired by answers to Could the lunar module have moved to a different spot? question but not talking about that specific relaunch scenario:
Could the LEM stack (descent configuration) be flown ...
- 189k
1
vote
0
answers
108
views
Control torque to a Reaction wheel that compensates for friction - need help understanding a working code
Reaction wheel in a s/c is driven by controller torque. However, since there is friction torque in RW, less than the reqd momentum change is achieved. Hence the control torque must be increased by ...
- 31
4
votes
0
answers
397
views
How do single-nozzle staged combustion rockets control roll?
Related: How do single engine rockets control roll?
While many single-nozzle rockets are gas generator powered & can deflect the pump exhaust asymmetrically to produce a torque, staged combustion ...
- 11.2k
7
votes
0
answers
150
views
Time scale separation and cascading control loops
The typical approach to designing flight control systems is to design an inner control loop to stabilize vehicle attitude and angular rates, while an outer loop tracks vehicle position. The reason ...
- 101
5
votes
1
answer
179
views
Would astronauts have been able to save the CST-100 mission?
The Boeing CST-100 Starliner failed an unmanned test because the timer on the spacecraft was off by 11 hours. This caused the spacecraft computer to think it was ahead in mission timing by 11 hours, ...
- 20.4k
16
votes
1
answer
889
views
Why are there advertisements in the Russian ISS flight control room?
I found a photograph of the Russian ISS flight control room:
Source: NASA https://commons.wikimedia.org/wiki/File:Russian_ISS_Flight_Control_Room.jpg
Below the large screen are several ...
- 263
0
votes
0
answers
392
views
How to filter a white noise or random noise in Matlab Simulink?
I am working on a sun-synchronous satellite Simulink model wich determines its attitude from a Sun sensor and a star sensor whom measure the sun and star direction in the satellite body reference ...
- 9
48
votes
3
answers
9k
views
Did a flight controller ever answer Flight with a no-go?
OK, all flight controllers, I'm going around the horn
Retro? Go
FIDO? Go
Guidance? Go
Control? Go
TELCOM? Go
GNC? Go
EECOM? Go
Surgeon? Go
Are there any recorded instances of a No-Go?
- 695
6
votes
2
answers
585
views
Can a spacecraft use an accelerometer to determine its orientation?
I know that almost every spacecraft uses a gyroscope to determine its orientation, but I don't know if an accelerometer could also be used in addition to a magnetometer to calculate it.
I have been ...
4
votes
1
answer
266
views
How do small, spin stabilized launchers follow a rhumb line?
This concise answer to What exactly is rhumb-line control in the context of a launch trajectory? explains the concept in the context of the SS-520 nanosatellite launch vehicle (which "doesn't exist"). ...
- 151k
4
votes
1
answer
802
views
What exactly is rhumb-line control in the context of a launch trajectory?
The conference paper SS-520 Nano satellite launcher and its flight result SSC18-IX-03 from the 32nd Annual AIAA/USU Conference on Small Satellites linked in this answer describes the use of rhumb-line ...
- 151k
4
votes
1
answer
526
views
Where are these historical IBM + Apollo related locations within NASA? What do these computers do?
In the Fortune Magazine video IBM's Moonshot: Past and Future with the notes
BM’s John Kelly reflects on Apollo 11’s historic mission and looks forward to what future technology will accomplish.
...
- 151k
5
votes
2
answers
203
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 ...
- 981
7
votes
1
answer
369
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, ...
- 981
2
votes
1
answer
224
views
Satellite mission design/performance requirements to attitude/orbit control design specifications
Are there any good sources that discuss: the steps involved in deriving attitude/orbit control design specifications, from satellite mission design/performance requirements?
- 186