Questions tagged [flight-control]
Systems and software used to control a space craft's trajectory.
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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.
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1answer
123 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--...
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1answer
100 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)?
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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 ...
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3answers
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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. ...
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0answers
53 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 ...
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4answers
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 ...
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1answer
870 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 ...
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0answers
57 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 ...
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0answers
100 views
How do single-nozzle staged combustion rockets control roll?
Related: How do single engine rockets control roll?
While many single-nozzle motors are gas generators & can deflect the pump exhaust asymmetrically to produce a torque, staged combustion motors ...
7
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0answers
76 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 ...
5
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1answer
131 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, ...
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1answer
631 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 ...
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0answers
119 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 ...
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3answers
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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?
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2answers
204 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 ...
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1answer
108 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"). ...
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1answer
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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 ...
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1answer
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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.
...
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2answers
130 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
110 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, ...
2
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1answer
94 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?
2
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1answer
138 views
What are the top most used satellite control system, flight dynamics solution at the moment ? Approx costs?
I am looking for a list of top most used satellite control systems, flight dynamics solutions by space agencies, private companies etc. the moment? How much do they cost approx for use by 1 person? Is ...
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184 views
Analyzing Amateur Rocket Stability and Range Safety
I am working with a university bunch of other university students on building a very large amateur rocket. Our objective with this rocket is just to go very high, with no significant payload or ...
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2answers
186 views
Among Quantitative Feedback Theory and H infinity, which one is preferred for robust control of satellites esp. small satellites? And why?
I am interested in designing a robust controller for a small satellite with antenna, sloshing propellant and flexible panels on board. I am mostly interested in achieving arcsec precision pointing ...
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784 views
Is it possible to navigate space travel with no computer?
From launch to land could a person travel in space with only mechanical devices like a sextant? With enough experience what would be the minimum devices needed? Which vehicle currently would be easier ...
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0answers
648 views
Why would someone use Modified Rodrigues Parameters over Quaternions for spacecraft attitude estimation? And vice versa?
I see quite some papers on spacecraft attitude determination and control, that rely on quaternions. While some others rely on MRPs. The advantage that I see so far is that... for quaternions, the ...
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454 views
Avionics Systems on board Falcon 9 (Reusable)
What kind of control systems are active and how do they function on board a Falcon 9 booster while it's landing ?
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1answer
4k views
How can a rocket go straight up after ignition? [duplicate]
We have seen during rocket launches that the rocket goes straight up after the launch clamps have disconnected.
What ensures that it doesn't tilt because of the uneven mass distribution?
How does a ...
8
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1answer
1k views
Machine Learning and Classical Navigation, Guidance and Control in Space Exploration
Due to the increasing availability of large quantities of data and computational power, machine learning (ML) is providing increasingly better results in various fields. Much research has been done on ...
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4answers
348 views
Using what technology one can keep a spacecraft truly non rotating
Inspired by the question I thought maybe a photon thruster can be used for precisely giving thrust to maintain spacecraft attitude. But soon I realized that for high precision attitude control, one ...
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1answer
117 views
An program that automatically generates a rocket guidance system?
This is for a liquid propelled rocket that launches from earth. It could also perhaps be used for orbital maneuvers and landing on the Moon (not mars or earth).
The inputs for such a program would ...
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4answers
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How were the pilots of the space shuttle able to operate the rudder after time in space?
I've just watched this video showing three astronauts who've returned from space. At around the 5:46 mark in the video we can see astronaut Chris Hadfield being carried out of the Soyuz capsule. I've ...
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2answers
156 views
Implementing control system to track position and velocity references simultaneously
I've been trying to implement a PI (proportional-integral) controller to allow a launch vehicle to track 2 reference states simultaneous, namely position and velocity, so that the launch vehicle will ...
3
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2answers
314 views
SpaceX stage 1 reentry control?
In watching today's BulgariaSat-1 broadcast:
It was mentioned that the drone ship had acquired the 1st stage as it was returning. I had always been under the ...
4
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2answers
582 views
Does the Hubble telescope use a “simple” PID-controller for its pointing control system?
I am wondering whether the Hubble Space Telescope uses a "simple" PID controller like this:
Or is it using another type of control system that may be much more complex?
4
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1answer
360 views
Controller to reaction wheel interface
A typical controller generally gives control torques which should be applied about the axis of a satellite. How exactly is this torque applied using a reaction wheel?
For example if control torques ...
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4answers
4k views
Why does spinning help stabilisation?
I don't really understand why do we use spin stabilisation for rocket launches?
If I understand correctly, the idea is to make the rocket spin really fast so that any asymmetry in the thrust/...
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2answers
237 views
How much can static cling be used to move things in space? Tractor Beam
Can static cling occurs in space? Can a static charge be amplified laterally to move objects in space similar to Star Trek's tractor beam? Can a static charge could be carried by a sustained particle ...
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0answers
76 views
Linear Control Lock?
Assume a spacecraft with a less-than-perfect maneuvering thruster configuration such that in a particular attitude while attempting to dock, the thrusters will not allow translation along a particular ...
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3answers
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Does this kill vehicle contains momentum wheels? Watch how it moves!
This comment below this answer about 'spacecraft' or at least 'craft' that can maneuver near the surface of low gravity bodies links to this video about Lockeed Martin's Multiple Kill Vehicle.
If I ...
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1answer
426 views
Apollo CSM thruster quad orientations vs LM
Can anyone explain to me the reasoning behind the differences in the placement and orientation of the thruster quad packages on the CSM and LM? On the CSM a quad is a + shape and are located in a ...
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2answers
175 views
Will there be torques on spacecraft due to interaction of magnetic torquer with the residual magnetic field of the spacecraft?
Assuming the magnetorquer and the field generating electronics are both rigidly fixed to the spacecraft cube. Reference to any supporting papers/articles would be great. Thanks.
Would the residual ...
4
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1answer
670 views
How to select/design a control algorithm for spacecraft attitude control?
Control algorithms are used on spacecraft to operate reaction wheels, RCS thrusters and other actuators. Since of the most common controllers I've come across are the PID and quaternion error command. ...
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0answers
538 views
How is retropropulsion by the Falcon 9 first stage being used to design retropropulsion entry on Mars?
Much has been made of how the reentry burns of Falcon 9 first stages occur at an altitude where the atmosphere is similar in density to the atmosphere of Mars, and so they demonstrate that supersonic ...
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2answers
599 views
Rocket drag and lift based on flight direction - in which frame of reference?
Drag is aerodynamic force component parallel to the direction of motion.
Lift is aerodynamic force component perpendicular to the direction of motion.
Direction of motion with respect to what?
1) ...
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3answers
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Is aerodynamic lift ever useful in rocket flight?
When a rocket is traveling through an atmosphere, the component of the aerodynamic force in the direction of motion is called drag, and the component perpendicular to that is called lift. Usually a ...
