Questions tagged [propulsion]
Systems for propelling a spacecraft from one place to another, such as rockets.
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Why is the thrust to weight ratio of ion thrusters so low?
The more power we feed an ion thruster, the more thrust it generates. In theory, if we could give it, let's say 10 gigawatts of power, it could generate pretty high thrust. In the example I calculated ...
2
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1answer
83 views
In theory, how much thrust could an ion thruster generate?
Ion thrusters require a lot of electrical power, while their thrust is incredibly low. However, the more power is available, the more thrust can be achieved. What would be the theoretical limit to ...
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1answer
141 views
Could a CubeSat be propelled by this low-tech electromagnetic propulsion system?
I have come up with a conceptual idea for a low-tech electromagnetic propulsion system for a CubeSat, and I would like to know if it would create (on a theoretical basis) a net force strong enough to ...
3
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0answers
73 views
How do you calculate burns needed to land?
Assume I was landing a rocket and wanted to do calculations on how to correctly land. How do you determine at what time you fire the engine and at what power to successfully land on a predetermined ...
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42 views
Exit pressure for Rocket Lab Curie engine
What do you think the exit pressure for rocket lab curie engine could be?and the area ratio as well? its a kickstage engine and it is said that it has about 25lbf thrust.
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1answer
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Exit pressure value for vacuum nozzle [duplicate]
What value of exit pressure should I use in the design equations for a small liquid rocket engine nozzle for 200km-500km operating conditions?
Since using zero as a value is not possible or else ...
5
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1answer
113 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.
2
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1answer
97 views
Under-expanded nozzle at sea level - is it a problem?
I'm designing a solid rocket motor with a fixed pressure in the combustion chamber $p_{cc} = 70~bar$. When it comes to the choice of the right nozzle, I have to consider the proper expansion ratio, in ...
4
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2answers
82 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 ...
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52 views
ECI to LVLH transformation [duplicate]
I am working on a transformation of ECI coordinates to LVLH (Local Vertical Local Horizontal) coordinates in order to calculate satellite maneuvers. Does anybody know how should I approach the problem?...
2
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1answer
167 views
Why we don't use cyclotron for ion thrusters?
We know that the advantage of thruster is high efficiency and 'everlasting' propulsion. Which It can not provide a sudden huge propulsion during launch like chemical fuel is its biggest problem. I ...
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1answer
100 views
What if GOCE rolled 90°?
Reading this question: Is GOCE a satellite or aircraft?
I wondered what would happen if GOCE rolled 90° in either direction, so that it's solar panels become parallel to Earth's horizon, and then ...
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1answer
99 views
Ambient pressure for vaccum nozzle design
How do I find out the ambient pressure for designing a vaccum rocket engine?
I am using the propellant combustion charts from the braeunig website. But I cannot figure out the ambient pressure for ...
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1answer
129 views
What is a mixture ratio of propellant?
I am a little confused, is the mixture ratio of a propellant Fuel/Oxidizer or Oxidizer to Fuel ratio?
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1answer
105 views
Can a reaction wheel decelerate to add momentum in the same direction? [closed]
Can a reaction wheel shed weight to gain speed?
Could a reaction wheel at its max spin be flipped or rearranged around 180 degrees then slowed to add to its velocity?
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118 views
What is the difference between “Air-augmented rocket propulsion” and “integral rocket-ramjet propulsion”?
While going through the topic called "Combinations of Ducted Jet Engines and Rocket Engines" in Chapter 1 of Sutton & Biblarz's Rocket Propulsion Elements, 9th Ed I found the section below.
Line ...
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1answer
105 views
Will a spacecraft accelerate in a gravitational field via the use of a powered rotating mass?
I believe that a powered rotating mass on board a spacecraft should result in the spacecraft being propelled in a continuous increasing velocity towards the source of the gravitational field.
To help ...
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1answer
171 views
Could this satellite wobble in orbit creating additional orbital angular momentum?
This question asks if this type of steam engine would work: Could a steam Engine outperform other electric producing devices in space? this not a sterling engine since it has far less moving parts.
...
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1answer
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What is the nozzle extension of merlin engine and rutherford engine made of?
It is clear from the pictures, that the nozzle extension of Merlin and Rutherford vacuum engine aren't actively cooled.
What is the material of construction for those nozzle extension to withstand ...
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9answers
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Would a grinding machine be a simple and workable propulsion system for an interplanetary spacecraft?
I am wondering if any space agency has ever considered using a grinding machine as a propulsion system for an interplanetary spacecraft. This system would not be used to lift the spacecraft off of a ...
4
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1answer
238 views
Could a “nuclear turbo-jet” be built?
Being familiar with jet engines myself, I wonder whether a similar device could be built to provide high $I_{\text{sp}}$ and high thrust in vacuum and space. Using the tried-and-true turbojet formula ...
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1answer
61 views
What differences exist between the pressurants and their associated systems between a pressure fed and pump fed liquid rocket engine
There is an apparent need to have pressurants in both pressure fed and pump fed systems. However, since pump fed systems can create the necessary pressure, they can work with less pressurants and ...
3
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1answer
204 views
Efficiency of a nuclear thermal rocket
I am trying to calculate the specific impulse and thrust of a nuclear thermal engine, given the thermal power of the reactor, the maximum working temperature and the propellant.
I'm calculating the ...
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2answers
1k views
Could a cubesat propel itself to Mars?
I wrote the answer below to the question Could a cubesat be propelled to the moon? before realizing that it said Moon and I'd written it for Mars, so I've cloned that question and moved the answer ...
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Could a cubesat be self propelled to the moon from LEO?
Is it possible with current technologies to propel a cubesat, which is launched from Earth, to the moon?
If current propulsion systems are able to do so, how do I continue the research in this topic ...
4
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1answer
151 views
What kind of “jet engine-like propulsion” does HyperSciences use to accelerate projectiles to sub-orbital altitudes?
The Teslarati article For HyperSciences, geothermal energy builds a path to space describes the use of technology which has been applied to drilling to launching projectiles to sub-orbital altitudes ...
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1answer
130 views
How do you determine what the temperature will be in the combustion chamber of a rocket engine?
I am guessing it is dependent on the fuel and oxidiser and the chamber pressure but is there an equation that would calculate the chamber temperature?
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1answer
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Weight Flow Rate
I read in the book INTRODUCTION TO ROCKET SCIENCE AND ENGINEERING by T.S.T that Rocket Engineers design how big the throat of the nozzle should be based on the Weight Flow Rate.
So my question is HOW?
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2answers
318 views
What could go wrong if someone overpowered an ion engine?
The X-3 ion engine is the most powerful ion engine ever made, and puts out an astounding 5.4 N of force, using 103 kW. It's fuel is inert xenon gas, ionized and heated to a plasma. Now, what would ...
3
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1answer
206 views
What type of propellant does Spacex plan to use in Starship for long duration missions?
For long duration missions such as ones to mars what type of propellant would be best suited?
2
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1answer
87 views
What happens when LOX and H2 are injected into the combustion chamber of a rocket?
I can't seem to find an answer on this.
I thought that when oxygen and hydrogen get injected they collide and break bonds etc. to form water vapour which because of the pressure in the combustion ...
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0answers
49 views
How to calculate the force drop due to multiple thrusters firing?
When multiple thrusters are connected to one pressurized propellant tank and multiple thrusters are fired simultaneously, this will cause a pressure drop in the supplying pipes and as such a drop in ...
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0answers
101 views
Very Low Gravity Bicycle
There are a couple of existing questions about riding bicycles off of Earth.
Designing a bicycle for Mars?
Can you ride a bicycle on Deimos?
Bicycles are lightweight and proved a reliable method ...
2
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1answer
296 views
Advantage of full-flow staged combustion vs conventional staged combustion engine
Referring to the question in
this thread.
What is the advantage of full-flow staged combustion (FFSC) vs conventional staged combustion rocket engine?
In FFSC we feed the full volume of fuel and ...
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1answer
47 views
Why does the pressure & temperature ratio in a diverging nozzle continue decreasing once it hits supersonic flow?
From Sutton chapter 3 he uses this figure to describe the ratios of pressure//area//temperature as functions of Mach Number.
I know that we are bringing the fluid to an adiabatic "stop" through ...
3
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2answers
183 views
Is presssuized gas absent in a turbopump-driven rocket engines?
For RL-10 rocket engines, are the propellent pumps able to provide the propellent without a source of pressurant gas?
5
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1answer
153 views
What methods are proposed for storing cryogenic fuels (esp. hydrogen) in space for months or years?
Current Launch vehicles and upper stages must only keep their fuels for minutes or hours, so they are only insulated to keep boiloff to a few % per day - I've seen 21% per day quoted for Centaur on ...
4
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1answer
159 views
Is it possible to protect a Cubesat's electronics from 100g of acceleration?
I am currently researching the feasibility of setting up a coilgun that launches Cubesats for a paper. 1 cubesat per launch total payload mass <100kg.
3
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1answer
165 views
Could protons in the Sun's solar wind be used to create a photonic laser thruster for a spacecraft?
I have a conceptual idea for a photonic laser thruster for a spacecraft and I am wondering if this particular idea has already been thought of and whether or not it is capable of generating enough ...
4
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3answers
263 views
If specific impulse is directly related to exhaust velocity, would a ion post-accelerator improve the Isp of a propulsion system?
I understand that ion- and hall thrusters resemble a particle accelerator, and that led me to wonder if a post-accelerator (particle accelerator) used to boost the velocity of the ions would improve ...
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1answer
173 views
Could a spacecraft be propelled by a 180 degree deflection of two charged particle beams?
I am wondering if the electrostatic deflection of two charged particle beams could create enough thrust, via the Lorentz Force, to propel a spacecraft.
Please reference the picture below.
This ...
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0answers
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Could a Soyuz-MS deorbit after a failure of its deorbit engine?
The scenario: A Soyuz-MS spacecraft is on-orbit and ready for its deorbit burn. The crew then discover that there is a fault in the propulsion system and the deorbit engine can't fire. The craft is ...
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1answer
101 views
Can I able to use RP 1 and LOX in metal tin small size rockets? Is that possible? [closed]
I love rockets. Planning to build a tin rocket but not with water and air pressure. I would like to build a small metal tin rocket using fuel as RP 1 and oxidizer as LOX. I know this is too hazardous ...
2
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2answers
205 views
Calculating thrust pressure from ion thruster for rocket thrust equation
So recently i have been very interested in the possibilities of using ion thrusters as power interstellar propulsion units, however when it comes to calculating ISP it have absolutely zero idea how ...
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2answers
573 views
What are some notable cold gas thruster propellants, and why?
Cold gas thrusters are a very simple and reliable form of thruster that operate only by spraying a compressed gas, without any chemical reaction.
What are the most common, performant, or otherwise ...
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1answer
128 views
How much delta-v is lost to heat of exhaust?
It occurred to me that all of the kinetic energy not going exactly in the opposite direction of a spacecraft is wasted! Since heat is essentially kinetic "noise" in objects, I wondered how much more ...
6
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1answer
186 views
Why did the MarCO space probes use fire extinguishant as their propellant?
In many news articles, it's mentioned that the MarCO spacecraft, launched with InSight, used fire extinguishant as the propellant for its cold gas thrusters. I originally assumed that this was ...
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2answers
98 views
Propellants used for different Mars landers [till 2018]
What propellants have been used by lander to land on Mars surface?
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1answer
189 views
How much thrust can plasma produced from water have?
If water could be converted to plasma for a propellant by electricity how much thrust would water produce? What would be the byproduct?
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Converting Discharge Voltage to Temperature? Hall Effect Thruster Calculation
Trying to follow a Hall Effect Thruster design process given in this video:
Hall Effect Thruster Design Video
In 25:59, there's a calculation in which the presenter takes discharge voltage and ...
