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# Questions tagged [propulsion]

Systems for propelling a spacecraft from one place to another, such as rockets.

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-2 votes
2 answers
158 views

### Can we just throw a satellite in to mars orbit with a very high spin?

I am thinking about this scenario of throwing a satellite to Mars orbit with a high spin, Can we just throw that? one hypothesis can be that high-frequency spinning generates apparent gravity so it ...
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1 vote
1 answer
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### What is the maximum payload in terms of mass delivered to LEO by launch vehicle which used pressure fed cycle in all stages?

Launch vehicles can use pressure fed cycle in any stage of the rocket, but here i am interested for those vehicles which used this cycle in all stages. What is the current record in terms of mass of ...
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3 votes
2 answers
154 views

### Viability of beamed regolith propulsion?

This question is inspired by two existing spacecraft propulsion concepts. Beam-powered propulsion involves a spacecraft being propelled by a beam of some kind, and one potential type of beam would ...
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1 answer
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### Spacecraft propulsion, Thrust, Delta V

For a spacecraft on an interplanetary mission (e.g. Mars), after deciding the propellant ISP value and Delta V required, how do you calculate the thrust required? $$F = \dot{m} V_e + (p_e - p_0) A_e$$ ...
0 votes
1 answer
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### Can a spacecraft be propelled by two electromagnets of different size? [duplicate]

I watched a video of a toy car moving with 2 magnets, one bigger than the other. The answer I received was that the video was real, the toy car indeed moves. So, I was wondering, if an object with 2 ...
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1 vote
1 answer
136 views

### Who won the first round of Limitless Interstellar Initiative Grants?

Wired's NASA's EmDrive Leader Has a New Interstellar Project also mentions White’s research pedigree may sound like it was cribbed from a mad scientist in a pulp sci-fi novel, but most of his work ...
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12 votes
1 answer
821 views

### How does tankage mass really scale?

A problem that frequently shows up is estimating the mass of the propellant tanks of some hypothetical rocket configuration. This need arises from the important role of the dry mass in a rather famous ...
6 votes
1 answer
340 views

### What was the influence of the military in the decision to use kerosene as fuel for LOX?

When it comes to hydrocarbons almost all state owned space agencies use kerosene in combination with LOX in bi-propellant rockets. But many hydrocarbons (such as methane, ethane, propane, ethylene, ...
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2 votes
1 answer
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### Why can I not use stoichiometry to calculate the O/F ratio of my rocket? [duplicate]

I am attempting to calculate the oxygen to fuel ratio (O/F) for my hybrid rocket engine (paraffin wax and gaseous oxygen). I know I can use the oxidizer to fuel equation to calculate this, but my ...
3 votes
1 answer
442 views

### Could pressurized ionized oxygen be used as a fuel source for an ion thruster?

I am wondering if a canister of pressurized oxygen could be used as a fuel source for an ion thruster. To show how this could work on a conceptual basis, please reference the following drawing: I ...
7 votes
2 answers
1k views

### Is the propulsion for the Scorpion nuclear-thermal-electric ship concept viable and credible?

Recently I've come across the proposal for the "Scorpion" spacecraft -- I originally ran across it on Project Rho (ctrl-F for it) but it looks like the article was published in the journal ...
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1 vote
1 answer
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### Is "nuclear electrothermal" a recognized term for a specific technology?

Is the term "nuclear electrothermal" recognized as referring to a specific type of propulsion technology (specifically, the nuclear thermal rocket with heat engine and arcjet afterburner)?
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2 votes
1 answer
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### 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, ...
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10 votes
1 answer
1k views

### How much krypton is stored on a Starlink satellite?

How much krypton (fuel) is there for the krypton-powered ion thrusters on Starlink satellites and how long does it last?
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### I've looked at the Science involved but have doubts this would work, how can you generate momentum with-in a sealed system to produce propulsion? [closed]

Could you use a magnetic super-capacitor compound which is charged so it gains the maximum amount of weight\mass then is pushed away from the main object down a chamber using a magnetic field. As the ...
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3 votes
1 answer
255 views

### Mars Sample Return Earth Return Orbiter -- which propulsion system for what?

Many sources (eg this one) show the Mars Sample Return Earth Return Orbiter with both ion and chemical propulsion, and also state that it will be launched on an Ariane 6, but I can't find a clear ...
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1 vote
0 answers
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### How to send a 6-km mirror close to the Sun to propel a light sail?

I have written a paper about a crewed interstellar spacecraft that I propose. I suggest to use either a laser, a Fresnel lens or a mirror to propel the sail of the spacecraft with sunlight. I have ...
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5 votes
1 answer
317 views

### Is there any possible reason to direct the electron gun specifically towards the ion trail behind an ion thruster?

This answer to Neutralization of ions in the ion thruster quotes the introduction to Wikipedia's Ion thruster: Temporarily stored electrons are finally reinjected by a neutralizer in the cloud of ...
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0 votes
0 answers
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### Freezing problem of hydrocarbon fuels in a LOX cooled engine

I assume that in a LOX/RP-1 engine where RP-1 is used as a coolant, we need not consider the freezing issues. The reason for my assumption is that we need not bring the chamber and injectors to the ...
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3 votes
1 answer
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### How to predict reaction of propellants at chamber temperature and pressure? [duplicate]

I would like to understand how to calculate the complete reaction of propellants at chamber temperature and pressure. For instance taking ethyl alcohol (75%) and LOX combustion with mixture ratio of 1....
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3 votes
0 answers
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### 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 ...
13 votes
2 answers
23k views

### Is the concept of the Epstein Drive based on actual theorized scientific research which is considered plausable?

I've always found it interesting when we see real life taking its cues from fictional arts, especially when it comes to Science Fiction technology. There are plenty of examples of classic books, TV ...
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0 answers
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### Anyone know of a "N71" Hall Effect Thruster currently in production or development?

In a NASA Goddard Q&A transcript for an upcoming proposal, the NASA representative mentioned that the mission designers were considering the "N71" Hall Effect Thruster as an option for an upcoming ...
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0 votes
0 answers
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### Ion Lifter Thrust Calculation Problem

I've recently started building an ion lifter. I tried calculating the thrust the lifter produces but I came to a value that is way to high for such a small lifter. I'm using a 40kV at 1800mA AC ...
4 votes
1 answer
506 views

### Why might krypton have a lower utilization fraction than xenon for ion propulsion, and what can be done to improve it?

A comment below Why will Starlink satellites use krypton instead of xenon for electric propulsion? links to the 2011 preprint A Performance Comparison of Xenon and KryptonPropellant on an SPT-100 Hall ...
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5 votes
2 answers
934 views

### Why is rocket engine flame usually clear/transparent at the nozzle?

This is a followup to a question about why the Falcon 9 second stage flame was invisible when out of the atmosphere. See: Why is the flame of the Falcon 9's 2nd stage invisible?. That was well ...
5 votes
2 answers
621 views

### single thrust vs. multiple thrust

Does using one 5000 pound thrust engine give the same amount of thrust as five 1000 pound thrust engines? I am asking in terms of effectiveness not efficiency. Do the two different configurations ...
8 votes
0 answers
606 views

### Is thermal soakback from the engine a problem for rocket stages? Especially ones that complete several burns over several hours (e.g. S-IVB, Centaur)?

Thermal soakback is a phenomenon whereby a hot, operating engine transfers heat into the spacecraft, usually conduction through the engine mounts. I've only ever seen this problem discussed with RCS ...
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4 votes
2 answers
516 views

### Why aren't rockets launched in movement? [duplicate]

Rockets launched to reach orbit usually start from a stationary position, engines are started and the rocket slowly gain acceleration upwards, eventually reaching orbit. What I'm thinking is that the ...
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2 votes
1 answer
226 views

### Delta V/Fuel Cost for Satellite Rotation

How would you figure out the fuel cost or delta V for spinning up a S/C to match the orbital period of 27.32 days (moon orbit)? Given that the S/C is initially not rotating about any axes. For ...
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5 votes
1 answer
275 views

### How much thrust is "high" thrust (for orbital transfers)

I understand that chemical rockets and nuclear thermal rockets (and possibly very high power electrical thrusters) are considered to provide "high" thrust for orbital transfers, while electrical ...
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3 votes
1 answer
260 views

### Could the kinetic energy in the Sun's solar wind power an ion propulsion system for an interplanetary spacecraft?

I am wondering if the kinetic energy of the Sun's solar wind could energize heavy ions to the point in which they would produce enough momentum to propel an interplanetary spacecraft. To help ...
3 votes
0 answers
51 views

### Are there substances that can effectively mined from asteroids that can be used for ion thrusters?

The most popular ion thruster design seems to use Xenon. Unfortunately, due to it's low boiling point Xenon isn't easily available in space. Are there other materials from which ion thrusters could ...
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4 votes
1 answer
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### Pump requirements in rotating detonation engines

The recent Wired article After 60 Years, Explosion-Powered Rockets Are Nearly Here about progress on rotating detonation engines contains the following quote: A rotating detonation engine doesn’t ...
13 votes
6 answers
3k views

### Why does this formula say rocket efficiency depends on velocity?

Wikipedia gives the following equation for the efficiency $\eta_p$ of an engine here: $$\eta_p= \frac {2\, (\frac {v} {v_e})} {1 + ( \frac {v} {v_e} )^2 }$$ where $v$ is the rocket speed and $v_e$ ...
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7 votes
6 answers
1k views

### Could moon ice be used to fuel a steam powered jetpack for EVA in space or high altitude exploration on the moon?

For long term moon operations, would it be practical to have a jetpack that used steam as a source for EVA on the moon surface and above it in orbit? I imagine a scenario where lunar ice deposits ...
1 vote
1 answer
157 views

### Would an incandescent light bulb be more efficient than a laser for photon propulsion?

In an incandescent light bulb pretty much almost all of the input power is radiated as photons. While perhaps 10% of the power is useful for human vision and the rest are longer wavelengths, it's all ...
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3 votes
1 answer
212 views

### Could a carbon arc lamp help to propel a spacecraft through interstellar space?

I would like to know, on a theoretical basis, if the electron flow entering into the anode of a carbon arc lamp would impart enough kinetic energy to the anode, and thus to the spacecraft, to help ...
1 vote
1 answer
326 views

### For a DAWN-like solar-electric deep space mission, would using propellant particles much heavier than xenon atoms be beneficial?

For deep space missions using ion propulsion that are power-limited, this answer explains that a large mass/charge ratio ($m/q$) species is desirable. The solar-electric propulsion system used by the ...
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1 vote
0 answers
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### Injectors Diameter and Numbers

how would you determine the diameter and the number of injectors if unlike doublets elements are used? The Data given is: Isp =286 s Chamber pressure= 25 bars Propellant pair: Fuel= Hydrazine and ...
5 votes
1 answer
269 views

### Proposed spacecraft propulsion with particle accelerator

With the new particle acceleration technology of plasma accelerator, electrons or protons can be accelerated to relativistic speed in a device much smaller than current Linac (According to wikipedia, ...
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1 answer
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### Why did SpaceX swap the LOX and CH4 tanks between Mk1 and SN1?

According to most sources, the Starship Mk.1 had its LOX main tank (not talking about the header tanks here) on top and its main methane tank below. But it seems the SN1 revision, and all subsequent ...
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### X-248 cape catastrophe [closed]

I was responsible for changing the ignition system on the fatal x-248. It was a result of poor igniter design and especially dangerous procedures by Cape personnel. I am looking for some facility of ...
2 votes
1 answer
81 views

### Going to Eros; what to consider choosing between ion and chemical propulsion?

When planning a mission to a close approach to the asteroid Eros and to remain nearby, what are the factors that one would need to consider when choosing between ion propulsion and chemical propulsion?...
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3 votes
1 answer
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### Can a strong magnetic field be used to propel a spacecraft towards Mars and outer planets in Solar system?

Sun is bombarding us with ionized particles and these particles are moving towards outer planets. During solar flares this effect is intensified greatly. If we are able to create very strong magnetic ...
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0 votes
3 answers
864 views

### Could a horseshoe magnet help a satellite stay in orbit?

If a horseshoe magnet was attached to a satellite orbiting the Earth, would the interaction of the Earth's magnetic field and the horseshoe magnet's magnetic field result in the magnet being propelled ...
1 vote
0 answers
69 views

### What is the most efficient way to go to Titan? [closed]

With ionic motors? or chemical engines? liquid propellant (LH2) or gas? What is the most compact way to make the trip? in the smallest possible rocket, for example the SS-520-5 is a 2-stage rocket, 11....
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2 votes
1 answer
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### What are the most effective deep-space propulsion systems?

I am looking for a powerful propulsion system for deep space missions. I am between a powerful ionic motor or a VASIMIR (variable specific impulse magnetoplasm motor). What do you think? The idea ...
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2 votes
0 answers
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### What is the load path for thrust in a rocket engine? [duplicate]

This may be a duplicate of this question but I wasn't sure if I could hijack that one to clarify or regenerate interest there. What is the distribution of axial force in a combustion chamber? My ...
5 votes
1 answer
1k views

### How does LOX-lead startup prevent hard starts?

In my experience with hybrid rockets, the igniter is always triggered prior to or concurrent with the oxidizer flow into the chamber (which already has fuel in it, hopefully lit). This is to prevent ...