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Questions tagged [propulsion]

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

-2
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1answer
216 views

Could electric fans lift a rocket? [closed]

An electric turbine engine used in planes have nowhere near the thrust needed to lift a rocket anywhere. What if the amount of electricity needed to lift a interplanetary rocket delivery system and ...
10
votes
1answer
148 views

When regenerative cooling is used, how is the nonuniform radius of the combustion chamber handled?

As the combustion chamber necks down and flares out, the 1-D cross section past which which fuel must pass as it cools the wall of the chamber will change. If there are lots of tubes, they will bunch ...
3
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0answers
66 views

How is supersonic rocket exhaust able to match sea-level pressures?

I understand that the diverging portion of a rocket nozzle speeds up the flow and also expands it, in order to best match ambient pressure outside. However, doesn't higher speed flow lower the ...
2
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2answers
238 views

Which propelling device would be the most efficient for a space elevator?

There are many types of propulsion from electric turbine engines to steam powered catapults once used on aircraft carriers. Which of the many types of propulsion would be the most efficient in getting ...
65
votes
17answers
19k views

Why is using a space elevator cheaper than rocket power?

Why is rocket power so much less efficient? In both cases you want to lift a given weight a certain height. What does climbing a tether give you that you don't have when using rockets? Wouldn't a ...
7
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2answers
123 views

Is there an absolute limit to single stage ∆V when tank mass is a fixed faction of propellant mass?

Many space exploration fans are familiar with the rocket equation [https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation] $$\Delta V = V_{e} \times ln\frac{M_0}{M_F}$$ where $V_e$ is the exhaust ...
3
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0answers
79 views

Could a laser ablation-based propulsion system really accelerate an object to 0.001 c?

Comments below this answer suggests that a laser ablation-based propulsion system, where the laser is separate from the object to be accelerated, could accelerate an object to about 1/1000 of the ...
4
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1answer
86 views

Hows does “Glenn Research Center's sapphire refractive secondary concentrator” work?

Clicking through NASA.spinoff.gov I came to the page for spinnoff 2001 Glenn Research Center and found this: Glenn Research Center's sapphire refractive secondary concentrator will be used with ...
2
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0answers
89 views

Would a flat superconductor create surface area to increase its diamagnetic field uni or bilaterally to propel in space? [closed]

Instead of using a standard solar sail material could the sail be built of diamagnetic material and sail faster? Is there a way to make a thin flat sail that both uses the dimagnetic properties of a ...
3
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3answers
99 views

Is there a practical size limit above-which a solar sail would stop increasing your acceleration?

Is there a point where the larger solar sail would not add more thrust? What is the most thrust a solar sail can produce? Can a solar sail be added to an ion engine and work better?
4
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1answer
107 views

Which of the orientation is preferred for static fire testing of a liquid rocket engine - vertical or horizontal?

Liquid rocket engine's hot fire testings are performed both vertically and horizontally. Vertical orientation - Falcon heavy, Falcon 9, Rutherford engine, UCSD Engine test from 2014 , Merlin 1D, ...
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0answers
55 views

Is there a use case describing the need to perform xenon propellant offloading?

I can understand hydrazine offloading and the hazards associated, but I'm wondering if there is such a need for xenon offloading.
5
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1answer
210 views

Which is the preferred mode of liquid rocket engine cutoff - fuel lean cutoff or fuel rich cutoff?

When a bi-propellant liquid rocket engine receives a command to shut down, will the fuel gets cut off first and then the oxidiser - a fuel lean cutoff? Will the oxidiser gets cut off first and then ...
1
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0answers
64 views

Transportation on the Mars I Air

Due to the thin atmosphere generating lift on Mars is difficult at a lower speed, Flying is hard until aircraft go supersonic and then it becomes difficult to control(Ref.). The landing would not be ...
2
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0answers
66 views

Optimal Thruster Layout For Cubesat

I am working on a simulation of a Cubesat for rendezvous. Using the Clohessy-Wiltshire equations I calculate delta-v. Now that I know the thrust needed for operation, I would like to know how to ...
4
votes
1answer
244 views

Is this description of the “dipole drive” and how it would work physically correct?

Comments in chat have noted the recent post in the Centauri Dreams blog titled The Dipole Drive: A New Concept for Space Propulsion. In contrast to the single positively charged screen employed by ...
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1answer
136 views

What kind of security while using solid propellent? [closed]

I'am going to to make a propulsion test with sugar and $\mathrm{KNO}_3$ (with large quantities). What should I wear before to protect myself?
0
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1answer
165 views

Could a spacecraft be propelled by the deflection of a very high number of charged particles?

I am wondering if a spacecraft could be propelled through interplanetary space via the deflection and/or displacement of a very high number of charged particles contained within the Sun's solar wind. ...
7
votes
1answer
230 views

STS: How much thrust did the nominal post-MECO LOX dump produce?

Following up to some questions asked in comments to the answer to this question: With pressure-fed engines, is any measurable thrust generated by venting the pressurant out the engine bell after ...
0
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1answer
83 views

Could the interaction of the Sun’s solar wind and trapped plasma ions be used to propel a rocket through interplanetary space?

I have recently had a renewed interest in comets and how comet tails are formed. From studying this process, a thought occurred to me that perhaps plasma ions can be created within a long hollow ...
2
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0answers
50 views

thrusters, force torque, distribution matrix , orbit maneuver

I have a few questions about computing torques and forces. I use the same configuration as in the thesis titled An Attitude Control Sysytem Design Based on the Turksat-1b Geostationary Satellite. ...
20
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4answers
3k views

Why does the Falcon 9 use RP-1/LOx and not LH2/LOx?

Why does SpaceX use RP-1 in the first and second stages of their rockets? In my view at least the second stage could use hydrogen as it currently is not being reused. I am aware that you have higher ...
2
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1answer
62 views

Rocket engine power vs. Sound

Is there any relationship between the sound emitted from a rocket engine and the amount of thrust it gets at surface temperature and pressure?
5
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0answers
93 views

What is the droplet size that is desirable for pintle injectors?

The pintle injectors tend to generate droplets after impingement of the fuel and the oxidiser stream and I understand that the droplets will be premixed. In such a case, even a larger premixed ...
5
votes
2answers
251 views

Exhaust products of hypergolic propellants

On videos of Soyuz docking to ISS we can see exhaust from the control engines (if background is dark enough). For example here Soyuz TMA-19M docked to ISS at ...
3
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1answer
148 views

What is the speed that we can reach using tsar bomba as a propellant?

The idea of using an atomic bomb as a propellant was introduced in project orion, but it did not work out because of the interdiction of using the atomic bombs. So I decided to calculate the speed ...
5
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0answers
385 views

Potential improvement to BFR or New Glenn if equipped with aerospike exhaust on their engines?

Aerospikes basically tackle the issue of the variability in required expansion ratio for a rocket engine to be efficient at a given altitude. A recent example though mired in legal issues is a small ...
6
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2answers
566 views

What ion engine is used by Hayabusa2?

Hayabusa2 is on its final approach to asteroid 162173 Ryugu, expected to arrive in July 2018. Like its predecessor, Hayabusa2 uses an ion thruster for deep-space propulsion, but I can't find any ...
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1answer
174 views

Can we hit speed of light using Antimatter?

if we use Antimatter as method of propulsion is it possible to reach speed of light ?
7
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1answer
127 views

Nozzle material of Apollo Lunar Module ascent engine?

There are some photos of the Apollo Lunar Module ascent engine, see 1, 2, 3. The nozzle looks like being made of epoxy and fiberglass. The fibers are wound in two different directions. Is it true ...
3
votes
1answer
126 views

Roughly how long will the SABRE engine need to switch from air-breathing to closed-cycle?

The SABRE engine is designed to be used on a single-stage-to-orbit type of spaceplane. What sort of delay might occur between shutting down the air-breathing operation and switching to a closed-cycle ...
4
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5answers
430 views

Can we thrust a rocket from earth using electric power?

I wanted to know if we can thrust a rocket from earth using electric power? If yes, how and has anyone tried to do that?
7
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2answers
1k views

“Magic Space Unicorns” disproven? Any technical write-ups of the explanation of Em-Drive results presented at Space Propulsion 2018?

@Antzi's answer links to the recent Ars Technica article NASA’s EM-drive is a magnetic WTF-thruster; Test reveals that the magic space unicorns pushing the EM-drive are magnetic fields.. According to ...
13
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5answers
967 views

If LOX/LH2 were used in a fuel cell powering an ion engine could it provide a greater delta-v than with a conventional engine?

Question: If LOX/LH2 were used in a fuel cell powering an ion engine could it provide a greater delta-v than with a conventional engine? Conditions: Start in space in a stable heliocentric orbit (no ...
1
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3answers
120 views

Can you avoid thermodynamic inefficiencies in space propulsion?

In @David Hammen's answer to this question, he highlights the discrepancy between the exhaust velocity that would be achieved by converting all the chemical energy of the fuel into KE of the exhaust (...
16
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3answers
2k views

What limits the speed at which rocket fuel is expelled?

Rocket propulsion is based on Newton's laws. The faster propellant is expelled, the faster the rocket is accelerated. At what speed is propellant expelled in a normal rocket? What are the factors ...
3
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1answer
161 views

Cosmic rays can be new energy source [closed]

Space is filled with cosmic rays that are high-energy particles. If we could convert that energy into electric (or any other) energy, then we could use it to power a rocket anywhere in the universe. ...
8
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4answers
165 views

In ion engines, how is energy removed from the electric field that is used to accelerate the particles?

A basic ion engine uses a positively charged plate and passes positively charged ions over it to accelerate them. How does the charged plate draw current to accelerate the ions? It seems that a ...
0
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0answers
48 views

American Railgun and rocket [duplicate]

So I've seen the railgun before, and it suddenly come up in my mind: can we accelerate a space shuttle/rocket to a high speed,before turning on the engines?Will it save fuel of destroy electronics?
4
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2answers
403 views

How does the Sabre engine's pre-cooler achieve such high performance?

The BBC News article Rolls-Royce and Boeing invest in UK space engine about Reaction Engines Limited (REL) and its Sabre engine states REL is developing what it calls the Sabre engine. This power ...
1
vote
1answer
109 views

What is the cost of the propulsion system and thrusters as a % of the total satellite?

Small (nano) satellites and cubesats are between \$100k and \$500k. What percentage of the total is the cost of the propulsion system?
2
votes
1answer
55 views

How to calculate mass of fuel for Venus Orbiter

I'm working on a hypothetical constellation of orbiters at Venus for a school project, and I am currently trying to figure out how much fuel I need in the transfer stage. I have already calculated ...
3
votes
1answer
374 views

Ion Thruster Thrust Calculation Problem

Trying to calculate the impulse of a little ion thruster I'm putting together. An old version of it can be found here, I'll be polarizing the AC current and putting in copper nails on the next ...
2
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0answers
42 views

Attitude and orbit thrusters catalog

Typically, when trying to adjust simulation parameters (of orbit control, attitude control...) to real world values in order to validate algorithms with comparisons with past and current mission ...
5
votes
1answer
170 views

Cost Estimation of Satellite propulsion systems

As part of my research project, i am evaluating various satellite propulsion systems. Are there any databases or forums where the ROM cost of a Satellite propulsion system is listed. A few new space ...
6
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0answers
143 views

Trade-offs in developing larger engines vs using more smaller engines

Looking to explore the inverse point of this question: What challenges are there for more, smaller liquid fuel engines instead of one large? As stated in the answer to the above question, fewer, ...
6
votes
2answers
484 views

Troubleshooting a DIY Ion Thruster

Been following a Make-Magazine article on how to make your own ion thruster: https://makezine.com/projects/ionic-thruster/ Went through the tutorial step by step, not seeming to get any thrust out of ...
3
votes
1answer
93 views

How can an electric sail be used for deorbiting considering that it doesn't work inside the magnetosphere?

An electric sail harnesses the solar wind for propulsion. Inside the magnetosphere of Earth, the solar wind does not reach. Yet the Aalto-1 satellite intends to deorbit using an electric sail. How ...
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1answer
100 views

Could affixed variable spaced magnets propel a spacecraft? [closed]

What if the craft itself had a magnet at the rear, with an equally sized magnet that you could either bring towards the craft to propel forward ....or controlling it away from the ships magnet to ...
0
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0answers
64 views

Can an ion drive attached to an asteroid move it into another orbit if given enough power?

After watching one of the videos from Curious Droid on Youtube talking about asteroid deflection and strikes I had an idea. Ion thrusters provide bits of mass velocities at the needed Isp (5-6 km/s ...