Questions tagged [propulsion]
The propulsion tag has no usage guidance.
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Rocket's momentum
It is well known that to give a liftoff a rocket, we use the momentum principle: The momentum of the gases emitted by a rocket and the rocket's momentum is equal to zero. So why is it not enough to ...
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How does the solar sailing concept work?
Wikipedia describes solar sailing as
a form of spacecraft propulsion using a combination of light and high speed ejected gasses from a star to push large ultra-thin mirrors to high speeds.
I ...
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Relativistic beamed photon propulsion
I am analysing the flight profiles possible with a lightsail powered by a photon beam, up into the relativistic regime. In an inertial frame, the sail acceleration is $A$. The onboard acceleration ...
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Regarding Speed of launched rocket inside the atmosphere
I am a 15 yr old, so please forgive my mistakes as I have not entirely read rocket mechanics.
I have been wondering why rockets accelerate to mind-boggling speeds, (mach7-8 or even more)when that must ...
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If explosive propellants are not used for rail guns, why does this image of a railgun being fired show fire?
The wikipedia article for railguns clearly states
The absence of explosive propellants or warheads to store and handle, as well as the low cost of projectiles compared to conventional weaponry come ...
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Unclear negative sign in rocket propulsion equation
The usual proof of Rocket propulsion goes something like this (University of Central Florida, Rocket propulsion)
$mv = (m-dm_g)(v+dv) + dm_g(v-v_{rel})$
where:
m - initial weight of rocket
v - ...
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Is the well known textbook-formula for net-thrust oversimplified or do I have a misinterpretation?
In order to understand how Jet-Engines works I came across the "famous" formula for net-thrust:
https://en.wikipedia.org/wiki/Turbojet#Net_thrust
$F_{thrust} = Q_{out} \cdot v_{out} - Q_{in}\...
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Model Rocket Stabilisation
I am designing a model rocket and am using 3 B6-4 Engines. Inevitably there will be perturbation of its trajectory by wind and engine/thrust inconsistencies. The way that I currently understand the ...
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Propulsion force on a laser pointer?
How to calculate propulsion force on a laser pointer in reaction to the emitted light power in watts?
Should I just divide power by speed of light? Since power is energy per unit of time, hence ...
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Are bacterial flagella the most efficient propulsion system at the microscopic scale?
Bacterial flagella can be regarded as microscopic propellers. The rotor is a long, helical protein filament powered by proton gradient. When protons pass through the gap between the rotor and stator, ...
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How can thrust be generated in space which is a vacuum?
Since thrusters have no matter to push off of, how can a spacecraft generate thrust in the vacuum of space?
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Can methane be used as a fuel to launch space vehicles?
Methane is apparently the most easily available hydrocarbon. It is also a flammable, and highly combustible fuel; does burning methane provide sufficient power-weight to be used to launch artificial ...
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Why does a rocket engine that produces a constant thrust over a set period of time have less energy if it has more mass? (Zero-$g$) [closed]
A rocket engine with the thrust of 1N working for 10 seconds will add more kinetic energy to the rocket if it is attached to a 10kg rocket and less if it is attached to a 20kg rocket. The rocket ...
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Why flapping rudder produce net thrust if one half-stroke produce thrust and second half-stroke drag?
In small sailing boat like optimist is well know technique when there is no wind, rudder pupming which push boat forward.You just need push-pull rudder stick left to right with fast movement.
Rudder ...
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Difference between deltaV and specific impulse
When reading any literature regarding space propulsion, I keep getting about these terms deltaV and ISP or specific impulse. I know specific impulse is supposed to be the velocity the propellant mass ...
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Theoretical rocket engine based on plasma shock waves particle acceleration
Credits for the article - https://www.quantamagazine.org/cosmic-map-of-ultrahigh-energy-particles-points-to-long-hidden-treasures-20210427
Can this mechanism be used to speed up gas particles to ...
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On two requirements in order for an equation describing the propulsion of a rocket to hold
A rocket moving with a velocity $v$ releases a mass $\Delta m$ (fuel exhaustion) at a speed $v_{0}$ in a time interval $t$ and $t+\Delta t$, and increases its velocity by $\Delta v$.
If we apply ...
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Would deuterium or tritium be a better rocket fuel? [closed]
Im not that scientifically literate but through my basics as hell understanding of chemistry is that denser=better wouldn't the denser forms of hydrogen be better for fuel since they would weigh ...
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Does a rocket engine apply more power as the rocket's speed increases? [duplicate]
To clarify my level of knowledge, I'm a high school student all the way through AP Physics C: Mechanics.
So, let's imagine that there is a rocket travelling through the vacuum of space (ignoring ...
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Could the dynamic Casimir effect be used for propulsion without propellant?
The dynamic Casimir effect has been demonstrated experimentally by Professor Wilson from Chalmers University in Sweden. Instead of moving mirrors at relativistic speeds, Professor Wilson circumvented ...
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Exploit a planetary magnetic field in orbit to alter orbit
Suppose we have a device with solar cells, an accumulator, a hardware/software system and a coil (the position of which can be altered in all 3 axes) that can use collected electricity to produce an ...
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Are all methods of propulsion based on the same principle?
I am struggling with coming up with a way to differentiate between propulsion on the most basic level.
Are all methods of propulsion based on throwing stuff in the opposite direction? Can the be no ...
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What are the theoretical limits of ion propulsion? [closed]
What is the theoretical limit in terms of thrust and energy efficiency a ion thruster can have?
Will they ever be able to lift humans on earth? If so, what would the minimum required conditions to do ...
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Deriving the Tsiolkovsky Rocket Equation using the rate at which the fuel burns
I'm trying to understand the derivation of the Tsiolkovsky Rocket Equation.
$$\Delta v= \int_{t_0}^{t_1} \dfrac{|T|}{m_0 - t\Delta m}dt$$
The Wikipedia page ...
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Derivation of the expression of a propeller pitch distance
The pitch distance of a propeller is given by:
$$p = 2\pi r \tan{\beta}$$
where $\beta$ is the pitch angle and $r$ is the radius.
I cannot find how this expression was derived.
Could you please ...
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Rocket fuel consumption
Consider a velocity change $dV$ for a rocket accelerated by an on-board thruster. Is the total amount of fuel consumed proportional to $dV$, or to $dE$, where $dE$ is the change in kinetic energy, or ...
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Propulsion system
Can a propulsion system be made by facing two air ionizers towards each other, accelerating the ions with fans, and having them repel each other? Would the force generated be greater than just ...
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How can I caculate the time to traverse a distance with the Tsiolkovsky equation?
Using the Tsiolkovsky equation I know what the change in velocity is after burning x amount of fuel.
$$
\Delta V = V_e \dot\ log(\frac{m_1}{m_1-m_2})
$$
$m_1$ is my starting mass and $m_2$ is the ...
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What parameters determine the acceleration a spacecraft can acquire using the gravity of a celestial body?
Contemporary spacecraft frequently rely upon gravity to accelerate/decelerate.
Given a spacecraft already in space - What factors determine the acceleration it can acquire from the gravity of another ...
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What percentage of a rocket fuel is used to lift fuel itself?
I don't need an exact number, also it can be to travel to the ISS or the moon, it's not important. I just want to get an idea of how much fuel is used in a «recursive» sort of way.
Edit: I am asking ...
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Can hydrogen plasma react with oxygen?
What if you put hydrogen in a vacuum and turned it into a plasma? There is no oxygen in the vacuum, but once you eject the plasma would it react drastically with the oxygen?
Would it explode?
Would ...
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Orbital Hyperloop for Approach to $c$?
We have a bunch of "orbital catapult" ideas to get things into orbit - most involve some sort of loop with mag levitation in vacuum. There is a practical limit on the top speed here due to whatever is ...
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A conceptual propulsion device based on instantaneous energy transfer of relativistic mass
Setup
Consider two objects $O_1$ and $O_2$ of mass $m$ each. The objects are connected one to another with a rod of say length $2\cdot l$. At the middle of the rod, $M$, there is a rotational joint ...
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Would an Electron Gun create thrust in space?
Using solar panels, and the resulting electrical energy, could an electron gun provide a suitable level of renewable thrust, better than an Ion thruster? If it would even create thrust at all that is.
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How does an ElectroDynamic Tether (EDT) clear space debris?
Earlier today (9 December 2016), the Japan Aerospace Exploration Agency (JAXA) launched their Kounotori Integrated Tether Experiments (KITE) into orbit. What I understand from the description is that ...
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Spacecraft acceleration and relativity
I have a question regarding the acceleration of a spacecraft.
A spacecraft travels at 0.20c relative to Earth and uses exactly half of its fuel to accelerate to 0.25c. Will it be able to accelerate ...
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Dyson air blade principle as a propulsion system for an autonomous underwater vehicle?
Any thoughts on applying this principle to an AUV (autonomous underwater vehicle) ?
if the power source is a battery, would its efficiency be beneficial to that of a propulsion system?
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Standing sound wave tube
If there was a standing sound wave tube and a flammable gas was introduced then ignited, would the combustion be more forceful and more efficient since its following a standing wave, than just a gas ...
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Fluid Virtual Mass
In this paper of Lighthill, the author studies the motion of a fish in a constant flow field $U$, modelling the movement of the fish as a deforming, rotationally symmetric, rigid surface in an ...
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How far from a spacecraft would it's exhaust cool to BR temperatures?
Just a thought that came to mind ...
The rockets on interplanetary scouts fire to impart motive/braking force to the craft. This force, I understand, is simply a reaction engine - the exhaust ...
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Wouldn't a black-hole starship quickly lose its black hole?
There seem to be somewhat serious proposals to propel a starship using a black hole (after all it has its own Wikipedia page!). The idea is to use the Hawking radiation from a small black hole and a ...
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Why cant there be a sonic velocity inside the convergent part of a nozzle? (ie upstream of the throat)
A convergent-divergent nozzle is typically used for accelerating or decelerating airflow to or from supersonic speeds. The typical configuration for such a nozzle is the de Laval nozzle that is ...
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What does the Lorentz force depends on? Is it the current or the voltage in case of Magnetohydrodynamic Propulsion?
I recently came across a paper named "Magnetohydrodynamic Propulsion for the Classroom" by Gabriel I. Font and Scott C. Dudley. In that they explain about an experiment in which they try to ...
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NASA's "Impossible" Space Engine, Take Two [closed]
This question seems to be a close parallel of this one, but it's about a different design by a different author.
I read a news article about a "helical engine" design by NASA engineer David Burns. ...
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How efficient is rocket engine clustering?
So I watched a video where a guy built his own rocket from scratch. I noticed he used some F15-0 rocket engines* to get this thing as high as 300m (he's built other rockets too, where he used the same ...
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Is a "cathode ray drive" feasible?
When I saw the headline, Fuel Free Spacecrafts Using Graphene, I thought it was another reactionless drive, but it turned out to be a bit more plausible :)
Original paper here. Long story short, ...
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If fuel was provided by an autonomous side ship, how much fuel would be required for a 10 metric tons rocket to reach the ISS?
The point here is that the rocket weight should never include fuel. It can take off from any departure base of your choice. The fuel provided by the side ship would then be used only to lift the ...
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Space Rocket Ionizing Its Path To Decrease Fuel Consumption [closed]
A beam(maybe multiple beams from ground crossing at, or just some very high alternating potential, something like focused haarp) on tip of rocket targeting at path of it, ionizing just the closest ...
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Why the path of a balloon left untied is unpredictable but of a rocket is predictable? [duplicate]
When a water rocket is projected, it goes in a specific trajectory.
But when a balloon is inflated and left untied, it does not follow a definite path. It goes in a random way.
I do not see any ...
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Why is accelerating more air slower more efficient than less air faster?
According to this answer on Aviation Stack Exchange, when propelling an airplane it is more efficient to accelerate a bigger amount of air a little than to accelerate a small amount of air a lot. Why ...