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5
votes
1answer
174 views

Why does deflating baloon spurting through the air make circular motion? [duplicate]

When you inflate a balloon and then let it go again, it will fly through the air in an unpredictable motion. My kids (1 and 3 year old) love watching this. At some point my oldest asked how it worked ...
-1
votes
0answers
19 views

Laser gun recoil or laser propulsion samples or videos?

Please, provide any videos or article links, depicting experiments of measurement of laser or optical propulsion effect. Not as laser beam pushing something or light pressure experiments, but ...
2
votes
1answer
46 views

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 ...
0
votes
1answer
37 views

Thrust and specific impulse of a rocket

A picture of the question this originates from is given below. Note: I normally work with SI units and am mostly unfamiliar with those used here. The specific impulse of a rocket can be calculated ...
1
vote
1answer
26 views

Prove thrust is double the dynamic pressure across a nozzle

I'm trying to teach myself some of the content from 'Rocket Propulsion Elements' by George P. Sutton. After reading over the first couple of chapters feeling like I understood everything, I came ...
3
votes
3answers
252 views

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 ...
6
votes
2answers
466 views

Why is Xenon favored as the propellant in electric thrusters?

Most of the articles I've read on electric thrusters mention that Xenon is generally, with some exceptions, used as the propellant (or would it be termed reaction mass?). They never mention why ...
1
vote
1answer
73 views

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 ...
6
votes
1answer
321 views

Self-Accelerating wavepackets: What are they and can they impulse a spaceship?

Nature today published a (paywalled) article that mentions 'Self-accelerating Dirac wavepackets'. They claim that they behave in a similar fashion as the diffractive tricks of polarized beams that ...
1
vote
2answers
72 views

Delta-V of ion thrusters

So I recently started a podcast along with a cohost. It's all about spaceflight. We ran into a question we couldn't quite resolve due to conflicting information on the internet. Put simply: Can the ...
0
votes
0answers
40 views

Electrostatic ion thruster neutralizers

All electrostatic Ion thrusters have a neutralizer electron beam, but why are they required? Is avoiding the accumulation of negative charge the only reason? I would've thought that the main reason ...
0
votes
1answer
97 views

Alternative air transportation and magneto-aerodynamics

Firstly, I am not a big fan of UFOs, however, a flying saucer makes me think if is there another, comparatively agile way to travel through the air without jets, turbines or propellers (balloons are ...
2
votes
2answers
122 views

A student of mine wants to build a Gyroscopic Inertial Thruster

I work as a tutor with students in their first three semesters. One of my more eager students is obsessed with this thing: A Gyroscopic Inertial Thruster Here is a Wikipedia Article on that. I was ...
4
votes
1answer
86 views

Why is specific impulse measured in seconds?

Specific impulse is usually defined as: $$I_{sp} = \frac{F_T}{\dot m ~ g_0} $$ This comes out in seconds. I interpret it as follows: If I want $F$ Newtons of thrust, every second I must burn a ...
0
votes
1answer
51 views

Maneuvering a space shuttle using propulsion systems?

A colleague and I randomly started on this subject, and, not being very good at anything science / physics related we were stumped at how this might work. So the question is: If I park my space ship ...
0
votes
1answer
110 views

What's the point of NASA's impossible space engine? Wouldn't a mirror work better?

My understanding (which is very little) is that the point of NASA's recent virtual-particle engine is to convert solar energy into momentum. That's fine, but what's the point? If the spacecraft is ...
14
votes
4answers
957 views

NASA's “Impossible” Space Engine

Recently, there was some news that said that the researchers at NASA have come across some impossible kind of space engine which does not require any fuel. I have read at a few places like here, here ...
2
votes
2answers
65 views

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 ...
3
votes
3answers
1k views

Why does the speed of the propellant limit the speed of a space ship in open space?

Isn't speed a relative thing in space? If so, why would the speed of a propellant matter? Why can't a space ship accelerate infinitely?
4
votes
2answers
73 views

Are Mach Diamonds radially symmetrical?

Videos like this show a form that suggests a radial symmetry in the gas jet. The same is reinforced by schematic illustrations. But other images, like this, look like there is a twisting structure ...
0
votes
1answer
58 views

Launching a unpropelled rocket

I have read about the application of railguns and other ground powered launch, where there is no need to carry any propellant in the rocket. I am wondering, to what velocity should the vehicle ...
1
vote
1answer
114 views

Why won't this reactionless drive idea work (motor with a moving weight in space)

I know people will say it violates many laws of motion and conservation but could anyone explain why it is so? It's NOT a question about free energy. Imagine a motor in space. It has an arm (rod) ...
2
votes
1answer
141 views

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?
1
vote
1answer
62 views

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 ...
1
vote
1answer
121 views

How jet engine works in vacuum

Its not about availability of oxygen for combustion of gases. I want to know since there is no air or friction providing things in vaccum, how the force applied by a jet engine get can make thrust to ...
0
votes
1answer
84 views

Propulsion force [closed]

My physics instructor gave us a general problem A box is sitting motionless on a rough, horizontal patch of ground. You give it a good kick, so that it slides to the right with an initial speed of ...
0
votes
1answer
261 views

Is it true that a Space Shuttle launch is powerful like an “average” nuclear explosion?

Kind of an odd question here. First let's define what an "average" nuclear explosion is, because that's quite a controversial term - "average". Considering that the peak of nuclear tests was at the ...
31
votes
6answers
3k views

Why are rockets so big?

I'm curious why rockets are so big in their size. Since both the gravitational potential one need to overcome in order to put thing into orbit, and the chemical energy burned from the fuel, are ...
1
vote
1answer
88 views

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 ...
1
vote
1answer
82 views

What sort of rocket propulsion would be required to send and retrieve ores from our solar system's asteroid belt, within a 2 year period? [closed]

I am looking for a form of propulsion to achieve a fraction of C that could send and retrieve mining robots to our solar system's asteroid belt. Does this type of propulsion even currently exist?
2
votes
1answer
48 views

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 ...
2
votes
3answers
353 views

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 ...
1
vote
2answers
637 views

Can Outer Space be used for Waste Disposal?

If harmful toxic, nuclear and other wastes are dangerous if improperly disposed on Earth, can't they be launched into space? If a large, tightly bound mass of waste were to be propelled into outer ...
5
votes
0answers
263 views

Mirrors and light beam divergence technology limits

There are many applications for orbital space mirrors in astronomy (better telescopes) and space propulsion (solar power for deep space probes), but this is limited by the minimum beam divergence ...
1
vote
2answers
196 views

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?
7
votes
0answers
405 views

Does positronium have a stable crystalline phase?

This is a long shot, but while the 100YSS conference is going on at Houston, i haven't been able to get a grip on myself and think in other, more mundane and short-term rewards as normal people do. ...
4
votes
1answer
287 views

Could this fountain, under the right conditions, technically be able to lift me up?

There is a big fountain in a lake in my city. I was talking with a friend and we were wondering whether it would be able to lift me up. I sent a few emails and obtained information about the ...
3
votes
0answers
92 views

positronium BEC stability

After reading this article regarding Positronium BEC formation (for lasing purposes), there is a mention in there regarding Ps "up" atoms not annihilating with "down" atoms, the article is pretty ...
4
votes
1answer
80 views

thermodynamics of a dual-face surface in space

This question is a continuation from this one. A material disk have two sides, one that is reflective and another absorptive of electromagnetic radiation in the range where the background cosmic ...
1
vote
2answers
2k views

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 ...
6
votes
2answers
248 views

relativistic spaceship, CMB radiation and thermodynamics

Scenario: a spaceship is travelling at a high fraction of $c$. The interstellar gas and CMB radiation has blueshifted significantly and we are facing a possible melting of the front radiation shield! ...
2
votes
1answer
157 views

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 ...
2
votes
1answer
106 views

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 ...
3
votes
3answers
616 views

Why is an Aircraft Runway NOT like a Teaspoon?

If the aircraft runway were like a teaspoon (by this I mean, flat in the beginning, then curving downwards and finally upwards), would it not work in favor of the propulsion of the aircraft? In spite ...
3
votes
1answer
2k views

Can Ionocrafts be improved by breaking them up into multiple stages?

Ionocraft or "lifters" are lightweight devices that produce thrust by ionizing the air around an electrode, and then accelerating the ions toward another electrode with an electric field, during which ...
0
votes
2answers
718 views

Does “Air caterpillar” exist or even possible?

Air-Elf Aircraft Concept Is Able to Take-off or Land Vertically Air-Elf aircraft concept is to solve road congestion. The core of the concept is a new type of wing, “Air Caterpillar”. It can be ...
3
votes
6answers
5k views

Ion Drive Propulsion Top Speed

I would like to know if there is some formula / graph which would provide / show the efficiency of a certain type of propeller in space. Specifically, I'm interested in the acceleration attainable at ...
6
votes
4answers
445 views

Would a fish in a sealed ball swim normally?

This question led me to wonder whether swimming would be the same experience for a fish in a full, sealed ball as it is normally. If the fish is about 7cm from the walls of the tank, a pressure wave ...