The tag has no wiki summary.

learn more… | top users | synonyms

1
vote
1answer
35 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
48 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
33 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 ...
0
votes
1answer
35 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
46 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
90 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 ...
21
votes
6answers
2k 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
0answers
54 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
61 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
45 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 ...
1
vote
3answers
242 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
332 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
237 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 ...
0
votes
2answers
142 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?
5
votes
0answers
313 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
164 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
85 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
71 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
1k 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
201 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
132 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
91 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
281 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
945 views

Can Ionocrafts be improved by breaking it 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
539 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
4answers
4k 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
439 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 ...