Colloquially referred to as one of the hardest professions, rocket science is actually a common name for spacecraft/space-systems engineering. However, one can also generalize this to include all forms of rocketry, including rockets that are not capable of space travel.

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Why do rocket engines have a throat?

Diagrams of rocket engines like this one, (source) always seem to show a combustion chamber with a throat, followed by a nozzle. Why is there a throat? Wouldn't the thrust be the same if the ...
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1answer
51 views

Relativistic Rocket Fuel Requirements

I am trying to reconcile two different calculations of fuel for a 1g constant acceleration/deceleration trip to Alpha Centauri. One found here ...
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0answers
32 views

Calculating rocket thrust [on hold]

for my recent project I'm trying to compute somewhat accurate rocket physics (although approximations are good enough - for example for aerodynamics). The project is about making "game-like" ...
32
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7answers
5k views

Supergun Launching of Satellites

I should say first that I don't believe this is a feasible launch method, otherwise NASA and other space agencies would be using it by now. It's based on this BBC news story Saddam Hussein's Supergun ...
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Vacuum chamber in a space rocket? [on hold]

FYI I am a complete noob in the field of rocket design. Question: Why don't space rockets that take off vertically from the ground have a vacuum chamber in the rocket during takeoff? Also, is the ...
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692 views

Rocket launch from a mountain

If we were to build a high speed rail up the side of a mountain like in some Science Fiction movies, what is the velocity needed at the point of leaving the mountain excluding angular momentum from ...
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19 views

How much pascals is needed to lift a human? [closed]

I wanna ask you that how much psi is required to lift a man 1000 metres up in the sky of weight 'bout 100 kgs??? I'm not much good at physics
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Speed of an object in air versus in vacuum

Okay, imagine that you are shooting a rocket down a tunnel that is 60 miles long and the rocket is travelling at 60mph, so the rocket should reach the end of the tunnel in a hour, right? Yep, in an ...
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2answers
62 views

Magnetism In Space

I am not an expert when it comes to physics. I was looking at maglev technology the other day and a thought crossed my mind. Would similar systems work for deep space exploration. I understand ...
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1answer
28 views

How is a rocket mounted w.r.t. gimbal?

Gimbal system is used to balance the rocket from tripping after its launch. But, how is a rocket mounted with respect to the gimbal system?
3
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1answer
61 views

2 times the velocity, 4 times the energy, 8 times the heat

In SpaceX's webcast today they talked about the first stage getting back to Earth with twice the velocity as usual. I quote: "So 4 times as much energy means harder on the stage, and 8 times as much ...
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13 views

What wavelengths of electromagnetic radiation are emitted by the LH2/LOX reaction?

Rocket engines such as the Rocketdyne Rocket System 68 and the Space Shuttle Main Engine use liquid hydrogen and liquid oxygen as propellants. The exhaust from this type of engine is notable in ...
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31 views

Can an accelerometer be used to determine orientation of a rocket under power?

I saw a project on Hackaday featuring a model rocket with moveable fins to stabilize the rocket's trajectory: Hackaday. The goal was to arc the rocket to a horizontal trajectory and keep it there. In ...
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2answers
58 views

Can AMO physics be applicable for space travel? [closed]

I know it sounds very stupid question. I am a Ph.D student currently working on the AMO physics (Quantum Optics). I recently saw articles about the Spacex, and I thought it is really amazing, and ...
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1answer
36 views

Question about Thrust; am I correct?

Basically, here's what I understand about Thrust: Thrust is a force. You get it by doing $v\times\frac{dM}{dT}$. Pretty basic, because that's the formula you're given. However, because I'm trying to ...
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3answers
2k views

Application of Newton's third law

By newton's third law , we know that every action has an equal and opposite reaction .We move left when we push slightly on the right and move forward as we push backward. But how do rockets, ...
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2answers
68 views

How does rocket thrust work?

I can't seem to find a specific answer to this anywhere. I understand that in a rocket there is a chemical reaction that causes gas particles to leave the rocket at high velocity. By Newton's third ...
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1answer
300 views

What is the optimal burn direction to lower periapsis of hyperbolic orbit?

I am an engineering student who is interested in orbital mechanics. I am doing some self study before taking some orbital mechanics courses next year. I was learning about various orbit types ...
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1answer
47 views

Force of Gravity of a stationary object acting on another object moving through space

Story: I have x and y positions of a spaceship as it moves through space to some goal location at [1000, 700]. A record of its movement is given by: ...
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2answers
23 views

Model velocity as function of distance in object subject to drag and propulsion

Given an initial speed $v_0$ and acceleration $\frac{dv}{dt}|_0=a_0$, I need to find velocity as a function of distance knowing that Drag is $ D = Av² $ Propulsion is $P = Bv + C$ I already found ...
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Maximum speed of a rocket with a potential of relativistic speeds

Ultimately, the factor limiting the maximum speed of a rocket is: the amount of fuel it carries the speed of ejection of the gases the mass of the rocket the length of the rocket ...
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3answers
142 views

Why can't space become fuel for spaceships? [closed]

I read somewhere that space is constitued mostly of hydrogen. So why can't space and its constituants (not only hydrogen) serve as fuel for future spaceships? The dreamer I am simply imagine a ...
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0answers
30 views

Rocket launch from equator

I am trying to simulate a rocket launch from the equator. I know that the earth's rotation around its axis will give the rocket an initial speed of $466$ m/s in the x axis. How much speed will the ...
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0answers
42 views

Velocity of rocket as a function depended of time and emitted gas?

First of all I'd like to say sorry if this question may seem be written weird in English. I got the original question in German and I have not the required vocabulary to translate it 100% correctly. ...
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1answer
96 views

Rocket equation derivation mistake by my professor

In one of my lectures our physics professor gave a derivation of the ideal rocket equation as follows: Let $v_G > 0$ be the velocity at which the gas is emitted from the rocket. Let $m$ and $v$ be ...
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6answers
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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 ...
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1answer
88 views

Fallacious derivation of the rocket equation

Consider a rocket in free space of initial mass (including fuel) of $m_0$ using up/ejecting fuel at a constant rate $r$ (mass per time). That means that at time $t$ the rocket has mass $m=m_0-rt$. The ...
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47 views

Motion in space

Does a space shuttle travelling in space experience any resistance to its motion? If a body in space is applied constant force, does it attain speed of light after sufficient time?
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How does constant thrust avoid quadratic kinetic energy accumulation?

I haven't found the right search terms for this question, so if it has been answered, references would be welcome. Suppose we start from experimental station in deep space (interstellar space if need ...
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54 views

Solving propulsion force of water rocket

As a note, I am not a physics student, although I am familiar with many physics concepts and calculations. I am trying to calculate the force of the thrust of a water rocket. I started with the ...
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0answers
19 views

Air Powered Vs. Water Powered Rockets [duplicate]

I was looking online to find a comparison between purely air powered rockets, and water/air powered rockets, but could not find any. To clarify, a "water rocket" is filled partially with water and ...
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1answer
30 views

How much force would an explosive decompression really provide?

In science fiction, explosive decompression is occasionally used to slow down or provide a nudge for very large spacecraft (for instance, recently in the 2015 movie The Martian, and in this old Star ...
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58 views

If humanity was to send a probe to Proxima Centauri, how long would the travel last?

If humanity was to send a probe to the nearest star: Proxima Centauri, at a distance of 4.24 light years from our sun, what would be the optimal propulsion technology to reach the destination as soon ...
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50 views

Finding the distance a spaceship would travel given a time of departure and velocity

Let's say a spaceship leaves Earth at a day t and with velocity v. Is there a way to know how many kilometers it will cover to arrive on Mars? This would be a trivial question were it not by the fact ...
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1answer
111 views

My theory to travel near the speed of light. Why will this theory not work? [closed]

Why can't a spacecraft travel near the speed of light? Here's my theory. We assemble the spacecraft in the Earth's orbit just like the International Space Station, each time, equipping it with lots ...
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1answer
61 views

Optimal time for satellite rocket launch considering moon gravity [closed]

As per this The Gravitational Force of the Earth and Moon on Each Other Moon is pulling us with a force equal to 1/300,000th of our weight. I have read this Is the fuel burn for a satellite launch ...
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2answers
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Can the technology behind Particle accelerators can be used for space propulsion?

As I understand, the kinetic energy of the proton beam in a hadron collider is quite large. Can you build a space propulsion system that is based on accelerating a proton bean to relativistic speeds ...
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2answers
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Why don't rockets tip over when they launch?

Rockets separate from the launch pad and supporting structures very early in flight. It seems like they should tip over once that happens. Why don't they tip over ? Is it due to a well designed ...
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1answer
44 views

Aircraft Thrust to weight ratio contradiction with energy conservation

Usually, airliners have (Thrust/Weight) T/W ratio in the range of 0.2 to 0.8 and for steady flight W = lift My question is, for example, that Antonov 225 has Thrust/weight: 0.234 for max takeoff ...
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1answer
119 views

What will I see if I travelled to a distant planet in 100 times faster than speed of light and look back? [closed]

Consider this scenario. I enter a space ship at 10:00 AM, it starts to move at a speed 100 times faster than light, I travel for 55 mins. And then slow down to very much less than speed of light and ...
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1answer
73 views

rocket vertical landing [closed]

SpaceX has published a couple of videos that show one of their heavy-lift rockets landing vertically in a highly specific location. How is it possible that they are able to control so many ...
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2answers
122 views

Violation of the Newton's first law of motion in the movement of spacecrafts in the vacuum of space [closed]

Suppose a rocket at rest in space where there is a complete vacuum and no force to influence the rocket: In the left we have the rocket with a metal ball in it. After the ball is thrown out of the ...
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2answers
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Can outgassing produce a significant thrust on a space ship?

There are a variety of materials that outgas in the atmosphere, and I imagine they would do so even more in the vacuum of space. I imagine an object in space would experience a small force as ...
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81 views

Saturn V horizontally attached to Earth

If the Saturn V rocket were attached to the ground facing in the opposite direction of the Earth's spin, would it in anyway slow the Earth's spin on its axis? How significant of an impact would it ...
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189 views

At What Point Does Mass Cease to Matter?

I know very little about physics so I naturally have a lot of simple minded questions. Assuming I am piloting a rocket and want to obtain the fastest speed possible. At what point does mass more ...
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1answer
84 views

How to calculate the thrust of a rocket with relativistic exhaust

The general thrust equation is $F = \frac{dm}{dt}\cdot v$, where $m$ is propellant's mass and $v$ is the exhaust velocity, is the equation right? What if the propellant is highly relativistic? One ...
29
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2answers
14k views

What is the possibility of a railgun assisted orbital launch?

Basic facts: The world's deepest mine is 2.4 miles deep. Railguns can acheive a muzzle velocity of a projectile on the order of 7.5 km/s. The Earth's escape velocity is 11.2 km/s. It seems to me ...
2
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1answer
104 views

Understanding rocket equations [closed]

I'm doing a science project where I have to explain the physics behind a trip to an exoplanet and I also have to explain about rocket equations while doing so. I know that a trip to an exoplanet is ...
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1answer
100 views

Conservation of energy during the flight of a fire cracker [closed]

We say that energy is neither created or destroyed. It can only be transformed. I hope this principle is applied in the flight of a fire cracker. The chemical energy is converted into physical energy ...
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Explain this contradiction of violation of “ energy conservation ” using classical mechanics

Consider a rocket moves upward with some acceleration for a very small time say '$dt$' then the kinetic energy increases (for acceleration). as well as as the potential energy increases (due to height ...