Questions tagged [rocket-science]

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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In the rocket equation, does lowering the acceleration due to gravity increase decrease exhaust velocity?

I'm doing work for an intro space flight class, and I have to calculate the amount of fuel I need to get sizable a space craft, around 200 thousand kg in dry mass, into a transfer orbit from the ...
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Can a radially launched projectile orbit a planet?

Imagine a spherical planet with no atmosphere. A ball is launched radially with a velocity $v$, maintaining $\frac{v_e}{\sqrt2}<v<v_e $ and there is no other objects in the universe (Ideal two ...
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What is mercury-like liquid on 2nd stage SpaceX engine [closed]

I was watching this: https://m.youtube.com/watch?v=UM8CDDAmp98 At around 22:33 It showed one side of the engine with what looked like some sort of liquid running on it. The liquid was at the top of ...
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Equation of Forces for Rocket - The Rocket Equation and Newton's Third Law

Assume a rocket is being vertically accelerated in a homogeneous gravitational field. In the reference frame of the rocket, the burnt fuel is being exhausted downwards with a velocity of $\Delta u$. ...
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Throwing darts in a rocket ship

Far from major gravitational sources... A man is standing throwing darts at a dartboard in a rocket ship. The thrust is upwards so he feels almost like he would on Earth but the G-force is slightly ...
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What can “action” mean in “All the action takes place inside the rocket”?

This answer to "How fast is fuel escaping a rocket for it to reach escape velocity 11km/s?" includes the following: From Rocket and Spacecraft Propulsion: Principles, Practice and New ...
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Relationship between payload weight to the range of a ballistic missile

is it possible to talk about how much extra range a ballistic missile gets if its warhead were to shrink by say 10x?? that is without knowing other details about the missile. For example: Iran claims ...
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How can I simulate a path for my model rocket?

I made a model rocket. Specifications: Total weight - 1.635 N (wet). It has a custom solid rocket motor with black powder producing 5 N for 15 sec. So how can I calculate how high will it travel? Some ...
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Deriving Tsiolkovsky Rocket Equation using Conservation of Momentum

I recently tried to derive the rocket equation using conservation of momentum, and did not get very far; was wondering what I am missing. Here's my attempt: Let's say that over some small time $dt$, ...
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Is this why a satellite ejects mass (decreasing its mass) into space so that its orbital radius decreases?

I was doing a Physics question and the question was: How does a satellite reduce their orbital radius. The answer was by ejecting mass (thus decreasing the mass) but it didn't explain more. This is my ...
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Relationship Between Specific Impulse and Expansion Ratio Equation

I am trying to find an equation with both Specific Impulse and Expansion Ratio (throat area is constant with exit area changing) of a rocket. This assumes the following constants (all of which I know):...
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Can we Predict the Trajectory of a hypersonic missile?

I read in a newspaper that we can't predict the trajectory of a hypersonic missile and this property makes the missile undetectable. But I couldn't understand why can't we predict it's trajectory? ...
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(BASIC) How do I solve this free falling question?

If someone could just show me how to solve part A, I think I can try the rest on my own. Here is the question: A model rocket is launched straight upward with an initial speed of 47.0 m/s. It ...
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How much anti-matter (combining with matter) is needed to give a rocket a velocity that approaches the speed of light (say 95 % of c)? [closed]

A question (very hot presently) about the propulsion of a rocket with compressed air prompted me to ask a somewhat related question. Maybe one sunny day it will be possible to construct an anti-matter ...
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Can rockets fly without burning any fuel with the help of gases under extreme pressure only?

Why is it necessary to burn the hydrogen fuel coming out of the engine for the lift of rockets? If it is done to create a greater reaction force on the rocket then why can't we do the same lift with ...
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Does launching spacecraft from the southern United States actually give a meaningful energy boost?

Many different sources (e.g. here, here, here, and here) say that Florida is the most common rocket launch site in the United States because it's the most southeastern part of the U.S. that is ...
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How do I find the spectral transmittance of a gas mixture?

I'm trying to replicate a paper on radiation modeling of a rocket plume. They define a line of sight (LOS) through the plume like this: And their equation for spectral intensity along the LOS is $$ ...
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Viscosity equations for rockets

I'm doing an experiment about the effect of viscosity on water rockets, and was wondering if there are any equations that include viscosity that are significant to rockets/water rockets.
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What happens to a mass if you apply an acceleration to it, apply a second (equal) acceleration to the accelerating mass, etc? [closed]

Suppose we have a mass that is being accelerated in empty space. Say by pulling on it by an accelerating rocket. This rocket is non-rigidly (say by a spring with spring constant $k$ and length $l$ ...
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Where the mechanical energy goes in a rocket flying in a space with no referential?

I know it's a big and confusing title, if someone could improve it I would appreciate. My question is a thought experiment. If kinetic energy is relative to other objects and the total energy of a ...
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Rocket chamber pressure equation

Recently, have been exploring amateur rocketry, doing a school report and came across an chamber pressure equation. $$\Delta L= \frac{pLD}{4Ed}(1-2v)\\ \Delta D=\frac{pD^2}{4Ed}\left(1-\frac{v}{2}\...
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What is the purpose of the roll maneuver on a rocket?

I have watched several videos on both rocket launches, ballistic missile launches, even a really cool one by Northrup Grumman on launching a nuclear missile. (https://www.youtube.com/watch?v=...
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Mechanical “squeeze” rocket

This may be a silly question, but I don't know how to approach an answer myself and I can't seem to find the right search terms to input. A simple rocket might be a compressed air bottle, where a ...
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Why do we use relative velocity when describing flow rate of exhaust gases leaving a nozzle?

Why do we take the relative velocity instead of the absolute velocity in the analysis of flow rates? More particularly when we write down momentum, isn't the 'velocity' term which we multiply with ...
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A string between two accelerating spaceships vs two falling spaceships

According to Bell's spaceship paradox, a string between two uniformly accelerating spaceships will break. According to the equivalence principle, a string between two spaceships freely falling in a ...
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Should negative pressure-thrust increase or decrease the nozzle-exit velocity of a rocket?

first post here. I've just started on George Sutton & Oscar Biblarz's Rocket Propulsion Elements and have stumbled upon contradictory solutions between the Eighth (PDF linked) and Ninth Edition (...
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Trajectory of an object when asymmetrical forces are acting on it [closed]

I'm trying to code a game that uses physics...but I don't how to figure something out: If I have a 2x2 square (in any unit), with two thrusters/jets whatever you want to call it, on the back, each 1x1 ...
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Why aren't orbits transferred at the perigee?

In example 10.6 titled "Satellite Orbit Transfer 1" of Kleppner and Kolenkow the author says The most energy-efficient way to put a satellite into circular orbit is to launch it into an ...
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The effect of Special Relavity's Time Dilation on Rocket propulsion

I'm familiar with how the mass of an object increases with the velocity, which makes it impossible to reach the speed of light. However does time dilation also add challenges to accelerating an object?...
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Burning prograde in orbit

I had a doubt regarding orbital mechanics. When a satellite burns prograde, ie, in the direction of the instantaneous velocity vector, it increases its orbital speed at the instant, whereas the ...
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Satellite return ro Earth

When satellite is return from space orbit to earth how they lower the potential energy? Do satellite need to fire engines as they launch? How we apply energy conservation laws?
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Gravitational waves emitted by accelerating rocket

What is the gravitational wave luminosity of a rocket with mass $m$ (kg) accelerating at $\Delta v$ (m/s$^2$)? Intuitively, I expect the luminosity (in Watt) to depend on the mass and acceleration. ...
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Determination of different properties in fluid film vs static properties for a Regeneratively Cooled Rocket Nozzle

This one, I hope, is pretty simple. I'm working on a school project that's looking at the feasibility of a methane fueled rocket motor. Right now I'm looking at regenerative cooling for the nozzle ...
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Why don’t astronauts “push” spacecraft?

Perhaps it goes without saying, but according to Newton’s laws “every action has an equal and opposite reaction”. How do astronauts, especially those inside small spacecraft like the Crew Dragon, not “...
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How does a rocket slow down in space?

I’ve been reading about the conservation of momentum and its applications in deriving the rocket equation. I’m curious whether how can a rocket slow down in space. As far as i can comprehend, a rocket’...
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Conservation of momentum and work

Consider the following scenario: I am alone in space with a ball. I threw the ball at a certain speed such that i am propelled backwards (like a rocket is) as to conserve momentum. Now, since my ...
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How is the kinetic energy change during a throttling process negligible?

Reference:https://web.mit.edu/16.unified/www/SPRING/propulsion/notes/node16.html The throttling process is a constant enthalpy process, in which the pressure decreases. So, $$h_1 = h_2$$ $$u_1 + ...
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Lift force on a rocket [closed]

How is the lift force is generated on a rocket? I've tried to find answer online but all efforts were in vain.
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Why aren't rockets launched in movement? [closed]

Rockets launched to reach orbit usually start from a stationary position, engines are started and the rocket slowly gain acceleration upwards, eventually reaching orbit. What I'm thinking is that the ...
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How to calculate temperature change of a decompressing gas canister?

I am currently trying to find the temperature drop of a decompressing gas canister for rocketry club to make sure that it doesn't get too cold to affect nearby components like electronics. The ...
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Derivation of Tsiolkovsky rocket equation

My textbook derives the rocket equation from conservation of momentum like so: $$\begin{align}p_i&=p_f \tag{1}\\ mv&={(m-dm_g)}{(v+dv)}+dm_g(v-u)\\ mv&=mv+m\,dv-dm_g\,v-dm_g\,dv+dm_g\,v-...
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Physics of Project Orion

I was reading the book "Project Orion" by George Dyson. For those who are unaware, Project Orion was basically a plan to launch a spaceship by flinging bombs out the rear and detonating them. The ...
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Is it possible to use the Sun's gravity to gain significant delta-v?

Someone asked here whether Sun's gravity has been used for delta-v gain, and from the answers it's not clear whether this is possible at all. There is this rule of thumb that "burning fuel inside a ...
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The Tsiolkovsky equation derived via the Lagrange funtion [closed]

I wanted to derive the Tsiolkovsky rocket equation using the Lagrange formalism. $$ T = \frac{m(t)}{2}\dot{\xi(t)}^2 + \frac{\mu(t)}{2}(\dot{\xi(t)} - u)^2$$ $m$ - mass of the rocket $\xi$ - some ...
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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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Travelling in outerspace

Firstly, is it correct that for travel in outer space, the distance that can be travelled with a given amount of fuel is determined by the energy required to overcome the following forces: gravity ...
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Antimatter propulsion

I was reading about antimatter propulsion systems on the internet, and apparently they would work by letting matter and antimatter react and then the reaction would be (magnetically) channeled out ...
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Does it take 41 Hiroshima “Little Boy” bombs worth of energy to send ISS in orbit? [closed]

I calculated the amount of energy needed to send ISS to orbit. It seems crazy expensive. I'm approximating my calculation with the following equation: $$\begin{align} E_\text{tot} &= E_\text{kin} ...
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Do rockets require stabilization so they don't wobble or even spin?

I have watched many videos of large but "amateur" (not military or NASA) rockets and I would have guessed that without some sort of stabilizers like gyroscopes or fins the rocket might wobble or show ...

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