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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Fuel injector design confirmation [closed]

Hi, I've been thinking of some new ideas for fuel injection. So I came up with this concept where kerosene and oxygen are injected into a combustion chamber diagonally and hit each other with a great ...
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Not sure how to set up this problem - terminal velocity of a rocket [closed]

We were just introduced to forces and I'm having some trouble understanding how to solve this: A cylindrical rocket weighing $750 g$ with a thrust of $10N$ is launched straight up until it reaches ...
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I need to figure thermochemical properties of mixed gases [closed]

I am trying to determine the thermochemical properties for mixed gases - namely a fuel-rich mixture of oxygen/methane (LOX/LCH4) and the resultant combustion products (CO2/H2O.) Properties I'm trying ...
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3DOF Rocket Dynamics for an LQR controller

I'm trying to define a simplified model of a rocket to implement an LQ regulator. What I need is the translational dynamics on the earth's inertial frame and the rotational dynamics in the body frame. ...
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What is the net force on a rocket immediately upon ignition?

While recently watching a rocket launch, I had a thought that I was a little bit confused about, involving the basic physics of a rocket launch. Before ignition, the rocket experiences no net force: ...
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Gravitational acceleration of an object towards earth which is not in freefall

This is a hypothetical question, a brain experiment, thought someone might be able to answer it for me, someone who has a good understanding of general relativity etc. Assume I take an object and ...
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237 views

A simple doubt on classical mechanics problem [closed]

Question: "At a certain instant of time, the mass of a rocket going up vertically is $100 kg$. If it is ejecting $5 kg$ of gas per second at a speed of $400 m/s$, the acceleration of the rocket ...
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Infinitesimals meaning in this context

I was solving this rocket propulsion's classic mechanics exercise: M is the instantaneous rocket's mass, and v its velocity. The exhaust gases are ejected with speed 𝑢 relative to the speed 𝑣 of the ...
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Can we connect several Nano Spacecraft moving at 20% speed of light? [closed]

Nano spacecrafts are one gram silicon chips that will be accelerated to 20% of the speed of light to reach Alpha Centauri in 20 years. I wonder could we connect several spacecraft after they were ...
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How much work could be got from temperature differences during a rocket's descent from low earth orbit?

It strikes me that there is a lot of energy dissipated during a typical rocket's descent from Low Earth Orbit. How could that energy be captured and used? I wonder whether it might be possible to ...
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Is it easier to apply angular momentum to a rocket with the engine off?

Let's say I've got a rocket that I need to rotate for my next maneuver. Assuming it's flying through full vacuum, I can turn off my engine first, and then use reaction control thrusters to rotate, or ...
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Solving global warming by moving Earth closer to Mars

One way to reduce global warming is to get our planet farther away from the Sun. If we placed a couple of thousands of SpaceX's Merlin rockets upside down in the tropics or Sahara i.e. somewhere where ...
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Expanding Newton's Second Law and changing $v$ to $V_e$ gives you the rocket equation. Where does this change of $v\to V_e$ come from?

I've noticed that from Newton's Second Law, if you expand the right side using the product rule and change the v to Ve, the rocket equation appears very easily... Why is this second term of velocity ...
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Rocket Trajectory (launching it vertically) [closed]

I don't have a camera that can produce a video at 240fps and i my physics experiment i am trying to find the maximum height reached by a water rocket. My question:- Can i use my iphone 11, that has ...
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Is momentum conserved in the rocket equation? If so, why is there force? [closed]

I'm studying the rocket equation and from what I get from it the momentum between the fuel and the rocket is conserved. But if that happens, how come the calculated force is not zero? The rocket ...
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“To come back to Earth…it can be five times the force of gravity” - video editor's mistake?

I've watched The Truth About Gravity With Professor Jim Al-Khalili | Gravity And Me | Spark where astronaut Chris Hadfield says at 3:55: To come back to Earth is violent Then after several seconds ...
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Are there real-world devices similar to the thrust reversers in this scene in Star Wars? [closed]

In Star Wars 3 in the initial crash scene where a spaceship enters the atmosphere for an emergency landing the thrust engine is blocked by a part of the ship and absorbs a part of the thrust which ...
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How do Roll, Pitch, and Yaw Interact?

I'm making a spaceship piloting game, and I'm trying to make the movement follow the laws of physics. The ship is able to control it's angular acceleration in pitch, yaw, and roll. The way I've ...
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Center of mass of a rocket

Is it correct to say that the center of mass of any space rocket is stationary here on earth? roughly speaking, without external forces the motion of the center of mass is preserved, so since the ...
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How to calculate Mars and Lunar payload if I have LEO payload? [closed]

I am working on a project and i need the payload capabilities of different rockets to LEO, mars and lunar orbit. Usually the LEO payload along with all other relevant data is given for all rockets. is ...
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Spacecraft propulsion, thrust and delta V relation

For a spacecraft which has interplanetary mission(eg mars) After deciding the propellant ISP value and Delta V required, how to calculate the thrust required? F = m dot * Ve + (pe - p0) * Ae According ...
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How does a rocket travel in a vacuum space? [duplicate]

OK.. let us consider a rocket initially at rest in outer space. Space is considered as vacuum so there is hardly something that rocket can insert a force on. So if the rocket fires up its engines will ...
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How do I calculate where a solid fuel rocket will land if the rocket is launched at a 45 degree angle?

Let's say I was launching a model rocket at a 45 degree angle to find the distance between the rocket's landing site and the rocket's launching site, but before launch I wanted to try and calculate ...
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How to calculate the positioning angle of a rocket for launch

I am building a model rocket. I want it to end up in a specific position. If I am taking into account the acceleration, starting position, end position, mass, and wind speed, how do I find the angle I ...
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In the rocket equation, does lowering the acceleration due to gravity increase decrease exhaust velocity? [closed]

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 get 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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