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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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Rocket speed (Is the equation my choose is the correct one and is my (asumption) and calculation is correct with regard to Hawking's sentences

Hawking wrote, "Exhaust speed of chemical rockets is 3 km/s. By jettisoning 30 % of their mass, they can achieve speed of about 0.5 km per second and then slow down again." So, I would like to know ...
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Are there two action-reaction pairs operating in a rocket

I'm confused about the action-reaction pair in a rocket. is it 1 The action of the explosion of gases in the combustion chamber on the rocket, and the reaction of the rocket on the gases, or 2 The ...
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What pressures make up the thrust of a rocket? [duplicate]

In most diagrams depicting rocket propulsion,the action force is downwards and the reaction force, upwards. In this way it would seem that it's the rocket that pushes first on the gases and the gases ...
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How does a rocket push on its exhaust? [duplicate]

How does a rocket push on its exhaust and how does the exhaust push back on the rocket? Also, why is the upward motion of a rocket linked to Newtons third law?
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How does a rocket obey Newton's third law? [duplicate]

How does a rocket push against its exhaust? Does the reaction come from the rocket nozzle or as a result of the imbalance of forces in the combustion chamber?
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If there is no atmosphere on a planet that is rotating on an axis and a rocket is launched “Straight up” from its surface,

If there is no atmosphere on a planet that is rotating on an axis and a rocket is launched "Straight up" from its surface, won't the rocket still have an angular/orbital velocity because the planet ...
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How is Geo Stationary Rocket placed exactly above the Location after Launch

My Question is bit deeper on the Satellite been put into orbit of GEO . Recently ISRO Launch GSLV Mark 3 to put into GSO . After the Rocket is launched and reached the Perigee ( 190 km ) the ...
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Rocket Equation

What formula can be used in order to find the final velocity of a rocket if the time travelled by the rocket, exhaust velocity, initial and final masses of the rocket and the initial acceleration of ...
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Vacuum thrust, and how it is proven

Let’s talk about “Vacuum Thrust”. Simply put, thrust that is exerted in a vacuum. Space is a vaccum correct? So therefore there is no matter is space, it is just empty space. Thrust is measure in ...
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Water rocket height calculations & alculation of the size(diameter) of the nozzle

I'm currently building a water rocket made out of carbon fiber pipes and fabric. Before that I built a simple water rocket made out of plastic bottles with my friend for a science competition. Now I ...
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1answer
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What is the minimum time required to travel 1 light-year from Earth and turn back? [duplicate]

Suppose I have a very powerful and durable rocket that is able to reach speed of light minus $10^{-1000^{1000^{1000}}}$ in $10^{-1000^{1000^{1000}}}$ milliseconds. Very instant acceleration. I can ...
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Ion optics of a gridded ion thruster

Followup to this question. The holes in the grid of an ion thruster should be thought of as an optical device for ions. As is shown here, ions are focused to the center of the stream. My question is ...
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2answers
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Hole size in ion thruster's accel-grid v. scoop-grid

In ion thrusters, the scoop grid is charged positively and "scoops" ions from the plasma. The accel grid is charged negatively and placed at some distance to accelerate the ions by the applied voltage....
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Action reaction pair rapidity or time delay

How much rapid is action reaction force ? Suppose i have a rocket of 10kg dry mass and 10kg reactive mass. On launching, 5 kg of reactive mass is burnt. And i get a thrust of 200 N. What will be the ...
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Analytic and numerical integration of the rocket equation yield different results [closed]

Background The mass of a rocket as a function of time is: $$ m = m_0 - \dot m t$$ Where $m_0 $ is the initial mass of the rocket and $\dot m$ is the mass flow rate. At a certain time all the fuel has ...
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Need help creating an equation for the time it takes for a rocket to deaccelerate (accounting for fuel mass lost)

I'm doing a Math Internal Assesment for school where I'm trying to create a model for a rocket's suicide burn. I've gotten stuck in one of the equations I need for it. I need to find the time it would ...
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2answers
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Delta-V of Earth to Moon mission using Moon orbit

I have read this article here and it talks about the delta-v cost of travelling to and from the Moon. Importantly it says that getting to an orbit round the Moon, and docking with a space station, and ...
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Why is the work done by a rocket engine greater at higher speeds? [duplicate]

From this comment by orlp: If I strap a rocket booster to a rocket in space and fire it for one second, then the work provided is much higher when the rocket is flying fast compared to when the ...
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2answers
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Sign problem in projectile with drag

So recently, I've been playing around with the variables in projectile motion with drag to see how the trajectory changes. I had my ODE and solved it using separation of variables but the equation ...
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1answer
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With respect to inertial observer standing at the starting point of why is the velocity of ejected mass of rocket $v + v_0$

We derived the equation of motion of a rocket this way: all the velocities are taken with respect to inertial observer standing where the rocket starts. As we take upwards direction to be positive. ...
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1answer
99 views

Gravity Turn initial ascent

When executing a gravity turn a rocket will generally first ascend vertically to around 10000m. I need to calculate this initial stretch while knowing the specifics of the rocket and how high I want ...
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In which direction is orbit around the moon easiest to achieve?

Suppose a conventional spacecraft is launched from Earth with the intention of establishing an orbit around the Moon. In the context of this question, the Earth/Moon system is viewed from far above ...
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2answers
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How to stop a moving rocket in space? [closed]

Newton third law? so to stop a rocket we should generate thrust (from thrusters mounted on front of the rocket) in opposite direction? If so then if a tank in motion shoots from cannon then recoil ...
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2answers
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Laws of motion in relation to balloon and rocket

Question: A spherical rubber balloon inflated with air is held stationary, with its opening, on the west side, pinched shut. (a) Describe the forces exerted by the air inside and outside the balloon ...
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1answer
203 views

Acceleration of a Rocket at Launch

I have been trying to understand the physics behind a rocket's acceleration at launch for a while now and by this point am more confused than ever. As net force is $F = ma$ --> $a =\frac Fm$. In a ...
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Do any of our satellites or space exploration craft need or use relativity for strictly navigational purposes?

I thought I read somewhere that everything we've ever sent into space used only Newton for navigation, because relativistic effects are orders of magnitude smaller than other causes of course ...
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1answer
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How to use the concept of variable mass system?

The general equation of variable mass motion is as follows: It's derivation is given below: Refer wikipedia page for more details and the link of it is given below: https://en.wikipedia.org/wiki/...
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1answer
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Orbital Hyperloop for Approach to $c$?

We have a bunch of "orbital catapult" ideas to get things into orbit - most involve some sort of loop with mag levitation in vacuum. There is a practical limit on the top speed here due to whatever is ...
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2answers
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Why does this rocket stop rolling while going up [duplicate]

I have been watching a ludicrous video about this insane notion of a flat earth and, among a lot of wrong and ill presented proofs (some fake ones) there is an interesting one which I don't have the ...
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1answer
52 views

Nuclear Fusion Rocket Problem [closed]

I bet on the problem of having the final speed of a spacecraft that has a fusion reactor that can move the star system with the bet of the friend. When the spacecraft's fusion efficiency is 0.01%, the ...
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2answers
242 views

Linear or Quadratic Air Resistance

I'm trying to model a rocket's position with air resistance as a factor. The rocket is fairly low-powered (Estes A8-3, 9.7N of thrust for 0.7 seconds), and I estimate it won't be going faster than 50 ...
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2answers
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Would it be possible to propel a spaceship by pushing against the sun's magnetic field?

Would it be possible to power a space ship by generating a magnetic field opposed to the sun's? For example, the spaceship could generate a magnetic field using massive coils of superconducting wire. ...
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236 views

What is the difference between orbital velocity and critical velocity? Are their values similar or not?

As critical velocity is the minimum velocity required to put a satellite into orbit. And orbital velocity is the velocity required to keep a satellite moving in an orbit.The value of critical velocity ...
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Derivation of rocket equation [duplicate]

Let $m$ be the mass of a rocket in free space (including fuel) at the time $t$. Now suppose that the rocket ejects a mass $\Delta m$ during the interval $\Delta t$ with velocity $v_e$ relative to the ...
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4answers
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A gravitational field is path independent. Why does a rocket not fly in serpentine lines? [closed]

in theory a gravitational field is path independent, a gravitational field is a gradient field and so conservative. why doesn't a rocket fly in serpentine lines to exit the gravitational field of the ...
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1answer
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Rocket fuel consumption

Consider a velocity change $dV$ for a rocket accelerated by an on-board thruster. Is the total amount of fuel consumed proportional to $dV$, or to $dE$, where $dE$ is the change in kinetic energy, or ...
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Why were the sonic booms produced by the landing SpaceX side boosters audible on the ground?

Supersonic vehicles produce Mach cones behind them, which observers hear as sonic booms as they pass by. So if, for example, a jet goes supersonic as it heads toward you, but decelerates to subsonic ...
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How is thrust per unit power measured?

Typically, thrust efficiency is measured in specific impulse, as thrust per fuel consumption rate: $$I_\text{sp} = \frac{F_\text{thrust}}{\dot{m}_\text{fuel}} \quad \text{or} \quad I_\text{sp} = \...
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Rocket Propulsion and Bernoulli's Theorem

This is what my textbook says on rocket propulsion:$\hspace{75px}$ Questions: The beginning of the textbook excerpt says that the fuel is converted into a gas at high pressure. Does this mean that, ...
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1answer
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How to calculate rocket thrust? [closed]

I’m trying to calculate the thrust of a theoretical rocket (for a simulator). The formula I’m using is F = pVeA . I can get the exhaust density by using the gas formed during combustion and then ...
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1answer
127 views

How to calculate rocket Burn Rate?

I’m trying to calculate the burn rate of a theoretical sugar rocket (for a computer game). The equation I have is $r = aP^n$ . Where $r$ is the burn rate, $a$ is the burn rate coefficient, $n$ is the ...
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3answers
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Nuclear reactor in a cruise missile. How?

So it is declared, that there are cruise missiles with nuclear reactors on board. As I understand, when it's working, the neutrons keep flying from off the fuel. Neutrons give induced radioactivity. ...
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Calculating spacecraft thrust manoeuvres with JPL data [closed]

I've recently programmed an animated simulation of the main elements (core planets and Sun) of our solar system: by using the initial coordinates from the JPL (Jet Propulsion Laboratory - NASA) ...
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Angular Velocity in a Gravity Turn

I am trying to simulate a gravity assisted ascent of a rocket. One of the differential equations I need to use for this is the sum of forces transverse to the axis of the rocket (gravitational and ...
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Practicality of a centrifugal space launch system

So, I read this article: https://techcrunch.com/2018/02/22/spinlaunch-2/ (TechCrunch seems to have issues with this URL: here's one from the Wayback Machine that seems reliable: https://web.archive....
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Why is the rocket equation different from the product rule? [duplicate]

So in my lectures we derived the rocket equation which is given by: $$F = m \cdot\frac{dv}{dt} + u\cdot \frac{dm}{dt}$$ Where m is the mass of the rocket, and u is the speed of the ejected fuel. ...
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Can water pressure be used to impulse a rocket out of the water?

Please bear in mind that I'm no physicist, my knowledge of hydrodynamics is limited. I've been thinking that when you push a floating object to the bottom of a swimming pool and then release it, it ...
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Rockets in vacuum vs. Rocket on earth

Recently my physics teacher during a rant said something that piqued my interest. Heres what he said "There are more problems visiting other stars if you wanted a rocket to go 99% the speed of light ...
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How can a rocket which is angled at 30° in relation to the Earth be able to fly?

Someone told me that SpaceX's Falcon Heavy would fall out of the sky because of the angle the rocket was at (at 125 seconds after launch). The angle was 30 degrees,the acceleration was ~25 meters per ...
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Conservation of momentum for rockets [closed]

I'm reading Kleppner & Kolenkow Example 4.16 on page 140-141 of the second edition and I am confused by something. So we have a rocket in free space. No friction and no gravity. The rocket has ...