Rockets Definition and 136 Threads

I know it is an homework excercise but I already tried all the isoentropic relations, the problem is not the Isp, I can't find a relation to calculate the thrust as I am missing some important parameters, such as Ae, At, mdot, and thrust. This is the text of the excercise: A bipropellant rocket...

That Life Science article is entitled "SpaceX rockets keep tearing blood-red 'atmospheric holes' in the sky, and scientists are concerned". The article suggests "astronomy and communications" as potential "unrecognized problems". Also from the articles: As a non-expert, non-scientist, I think...

I am having difficulty understanding the information below. In the second line it states that F=0 as there is no external force on the system. However it later calculates acceleration of the rocket. How can Force=0 if there is acceleration? (This is the first time I have encountered the...

I'm interested in how rocket engines perform in a vacuum. My first impression is that an atmosphere is needed for the action/reaction to push against in order to get forward movement. I saw a demonstration using a long balloon attached to a long length of string stretched across a room. When the...

Per Spacenews.com: It appears that Zhuque-2, built by the Chinese firm Landscape, failed to reach orbit yesterday. That was the first attempt to reach orbit using methane/oxygen boosters. However, more methalox orbital attempts are coming soon: * Relativity, a Long Beach, CA company that uses...

Hi guys, I'm about to start my degree in a few months and I know what field I want to major in but I don't know what track I should take. In the future I want to work with rockets and spacecraft engines, I want to help develop the new generation. Correct me if I'm wrong but it's called a...

If I need to ask doubts about very basics of rockets and satellites, for example about what basically Ramjet and Scramjet are, which sub-forum should be suitable.

Hi all, Why not build an electron rocket? Why won't this idea work? Seems like someone could just hitch an electron gun onto a spaceship. Boom! Electron Rocket. I was thinking about ion thrusters. These use ions to achieve thrust. They are problematic for achieving a high delta V because...

pls help me

Suppose a rocket is moving at radial velocity vr and tangential velocity vt in the Sun's gravitational field. At some time, the rocket enters the gravitational field of Mars (with the above mentioned velocities), and gravitation effects due to the Sun can be ignored. After more time, the rocket...

While attempting this question , velocity of ##B## wrt ##A## ,##u'_x=\frac{u_x-v}{1-u_xv/c^2}## where ##u_x=-0.6c,v=0.8c## comes out to be ##-0.945c## (approaching).. The distance between ##A## and ##B## seen by ##A## at ## t=0## is ##d=\sqrt(1-.8^2)4.2×10^8## comes out to be ##252*10^6m##...

When other countries are launching rockets into space do they have to get permission from USA for the launch? i.e. China, Iran, India, Japan, Do they just simply coordinate with the local airspace to avoid any conflict or do they actually have to attain a launch permission from a body in USA.

Plasma-powered rockets could reduce the travel time to Mars by roughly half. https://theconversation.com/traveling-to-mars-with-immortal-plasma-rockets-58705

Summary:: In need of help determining the exhaust velocity of a rocket nozzle given temperature and propellant molar mass Greetings and salutations! My name is Robert DeVries, world builder extraordinaire. I have come with questions in search of answers. So for the last few days I've been...

So I'm playing around with some water rockets and I'm trying to figure out how fast the exhaust velocity of the water is. I've had an experimental approach using high fps camera to record and analyse (using tracker) the exhaust velocity. I'm using a 0,5 l soda bottle with 0,085 L ; 0,135 ; L...

Black powder has specific impulse of around 80s, while rocket candy has up to 130s of specific impulse. Does that mean I could replace the propellant in a BP cartridge with 80/130 of the weight in rocket candy and obtain the same performance in an idealized gun? (as in without considering...

Homework Statement: Hi, I just got my first year 12 assignment which is a depth study of advanced mechanics. I had one idea of investigating the motion of rockets and satellites. I could even do something with circular motion or projectile motion, taking air resistance into consideration. I...

The world is ending bla bla bla. :) The core question is, how many rockets can launch at the same time around the entire earth. Doesn’t matter if the atmosphere is destroyed after, anyone left behind is already dead. What matters is getting as many people off the planet at the same time. I can...

Hello. I have a question on inertial motion transverse to gravity force, e.g. blocks of dry ice floating on the smooth and flat floor on Earth. For simple mathematics I explain my problem in Rindler case. Let a group of N rockets gather at origin (0,0,0,0) of a IFR and let them start...

I found this interesting engine design on the internet. It is one of the most powerful and largest machines human have ever designed. It is a fusion powered propulsion device, it uses “heavy fusion technology” which can use any elements lighter than Fe-56 as power source. Is this design feasible?

Assume that there are 2 rockets in deep space or a place where there is nothing around to compare their motion to. Rocket A starts its thrusters but the observer in rocket A doesn't know about it. So my question is, if rocket A is considered to be stationary by the observer then how can he...

So I'll soon be writing an assigntment on the physics and chemistry behind firework rockets and that's why I'm here! I've already prepared for the chemistry part but when it comes to the physics part then I am a bit lost. Bare in mind that I'm supposed to learn something new (myself) and explain...

Homework Statement A rocket burns out at an altitude h above the Earth's surface. Its speed v0 at burnout exceeds the escape speed vesc appropriate to the burnout altitude. Show that the speed v of the rocket very far from the Earth is given by v=(v02-v2esc)1/2 Homework Equations KEf-KEi=Ui-Uf...

Hi there, Recently i was watching some rocket launches and was wondering why they are tethered before takeoff, after some searching i found out that they are used to keep a constant supply of fuel to replace the part that boils off. But is there any other uses for such tethers?

So, I'm investigating a certain way of steering a rocket in space for my first undergraduate research project. Essentially, the idea is to control the location of some mass located on a horizontal track perpendicular to a rocket, so that when the mass is moved, the center of mass of the rocket...

How efficiently is the fuel burned in a typical liquid fuel rocket engine? I've heard numbers ranging from 95% to below 50%.

I've seen the SpaceX fail videos, even when they tip over on water the rockets still explode. Why?

My 12 year old asked me this question. I have a MS in Mechanical Engineering, so I can usually answer his physics questions, but this one stumped me. When lifting off, why do most rockets turn close to horizontal almost immediately? Of course we know they need mostly horizontal speed to...

Hello everyone, I am currently working on an undergraduate club team for the Intercollegiate Rocket Engineering Competition. I am attempting to do a calculation to determine the pressure needed in a vessel leading to another pressurized combustion chamber to achieve a desired mass flow rate...

Rockets are quite expensive and it takes about 2000 to 10000 dollars to place 1 pound into orbit. So I was wondering: Is the size or the fuel mass of a rocket a big concern or will it be of no help economically if we make smaller rockets with less fuel mass for the same amount of payload...

How much energy needs to be be expended to throw a non operating satellite (or other space trash) out of orbit (L4 or L5) or L2 into deeper space... thus minimizing space debris in Earth orbit. I could only find formulas for getting an object INTO orbit... Background of question: we were...

This is an IB problem from November 2017. Two rockets are separated by 6E8m (2 sec x c, or two light-seconds), w.r.t. Earth, and are approaching Earth from opposite directions. Rocket A approaches from left at 0.6c. Rocket B approaches form right at 0.4c. According to Earth, when do they...

if you and your friend ride a supersonic rocket , do you can listen to your friend voice ? I mean if you travel faster than sound will you can hear anything ,It's difficult to imagine. And thanks so much,

Well, first thing, I am new to this forum and it looks pretty good and I'm looking forward to reading more from it and post more questions. Well rocket propeling (or anything that uses some material to propel up when shooting it down) seems pretty straight forward at first, you have some gas...

Hello all! I was wondering if there is a scenario, where a single stage rocket will be superior to a multi-stage rocket, and if so, why? i'm under the impression that multi stage is always better, but i don't think that is entirely correct. Good day to you all

Homework Statement Hello all I have to show why there advantageously can be employed multi-stage rockets Homework Equations How do i do this best, a graph/plot? The Attempt at a Solution i have done some calculations for a single stage rocket and a multistage rocket, but how can i show this...

Homework Statement Show why it is advantageous to use multistage rockets Homework Equations - 3. The Attempt at a Solution [/B] Hello there I have to show why using multi stage rockets are an advantage, i have done som calculations for a 2. stage rocket and a singel stage, with the same...

Homework Statement Assess why there can advantageously be used multistage rockets, with a calculation example. Homework Equations - The Attempt at a Solution [/B] Hello all, i need to show why it is an advantage to use multistage rockets, with some mathematical proof, and I am a bit lost. I...

Hi all! I've come here to seek your expertise because I've ran into a bit of a heated discussion (well, heated from the other side ;-) about rockets, hovering and center of gravity. Basically people are referencing to the pendulum fallacy when I say that a rocket which is hovering would be...

I've been looking after some good books dealing with structural engineering of rockets and spacecraft s in general. I know that Rocket Propulsion Elements is a good book on rocket science, but I'm looking not only for propulsion but more specifically for structural design (loads, stress...)...

Homework Statement In Example 2.6, we considered a simple model for a rocket launched from the surface of the Earth. A better expression for a rocket's position measured from the center of the Earth is given by Y(t)=(RE3/2+3(√g/2)REt)2/3 where RE is the radius of the Earth (6.38 ✕ 106 m) and g...

Suppose we had two rockets traveling in opposite directions at 0.99c each. Would a rocket in one frame of reference see the other traveling at 1.98c? The argument would be that we would observe the rocket going slower, since time would slow down at near c speeds but who does the time slow...

Challenger Engineer Who Warned Of Shuttle Disaster Dies http://www.npr.org/sections/thetwo-way/2016/03/21/470870426/challenger-engineer-who-warned-of-shuttle-disaster-dies Thanks, Bob, you did right!

Homework Statement A rocket ship leaves Earth at 0.6c. The clock of the rocket says 1hr has elapsed. (a.) According to the earth clock, when was the signal SENT? (b.) According to the earth clock, how long after the rocket left did the signal arrive BACK on earth? (c.) According to the rocket...

Homework Statement A rocket with an initial mass of 60,000kg ignites its engines and burns fuel at a rate of 300 kg/s with an exhaust velocity of 2220 m/s. How long after the engines start does the rocket lift off the ground? Homework Equations From Newton's second law F = Ma this equation can...

Hi, I can´t understand how a rocket is not flipped over by the thrusters (especially without finns). I know this is a general misconception of how a rocket works, but it seams intuitive that it would behave like a inverted pendulum, since the force works below the center of mass, of the rocket...

Could there perhaps ever be floating cities? If we could get the type of technology that sends rockets into space, and have the boosters running at a constant and equal velocity inversely, could this cause anything to levitate? If so, would this even be habitable? Considering that the fumes...

I am doing a experiment with model rockets to see if a added compression nozzle on a model rocket would make the engine perform better. As you can see in this picture there is a small clay nozzle immediate to the propellant. This is the same place that you put the igniter. My experiment is...

Hello everyone, I am brand new here in the PhysicsForum and this is my very first message. So it's apleasure to meet likeminded people sharing the same interest and probably also profession. The latter is also the reason why I finally registered in this forum and I sincerely hopethat I am given...

So I'm trying to make a Hot-Water Rocket. But I want to make the necessary thermodynamics calculations first. What kind of flow will it be in such systems I think it's obviously going to be an unsteady flow but is it uniform or not? I also would love if you guys linked me to unsteady...