# Questions tagged [thrust]

Force produced by pushing against a reaction mass in space à la Newton's third law: "For every action there is an equal and opposite reaction." The thrust of a rocket engine is the forward force produced by expelling the exhaust mass (reaction mass) in the backwards direction.

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### Thrust to weight of large solid fuel boosters

I have been looking at examples of large solid fuel rocket boosters or first stages used for space launch, such as P80, the Space Shuttle SRB, the various versions of Graphite-Epoxy-Motor, the solid ...
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### Pressure Term in Rocket Thrust Equation

In the rocket thrust equation, as well as the thrust due to the mass flow rate of the exiting propellant, there is also an additional pressure term included. However I have noticed that this term is ...
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### Engine most likely to be available in the next 80 years to accelerate a craft at 1G for 4 weeks [closed]

I am wondering what type of engine would most likely be available in the next 80 that can constantly accelerate a spacecraft at 1G. Preferably, it could accelerate it for 4 weeks. The engine could be ...
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### What single figure best compares the mass launch capabilities of different rockets?

Could all launches be fairly lined up according to one single scalar metric representing how much kinetic energy they impart to their payloads - from launch pad to whatever trajectory the payload ends ...
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### Some exercise questions about Tsiolkovsky's Rocket Equation and Thrust Equation

I have found 6 of the question's answers, but I don't know they are correct. The last question about time of the burn I get negative result -0.42 seconds. Time could not be a negative value, so I ...
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### Computing Flight Characteristics for Different Propellant Grain Geometries?

Consider the following image: I am interested in mathematically accounting for some of these different geometries but have had little success so far in finding how this can be done. The first thought ...
1 vote
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### How can I find the predicted approximate altitude of a rocket based on simply the propellant, specific impulse, and propellant mass?(solid propellant) [duplicate]

I am getting all the inputs I outlined above, including burn-time which I could not mention above(character limit), from a small scale motor test. I know there are specific specific impulses for each ...
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### Commercial Sources of variable thrust Rocket Engines [closed]

The project is to build a model rocket to take off and land vertically. Max height perhaps 100 feet. Looking for a suitable engine which can provide variable thrust control and thrust vectoring which ...
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### What is missing in the conversion of specific impulse from units of seconds to thrust/mass flow rate? [duplicate]

I was trying to get the Specific Impulse of the Saturn V engines, hoping for a value in N/kg/s, as I need to know the mass consumption rate per thrust value. Any and all sources give me the value in ...
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### Falcon 9 Merlin 1d thrust calculated through every moment of flight

I am currently trying to recreate the launch of falcon 9 in unity. For the calculations I need the thrust of the first stage (only doing it for one stage for now). How to calculate it depending on the ...
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### Is specific impulse and thrust maximum in vacuum or for exit pressure equals atmospheric pressure?

According to the thrust formulation of a rocket one can show, that maximum thrust is not delivered for pambient= 0 but for pambient=pnozzle_exit since then the momentum term is maximized. But then I ...
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### Wasn't it 1 engine out at liftoff, then another 5 were lost my the end of max-Q? [closed]

Here's a picture. 27 engines running out of 33. Probably not as bad as you'd think. Yes there's less thrust, but the other engines will be able to run longer.
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### Thrust needed for Ion Thruster Lift off from Earth surface

I've been calculating the needed mass flow rate for a hypothetical ion rocket, lifting off from Earth's surface and propelled with a Dual-Stage 4-Grid ion thruster. Data given: mass of the spaceship /...
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### How did NASA calculate 22 million "rocket horsepower" for the SLS Booster?

This answer to Does NASA really report the power of rockets in horsepower? cites NASA news item Space Launch System Booster Aimed and Ready to Fire which says "What's impressive about this test is ...
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### Is it wrong to say that the thrust increases with time?

Is it wrong to state that the thrust increases with time? Because it implies that it actually increases over increasing altitude, with time?
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### Higher nozzle exit velocity generally means higher thrust right?

Higher nozzle exit velocity generally means higher thrust right? If that is the case, then a higher heat capacity could potentially lead to a higher exit velocity, thus higher thrust?
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Considering the answer of user Mark Adler here, to calculate how much ΔV is needed to raise orbit we can simply approximate it as the change in orbital velocity. Starlink satellites seem to be ...
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### Thrust & acceleration produced by a rocket engine

For given propellants, with their mass flow decided by the rpm of the turbo pump, what decides the thrust and acceleration produced by a rocket engine? Can we control them independently?
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### How high is the ISP of a fire extinguisher

After seeing this question Flying around on a fire extinguisher I wondered how high the ISP of a fire extinguisher is. What is the ISP of a fire extinguisher?
1 vote
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### Is the critical inclination the same on every planet in the solar system?

I am learning about Space exploration. Is the critical inclination the same on every planet (in the solar system) or does it depend on the planet?
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### How throttle changes affect calculations of thrust?

So, for constant throttle setting equation to calculate thrust looks like $\ F = \dot{m}_\mathrm e V_\mathrm e + (p_\mathrm e - p_0) A_\mathrm e$ But if we are looking at flightclub.io simulation, ...
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### Does "% Throttle" refer to fuel flow or thrust?

the question Is it possible to throttle down the thrust in a rocket engine to 1% just like in KSP? discusses the ability of liquid fuel rockets to throttle. By convention, does the “% throttle level” ...
1 vote
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### Is it possible to throttle down the thrust in a rocket engine to 1% just like in KSP?

With any normal liquid fuelled rocket engine it is possible to throttle the thrust up and down, but in Kerbal space program it is possible to bring it all the way down to around a percent thrust. Is ...
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### Rocket maximum distance [closed]

let's say I have a liquid rocket what would maximize the distance traveled by the rocket thus consume less fuel constant velocity or acceleration or why?
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### Upper stage structural loads on ascent?

In another question, this came up: For example, if a Falcon 9 launches 20 tons of fuel to dock in LEO, how can the same upper stage be used to launch 40 tons of fuel to the same orbit? Doesn't it ...
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### What is the fuel cost of deorbiting a kilo of space junk?

Removing debris from LEO requires a significant delta-V which most schemes propose to accomplish via rocket propulsion. Source The ratio of launch fuel to payload mass is often given as 9:1 for LOE. ...
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### HIghest thrust vehicles

Eric Ralph in an article about Falcon Heavy static fire test, wrote this: the most capable rocket currently operational – appeared to ignite all 27 of its first stage’s Merlin 1D engines, likely ...
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### How fast can a rocket with constant thrust but changing mass travel a linear distance with limited delta V?

Background I am developing a game / simulation that has spacecraft with advanced albeit at least not physically impossible drives travelling in the solar system. As operation time should be far more ...
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### Equations evaluating engine performance

What kind of equation would best evaluate a rocket engine's performance in foreign atmospheres such as Mars? Does it matter that specific impulse does not consider air resistance? Should I focus on ...
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### Using a reverse sling + compression sock to give an asteroid an initial boost - possible?

building my a related question, I have a hypothesis in question: Assuming that we can get a tug spacecraft near an asteroid worth mining, at appropriate but faster speeds can we use a slingshot with a ...
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### Which orbital class rocket has highest TWR at liftoff?

Which orbital class rocket (active or retired) has the highest thrust to weight ratio at liftoff?
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### What is the maximum weight a raptor 2 engine can lift up at sea level on earth?

Regardless of target orbit, how can I calculate the maximum weight one engine can lift? If the raptor's TWR is 140 and its Thrust is 1.81 MN then: W = F / TWR = 12,900 N ==> m = W / g = 1.3 tons ...
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### Is the momentum thrust of a liquid rocket engine in a static test fire the same as in flight?

Assuming vacuum exit conditions are matched by means of a suitable ejector mechanism, is the exhaust velocity of combustion products relative to static engine the same as that of a flying rocket ...
1 vote
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### Cold Gas Thruster to space engineering challenges

I have seen this question. The natural extension of this question would be - could you lift a human or an equivalent payload to LEO with cold gas thruster only? For numbers, take 100 kg mass for the ...
1 vote
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### How to propagate the trajectory in GMAT with a custom thrust profile

So basically I was trying to design a low thrust maneuver to increase the apogee of the spacecraft. I solved it separately and got some thrust profile (thrust and it's direction as a function of time)....
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### Where do the numbers 101,972 and 3,600 come from in terms of Thrust-Specific Fuel Consumption (TSFC or SFC)?

Online, on sites such as Wikipedia's for Specific Impulse and Thrust-specific fuel consumption, there are these units: 101,972/x g/(kN·s) and 3,600/x lb/(lbf·hr) Perhaps 3600 comes from the number of ...
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### Study of selection higher stages for a multistage rocket

Will it be correct to say that the thrust produced by the first stage is the ultimate limiting factor for a rocket's ability? The logic behind this thought is like this: Higher quantity of its ...
1 vote
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### Is it possible to stand still in space?

I am wondering to know if it's possible to stand still (no movement at all with respect to the Sun) in space. Can it be possible? I am thinking that when we move upwards from Earth's surface an ...
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### What is the maximum thrust of the Starlink satellites?

As in the title, what is the maximum thrust (in N) that the satellites of the Starlink constellation can achieve? I read that they use Hall-effect thrusters, but I couldn't find a specification of the ...
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### How do you calculate thrust produced by a rocket engine?

I was planning on building a water-powered rocket. I also wanted to know how high my rocket might go. Could someone help me figure out, how to calculate thrust produced by a rocket engine?
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### Rocket engine test bed structure

Rocket engine thrust will eventually "lift" a certain amount of weight, to a certain height. For Saturn V, they used 5# F1 engines, each of which produced a thrust sufficient to lift ...
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### Where to send invention ideas?

I invented a new type of thruster for satellites. I would like to know where can I send the report I made. The report was reviewed by several physicists and engineers in my environment, but I would ...
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### What was the first rocket to use gimbaled thrust?

A gimbaled thrust system was used on the Space Shuttle, which is easily recognized in the beginning of this launch video. Was this technology first used by jet fighters, or was it first invented for ...