Skip to main content

Questions tagged [rocket-equation]

Equation stating that the change in velocity (delta-v) of a single stage rocket is equal to the exhaust velocity times the natural log of the ratio of final to initial mass, named after Russian scientist Konstantin Tsiolkovsky.

Filter by
Sorted by
Tagged with
4 votes
1 answer
195 views

Would that asteroid transport be possible?

I did the mistake of watching an episode of the Science Fiction series "For All Mankind". There they are trying to catch an asteroid in order to bring it back to Mars. I know this series is ...
Tobias Reich's user avatar
3 votes
0 answers
99 views

How can I calculate the altitude my waterrocket will fly with a certain amount of pressure?

I am trying to calculate how high my waterrocket will fly before launching it at different pressure using the Tsiolkovsky rocket equation. However, I stumbled upon an issue since the altitude that it ...
The Rocket fan's user avatar
4 votes
2 answers
270 views

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 ...
Tom's user avatar
  • 141
-1 votes
1 answer
124 views

What should be the fuel mass of a hypersonic (Mach 7) rocket using APCP fuel that would deliver a 50 gram payload?

Well, I used this rocket calculator besides asking ChatGPT and BingGPT and both gave me similar answers where the amount of fuel would be around 300 to 4000 grams of APCP fuel. And 30 to 100 grams for ...
Fulano's user avatar
  • 153
1 vote
0 answers
108 views

How high will this rocket be, when MECO occurs?

Find the altitude of the rocket at the time of engine cut-off. Rocket Mass = 369208 kg, Rocket Area = 391 m2, Fuel = 170697 L, Fuel density = 21 kg/l, Exhaust Speed = 1338 m/s, Exhaust Area = 164 m2
Praveen Kumar's user avatar
2 votes
0 answers
143 views

What was the exhaust pressure of the Saturn V? [duplicate]

I am trying to write some code to simulate rocket launches, and I am doing a proof of concept using the Apollo 11 as a model, to fill my values. When calculating thrust I am using the equation: F=m⋅Ve+...
owinius's user avatar
  • 31
7 votes
1 answer
1k views

How do you find the propellant mass needed to reach an specified altitude? (altitude at end of burn plus altitude during coast)

This question is basically entirely explained in the title, but I'll explain it more so this question doesn't get shut down. Basically, does anyone have an equation to find the propellant mass(solid) ...
Anish Kommireddy's user avatar
3 votes
1 answer
152 views

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 ...
confused_aspirant's user avatar
5 votes
1 answer
196 views

How to calculate the optimal mass ratio for a multistage water rocket?

I do know about the Tsiolkovsky rocket equation for optimising multistage rockets, however the equation requires a fixed exhaust velocity which is something that water rockets don't have, however I ...
notanengineer's user avatar
0 votes
0 answers
130 views

How to estimate the fuel required to send 1 kg to lower mars orbit?

Imagine a rocket with a payload of 1 kg. How much liquid fuel would be required to send that 1 kg payload to lower mars orbit. (1 kg is just the payload not the whole dry mass of the rocket) I want ...
Shardul's user avatar
1 vote
0 answers
54 views

How is the rocket equation affected by changing the number of engines or boosters? [duplicate]

Specific impulse is not affected by the number of boosters or engines on a rocket, correct? Let's say I take a rocket with two SRBs and add to more for the first stage. The specific impulse of the ...
Put1demerde's user avatar
3 votes
2 answers
2k views

How to account for burned fuel mass when calculating spacecraft acceleration?

I thought I could simply remove half of the burned fuel mass to account for the mass lost during the engine burn. But I could not find a Newton's Second Law formula Calculator that would allow that, ...
TheMatrix Equation-balance's user avatar
-3 votes
1 answer
172 views

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?
Peanut 's user avatar
3 votes
2 answers
1k views

Comparing Newtons 2nd law and Tsiolkovskys

I've been attempting to simulate a rocket launch, using: ΣF= ma + md/dt*v If ΣF is simplified to only include F_m, being the rocket's thrust, the equation, if solved for a, is: a = (F_m - md/dt*v)/...
Lodmun's user avatar
  • 31
1 vote
0 answers
96 views

rocket propulsion elements [closed]

i tried to solve the following problem this rocket engine area is cut off at 50% of the exit area, calculate the new Mach value. data old engine: P1=2068Mpa , chamber temp 2222k , flow mass 1kg/sec ,...
richard p's user avatar
2 votes
2 answers
485 views

How do you calculate fuel usage ratio for rocket acceleration vs deceleration using a fixed total amount of fuel?

If a rocket is accelerating and then decelerating to stop at a destination (not necessarily continuous acceleration), and you want to use a given total amount of fuel, how do you calculate the amount ...
tomwoodward's user avatar
5 votes
1 answer
216 views

Variant of the Tsiolkovsky rocket equation including engine specific power and efficiency, can anyone help me under stand how this works

First of all this code is not mine I am trying to understand how the equation for m_u works. This comes from a master thesis called Trajectory design for a Titan mission using the Direct Fusion Drive ...
Gwyn Davies's user avatar
4 votes
1 answer
317 views

Chamber Pressure and Burn Rate equations

I know that chamber pressure is $$P_0=p \left[ 1+ \frac{1}{2}(k-1)M^2 \right]^\frac{k}{k-1}$$ where $M$ is exit Mach number and according this equation $$M= \sqrt{ \frac{2}{k-1} \left[ \left( \frac{...
user3473485's user avatar
1 vote
1 answer
104 views

How would I calculate the extra change in velocity due to residual thrust?

I'm trying to script a hover slam in a simulated environment using generic kinematic equations to calculate the correct throttle values I should be matching. I cut the throttle of my engine when my ...
Sam's user avatar
  • 373
0 votes
1 answer
81 views

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 ...
Jithin's user avatar
  • 61
1 vote
1 answer
1k views

Formula for Determining Time to Perform Delta-V Burn Given Propulsion System Parameters

Question is as stated. Determining how much delta-V one needs to change orbits is pretty straight forward with the rocket equation. However, I’d like to see if there’s a way to calculate delta-V from ...
Colin Warn's user avatar
5 votes
1 answer
776 views

Calculating the propellant needed for a trip from LEO to Low Mars Orbit at constant acceleration of 1g

I’ve been trying to calculate how much propellant a spaceship from Earth /LEO/ to Mars /LMO/ at constant acceleration of 1g would need. Here’s the data given: dry mass mf=100 t; g=9,81 m/s^2; Isp=...
sea_for's user avatar
  • 91
1 vote
1 answer
150 views

What is the equation to find how much fuel you need to reach a velocity? [closed]

Theoretically, I need to launch a rocket, and I need to find how much fuel I need to reach a velocity however I do not know the equation.
user46782's user avatar
13 votes
4 answers
4k views

What does `ln` mean in the Delta V equation?

I am working on a project for school and can't figure out what ln means in the Delta-V equation, as in Δv = VE * ln(ML / ME). I know that Δv is Delta V, VE is ...
Curious 8th grader's user avatar
0 votes
0 answers
127 views

What are the Specific heat ratios of fluorine, Isopropyl Alcohol and Uranium?

I needed to calculate thrust and velocities of a rocket engine and its exhaust and in order to do that, I needed the values of Specific heat ratio(k) of Fluorine and k of Uranium and Isopropyl Alcohol....
TheNerdium's user avatar
1 vote
0 answers
256 views

Tsiolkowsky including gravity and air drag

in the classical theory Tsiolkowsky is normally explained as: $\Delta v=v_{eff}*\text{ln}\frac{m_0}{m_b} $ Then the books say, for staying in LEO one need approx. $\Delta v=7.8$ km/s But what about ...
Max H.'s user avatar
  • 11
3 votes
1 answer
289 views

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 ...
Kurt Hikes's user avatar
0 votes
1 answer
229 views

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?
Ishaan Manish's user avatar
3 votes
1 answer
338 views

The thrust in the calculation of specific impulse

In calculating the specific impulse using the thrust generated as one of the parameters, do we take the total thrust generated or the average thrust over the period of the burn? $I_{sp} = \frac{F_{...
Rocket Hack's user avatar
3 votes
0 answers
205 views

How would you calculate the Delta-v needed to intersect a target on the ground on a sub-orbital trajectory?

Let's say I have a sub-orbital trajectory, meaning I'm going to crash into the earth at some point within the first orbital period. I know the true anomaly in which I will impact the surface and by ...
Sam's user avatar
  • 373
5 votes
2 answers
801 views

About optimal staging and structure fractions

I have recently came across an assignment where I have to do optimal staging of rockets using Lagrange multipliers. I am suppose to optimize the mass of each stage of a well-known rocket(I chose ...
Joshua Woo's user avatar
2 votes
2 answers
464 views

What does "m Δv" stand for in the rocket equation?

I'm currently trying to understand how the Rocket Equation works. I've gotten this far: mv = (m+Δm)(v+Δv) − Δm(v−ve) Left side is the momentum of the rocket+fuel BEFORE, and right side is the momentum ...
Cliff Miles's user avatar
0 votes
0 answers
128 views

How could I find the pressure and/or the Isp at the exit of a rocket nozzle if I have data for the throat and comb. chamber?

I've been looking at this for some time and working with CEA which will only give me data points for the pressure, temperature, Isp, etc. for the Injection, Combustion Chamber End, and the Throat; but ...
Juanita's user avatar
3 votes
5 answers
963 views

Why is hydrogen better than helium as remass?

I just watched a very good YouTube video on why nuclear engines might be useful, and it also goes into why Hall Effect thrusters are super good at squeezing obscene ISP out of things. During the video,...
William Walker III's user avatar
4 votes
2 answers
855 views

Specific impulse and delta-v in Tsiolkovsky's rocket equation

According to Tsiolkovsky's rocket equation, it is possible to calculate the delta-v of a multistage rocket if you know the characteristics of each stage of the rocket. In my case, the only ...
Miguel's user avatar
  • 103
3 votes
1 answer
202 views

Is a cheap English translation available of Tsiolkovsky's "Outside the Earth"?

Anyone know where to pick up a copy of Konstantin Tsiolkovsky's science fiction book titled "Outside the Earth" (alternately titled: "Beyond the Planet Earth" and "Beyond ...
SpaceDisgrace's user avatar
1 vote
0 answers
69 views

Sources for values for realistic thrust calculation exercise?

I want to use this simplified equation to calculate the thrust of multiple different real engines: $$F = \dot{m} V_e + (p_e - p_0) A_e$$ Source: https://www.grc.nasa.gov/www/k-12/airplane/rockth....
JKamue's user avatar
  • 11
3 votes
1 answer
162 views

How can I use the Rocket Equation and Staging for a ballistic flight?

I want to calculate the a) thrust b) mass of fuel c) optimal staging of a rocket, which shall fly up to for example an altitude of 50 km in a ballistic flight trajectory. In school I learned the ...
Lucas's user avatar
  • 31
1 vote
0 answers
138 views

Design impact on Chamber pressure

What is forming the amount of chamber pressure which is produced in a rocket engine and why would you like to have an higher chamber pressure? I was calculating the SpaceX Raptor engine for myself, ...
Steve's user avatar
  • 11
2 votes
0 answers
172 views

How much lower is max q if launching from high altitude (i.e. mountain top)?

I looked at very simple max q formula: q=1/2 ρv^2 (https://en.wikipedia.org/wiki/Max_q). As air density is lower with altitude, the max q should be lower as well, and also should occur at higher ...
gvidas astromskas's user avatar
1 vote
1 answer
87 views

Would major changes since "Equations of powered rocket ascent and orbit trajectory" was written reduce its applicability?

I was wondering where I can learn how to calculate the trajectory of present day launch vehicles. I've stumbled upon this book, called Equations of powered rocket ascent and orbit trajectory. ...
mad.redhead's user avatar
4 votes
4 answers
2k views

Payload capacity of a rocket

Why does a rocket have far more payload capacity when placing an object in LEO compared to when it's placing the object in farther orbits, like on the Moon? If a rocket has sufficient thrust to take ...
Niranjan's user avatar
  • 3,758
1 vote
1 answer
948 views

Spacecraft propulsion, Thrust, Delta V

For a spacecraft on an interplanetary mission (e.g. Mars), after deciding the propellant ISP value and Delta V required, how do you calculate the thrust required? $$F = \dot{m} V_e + (p_e - p_0) A_e$$ ...
RR batman's user avatar
2 votes
1 answer
966 views

Why can I not use stoichiometry to calculate the O/F ratio of my rocket? [duplicate]

I am attempting to calculate the oxygen to fuel ratio (O/F) for my hybrid rocket engine (paraffin wax and gaseous oxygen). I know I can use the oxidizer to fuel equation to calculate this, but my ...
Joaquin Revello Lerena's user avatar
2 votes
1 answer
102 views

Specific Heat Ratio for a perfect gas mixture

I am reading Rocket Propulsion Elements by George P. Sutton & Oscar Biblarz, 9th Edition. In the fifth chapter, I was introduce to the specific heat ratio k for the perfect gas mixture, Eq. 5-7: (...
John Ortiz's user avatar
10 votes
2 answers
714 views

Do lower pressure pressure-fed rockets get more Delta-V?

I was playing around with the math for getting a pressure-fed rocket to orbit and came across something that I haven't seen addressed anywhere. In a pressure-fed rocket, the chamber pressure of the ...
Orion DeYoe's user avatar
5 votes
1 answer
305 views

Convert the impulsive solution to a low-thrust

The spacecraft transfers from an orbit with the following parameters: Perigee - 700 km Apogee - 6000 km Inclination - 64 deg Argument of perigee - 250 deg to and orbit with the parameters: Perigee -...
Leeloo's user avatar
  • 703
3 votes
1 answer
461 views

I don't know where to start with the calculations - rocket engine

Last year I stumbled upon the "How to design, build and test a rocket engine" pdf and since then I have been intrigued by making one (or at least calculating it). So I've been doing some ...
StarshipGood's user avatar
1 vote
0 answers
86 views

Need help finding a clean expression for exit velocity [duplicate]

I'm trying to calculate a engine burning LOX and ethanol (96%) and for that I am using both CEAgui, a GUI for NASA's CEA (Chemical Equilibrium with Applications) code Sutton's Rocket Propulsion ...
StarshipGood's user avatar
1 vote
1 answer
1k views

Delta-v difference between Mars and Moon

Considering a simple Hohmann transfer, does it take less Delta-v and propellant to go to Mars than to the Moon
HAL4108's user avatar
  • 21