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.

The Tsiolkovsky Rocket Equation states 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. It is named after Russian scientist Konstantin Tsiolkovsky.

$$\Delta v = v_{ex} log\left( \frac{m_0}{m_f} \right)$$

where $m_0$ and $m_f$ are the initial and final masses and $v_e$ is the exhaust velocity.

The equation should be applied to a single stage at a time, because it assumes that all of the change in mass ($m_0 - m_f$) is reaction mass, leaving at the exhaust velocity $v_e$.

Further reading:

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How does the Rocket Equation work when you use boosters?

For simple rockets, using the rocket equation is simple enough. $$ \Delta v = v_e ln\left(\frac{m_i}{m_f}\right) = I_{sp} \ g \ ln\left(\frac{m_i}{m_f}\right) $$ plug in full and empty weights and Isp, and you're done. But what to do when a rocket…
Hobbes
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How much thrust needed to move 6,000 kg from LEO to Lunar Orbit?

I'm trying to see how much thrust in needed to move 6,000 kg (1 surplus LK lander) from low earth orbit to lunar orbit? Even better would be to know what is currently available (off the shelf) to do the job knowing that there will have to be…
Jeff
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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 the drag resistance the rocket encounters and the…
Max H.
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Saturn S-IVB math

https://en.m.wikipedia.org/wiki/Saturn_V https://physics.stackexchange.com/questions/88145/why-are-rockets-so-big/88163#88163 User Asad posted a graph based on rocket science. https://i.stack.imgur.com/hZ8Tn.png His graph indicates that the dry mass…