One big factor that the Tsiolkovsky rocket equation fails to account for is the square–cube law. When you scale up a rocket, the mass of the structure of the ro

One big factor that the Tsiolkovsky rocket equation fails to account for is the square–cube law. When you scale up a rocket, the mass of the structure of the rocket tends to grow more slowly than the mass of the fuel it contains, which more or less cancels out the log term in the rocket equation. Note that this does not necessarily hold true for extremely small or extremely large rockets.