Sorry, but this does not make sense in the way you intended. Your 42.1 km/s escape velocity "from earth" is the velocity you need, relative to the sun, at eart

Sorry, but this does not make sense in the way you intended. Your 42.1 km/s escape velocity "from earth" is the velocity you need, relative to the sun, at earth's orbital distance from the sun, to escape from the solar system [1]. As you get farther away from the center of gravity, your speed gradually slows down and reaches zero at infinity [2]. So your maximum amount of time for interstellar travel calculation is flawed and underestimates travel time by assumedly few orders of magnitude. [1] https://encyclopedia2.thefreedictionary.com/Solar+System+Escape+Velocity https://encyclopedia2.thefreedictionary.com/Solar+System+Esc... [2] https://en.wikipedia.org/wiki/Escape_velocity https://en.wikipedia.org/wiki/Escape_velocity