eindmassa

Eindmassa, in Dutch, refers to the final mass of a system after a defined process has ended. It is the mass remaining at the end of the considered interval and is typically used to describe the state after a change such as propellant burn or stage separation. The concept is usually paired with beginmassa (initial mass), so that the mass ratio m0/mf expresses how much mass was expended during the process.

In propulsion, eindmassa is a central quantity. The initial mass m0 represents the vehicle with its full propellant load, while the eindmassa mf is the mass after burning a portion of that propellant. The mass ratio m0/mf is a key parameter in determining velocity change, as illustrated by the Tsiolkovsky rocket equation: Δv = Isp · g0 · ln(m0/mf). The final mass mf is given by mf = m0 − m_propellant, where m_propellant is the mass of propellant consumed during the burn.

Beyond rocketry, eindmassa is used in other engineering contexts to track mass changes during stages, separations, payload deployment, or any scenario where the end-state mass is needed for performance, stability, or structural analyses. It is a practical measure of how much mass remains after a defined operation.

Etymologically, eindmassa literally means final mass in Dutch, contrasting with beginmassa (initial mass). It is distinct from rustmassa (rest mass) in its role as a state variable tied to a particular process, rather than a property of a particle. The term is common in Dutch technical literature and manuals dealing with mass budgeting and propulsion.