Residual fuel

Residual propellant refers to liquid or gaseous propellants and other liquids that remain in spacecraft or launch vehicles after completion of their mission or a specific mission segment. These propellants cannot be used as expendable propellants or drained from the vehicle without significant disassembly of the system.

Residual fuel in spacecraft

In spacecraft, residual fuel includes all liquid or gaseous propellants that remain in the vehicle after the mission or a specific maneuver has been completed. These propellants are often no longer usable as they cannot be easily removed from the system. Residual fuel can remain in the system for various reasons, including

Incomplete combustion: Not all fuels are completely burned during the mission, resulting in residual quantities.
System design: Certain design aspects of the spacecraft may result in propellants remaining in tanks or lines that cannot be completely drained.
Safety requirements: For safety reasons, it may be necessary to leave certain quantities of fuel in the system in order to minimize risks.

Residual propellant in launch vehicles

For launch vehicles, residual propellant refers to liquid or gaseous propellants that remain on board a stage after that stage has completed its part of the mission. This residual propellant can be present for various reasons:

Fuel management: During the flight, it can be difficult to control fuel consumption precisely, resulting in residual quantities.
Step separation: When separating a stage, not all of the fuel can be consumed, resulting in residual fuel in the tanks.
Safety margins: To ensure that the stage can successfully complete its mission, an additional amount of fuel is often carried that is not fully consumed.

Meaning of residual fuel

The residual fuel is important for several reasons:

Mass calculations: The residual propellant contributes to the total mass of the spacecraft or launch vehicle and must be taken into account in mass calculations and performance analyses.
Safety aspects: The handling of residual fuel is of great importance for safety reasons, as remaining fuel can pose potential risks.
Mission efficiency: The amount of residual fuel can influence the efficiency of a mission, as unused fuel represents additional mass that needs to be transported.

Dealing with residual fuel

The handling of residual fuel requires careful planning and management to ensure that all safety and performance requirements are met. This may include the following measures:

Fuel management systems: These systems help to optimize fuel consumption and minimize the amount of residual fuel.
Security protocols: Safety protocols are required to ensure that residual fuels are handled and stored safely.
Design optimization: By optimizing the design of spacecraft and launch vehicles, the amount of residual fuel can be reduced.

Summary