US Patent 12104559 Vapor retention device

Embodiments of the present invention generally relate to a vapor retention device and methods of using a vapor retention device to manage propellant for upper stage space vehicles. The use of a vapor retention device, in combination with controlled acceleration, drives liquid propellant from a propellant supply line communicating with an upper stage main engine back into a propellant tank and establishes an insulating liquid/gas propellant interface that prevents the exchange of gaseous propellant across the interface.