Determining a gas volume in a tank device

A rocket for use in space, comprising

• a power unit, and
• at least one tank device for a tank liquid, wherein the tank device comprises:
• a pressure vessel, in an interior of which a first chamber for the tank liquid and a second chamber are constructed, wherein the first and the second chamber are closed off with respect to each other and are in operative connection by means of at least one membrane, which separates the first and second chambers and is configured to vibrate;
• at least one controllable element for effecting a pressure surge in the pressure vessel;
• a pressure sensor for detecting a pressure vibration in at least one of the first or second chambers resulting from the pressure surge;
• a temperature sensor for measuring a temperature in the pressure vessel, and
• an evaluation device configured to determine a gas volume in the pressure vessel from a detected pressure vibration and a measured temperature,
• the tank being configured to supply the rocket with fuel,
• wherein the controllable element comprises a controllable valve, via which a gas for effecting a pressure surge is let into the first chamber or is drained out of the first chamber.

A method for determining a gas volume in a pressure vessel of a tank device, wherein the pressure vessel has a first chamber for a tank liquid and a second chamber wherein the first and the second chamber are closed off with respect to each other and are in operative connection by means of at least one membrane which separates the first and second chambers and is capable of vibration, and wherein the method comprises:

• exciting a pressure vibration in the first chamber by means of at least one of
• supplying gas into the first chamber by means of a controllable valve of the pressure vessel,
• draining gas out of the first chamber by means of a controllable valve of the pressure vessel;
• detecting a pressure vibration in at least one of the first or second chamber;
• measuring a temperature in the pressure vessel;
• and
• determining the gas volume in the pressure vessel from a detected pressure vibration and a measured temperature.