Integration of a Liquid Hydrogen Fuel Tank into the Concept of the Flying-V

The amount of emissions produced by aviation resulting from the use of kerosene is raising concerns. Therefore, a main point of developments and research in the aviation sector is regarding the reduction of its climate impact. The climate impact of aviation can be reduced by making use of alternative fuels, such as liquid hydrogen. A suitable candidate for the use of liquid hydrogen may<br/>be the Flying-V. The Flying-V is a flying wing aircraft with the fuselage sections inside the wings. The wing are swept back to form the shape of a V. The original concept of the Flying-V promised improvements in aerodynamic efficiency and a lower mass compared to its reference aircraft, an A350-900. The Flying-V is in further development at the TU Delft. A liquid hydrogen fuel tank is integrated into the concept of the Flying-V. The objective of the research is to contribute to the development of a Flying-V with liquid hydrogen, by making an assessment of the implications on the fuel system and the effect on mission performance resulting from the change of fuel. A parametrization of the fuel tank is defined while keeping the outer mold line of the Flying-V constant. The fuel tank is located in the tapered part of the wing and is designed to be an integral fuel tank. The mechanical and thermal design of the tank is analyzed for a range of pressures and insulation thickness. Using a thermal resistance analogy the heat transfer rate of the ambient temperature to the liquid hydrogen is determined, resulting in the performance of the fuel tank. The main performance parameters of the fuel tank are the available fuel volume and the fuel tank weight. The influence of the integration of the fuel tank on the mission performance is analyzed and compared to the flight performance of a kerosene based Flying-V, the FV-900. The flight performance analysis uses fuel fractions and the Breguet range equation to determine the available cruise range fromthe available fuel volume. The FV-900 is compared to two case studies each using three different configurations. The first case study consists of a retrofit case, where an existing Flying-V is retrofitted with a set of hydrogen fuel tanks. The second case study allows an iteration of the structure to take into account the portion of the maximum take-off weight that is not used due to the decrease in fuel weight when changing kerosene for liquid hydrogen. Regarding the different configurations, these include different combinations of fuel volume and cargo volume. Configuration 1 has the largest fuel volume with a minimal cargo volume. Configuration 2 ensures there is enough cargo volume for the luggage of 440 passengers in exchange for fuel volume. Configuration 3 increase the fuel volume slightly, compared to configuration 2, and has enough cargo volume for the luggage of the design number of 328 passengers. It is concluded the available fuel volume is not enough for liquid hydrogen to have equivalent flight performance compared to a kerosene based Flying-V. In case of the retrofit the operating empty weight is increased up to 8.7%. All configurations have a lower range. Regarding the largest fuel volume, the range is 35%, 42% and 51% lower for 440, 328 and 250 passengers, respectively, compared to the FV-900. In case of the structure iteration the take-off weight is reduced by 32%, 37% and 37% for configuration 1 to 3, respectively. All the configurations have a lower range compared to the FV-900. Again, regarding the largest fuel volume, the range is 18%, 23% and 32% lower for 440, 328 and 250 passengers, respectively, compared to the FV-900. The configurationswhere the payload volume is sufficient have a significantly lower range. This research provides usable designs of a Flying-V using liquid hydrogen if one is willing to compromise on the range and available payload weight for no CO2 emissions. However, keeping the payload weight up, the available volume left is not enough volume for liquid hydrogen to have equivalent flight performance.