The landing gear is one of the major aircraft systems, which has a significant effect on the overall aircraft performance. It is one of the largest aircraft systems which contributes a large part to the overall aircraft weight. Landing gear attachment loads from landing, take-off and ground maneuvers of the aircraft are usually design load cases of major airframe parts such as the rear fuselage and the wing center section. As a result, an optimum design of the landing gear system plays a significant role in the final optimum aircraft design. The current state-of-the-art of the landing gear conceptual design process is based on experience from existing aircraft configurations. This process has been proven in most cases to lead to satisfactory designs. The current process reaches its limitation, however, if the landing gear system must be designed for an unconventional aircraft like a Blended Wing Body (BWB), where no data is available for comparison. In the past years a number of design suggestions have been proposed for the BWB such as several wing planforms or a number of distributed propulsion systems. However, there have been only few proposals for BWB landing gear configurations. Because of these reasons the objective of this thesis is to propose a landing gear conceptual configuration for the BWB and to investigate the ground loads-related design issues of the BWB. The research focuses on the following design aspects: a BWB ground loads determination, a BWB landing gear weight estimation, the assessment of the ground loads effect on the aircraft structure and finally the proposal of a conceptual landing gear configuration. In order to investigate these issues, this thesis introduces a new integrated Multidisciplinary Optimization process. The first essential element of the process is the determination of the unknown dynamical ground loads for a BWB. The Multi-Body Simulation method is selected because of its capability for the analysis of complex system dynamics including dynamic loads. The second element is the landing gear weight determination. An analytical conceptual design method is implemented to design each landing gear component individually for the weight determination. As the third element, a conceptual landing gear bay 3D finite element model is generated to investigate the ground loads effect on the aircraft structure. The capability of the new process is validated by a conceptual redesign of the landing gear system of an aircraft comparable to the BWB in terms of aircraft total weight and landing gear configuration. The process is then implemented for the landing gear conceptual design of a BWB transport aircraft. Four different configurations of different numbers of main landing gears (MLG) of 4, 6, 8 and 12 are designed, analyzed and optimized. According to the results from the validation design case, the process has been proven to be able to realistically predict the ground loads for the BWB. It has been found that the lateral ground loads from the asymmetric landing case play a significant role for the landing gear design. One MLG must be located at the most backward corner and other MLGs must be positioned in a triangle-like topology in order to distribute the landing energy from this landing case. Concerning the total weight result, it has been discovered that the total weight is reduced with an increase in the number of MLG. The weight reduction comes from the lower ground loads of the high MLG number configurations. However, if the number of MLG is too high this advantage will be outstripped by too many MLG components. As the result, the concept with 8 MLG has an optimum total weight for the given BWB configuration. Finally, the obtained knowledge, the new process accomplishments and open problems are discussed.
