Propeller Design for Conceptual Turboprop Aircraft

In the conceptual design phase of a turboprop aircraft, the configuration is determined and primary components like the wing, fuselage and propulsion are sized. Exact subsystem performance remains unknown. Propeller performance is estimated to size the aircraft propulsion. This thesis explores the consequences on the aircraft’s maximumtake-off mass if the propeller estimation is removed in favor of a higher fidelity design approach. The influence is determined by implementing an optimization routine whichminimizes aircraft maximum take-off mass by adjusting the propeller design. A rapid conceptual design tool is used to establish the interdependence between propeller and aircraft: ‘The Aircraft Design Initiator’. This tool is able to quickly conceive realistic aircraft designs to investigate the effect of new technologies and aircraft configurations. The Initiator is employed to create a design objective. This objective contains the information needed to achieve an optimumbetween propeller aerodynamic efficiency and its implication on the mass of the propulsion unit. These two factors determine the fuel required for the mission, as well as the mass of the propeller engine combination. In turn, these masses impact the maximum take-off mass of the aircraft. To establish a propeller design, a set of tools is developed. Aerodynamic performance is calculated from blade element momentum theory. Mass estimation is performed by a class II sizing approach. A limited structural tool is used to size the propeller blade root. Propeller optimization is performed with two strategies: a gradient descent optimization and a genetic algorithm. It is concluded that the propeller design space features a lot of local minima and is poorly suited for gradient based optimization. Genetic optimization is better suited for propeller design. This strategy results in certain conclusions regarding propeller design influences on the aircraft’smaximumtake-off mass. The influence of the propeller on the maximumtake-off mass is determined to be less than 1% compared to initial performance estimations. The applicability to conceptual aircraft design is therefore limited. However, the results do clearly show the influence of the propeller design parameters on the aircraft’s maximum take-off mass.