Selected methods of the aviation safety assessment process according to ARP 4761 are introduced and conducted within the scope of a concept study for future broadband acoustic liners. While having similar primary functions and basic design, the acoustic liner concepts diverge concerning subfunctions and potential malfunctions. With the ARP 4761 safety assessment methods, significant differences in sub functions and possible malfunctions of the concepts can be identified. The results of the safety assessment are discussed, and the concepts are evaluated in terms of feasibility and safety.
The challenge of determining ideal inlet geometries for variable pitot aero engine inlets in transonic and supersonic civil aviation is presented. The trade-off in inlet design and the geometric inlet parameters are introduced. By means of a parametric design study, feasible inlet geometries for variable inlets are identified and the potential aerodynamic benefit of using variable pitot inlets for flight speeds from Mach 0.95, 1.3 up to 1.6 is examined. After considering the additional weight of variable inlets, for instance due to required actuators, a remaining range benefit of over 20% at a flight speed of Mach 1.6 is determined.
This paper focusses on the challenge of determining the ideal inlet geometries within a concept study for variable pitot aero engine inlets in transonic and supersonic civil aviation. The trade-off in inlet design and the geometric parameters of inlets for different Mach numbers are introduced. The utilised process of the parametric design study and its implementation are presented. The dependencies of inlet drag and occurrence of flow separation from geometric parameters are examined. The ideal inlet geometries are identified to determine the potential aerodynamic benefit of using variable pitot inlets. The comparison of the identified geometries with the reference reveals a significant drag reduction at the investigated flight speeds of Mach 0.95, 1.3 and 1.6. While the drag reduction potentially leads to decreased fuel consumption and increased flight range, the application of variable inlet systems entails additional weight and complexity. By means of a simplified Breguet range equation, the benefit of using variable pitot inlets has been determined. For an additional weight of 500 kg per variable inlet, the range benefit nearly disappears for subsonic applications up to Mach 0.95, while a range benefit of over 20% remains for supersonic applications at Mach 1.6.
The motivation for designing variable pitot inlets for future supersonic transport (SST) is explained. A comprehensive overview of existing technological solutions for variable leading edges of aircraft wings and engine inlets is given. The advantages and limitations of over 80 solutions, as well as their relevance for application on variable pitot inlets for SST are described. The challenges of existing solution options concerning design methodologies, level of detail, and experience with a technology are identified.