Abstract

New fuel-efficient aircraft designs have high aspect ratio wings. Consequently, those aircraft are more flexible. Additionally, load alleviation functions are implemented to reduce the structural loads, which results in further reductions of the structural stiffness. At the same time, the structural design impacts other disciplines in preliminary aircraft design, especially flight mechanics. For example, it is important to know how at that design stage such flexible aircraft with load alleviation affect passenger ride comfort in turbulent flight. For an efficient design process, it is essential to answer such questions with accurate multi-disciplinary tools and methods as early as possible to minimize development risk and avoid costly and time-consuming redesign loops. Current available tools and methods are not accurate enough for this task. To address this issue, the DLR MONA based design and the TUB flight mechanical assessment tool MITRA are linked to investigate the impact of the structural design on specific flight mechanical assessments such as passenger ride comfort. This is particularly interesting since the implemented load alleviation functions are designed to reduce loads, and not explicitly to improve passenger ride comfort. By conducting this assessment for a particular aircraft configuration, more insight into passenger ride comfort and the key contributors can be gained during preliminary design. This paper describes the combined toolchain and its application on a generic long-range reference aircraft to investigate the effects of load alleviation functions on passenger ride comfort and discusses the results.

Highlights

  • New fuel-efficient aircraft designs have high aspect ratio wings and lower structural masses, as currently shown with A330-800 and B777x, and are more flexible

  • First vertical fuselage bending mode. This toolchain and the subsequent assessment is demonstrated on a generic long-range reference (GLR) aircraft configuration designed for 250 passengers, see Sect

  • For the design process and for the ride comfort investigation in this work, the reference aircraft is equipped with load alleviation functions comprising manoeuvre load alleviation (MLA) and gust load alleviation (GLA) based on Ref. [6]

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Summary

Introduction

New fuel-efficient aircraft designs have high aspect ratio wings and lower structural masses, as currently shown with A330-800 and B777x, and are more flexible. They are not accurate enough to investigate the impact of coupling effects of advanced load design and flight mechanics To address this issue, the German Aerospace Center (DLR) loads analysis and structural optimization process [2] and the flight mechanical assessment tool MITRA of Technische Universität Berlin (TUB) [3] are linked together for a seamless flight mechanical evaluation of structural design choices, see Fig. 1. Wing area Wing span Mean aerodynamic chord Operating empty mass (OEM) Maximum take off mass (MTOM) Cruise Mach number This toolchain and the subsequent assessment is demonstrated on a generic long-range reference (GLR) aircraft configuration designed for 250 passengers, see Sect. Due to the modular tool structure, other control configurations can be implemented and assessed using the same methods to find an optimal design

Design process with integrated load alleviation
Process of loads analysis and structural optimization
Gust load alleviation
Export for flight mechanical evaluation
Flight mechanical evaluation
Passenger ride comfort criteria
Test description
Simulation results
Discomfort results
Conclusion
Findings
12. US Department of Defense
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