Basic Maneuver Load Alleviation in Conceptual Aircraft Design

Abstract

Evaluating load alleviation technologies in conceptual aircraft design requires a cross-disciplinary simulation approach. In particular the design framework has to include a coupled, physics-based consideration of the disciplines aerodynamics, structures and flight dynamics rather than handbook equations. An approach like that enables the identification of possible overall aircraft efficiency benefits with active load alleviation. This paper presents a process that complies with the required level of fidelity, integrating flight control and aero-elasticity into the conceptual aircraft design. The software ASWING is included and provides an unsteady lifting-line calculation combined with non-linear Euler beam theory. It is evaluated how aerodynamic load reduction and wing geometry layouts affect the overall aircraft design. The aircraft design is, in contrast to the more detailed wing sizing, based on handbook methods. Maneuver load cases are evaluated. A combined fuel consumption of three flight missions is the main parameter for the evaluation. Geometrical constraints for the tank volume and the span limit are discussed. A simplified, so-called 2.5D- method sizes the wing box based on a carbon-fiber-reinforced polymer topology. The design space contains up to 1008 aircraft designs varied in six design parameters. This set of aircraft design points is evaluated without any and with maneuver load alleviation. The findings show a combined maximum load alleviation and shape optimization potential in fuel burn of 17.6 % without further constraints. For the constrained design space the maximum fuel benefit is 11.4 % compared to the reference aircraft.