Flying qualities reliability constraints in aircraft conceptual design using time-marching simulations

Abstract

Aircraft conceptual design, especially when novel concepts are involved, is inherently affected by uncertainty. Although many efforts are done to include more physics at the earliest design phases, often information on impact of the underlying uncertainty is missing. This work proposes an approach to incorporate uncertainty into aircraft conceptual design through reliability constraints on some desired dynamic performance requirements. These are estimated from unsteady time-domain simulations through a system identification process, leveraging on three available aerodynamic fidelity levels. Uncertainty propagation is addressed by a polynomial chaos expansion technique. After presenting the structure and the validation of the proposed framework, a demonstrative application of fuel mass optimization for a transport aircraft under uncertainty is performed, with reliability constraints on short period characteristics.

Toward Building a Functional Image of the Design Object in CAD

“…The traditional solution to the problem of selecting rational options for design solutions at the preliminary design stage is to use empirical or approximate analytical dependencies to determine the aerodynamic and flight characteristics [14]. The same path was proposed in the works of recent years [15,16]. A similar approach to the AS problem (search for analogs, enumeration of combinations of circuit features, and calculation of characteristics based on simplified dependencies) also prevailed in [17,18].…”