On the Importance of Nonlinear Aeroelasticity and Energy Efficiency in Design of Flying Wing Aircraft

Abstract

Energy efficiency plays important role in aeroelastic design of flying wing aircraft and may be attained by use of lightweight structures as well as solar energy. NATASHA (Nonlinear Aeroelastic Trim And Stability of HALE Aircraft) is a newly developed computer program which uses a nonlinear composite beam theory that eliminates the difficulties in aeroelastic simulations of flexible high-aspect-ratio wings which undergoes large deformation, as well as the singularities due to finite rotations. NATASHA has shown that proper engine placement could significantly increase the aeroelastic flight envelope which typically leads to more flexible and lighter aircraft. The areas of minimum kinetic energy for the lower frequency modes are in accordance with the zones with maximum flutter speed and have the potential to save computational effort. Another aspect of energy efficiency for High Altitude, Long Endurance (HALE) drones stems from needing to minimize energy consumption because of limitations on the source of energy, that is, solar power. NATASHA is capable of simulating the aeroelastic passive morphing maneuver (i.e., morphing without relying on actuators) and at as near zero energy cost as possible of the aircraft so as the solar panels installed on the wing are in maximum exposure to sun during different time of the day.

Propeller influence on the aeroelastic stability of High Altitude Long Endurance aircraft

“…Separate research group efforts have developed aeroelastic framework capable of taking into account the nonlinear aspects of the VFA behavior. Examples of state of the art codes in this context cited on literature are UM/NAST (17,18,19) from University of Michigan, SHARPy (20,21,22,23) from London Imperial College, ASWING (24,25,26) from Massachusetts Institute of Technology, NATASHA (27,28) , from Georgia Institute of Technology, and DLR toolbox (29,30) , from Deutsches Zentrum für Luft-und Raumfahrt (DLR).…”

Nonlinear Modal Condensation of Large Finite Element Models: Application of Hodges’s Intrinsic Theory

“…Upon calculation of the discrete intrinsic modes, Φ Φ Φ 1 and Φ Φ Φ 2 , interpolation is required to construct the functionals that will be integrated to obtain the nonlinear coefficients in Eqs. (9). Moreover, the discrete values have been calculated in the global reference frame while the intrinsic modes are defined in the initial configuration.…”

“…With the intrinsic modes approximated, the nonlinear coefficients, Γ Γ Γ 1 and Γ Γ Γ 2 , can be now calculated from Eq. (9). Application of Lebesgue integral on Dirac's function makes those integrals the discretised sums…”

“…Nonlinear formulations based on displacements [4], strains [5] and mixed intrinsic formulations [6] have been developed and applied to a wide range of situations and vehicles. They have provided relevant insight into the analysis of radical new configurations [7][8][9], nonlinear aeroelasticity [10], and design of large wind turbines [11,12].…”

Data-driven State Awareness for Fly-by-feel Aerial Vehicles: Experimental Assessment of a Non-parametric Probabilistic Stall Detection Approach

“…The most critical challenge for the postulation of a complete and applicable datadriven state-awareness framework is the effective modeling and interpretation of data recorded in dynamic environments under multiple flight states and varying structural health conditions. For aerial vehicles, the investigation of the aeroelastic response requires careful consideration throughout the design phase of the air vehicle and poses a major factor in the qualification of aircraft into service [10][11][12][13][14][15][16]. It is therefore evident that the flight states and operating conditions -characterized by one or more variables, such as airspeed, angle of attack (AoA), altitude, temperature, humidity, icing, and so on-may vary over time, and consequently affect the system dynamics and aeroelastic response.…”