From Spreadsheets to Simulation-Based Aircraft Conceptual Design

Abstract

An automated, simulation-based aircraft design process allows for the prediction of unanticipated problems early in the design stage, leading to reduced turn-around time and development cost. Having reliable, and affordable (fast) design tools is crucial to achieving this level of automation in the design process. An example of this is illustrated for a jet trainer aircraft using two aircraft design codes: Jet Designer and CEASIOM which includes Digital DATCOM, a Vortex lattice method, and an Euler flow solver. A set of aerodynamic methods with different degrees of fidelity and computational expense is considered, with the limitations of each method provided. In particular, this paper examines the challenges that CFD-based aircraft design poses to a designer, including: a) the cost of generation of large data tables, b) the automated handling of geometry, c) treating control surface deflections, d) and calculation of dynamic derivatives using CFD. A Kriging-based sampling approach was used for generating aerodynamic tables with a reasonable computational cost compared with a brute-force approach. For Euler calculations, an automated CAD and mesh generation approach from a geometry description was used. It is demonstrated that application of Euler solutions to low fidelity aircraft geometry shows the expected design trends. Also, results show that the wave drag at transonic speeds can be predicted with Euler equations, but not with Vortex lattice or Digital DATCOM. The treatment of control surface deflections was also investigated for the Vortex lattice solver and the Euler code. A transpiration boundary condition was used in the Euler code to model the flap surface movements, although this approach is limited for large deflections. The calculated aero tables form each aero source were used next to study the vehicle flying qualities. Results presented demonstrate the validity and feasibility of the simulation-based approach for aircraft conceptual design. Nomenclaturelift curve slope, 1/rad C Lq lift derivative with respect to normalized pitch rate, 1/rad C m pitching moment coefficient, m/q ∞ Sc C mα pitching moment slope, 1/rad C mq pitching moment derivative with respect to normalized pitch rate, 1/rad C mδe pitching moment derivative with respect to elevator deflection, 1/rad C Y side-force coefficient, Y /q ∞ S *

EVTOL Tilt-Wing Aircraft Design under Uncertainty Using a Multidisciplinary Possibilistic Approach

“…For Short Period oscillations, according to the CS-23 criteria, the characteristics were very significant. With respect to Figure 17 which shows the short period undamped natural frequency against different acceleration sensitivity values, the results met the Level 1 requirements according to MIL requirements [70]. Furthermore, Figure 18 presents the damping ratio for the short mode, which nicely satisfies Level 1 of handling quality according to the CS-23 criteria [34].…”

Development and validation of an enhanced semi-empirical method for estimation of aerodynamic characteristics of light, propeller-driven airplanes

“…Kostic´et al 11 compared results of a VLM-based method with the DD for a light aircraft in the linear range, and indicated that the lift and pitching moment coefficients of two methods agree well with each other in the presence of elevator and flap deflections. For more information about the verification and validation of semi-empirical methods, one can refer to Smith, 12 Da Ronch et al, 13 Siddiqui et al, 14 Ghoreyshi and Cummings, 15 Gabor et al 16 and Ul Haque et al 17…”

Computational Modelling of Wing Downwash Profile with Reynolds-Averaged and Delayed Detached-Eddy Simulations

“…6 The absence of the fuselage has a considerable impact on the stability and aerodynamics of the geometry as a fuselage typically shifts the aerodynamic centre aft, thus a Wing-Tail geometry is likely to be longitudinally stiffer than a Wing-Body-Tail configuration. 13 In the context of a wing-tail only configuration, this makes the choice of location to be studied challenging as computationally modelling of such comprehensive datasets 9 would be exhaustive. Furthermore, results involving the midspan (along aircraft symmetry plane) are likely to be interfered by a fuselage.…”