Aerodynamic Analysis of a Generic Fighter with a Chine Fuselage/Delta Wing Configuration Using Delayed Detached-Eddy Simulation

The Modular Transonic Vortex Investigation (MTVI) program at NASA Langley Research Center investigated the transonic characteristics of generic fighter configurations with chined fuselages and delta wings. Previous experiments show that the fuselage and leading edge vortex interactions are detrimental to the vehicle’s aerodynamic characteristics for angles of attack greater than 23º at low angles of sideslip. This is largely due to abrupt asymmetric vortex breakdown, which leads to pronounced pitch-up and significant nonlinearities in lateral stability that could result in roll departure. An improved understanding of the exact origins of this nonlinear behavior would improve future fighter design, and predictive capabilities of such nonlinearities could drastically reduce the cost associated with flight testing new or modified aircraft. The nonlinearities experienced by the MTVI configuration at 30 degrees angle of attack, Reynolds number of 2.68x106, and Mach number of 0.4 are computed using Delayed Detached-Eddy Simulation. Computational predictions of rolling moment compare very well with previous wind tunnel experiments at the same conditions, including the abrupt, nonlinear increase in rolling moment as a function of sideslip angle at small sideslip angles. A detailed investigation of the CFD data confirms that this nonlinearity is due to a rapid change in the flow field structures from symmetric to asymmetric vortex breakdown

Improved Methodologies for Maneuver Design of Aircraft Stability and Control Simulations

With many modern fighter aircraft experiencing unpredicted flight dynamics during flight tests, recent research has focused on developing methodologies for incorporating computational fluid dynamics into the aircraft development process. The goal of this approach is to identify configurations susceptible to stability and control issues early in the design process. Previous research has primarily focused on full aircraft configurations, however, to increase the rate of development the current study focused on a two-dimensional NACA0012 airfoil. The two-dimensional NACA0012 airfoil has the advantage of reducing the computational cost by orders of magnitude compared to full scale aircraft simulations, while still providing complicated aerodynamics at high angles of attack. Computationally predicted lift coefficients from a number of newly developed training maneuvers were used to generate reduced order aerodynamic loads models. For evaluation, these models were compared to generated static and dynamic validation data. Methods of improving both the computational training maneuver and the reduced order modeling approach are suggested

Multi-Disciplinary Design and Performance Assessment of Effective, Agile NATO Air Vehicles

This article belongs to a series of publications about the activities performed within the NATO STO Research Task Group AVT-251 on "Multi-Disciplinary design and performance assessment of effective, agile NATO Air Vehicles". The article concentrates on the development and investigation of the MULDICON UCAV configuration, as well as on the organization and assessment of the AVT-251 task group itself. After a brief introduction to the preceding task groups and the research questions that lead to AVT-251, the selection of design requirements is discussed and the chosen way for developing MULDICON out of its predecessor, the SACCON concept, is sketched. A special focus is placed on the various aerodynamic investigations with the aim to control the vortex flow topology at medium to high angles of attack. Thereafter, the overall aircraft design work on the re-designed outer shape is presented and the resulting MULDICON configuration is investigated and assessed. Finally, a concluding summary of the MULDICON concept and the AVT-251 task group is presented