Aerodynamic models were generated to simulate the flight dynamics of a parafoil wing with and without trailing-edge deflection. The airfoil was provided by the Natick Soldier Research, Development, and Engineering Center (NSRDEC) and was based on a modified Clark-Y with a flat lower surface used as the cut pattern for drop tested systems. The wing is characterized with an aspect ratio of two and zero anhedral angle. Several derivatives of this wing geometry were tested in the Subsonic Wind Tunnel (SWT) of United States Air Force Academy (USAFA).

These wings have either an open or closed inlet, a round or flat leading edge (for closed wings) and are with and without the trailing edge deflection. The flat leading edge wings consist of a straight line connecting the wing’s lower surface to the upper surface. The TE deflection is approximately 45^◦ as measured from the flat lower surface. For convenience, these wings were named S R, B R, S F , B F , in which S and B denote straight and bent trailing edges; R and F indicate round and flat leading edges.

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Effects of canard wing interference on the flight characteristics of a civilian transonic cruiser are examined. The aircraft is an unconventional design concept with no historical data. The flight characteristics of the aircraft are predicted using aerodynamic models in the form of look-up tables, generated using high-fidelity computational fluid dynamics simulations and a potential ow solver. These tables contain longitudinal and lateral force and moment coefficients for different combinations of angle of attack, side-slip angle, and control surface deflections. Dynamic damping derivatives are calculated from time-accurate simulations of the aircraft models oscillating in pitch, roll, and yaw direction and using a linear regression estimation method. The static simulations are performed at a Mach number of 0.117, as reported in wind tunnel experiments, and for two different canard positions using an overset grid approach. The aerodynamic tables include canard deflections of [-30, -10, 0, 10] at angles of attack from -4 to 30 degrees. Lateral coefficients are simulated at sideslip angles of -6 and 6 degrees as well. The dynamic simulations are performed for aircraft oscillations about mean angles of attack between zero to ten degrees with a motion frequency of 1Hz and amplitude of 0.5 degrees. The predicted aerodynamic data are then compared with those measured in wind tunnel experiments and calculated from the potential ow solver. The results show that both static and dynamic predictions match reasonably well with experiments for the range of angles considered.Continue reading→

This article discusses the current phase of a multi-year development effort to provide a computational method for determining static and dynamic stability and control characteristics of USAF high-performance fighter aircraft. The focus of this work is on the virtual flight test capability achieved by incorporating a pilot model, the F-16 flight control system (FLCS), and six degree-of-freedom (6-DoF) motion computation into the CFD maneuver simulation. Flight test maneuvers were performed in a virtual environment by using CFD to determine the forces and moments acting upon the aircraft and allowing the aircraft to respond as governed by the pilot model, FLCS, and 6-DoF. Virtual flight test simulations were accomplished with a full-scale F-16C aircraft using unstructured, viscous, overset grids and Cobalt with a MATLAB interface. Virtual flight test maneuver response is shown to compare well to validated, flight-test corrected data. This marriage of capabilities is rolled into a software suite known to the developers as COMSAC, which stands for COMputational Stability And Control.Continue reading→

Cavity flows have been the subject of aerodynamic research since the early days of high-speed aircraft with internal store carriage in the 1950s. Low observability design requirements for current combat aircraft has renewed the interest in this field. The presence of an open cavity, such as a weapon or undercarriage bay, exposed to a high-speed grazing flow can result in severe pressure fluctuations. These pressure fluctuations can reach intensities of up to 165dB SPL and may cause damage to both the aircraft and to any sensitive components within the bay. Results for this study were generated using an existing generic rectangular planform cavity wind tunnel model, designated as M219/1. This small scale model was the forerunner for the more widely known larger scale M219 generic cavity model.

Numerical simulations were performed for two geometries, the 38mm and 80mm deep cavities, at a freestream Mach number of 0.80. In order to capture the unsteady flow behaviour in the cavity, a time accurate detached eddy simulation (DES) model was run which uses Reynolds averaged Navier-Stokes (RANS) near to the wall to reduce computational cost and a large eddy simulation (LES) model in the separated flow region far from the walls.Continue reading→