Pitching moment

About: Pitching moment is a research topic. Over the lifetime, 3213 publications have been published within this topic receiving 38721 citations.

Fundamentals of Airplane Flight Mechanics

Abstract: Flight mechanics is the application of Newton's laws to the study of vehicle trajectories (performance), stability, and aerodynamic control. This text is concerned with the derivation of analytical solutions of airplane flight mechanics problems associated with flight in a vertical plane. Algorithms are presented for calculating lift, drag, pitching moment, and stability derivatives. Flight mechanics is a discipline. As such, it has equations of motion, acceptable approximations, and solution techniques for the approximate equations of motion. Once an analytical solution has been obtained, numbers are calculated in order to compare the answer with the assumptions used to derive it and to acquaint students with the sizes of the numbers. A subsonic business jet is used for these calculations.

Dynamic stall experiments on the NACA 0012 airfoil

Abstract: The flow over a NACA 0012 airfoil undergoing large oscillations in pitch was experimentally studied at a Reynolds number of and over a range of frequencies and amplitudes. Hot-wire probes and surface-pressure transducers were used to clarify the role of the laminar separation bubble, to delineate the growth and shedding of the stall vortex, and to quantify the resultant aerodynamic loads. In addition to the pressure distributions and normal force and pitching moment data that have often been obtained in previous investigations, estimates of the unsteady drag force during dynamic stall have been derived from the surface pressure measurements. Special characteristics of the pressure response, which are symptomatic of the occurrence and relative severity of moment stall, have also been examined.

Aerodynamic and Aeroelastic Characteristics of Wings with Conformal Control Surfaces for Morphing Aircraft

Abstract: Investigations are conducted on lifting surfaces with conventional and conformal trailing-edge control surfaces. The Sohngen inversion formula is used with the thin-airfoil integral equation to determine the aerodynamic pressure for various control surface chord-to-airfoil chord ratios. Comparisons to a conventional control surface show increases in lift and pitching moment of the airfoil with a conformal control surface. Aerodynamic pressure distributions acting on a wing with control surfaces are determined with the vortex lattice technique. Predicted aerodynamic pressures and roll moments are compared to available wind-tunnel data and provide a more general understanding of theaerodynamicbehavior observed there. Roll performance of a rectangular wing is determined for various control surface chord-to-wing chord ratios. It is found that the maximum roll rate is greater for a wing with a conformal control surface, but has a lower reversal dynamic pressure than the wing with a conventional control surface. The aerodynamic and aeroelastic results obtained from this investigation provide some insight for wings designed with conformal control surfaces.

A Quasi-Vortex-Lattice Method in Thin Wing Theory

Abstract: A quasi-continuous method is developed for solving thin-wing problems. For the purpose of satisfying the wing boundary conditions, the spanwise vortex distribution is assumed to be stepwise-constant, while the chordwise vortex integral is reduced to a finite sum through a modified trapezoidal rule and the theory of Chebyshev polynomials. Wing-edge and Cauchy singularities are acounted for. The total aerodynamic characteristics are obtained by an appropriate quadrature integration. The two-dimensional results for airfoils without flap deflection reproduce the exact solutions in lift and pitching moment coefficients, the leading edge suction, and the pressure difference at a finite number of points. For a flapped airfoil, the present results are more accurate than those given by the vortex-lattice method. The three-dimensional results also show an improvement over the results of the vortex-lattice method. Extension to nonplanar applications is discussed.