Pitching moment

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

Mechanics of Flight

Abstract: Preface. Acknowledgments. 1. Overview of Aerodynamics. 1.1. Introduction and Notation. 1.2. Fluid Statics and the Atmosphere. 1.3. The Boundary Layer Concept. 1.4. Inviscid Aerodynamics. 1.5. Review of Elementary Potential Flows. 1.6. Incompressible Flow over Airfoils. 1.7. Trailing-Edge Flaps and Section Flap Effectiveness. 1.8. Incompressible Flow over Finite Wings. 1.9. Flow over Multiple Lifting Surfaces. 1.10. Wing Stall and Maximum Lift Coefficient. 1.11. Wing Aerodynamic Center and Pitching Moment. 1.12. Inviscid Compressible Aerodynamics. 1.13. Compressible Subsonic Flow. 1.14. Supersonic Flow. 1.15. Problems. 2. Overview of Propulsion. 2.1. Introduction. 2.2. The Propeller. 2.3. Propeller Blade Theory. 2.4. Propeller Momentum Theory. 2.5. Off-Axis Forces and Moments Developed by a Propeller. 2.6. Turbojet Engines: The Thrust Equation. 2.7. Turbojet Engines: Cycle Analysis. 2.8. The Turbojet Engine with Afterburner. 2.9. Turbofan Engines. 2.10. Concluding Remarks. 2.11. Problems. 3. Aircraft Performance. 3.1. Introduction. 3.2. Thrust Required. 3.3. Power Required. 3.4. Rate of Climb and Power Available. 3.5. Fuel Consumption and Endurance. 3.6. Fuel Consumption and Range. 3.7. Power Failure and Gliding Flight. 3.8. Airspeed, Wing Loading, and Stall. 3.9. The Steady Coordinated Turn. 3.10. Takeoff and Landing Performance. 3.11. Accelerating Climb and Balanced Field Length. 3.12. Problems. 4. Longitudinal Static Stability and Trim. 4.1. Fundamentals of Static Equilibrium and Stability. 4.2. Pitch Stability of a Cambered Wing. 4.3. Simplified Pitch Stability Analysis for a Wing-Tail Combination. 4.4. Stick-Fixed Neutral Point and Static Margin. 4.5. Estimating the Downwash Angle on an Aft Tail. 4.6. Simplified Pitch Stability Analysis for a Wing-Canard Combination. 4.7. Effects of Drag and Vertical Offset. 4.8. Effects of Nonlinearities on the Aerodynamic Center. 4.9. Effect of the Fuselage, Nacelles, and External Stores. 4.10. Contribution of Running Propellers. 4.11. Contribution of Jet Engines. 4.12. Problems. 5. Lateral Static Stability and Trim. 5.1. Introduction. 5.2. Yaw Stability and Trim. 5.3. Estimating the Sidewash Gradient on a Vertical Tail. 5.4. Estimating the Lift Slope for a Vertical Tail. 5.5. Effects of Tail Dihedral on Yaw Stability. 5.6. Roll Stability and Dihedral Effect. 5.7. Roll Control and Trim Requirements. 5.8. The Generalized Small-Angle Lateral Trim Requirements. 5.9. Steady-Heading Sideslip. 5.10. Engine Failure and Minimum-Control Airspeed. 5.11. Longitudinal-Lateral Coupling. 5.12. Control Surface Sign Conventions. 5.13. Problems. 6. Aircraft Controls and Maneuverability. 6.1. Longitudinal Control and Maneuverability. 6.2. Effects of Structural Flexibility. 6.3. Control Force and Trim Tabs. 6.4. Stick-Free Neutral and Maneuver Points. 6.5. Ground Effect, Elevator Sizing, and CG Limits. 6.6. Stall Recovery. 6.7. Lateral Control and Maneuverability. 6.8. Aileron Reversal. 6.9. Other Control Surface Configurations. 6.10. Airplane Spin. 6.11. Problems. 7. Aircraft Equations of Motion. 7.1. Introduction. 7.2. Newton's Second Law for Rigid-Body Dynamics. 7.3. Position and Orientation: The Euler Angle Formulation. 7.4. Rigid-Body 6-DOF Equations of Motion. 7.5. Linearized Equations of Motion. 7.6. Force and Moment Derivatives. 7.7. Nondimensional Linearized Equations of Motion. 7.8. Transformation of Stability Axes. 7.9. Inertial and Gyroscopic Coupling. 7.10. Problems. 8. Linearized Longitudinal Dynamics. 8.1. Fundamentals of Dynamics: Eigenproblems. 8.2. Longitudinal Motion: The Linearized Coupled Equations. 8.3. Short-Period Approximation. 8.4. Long-Period Approximation. 8.5. Pure Pitching Motion. 8.6. Summary. 8.7. Problems. 9. Linearized Lateral Dynamics. 9.1. Introduction. 9.2. Lateral Motion: The Linearized Coupled Equations. 9.3. Roll Approximation. 9.4. Spiral Approximation. 9.5. Dutch Roll Approximation. 9.6. Pure Rolling Motion. 9.7. Pure Yawing Motion. 9.8. Longitudinal-Lateral Coupling. 9.9. Nonlinear Effects. 9.10. Summary. 9.11. Problems. 10. Aircraft Handling Qualities and Control Response. 10.1. Introduction. 10.2. Pilot Opinion. 10.3. Dynamic Handling Quality Prediction. 10.4. Response to Control Inputs. 10.5. Nonlinear Effects and Longitudinal-Lateral Coupling. 10.6. Problems. 11. Aircraft Flight Simulation. 11.1. Introduction. 11.2. Euler Angle Formulations. 11.3. Direction-Cosine Formulation. 11.4. Euler Axis Formulation. 11.5. The Euler-Rodrigues Quaternion Formulation. 11.6. Quaternion Algebra. 11.7. Relations between the Quaternion and Other Attitude Descriptors. 11.8. Applying Rotational Constraints to the Quaternion Formulation. 11.9. Closed-Form Quaternion Solution for Constant Rotation. 11.10. Numerical Integration of the Quaternion Formulation. 11.11. Summary of the Flat-Earth Quaternion Formulation. 11.12. Aircraft Position in Geographic Coordinates. 11.13. Problems. Bibliography. Appendixes. A Standard Atmosphere, SI Units. B Standard Atmosphere, English Units. C Aircraft Moments of Inertia. Nomenclature. Index.

Summary of the Fourth AIAA CFD Drag Prediction Workshop

Abstract: Results from the Fourth AIAA Drag Prediction Workshop (DPW-IV) are summarized. The workshop focused on the prediction of both absolute and differential drag levels for wing-body and wing-body-horizontal-tail configurations that are representative of transonic transport air- craft. Numerical calculations are performed using industry-relevant test cases that include lift- specific flight conditions, trimmed drag polars, downwash variations, dragrises and Reynolds- number effects. Drag, lift and pitching moment predictions from numerous Reynolds-Averaged Navier-Stokes computational fluid dynamics methods are presented. Solutions are performed on structured, unstructured and hybrid grid systems. The structured-grid sets include point- matched multi-block meshes and over-set grid systems. The unstructured and hybrid grid sets are comprised of tetrahedral, pyramid, prismatic, and hexahedral elements. Effort is made to provide a high-quality and parametrically consistent family of grids for each grid type about each configuration under study. The wing-body-horizontal families are comprised of a coarse, medium and fine grid; an optional extra-fine grid augments several of the grid families. These mesh sequences are utilized to determine asymptotic grid-convergence characteristics of the solution sets, and to estimate grid-converged absolute drag levels of the wing-body-horizontal configuration using Richardson extrapolation.

Mechanics of Forward Flight in Bumblebees: II. QUASI-STEADY LIFT AND POWER REQUIREMENTS

Abstract: This paper examines the aerodynamics and power requirements of forward flight in bumblebees. Measurements weremade of the steady-state lift and drag forces acting on bumblebee wings and bodies. The aerodynamic force and pitching moment balances for bumblebees previously filmed in free flight were calculated. A detailed aerodynamic analysis was used to show that quasi-steady aerodynamic mechanisms are inadequate to explain even fast forward flight. Calculations of the mechanical power requirements of forward flight show that the power required to fly is independent of airspeed over a range from hovering flight to an airspeed of 4.5 ms −1

Aerodynamic Shape Optimization Investigations of the Common Research Model Wing Benchmark

Abstract: Despite considerable research on aerodynamic shape optimization, there is no standard benchmark problem allowing researchers to compare results. This work addresses this issue by solving a series of aerodynamic shape optimization problems based on the Common Research Model wing benchmark case defined by the Aerodynamic Design Optimization Discussion Group. The aerodynamic model solves the Reynolds-averaged Navier–Stokes equations with a Spalart–Allmaras turbulence model. A gradient-based optimization algorithm is used in conjunction with an adjoint method that computes the required derivatives. The drag coefficient is minimized subject to lift, pitching moment, and geometric constraints. A multilevel technique is used to reduce the computational cost of the optimization. A single-point optimization is solved with 720 shape variables using a 28.8-million-cell mesh, reducing the drag by 8.5%. A more realistic design is achieved through a multipoint optimization. Multiple local minima are found when starting...

Investigation of the flow structure around a rapidly pitching airfoil

Abstract: A numerical study is presented for unsteady laminar flow past a NACA 0015 airfoil that is pitched, at a nominally constant rate, from zero incidence to a very high angle of attack. The flowfield simulation is obtained by solving the full two-dimensional compressible Navier-Stokes equations on a moving grid employing an implicit approximate-factorization algorithm. An evaluation of the accuracy of the computed solutions is presented, and the numerical results are shown to be of sufficient quality to merit physical interpretation. The highly unsteady flowfield structure is described and is found to be in qualitative agreement with available experimental observations. A discussion is provided for the effects of pitch rate and pitch axis location on the induced vortical structures and on the airfoil aerodynamic forces.