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Pitching moment

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


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Journal ArticleDOI
TL;DR: In this article, the effect of a low Reynolds number in the range of 2.0 × 10 4 Re c 5.0 on the aerodynamic characteristics of a pitching NACA0012 airfoil was investigated.

56 citations

Journal ArticleDOI
TL;DR: In this article, a non-linear formulation of the classical Vortex Lattice Method (VLM) approach for calculating the aerodynamic properties of lifting surfaces is presented. But the method is not suitable for the analysis of a single aircraft.

56 citations

Journal ArticleDOI
TL;DR: In this paper, the authors compared the measured data from flight and wind-tunnel tests were compared with calculations obtained using the comprehensive analysis CAMRAD II, and the analysis showed that the aerodynamic tip design (chord length and quarter-chord location) has an important influence on the phase correlation.
Abstract: Blade section normal force and pitching moment were investigated for six rotors operating at transition and high speeds: H-34 in flight and wind tunnel, SA 330 (research Puma), SA 349/2, UH-60A full-scale, and BO-105 model (Higher-Harmonic Acoustics Rotor Test I). The measured data from flight and wind-tunnel tests were compared with calculations obtained using the comprehensive analysis CAMRAD II. The calculations were made using two free-wake models: rolled up and multiple trailer with consolidation models. At transition speed, there is fair to good agreement for the blade section normal force between the test data and analysis for the H-34, research Puma, and SA 349/2 with the rolled-up wake. The calculated airloads differ significantly from the measurements for the UH-60A and BO-105. Better correlation is obtained for the UH-60A and BO-105 by using the multiple trailer with consolidation wake model. In the high-speed condition, the analysis shows generally good agreement with the research Puma flight data in both magnitude and phase. However, poor agreement is obtained for the other rotors examined. The analysis shows that the aerodynamic tip design (chord length and quarter-chord location) of the research Puma has an important influence on the phase correlation.

56 citations

Journal ArticleDOI
TL;DR: In this paper, a computational fluid dynamic (CFD) method is used to simulate the unsteady flow about a realistic hawkmoth model and to compute aerodynamic derivatives of the aerodynamic forces and pitching moment in response with a series of small disturbances.
Abstract: A numerical analysis of dynamic flight stability of a hovering hawkmoth is presented. A computational fluid dynamic (CFD) method is used to simulate the unsteady flow about a realistic hawkmoth model and to compute the aerodynamic derivatives of the aerodynamic forces and pitching moment in response with a series of small disturbances. With these parameters, the techniques of eigenvalue and eigenvector analysis is employed to investigate dynamic flight stability of the hawkmoth hovering. In the longitudinal disturbance motion, three natural modes are identified of a stable oscillatory mode, a stable fast subsidence mode and a stable slow subsidence mode, which indicate that the hawkmoth hovering flight is stable. In short, a hovering hawkmoth, if the body motion is dynamically stable and hence the disturbance dies out fast, might not need to make any adjustment with wing motions and could return to the equilibrium state ‘automatically’.

55 citations

Journal ArticleDOI
TL;DR: In this paper, the flight dynamics of a flapping-wing air vehicle (ornithopter) were investigated. Butler et al. used a wind tunnel test with the control surfaces fixed in the trimmed position and flapping motion of the wings activated by a motor at a constant throttle setting.
Abstract: The research and development efforts presented in this paper address the flight dynamics of a flapping-wing air vehicle (ornithopter). The 74-cm-wing-span ornithopter was equipped with an automatic flight control system that provides stability augmentation and navigation of the vehicle and flight data acquisition. Wind tunnel tests were conducted with the control surfaces fixed in the trimmed position and flapping motion of the wings activated by a motor at a constant throttle setting. Coefficients of vertical and horizontal force, and pitching moment were determined at a free stream velocity of 7.25 m/sec, and the angle of the stroke plane varied from 0 to 40 degrees. A series of flight tests were conducted with fixed controls, demonstrating ornithopter stability in all axes. Proportional control laws were programmed into the autopilot for the closed-loop controls. A number of flights of the autonomous ornithopter were conducted with the telemetry acquisition. During the autonomous flights, the ornithopt...

55 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202353
202294
202168
202076
201983
201886