Performance, Stability, Dynamics, and Control of Airplanes, Second Edition

Pamadi, Bandu N.

doi:10.2514/4.862274

Cited by 139 publications

(73 citation statements)

References 26 publications

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“…The forward sweep of its wings gives advantages in the stall regime, causing the root of the wing to stall first so that the bat can still maintain control of the wing shape with its fingers. 27 Thus, the bat can maintain roll control at stall and is resistant to spin. The low aspect ratio of its wing also delays stall.…”

Section: Comparison Between Species and Naturementioning

confidence: 99%

Analysis of bat wings for morphing

2008

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The morphing of wings from three different bat species is studied using an extension of the Weissinger method. To understand how camber affects performance factors such as lift and lift to drag ratio, XFOIL is used to study thin (3% thickness to chord ratio) airfoils at a low Reynolds number of 100,000. The maximum camber of 9% yielded the largest lift coefficient, and a mid-range camber of 7% yielded the largest lift to drag ratio. Correlations between bat wing morphology and flight characteristics are covered, and the three bat wing planforms chosen represent various combinations of morphological components and different flight modes. The wings are studied using the extended Weissinger method in an "unmorphed" configuration using a thin, symmetric airfoil across the span of the wing through angles of attack of 0°-15°. The wings are then run in the Weissinger method at angles of attack of -2° to 12° in a "morphed" configuration modeled after bat wings seen in flight, where the camber of the airfoils comprising the wings is varied along the span and a twist distribution along the span is introduced. The morphed wing configurations increase the lift coefficient over 1000% from the unmorphed configuration and increase the lift to drag ratio over 175%. The results of the three different species correlate well with their flight in nature.

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Section: Comparison Between Species and Naturementioning

confidence: 99%

Analysis of bat wings for morphing

2008

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“…Attempts were made to use classical planform efficiency models proposed by Anderson [16], Bertin [18], Corke [19], Loth [17], Oswald [20], Pamadi [21], Raymer [22], and Roskam[23] to predict the efficiency of the studied planforms. Unfortunately, these classical high Re empirical fit equations break down at low AR and low Re.…”

Section: Modeling Of Planform Efficiencymentioning

confidence: 99%

Computational Investigation of AR and Lambda Effects on Wings Operating in the Transitional Low Reynolds Number Flight Regime

Hamburg

Napolillo²,

Gautam³

et al. 2011

29th AIAA Applied Aerodynamics Conference

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A detailed computational investigation of the effects of aspect ratio and taper ratio on wings using the NACA 0009 airfoil operating at 30 m/s and a wing area of 0.01 m 2 was conducted. This required the construction of an extremely flexible geometry and mesh structure model and the preliminary validation of a steady-state turbulence model for low Reynolds number wings to complete the large parameter study required. The point of transition between low aspect ratio vortex lift and high aspect ratio circulation lift and the point of diminishing efficiency return on increasingly large aspect ratios are proposed. It is suggested that current high maneuverability MAV designs would not benefit from significant planform changes, but significant endurance and cruise efficiency benefits can be gained from higher aspect ratio designs. In addition, a preliminary model for the estimation of planform efficiency at low Reynolds numbers for low aspect ratio trapezoidal wings is proposed. An initial investigation into the formation of leading edge vortices and boundary layer recirculation bubbles is also performed. Nomenclature AR= aspect ratio c MAC = mean aerodynamic chord C L = three dimensional planform lift coefficient C l = two dimensional lift coefficient C Lα = derivative of three dimensional lift coefficient with respect to angle of attack C D = planform drag coefficient C d = two dimensional drag coefficient C D0 = three dimensional planform drag coefficient at zero lift PEF = planform efficiency factor Re = Reynolds number k n = constant of index n S W = wing area V ∞ = free stream velocity k n = constant of index n α = angle of attack λ = taper ratio

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“…For aircraft with appreciable wing sweep the dihedral effect (L v ) is increased (by the equivalent of roughly 1 • of dihedral angle per 5-7 • of sweep; Schmidt, 1998), increasing roll response and reducing the Dutch roll damping. In many fighter aircraft, which have high sweep angles for trans-and supersonic operation, the Dutch roll mode becomes unstable at higher incidences, exacerbated by the tail fin operating in the lowenergy wake of the fuselage/wing flows; the result is usually a nonlinear variation of roll damping leading to a sustained oscillation known as a "wing rock" limit cycle (see Schmidt, 1998;Pamadi, 1998). Figure 7 (from Etkin, 1982 depicts the eigenvector of an aircraft Dutch roll mode.…”

Section: Dutch Roll Modementioning

confidence: 99%

“…Highly swept wing leading-edge strakes are sometimes used to generate a strong vortex that helps to maintain high lift at high angles of attack; but above a critical incidence the vortex will break down, leading to the possibility of sudden pitch changes and even nonlinear time-dependent motions such as limit cycles. The unexpected behaviors arising at high angles of attack and/or high rotation rates are discussed in some detail by Pamadi (1998).…”

Section: Nonlinear Effectsmentioning

confidence: 99%

Fixed‐Wing Lateral and Directional Dynamic Stability

Löwenberg

2010

Encyclopedia of Aerospace Engineering

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Stability and control are fundamental properties of an aircraft's dynamic characteristics, influencing flying qualities and hence pilot workload and safety. They are closely linked to other fundamental aspects of aircraft design, including aerodynamics, performance, systems, structure, and operating cost factors. This chapter discusses the governing equations of motion for a rigid‐body aircraft and their linearized form, the latter facilitating the decoupling of lateral–directional stability and control from its longitudinal counterparts for conventional aircraft. The consideration of flight responses in terms of their constituent modes of motion is introduced, using the linear state‐space form of the equations and a stability‐and‐control‐derivative representation of the aerodynamic loads. Thereafter, the stability and response associated with each lateral–directional mode is described in some detail for standard aircraft configurations, with reference to the aerodynamic parameters governing the behavior. The chapter concludes with a brief comment on nonlinearity and how it may modify the linear system stability and control characteristics.

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Performance, Stability, Dynamics, and Control of Airplanes, Second Edition

Cited by 139 publications

References 26 publications

Analysis of bat wings for morphing

Analysis of bat wings for morphing

Computational Investigation of AR and Lambda Effects on Wings Operating in the Transitional Low Reynolds Number Flight Regime

Fixed‐Wing Lateral and Directional Dynamic Stability

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