Dynamic soaring: aerodynamics for albatrosses

Denny, Mark

doi:10.1088/0143-0807/30/1/008

Cited by 40 publications

(27 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The theory of wind-gradient soaring is based on the wind gradient in the shear layer above the sea surface (Lighthill, 1975;Norberg, 1990;Spedding, 1992;Tickell, 2000;Dhawan, 2002;Lindhe Norberg, 2004;Azuma, 2006;Denny, 2009). According to this theory, energy can be obtained by climbing against the wind because the wind speed increases as a result of the wind gradient.…”

Section: Comparison With Current Theories and Explanations For Dynamimentioning

confidence: 99%

“…The current state of knowledge manifests in a variety of theories and explanations for the small-scale dynamic soaring flight of albatrosses. There is a theory termed wind-gradient soaring (Lighthill, 1975;Norberg, 1990;Spedding, 1992;Tickell, 2000;Dhawan, 2002;Lindhe Norberg, 2004;Azuma, 2006;Denny, 2009); according to this theory, soaring is continually possible using the wind gradient in the shear layer above the sea surface. Another theory termed gust soaring relates to discontinuities in the wind flow (Pennycuick, 2002;Pennycuick, 2008;Suryan et al, 2008;Langelaan, 2008;Langelaan and Bramesfeld, 2008); according to this theory, energy pulses are obtained from flight through the separated air flow region behind wave crests.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental verification of dynamic soaring in albatrosses

Sachs

Traugott

Nesterova

et al. 2013

Journal of Experimental Biology

106

View full text Add to dashboard Cite

SUMMARYDynamic soaring is a small-scale flight manoeuvre which is the basis for the extreme flight performance of albatrosses and other large seabirds to travel huge distances in sustained non-flapping flight. As experimental data with sufficient resolution of these small-scale movements are not available, knowledge is lacking about dynamic soaring and the physical mechanism of the energy gain of the bird from the wind. With new in-house developments of GPS logging units for recording raw phase observations and of a dedicated mathematical method for postprocessing these measurements, it was possible to determine the small-scale flight manoeuvre with the required high precision. Experimental results from tracking 16 wandering albatrosses (Diomedea exulans) in the southern Indian Ocean show the characteristic pattern of dynamic soaring. This pattern consists of four flight phases comprising a windward climb, an upper curve, a leeward descent and a lower curve, which are continually repeated. It is shown that the primary energy gain from the shear wind is attained in the upper curve where the bird changes the flight direction from windward to leeward. As a result, the upper curve is the characteristic flight phase of dynamic soaring for achieving the energy gain necessary for sustained non-flapping flight.

show abstract

Section: Comparison With Current Theories and Explanations For Dynamimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental verification of dynamic soaring in albatrosses

Sachs

Traugott

Nesterova

et al. 2013

Journal of Experimental Biology

106

View full text Add to dashboard Cite

show abstract

“…An albatross exploits energy from the velocity gradients of the oceanic boundary layer through dynamic soaring (Denny 2009), and numerous kinds of birds take advantage of the spatial and temporal gradients of the atmospheric gust to remain aloft without flapping their wings. Thermals and the upward draft created by the topology provide additional sources of energy (Weimerskirch et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Surging and plunging oscillations of an airfoil at low Reynolds number

2014

View full text Add to dashboard Cite

We investigate the forces and unsteady flow structures associated with harmonic oscillations of an airfoil in the streamwise (surging) and transverse (plunging) directions in two-dimensional simulations at low Reynolds number. For the surging case, we show that there are specific frequencies where the wake instability synchronizes with the unsteady motion of the airfoil, leading to significant changes in the mean forces. Resonant behaviour of the time-averaged forces is observed near the vortex shedding frequency and its subharmonic; the behaviour is reminiscent of the dynamics of the generic nonlinear oscillator known as the Arnol'd tongue or the resonance horn. Below the wake instability frequency, there are two regimes where the fluctuating forces are amplified and attenuated, respectively. A detailed study of the flow structures associated with leading-edge vortex (LEV) growth and detachment are used to relate this behaviour with the LEV acting either in phase with the quasi-steady component of the forces for the amplification case, or out of phase for the attenuation case. Comparisons with wind tunnel measurements show that phenomenologically similar dynamics occur at higher Reynolds number. Finally, we show that qualitatively similar phenomena occur during both surging and plunging.

show abstract

“…According to the geometric relationship shown in Figure 2, we transform the equations above to the following equations in Cartesian coordinates by vx = vcosθcosψ, vy = vcosθsinψ and vz =vsinθ, where vx, vy, and vz denote the velocities of the aircraft along the respective axes. The problem formulation and modeling procedures adopted in this study are similar to those of some relevant previous works [16,21,23,36]. The aircraft is under the action of its weight, aerodynamics, and inertial force.…”

Section: Dynamic Modelmentioning

confidence: 99%

Albatross-Like Utilization of Wind Gradient for Unpowered Flight of Fixed-Wing Aircraft

2017

View full text Add to dashboard Cite

Abstract:The endurance of an aircraft can be considerably extended by its exploitation of the hidden energy of a wind gradient, as an albatross does. The process is referred to as dynamic soaring and there are two methods for its implementation, namely, sustainable climbing and the Rayleigh cycle. In this study, the criterion for sustainable climbing was determined, and a bio-inspired method for implementing the Rayleigh cycle in a shear wind was developed. The determined sustainable climbing criterion promises to facilitate the development of an unpowered aircraft and the choice of a more appropriate soaring environment, as was demonstrated in this study. The criterion consists of three factors, namely, the environment, aerodynamics, and wing loading. We develop an intuitive explanation of the Raleigh cycle and analyze the energy mechanics of utilizing a wind gradient in unpowered flight. The energy harvest boundary and extreme power point were determined and used to design a simple bio-inspired guidance strategy for implementing the Rayleigh cycle. The proposed strategy, which involves the tuning of a single parameter, can be easily implemented in real-time applications. In the results and discussions, the effects of each factor on climbing performance are examined and the sensitivity of the aircraft factor is discussed using five examples. Experimental MATLAB simulations of the proposed strategy and the comparison of the results with those of Gauss Pseudospectral Optimization Software confirm the feasibility of the proposed strategy.

show abstract

Dynamic soaring: aerodynamics for albatrosses

Cited by 40 publications

References 17 publications

Experimental verification of dynamic soaring in albatrosses

Experimental verification of dynamic soaring in albatrosses

Surging and plunging oscillations of an airfoil at low Reynolds number

Albatross-Like Utilization of Wind Gradient for Unpowered Flight of Fixed-Wing Aircraft

Contact Info

Product

Resources

About