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The kinematics of hoverfly flight
Abstracts / Comparative Biochemistry and Physiology, Part A 146 (2007) S107–S127
Conjugating the optical triangulation based on the comb-fringe technique with the two-channel telemetry, the wing and body kinematics accompanying with the muscle activities of freeflying hawkmoths were recorded and analyzed synchronously when they performed rapid flight maneuvers to avoid the collision with static obstacles. The results indicate that the timing around supination is the important phase for the steering, during which a hawkmoth can generate reasonable torques for rapid maneuvers with subtle modifications in wing motion and body deflection. The corresponding electromyography suggests that the indirect dorsal–ventral muscles, besides the direct steering muscles, may also contribute to the steering control. doi:10.1016/j.cbpa.2007.01.199
A6.26 The kinematics of hoverfly flight J. Gundry, C. Ellington, (University of Cambridge, United Kingdom) Hoverflies (family: Syrphidae) are the most agile and aerodynamically gifted of all insects. They possess both very fine control as well as the ability to achieve high accelerations (at least 3 g) and maximum velocities (10 m s−1.) However, their kinematics, and therefore the means by which they hover, accelerate and manoeuvre are poorly known. We have filmed hoverflies, of both the smaller, lighter Syrphus group and the larger, heavier Eristalis genus, in free, untethered flight, using a twin digital high speed video camera setup to generate an accurate three dimensional representation of the body kinematics and path of flight. In particular, angle of attack can be accurately measured for the first time. We present here an accurate and complete set of kinematic results to describe the free flight of these remarkable insects. Episyrphus balteatus (21.8 mg) can yaw (rotate on the spot) through 90° in 45.6 ms, and the far larger Eristalis tenax (170.6 mg) rotates 90° in 59.4 m s. The much smaller Drosophila (1 mg) takes 60 m s to accomplish such a rotation. It is suggested that a ‘paddling’ upstroke generates much of the yawing acceleration, and that the yaws are primarily inertiadriven, as there is clear evidence that a ‘stopping’ stroke is required to arrest the yaw. Fascinatingly, it is likely that Syrphids can modulate their wingstrokes on a stroke-by-stroke basis: at a rate of 150 to 200 times a second. doi:10.1016/j.cbpa.2007.01.200
A6.27 The wingtip fold of the bat Miniopterus schreibersii: A novel mechanism for thrust generation during slow-flight? R. Nudds, (University of Leeds, United Kingdom)
S115
Many bats roost in caves and flight within narrow cave passages requires ability for slow manoeuvrable flight. For species that utilise slow flight for foraging, such as ground gleaners and trawlers (e.g. Myotis blythii and Myotis capaccinii) or species that aerial hawk in cluttered woodland environments (e.g. Rhinolophus mehelyi), foraging flight requirements are similar to the requirements within a cave environment. In contrast, for Miniopterus schreibersii – a cave dweller and swift-like aerial hawker of insects – there is an apparent mismatch between its foraging flight and cave flight. Intriguingly, M. schreibersii possesses an extra wing-membrane fold in comparison with the species (see above) it coexists with in caves. This additional membrane fold occurs across the phalanges and at rest results in the wingtip being folded back up between what is the last wingfold for its cohabiting species of bats. M. schreibersii wings are not exceptionally long in comparison with other species, so a simple wing-folding at rest function is an unlikely explanation. High-speed video shows that during the first wing-strokes of take-off, the wingtip fold is folded downward during the latter stages of the upstroke before being rapidly straightened immediately prior to the start of the down-stroke. In addition, the take-off ability of M. schreibersii is better than might be expected given its wing-morphology. Early indications are that the wingtip fold of M. schreibersii may represent a novel mechanism for producing additional thrust during slow-flight. doi:10.1016/j.cbpa.2007.01.201
A6.28 Hovering aerodynamics in hummingbirds: Comparing a dynamically-scaled robot with live birds B. Tobalske, (University of Portland, United States); D. Warrick, (Oregon State University, United States); W. Dickson, M. Dickinson, (California Institute of Technology, United States); D. Altshuler, (University of California, Riverside, United States) To help elucidate the mechanisms that permit hovering in hummingbirds, we used digital particle image velocimetry (DPIV) to measure flow in the near-field and wake of the wings of live birds and of a dynamically-scaled, flat-plate, robotic wing (Re ∼4000) that was equipped with force transducers at the wing root. Flow about the wings of live birds was laminar and lacked a stable leading-edge vortex (LEV) through most of the translational phases of the wingbeat In contrast, at mid-upstroke and mid-downstroke, the robotic wing always exhibited LEV's and trailing-edge vortices (TEV's). This reveals that a flat plate is not fully adequate for modeling flow about a cambered, flexible bird wing. Our measures of bound circulation on the robotic wing lead to estimates of aerodynamic force that matched measured force for upstroke but were 60% of measured force for downstroke, which suggests that LEV's and TEV's were not stable during downstroke. Estimates of force from circulation in the trailing tip vortices matched measured forces at the wing root when circulation was measured within one chord
Conjugating the optical triangulation based on the comb-fringe technique with the two-channel telemetry, the wing and body kinematics accompanying with the muscle activities of freeflying hawkmoths were recorded and analyzed synchronously when they performed rapid flight maneuvers to avoid the collision with static obstacles. The results indicate that the timing around supination is the important phase for the steering, during which a hawkmoth can generate reasonable torques for rapid maneuvers with subtle modifications in wing motion and body deflection. The corresponding electromyography suggests that the indirect dorsal–ventral muscles, besides the direct steering muscles, may also contribute to the steering control. doi:10.1016/j.cbpa.2007.01.199
A6.26 The kinematics of hoverfly flight J. Gundry, C. Ellington, (University of Cambridge, United Kingdom) Hoverflies (family: Syrphidae) are the most agile and aerodynamically gifted of all insects. They possess both very fine control as well as the ability to achieve high accelerations (at least 3 g) and maximum velocities (10 m s−1.) However, their kinematics, and therefore the means by which they hover, accelerate and manoeuvre are poorly known. We have filmed hoverflies, of both the smaller, lighter Syrphus group and the larger, heavier Eristalis genus, in free, untethered flight, using a twin digital high speed video camera setup to generate an accurate three dimensional representation of the body kinematics and path of flight. In particular, angle of attack can be accurately measured for the first time. We present here an accurate and complete set of kinematic results to describe the free flight of these remarkable insects. Episyrphus balteatus (21.8 mg) can yaw (rotate on the spot) through 90° in 45.6 ms, and the far larger Eristalis tenax (170.6 mg) rotates 90° in 59.4 m s. The much smaller Drosophila (1 mg) takes 60 m s to accomplish such a rotation. It is suggested that a ‘paddling’ upstroke generates much of the yawing acceleration, and that the yaws are primarily inertiadriven, as there is clear evidence that a ‘stopping’ stroke is required to arrest the yaw. Fascinatingly, it is likely that Syrphids can modulate their wingstrokes on a stroke-by-stroke basis: at a rate of 150 to 200 times a second. doi:10.1016/j.cbpa.2007.01.200
A6.27 The wingtip fold of the bat Miniopterus schreibersii: A novel mechanism for thrust generation during slow-flight? R. Nudds, (University of Leeds, United Kingdom)
S115
Many bats roost in caves and flight within narrow cave passages requires ability for slow manoeuvrable flight. For species that utilise slow flight for foraging, such as ground gleaners and trawlers (e.g. Myotis blythii and Myotis capaccinii) or species that aerial hawk in cluttered woodland environments (e.g. Rhinolophus mehelyi), foraging flight requirements are similar to the requirements within a cave environment. In contrast, for Miniopterus schreibersii – a cave dweller and swift-like aerial hawker of insects – there is an apparent mismatch between its foraging flight and cave flight. Intriguingly, M. schreibersii possesses an extra wing-membrane fold in comparison with the species (see above) it coexists with in caves. This additional membrane fold occurs across the phalanges and at rest results in the wingtip being folded back up between what is the last wingfold for its cohabiting species of bats. M. schreibersii wings are not exceptionally long in comparison with other species, so a simple wing-folding at rest function is an unlikely explanation. High-speed video shows that during the first wing-strokes of take-off, the wingtip fold is folded downward during the latter stages of the upstroke before being rapidly straightened immediately prior to the start of the down-stroke. In addition, the take-off ability of M. schreibersii is better than might be expected given its wing-morphology. Early indications are that the wingtip fold of M. schreibersii may represent a novel mechanism for producing additional thrust during slow-flight. doi:10.1016/j.cbpa.2007.01.201
A6.28 Hovering aerodynamics in hummingbirds: Comparing a dynamically-scaled robot with live birds B. Tobalske, (University of Portland, United States); D. Warrick, (Oregon State University, United States); W. Dickson, M. Dickinson, (California Institute of Technology, United States); D. Altshuler, (University of California, Riverside, United States) To help elucidate the mechanisms that permit hovering in hummingbirds, we used digital particle image velocimetry (DPIV) to measure flow in the near-field and wake of the wings of live birds and of a dynamically-scaled, flat-plate, robotic wing (Re ∼4000) that was equipped with force transducers at the wing root. Flow about the wings of live birds was laminar and lacked a stable leading-edge vortex (LEV) through most of the translational phases of the wingbeat In contrast, at mid-upstroke and mid-downstroke, the robotic wing always exhibited LEV's and trailing-edge vortices (TEV's). This reveals that a flat plate is not fully adequate for modeling flow about a cambered, flexible bird wing. Our measures of bound circulation on the robotic wing lead to estimates of aerodynamic force that matched measured force for upstroke but were 60% of measured force for downstroke, which suggests that LEV's and TEV's were not stable during downstroke. Estimates of force from circulation in the trailing tip vortices matched measured forces at the wing root when circulation was measured within one chord