Vortex Formation in the Tethered Flight of the Peacock Butterfly Inachis io L. (Lepidoptera, Nymphalidae) and some Aspects of Insect Flight Evolution

1991 ◽  
Vol 161 (1) ◽  
pp. 77-95 ◽  
Author(s):  
A. K. BRODSKY
Keyword(s):  
High Speed ◽  
Insect Flight ◽  
Aerodynamic Force ◽  
Vortex Formation ◽  
Flow Distribution ◽  
The Body ◽  
Body Axis ◽  
Vortex Rings ◽  
Lower Amplitude ◽  
Inachis Io

High-speed filming has been used to investigate the performance of the peacock butterfly Inachis io while flying in a wind-tunnel. The wake of the butterfly in ‘feeding’ flight is a system of discrete pairs of vortex rings: in each pair the vortex rings are coupled at right angles. The flow distribution around the butterfly and the dynamics of the vortex rings suggest that useful force is produced continuously throughout the wingbeat. The butterfly's flapping flight can be divided into three successive stages: during the downstroke, force generation can be explained by quasi-steady aerofoil action; during the upstroke and supination, by unsteady aerofoil action; and during pronation, by a jet mechanism. The study of airflow around the peacock butterfly throws light on the evolutionary changes in the pattern of interaction between insect wings and the air. At the first stage of the evolution of insect flight, documented in a subimago of the mayfly Heptagenia sulphurea and some other primitive insects, flapping wings generate a system of coupled vortex rings; the aerodynamic force, being perpendicular to the stroke plane, coincides with the direction of the longitudinal body axis. At the second stage, this force is directed forwards and upwards relative to the body axis; the vortex wake is the same as that at the first stage. From this point, two paths of evolution are possible. The first leads to the vortex pattern recorded in the peacock butterfly. The second is typically found in higher orders, where the narrow and relatively short wings flap with lower amplitude and higher frequency, leaving in their wake two chains of uncoupled small vortex rings.

scholarly journals Operation of the alula as an indicator of gear change in hoverflies

2011 ◽  
Vol 9 (71) ◽  
pp. 1194-1207 ◽  
Author(s):  
Simon M. Walker ◽  
Adrian L. R. Thomas ◽  
Graham K. Taylor
Keyword(s):  
High Speed ◽  
Aerodynamic Force ◽  
Angular Acceleration ◽  
The State ◽  
The Body ◽  
Kinematic Parameters ◽  
Wing Kinematics ◽  
Change Mechanism ◽  
The Third ◽  
Gear Change

The alula is a hinged flap found at the base of the wings of most brachyceran Diptera. The alula accounts for up to 10 per cent of the total wing area in hoverflies (Syrphidae), and its hinged arrangement allows the wings to be swept back over the thorax and abdomen at rest. The alula is actuated via the third axillary sclerite, which is a component of the wing hinge that is involved in wing retraction and control. The third axillary sclerite has also been implicated in the gear change mechanism of flies. This mechanism allows rapid switching between different modes of wing kinematics, by imposing or removing contact with a mechanical stop limiting movement of the wing during the lower half of the downstroke. The alula operates in two distinct states during flight—flipped or flat—and we hypothesize that its state indicates switching between different flight modes. We used high-speed digital video of free-flying hoverflies ( Eristalis tenax and Eristalis pertinax ) to investigate whether flipping of the alula was associated with changes in wing and body kinematics. We found that alula state was associated with different distributions of multiple wing kinematic parameters, including stroke amplitude, stroke deviation angle, downstroke angle of incidence and timing of supination. Changes in all of these parameters have previously been linked to gear change in flies. Symmetric flipping of the alulae was associated with changes in the symmetric linear acceleration of the body, while asymmetric flipping of the alulae was associated with asymmetric angular acceleration of the body. We conclude that the wings produce less aerodynamic force when the alula is flipped, largely as a result of the accompanying changes in wing kinematics. The alula changes state at mid-downstroke, which is the point at which the gear change mechanism is known to come into effect. This transition is accompanied by changes in the other wing kinematic parameters. We therefore find that the state of the alula is linked to the same parameters as are affected by the gear change mechanism. We conclude that the state of the alula does indeed indicate the operation of different flight modes in Eristalis , and infer that a likely mechanism for these changes in flight mode is the gear change mechanism.

Lift based mechanisms for swimming in eurypterids and portunid crabs

1985 ◽  
Vol 76 (2-3) ◽  
pp. 325-337 ◽  
Author(s):  
Roy E. Plotnick
Keyword(s):  
Blue Crab ◽  
High Speed ◽  
Insect Flight ◽  
Callinectes Sapidus ◽  
Experimental Studies ◽  
The Body ◽  
Functional Constraints ◽  
Thrust Generation ◽  
Kinetics Of ◽  
Physical Principles

ABSTRACTThe striking morphological similarity that exists between appendages of the extant portunid crabs, such as Callinectes sapidus, and those of the extinet eurypterids has long been noted. The fifth pair of pereiopods in blue crags and other portunids are modified to form the broad, flat, highly mobile ‘swim paddles.’ A nearly identical modification is seen in the sixth pair of prosomal appendages of many eurypterids. The similarities are due to convergence and not to shared descent.The kinetics of blue crab swimming were studied using high speed films. The animals are capable of slow upwards locomotion (‘hovering’) and rapid sideways swimming. The blue crab paddles apparently act as reciprocating hydrofoils, employing well-understood principles of lift and thrust generation to overcome the animal's weight and drag. Experimental studies indicated that the paddles are capable of producing appreciable amounts of lift. Drag on the body and paddles was also determined. Resxults are similar to those obtained in previous studies of bird and insect flight.The physical principles employed to study blue crab swimming can be applied to the study of eurypterid locomotion. The eurypterid paddles may have functioned as hydrofoils, producing lift and thrust on forestroke and backstroke. Eurypterids were probably highly agile and manoueverable swimmers, capable of hovering and of high speed swimming. This model predicts observed morphological correlates. Predicted morphological correlates of earlier models (often based on analogies with Limulus) were not found.The observed convergence between eurypterids and blue crabs may have resulted from similar functional constraints and parallel phylogenetic histories.

scholarly journals Speed Control and Force-Vectoring of Blue Bottle Flies in a Magnetically-Levitated Flight Mill

2018 ◽  
Author(s):  
Shih-Jung Hsu ◽  
Neel Thakur ◽  
Bo Cheng
Keyword(s):  
Flight Control ◽  
Insect Flight ◽  
Aerodynamic Force ◽  
Speed Control ◽  
The Body ◽  
Flight Mill ◽  
Wing Motion ◽  
Force Magnitude ◽  
Magnetically Levitated ◽  
And Control

Flies fly at a broad range of speeds and produce sophisticated aerial maneuvers with precisely controlled wing movements. Remarkably, only subtle changes in wing motion are used by flies to produce aerial maneuvers, resulting in little directional tilt of aerodynamic force vector relative to the body. Therefore, it is often considered that flies fly according to a helicopter model and control speed mainly via force-vectoring enabled primarily by body-pitch change. Here we examine the speed control of blue bottle flies using a magnetically-levitated (MAGLEV) flight mill, as they fly at different body pitch and with different augmented aerodynamic damping. We identify wing kinematic contributors to the changes of estimated aerodynamic force through testing two force-vectoring models. Results show that in addition to body pitch, flies also use a collection of wing kinematic variables to control both force magnitude and direction, the roles of which are analogous to those of throttle, collective and cyclic pitch of helicopters. Our results also suggest that the MAGLEV flight mill system can be potentially used to study the roles of visual and mechanosensory feedback in insect flight control.

scholarly journals Flying in reverse: kinematics and aerodynamics of a dragonfly in backward free flight

2018 ◽  
Vol 15 (143) ◽  
pp. 20180102 ◽  
Author(s):  
Ayodeji T. Bode-Oke ◽  
Samane Zeyghami ◽  
Haibo Dong
Keyword(s):  
High Speed ◽  
Aerodynamic Force ◽  
Force Production ◽  
Leading Edge ◽  
The Body ◽  
Body Posture ◽  
Immersed Boundary ◽  
Reconstruction Method ◽  
Free Flight ◽  
The Us

In this study, we investigated the backward free flight of a dragonfly, accelerating in a flight path inclined to the horizontal. The wing and body kinematics were reconstructed from the output of three high-speed cameras using a template-based subdivision surface reconstruction method, and numerical simulations using an immersed boundary flow solver were conducted to compute the forces and visualize the flow features. During backward flight, the dragonfly maintained an upright body posture of approximately 90° relative to the horizon. The upright body posture was used to reorient the stroke plane and the flight force in the global frame; a mechanism known as ‘force vectoring’ which was previously observed in manoeuvres of other flying animals. In addition to force vectoring, we found that while flying backward, the dragonfly flaps its wings with larger angles of attack in the upstroke (US) when compared with forward flight. Also, the backward velocity of the body in the upright position enhances the wings' net velocity in the US. The combined effect of the angle of attack and wing net velocity yields large aerodynamic force generation in the US, with the average magnitude of the force reaching values as high as two to three times the body weight. Corresponding to these large forces was the presence of a strong leading edge vortex (LEV) at the onset of US which remained attached up until wing reversal. Finally, wing–wing interaction was found to enhance the aerodynamic performance of the hindwings (HW) during backward flight. Vorticity from the forewings’ trailing edge fed directly into the HW LEV to increase its circulation and enhance force production.

The flight of the dipterous fly Muscina stabulans Fallén

1940 ◽  
Vol 230 (572) ◽  
pp. 357-390 ◽  
Keyword(s):  
Insect Flight ◽  
The Body ◽  
Body Axis ◽  
Resultant Force ◽  
Wing Beat ◽  
Free Flight ◽  
Experimental Conditions ◽  
Forward Displacement ◽  
The Third ◽  
Centre Of Gravity

As a preliminary step in the study of a system consisting of a flying insect and the air surrounding it, a comparison is made between the system under natural conditions of free flight and under experimental conditions (when the insect is held stationary), in order to ascertain under what conditions conclusions reached with the insect held stationary would hold for free flight. To avoid the difficulty of making this comparison directly in respect of each of the many factors involved, the resultant force which, acting continuously on the body of the insect, would most nearly replace those cyclicly changing forces that normally maintain or modify the state of motion in flight, is taken as an index of what is occurring in the system. When the insect is held stationary in ‘still air’ it is found in most cases that this resultant, though of sufficient magnitude to support the insect in flight, does not act through the centre of gravity: the line of action of the resultant intersects the body axis at some point behind the centre of gravity. The position of this point depends on the amplitude of wing beat. W hen the insect is exposed in a wind tunnel to a stream of air of appropriate speed and direction, however, the resultant acts through the centre of gravity, as in free flight. The forward displacement of the point of intersection between the line of action of the resultant and the body axis, when the insect is exposed to a stream of air, is analysed further, and it is found: (1) that the effect of the stream of air on the body of the insect is negligible in this connexion as compared with the effect on the wings; (2) that changes in amplitude of wing beat do not account for the forward displacement of the resultant; and (3) that when the insect is exposed to a stream of air the path travelled by the wing tip on its downward beat is displaced forwards along the body axis in a direction which would tend to produce the observed displacement of the resultant force. This forward displacement of the path travelled by the wing on its downward beat converts the elliptical course, characteristic of wing movements when the insect is held stationary in ‘still air’, into the figure of ‘8’ course commonly associated with insect flight, and is dependent on the movement or position of the third antennal joint relative to the second, which in turn is determined by the action of the stream of air on the third joint with its arista. The characteristic attitude of the legs in flight, and the continued vibration of the wings when air is blown at the insect from in front also depend on the sensory inflow from the antennae. The maintenance of the figure of ‘8’ path involves the interaction of the sensory inflow both from the antennae and from the halteres.

scholarly journals A Study of an Automated Scoring System for the Twist Skill in Horizontal Bar of Artistic Gymnastics

1970 ◽  
Vol 7 (1) ◽  
pp. 1-6
Author(s):  
Haruki Shimamoto ◽  
Tsuyoshi Taki ◽  
Junichi Hasegawa
Keyword(s):  
Scoring System ◽  
High Speed ◽  
Video Camera ◽  
The Body ◽  
Body Axis ◽  
Automated Scoring ◽  
Subtraction Method ◽  
Video Images ◽  
High Speed Video Camera ◽  
The Moment

This paper presents an automated scoring system for the twist skill in Horizontal bar based on motion image analysis. In this system, training scenes of Horizontal bar are taken by a high-speed video camera, and then a gymnast’s region is extracted from a video image frame by frame based on a background subtraction method. Next, the body axis of the gymnast in the moment when a twist skill completed is estimated from the gymnast’s region. Finally, the deduction point for the twist skill is automatically decided according to the rules described in the Code of Points. In experiments using video images for 26 practices, it was shown that about 80.8% of the correspondence rate between estimated deduction scores and true ones calculated by the correct ‘SCF’ and ‘Body axis’ was obtained. This can be promising as a result at the preliminary stage of this research.

Some Special Aspects of Hypersonic Flow Fields

1959 ◽  
Vol 63 (585) ◽  
pp. 508-512 ◽  
Author(s):  
K. W. Mangler
Keyword(s):  
Hypersonic Flow ◽  
High Speed ◽  
Flow Fields ◽  
The Body ◽  
Lower Velocity ◽  
Bow Wave ◽  
Total Head ◽  
Bow Shocks ◽  
Lower Entropy ◽  
Subsonic Region

When a body moves through air at very high speed at such a height that the air can be considered as a continuum, the distinction between sharp and blunt noses with their attached or detached bow shocks loses its significance, since, in practical cases, the bow wave is always detached and fairly strong. In practice, all bodies behave as blunt shapes with a smaller or larger subsonic region near the nose where the entropy and the corresponding loss of total head change from streamline to streamline due to the curvature of the bow shock. These entropy gradients determine the behaviour of the hypersonic flow fields to a large extent. Even in regions where viscosity effects are small they give rise to gradients of the velocity and shear layers with a lower velocity and a higher entropy near the surface than would occur in their absence. Thus one can expect to gain some relief in the heating problems arising on the surface of the body. On the other hand, one would lose farther downstream on long slender shapes as more and more air of lower entropy is entrained into the boundary layer so that the heat transfer to the surface goes up again. Both these flow regions will be discussed here for the simple case of a body of axial symmetry at zero incidence. Finally, some remarks on the flow field past a lifting body will be made. Recently, a great deal of information on these subjects has appeared in a number of reviewing papers so that little can be added. The numerical results on the subsonic flow regions in Section 2 have not been published before.

scholarly journals Wearable Vibration Sensor for Measuring the Wing Flapping of Insects

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 593
Author(s):  
Ryota Yanagisawa ◽  
Shunsuke Shigaki ◽  
Kotaro Yasui ◽  
Dai Owaki ◽  
Yasuhiro Sugimoto ◽  
...  
Keyword(s):  
High Speed ◽  
Environmental Changes ◽  
Underlying Mechanism ◽  
Indirect Measurement ◽  
Feedback Mechanism ◽  
The Body ◽  
Vibration Sensor ◽  
Wingbeat Frequency ◽  
Film Sensor ◽  
Insect Wing

In this study, we fabricated a novel wearable vibration sensor for insects and measured their wing flapping. An analysis of insect wing deformation in relation to changes in the environment plays an important role in understanding the underlying mechanism enabling insects to dynamically interact with their surrounding environment. It is common to use a high-speed camera to measure the wing flapping; however, it is difficult to analyze the feedback mechanism caused by the environmental changes caused by the flapping because this method applies an indirect measurement. Therefore, we propose the fabrication of a novel film sensor that is capable of measuring the changes in the wingbeat frequency of an insect. This novel sensor is composed of flat silver particles admixed with a silicone polymer, which changes the value of the resistor when a bending deformation occurs. As a result of attaching this sensor to the wings of a moth and a dragonfly and measuring the flapping of the wings, we were able to measure the frequency of the flapping with high accuracy. In addition, as a result of simultaneously measuring the relationship between the behavior of a moth during its search for an odor source and its wing flapping, it became clear that the frequency of the flapping changed depending on the frequency of the odor reception. From this result, a wearable film sensor for an insect that can measure the displacement of the body during a particular behavior was fabricated.

scholarly journals Slithering CSF: Cerebrospinal Fluid Dynamics in the Stationary and Moving Viper Boa, Candoia aspera

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 672
Author(s):  
Bruce A. Young ◽  
Skye Greer ◽  
Michael Cramberg
Keyword(s):  
Cerebrospinal Fluid ◽  
Cardiac Cycle ◽  
Low Frequency ◽  
Mean Amplitude ◽  
The Body ◽  
Body Waves ◽  
Lower Amplitude ◽  
Lateral Undulation ◽  
Recovery From Anesthesia ◽  
The Relationship

In the viper boa (Candoia aspera), the cerebrospinal fluid (CSF) shows two stable overlapping patterns of pulsations: low-frequency (0.08 Hz) pulses with a mean amplitude of 4.1 mmHg that correspond to the ventilatory cycle, and higher-frequency (0.66 Hz) pulses with a mean amplitude of 1.2 mmHg that correspond to the cardiac cycle. Manual oscillations of anesthetized C. aspera induced propagating sinusoidal body waves. These waves resulted in a different pattern of CSF pulsations with frequencies corresponding to the displacement frequency of the body and with amplitudes greater than those of the cardiac or ventilatory cycles. After recovery from anesthesia, the snakes moved independently using lateral undulation and concertina locomotion. The episodes of lateral undulation produced similar influences on the CSF pressure as were observed during the manual oscillations, though the induced CSF pulsations were of lower amplitude during lateral undulation. No impact on the CSF was found while C. aspera was performing concertina locomotion. The relationship between the propagation of the body and the CSF pulsations suggests that the body movements produce an impulse on the spinal CSF.

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