scholarly journals WING MOVEMENTS ASSOCIATED WITH COLLISIONAVOIDANCE MANOEUVRES DURING FLIGHT IN THE LOCUST LOCUSTA MIGRATORIA

1992 ◽  
Vol 163 (1) ◽  
pp. 231-258 ◽  
Author(s):  
R. MELDRUM ROBERTSON ◽  
DAVID N. REYE
Keyword(s):  
Wind Tunnel ◽  
Collision Avoidance ◽  
High Speed ◽  
Locusta Migratoria ◽  
Video Camera ◽  
Flight Path ◽  
The Body ◽  
Force Vector ◽  
High Speed Cinematography ◽  
The Asymmetry

1. Flying locusts will try to avoid colliding with objects directly in their flight path. This study investigated the wing movements and behaviour patterns associated with collision avoidance. 2. Tethered locusts were flown in a wind tunnel. Targets were transported at different speeds either directly towards the head of the animal or to one side of the midline but parallel to it. Changes in the form of the wingbeat for each of the wings were monitored using either a video camera or a high-speed ciné camera. 3. Animals attempted to avoid an impending collision by making movements interpreted here as (a) increasing lift to fly over the object, (b) gliding and extending the forelegs to land on the object, and (c) steering to one side of the object. Steering was monitored by observation of abdominal movements. 4. Steering to one side of an approaching target was reliably associated with an earlier and more pronounced pronation of the wings on the inside of the turn. Also, in the middle of the downstroke, the forewings were markedly asymmetrical. On the outside of the turn, the forewing was more elevated and separate from the hindwing. On the inside of the turn, the forewing was more depressed and often came down in conjunction with, or in advance of, the hindwing on that side. 5. The forewing asymmetry correlated with the position of the target such that most attempted turns were in the direction that would take the animal around the closest edge. High-speed cinematography showed that the asymmetry was caused both by changes in the timing of the two wings and by changes in the angular ranges of the wingbeats. 6. We propose that these changes in the form and timing of the wingbeats are likely to have swung the flight force vector around the long axis of the body to produce a banked turn around the closest edge of the object.

Interaction Between Wind Loading and Japanese Slates: Effect on Vibration and Scattering

2008 ◽  
Author(s):  
Satoru Okamoto
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Natural Frequencies ◽  
Basic Mechanism ◽  
Video Camera ◽  
Flow Speed ◽  
Test Method ◽  
Wind Loading ◽  
Natural Mode ◽  
Set Up

A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.

Effect on Slates by Wind Over Roof of Japanese Residence

2009 ◽  
Author(s):  
Satoru Okamoto
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Natural Frequencies ◽  
Basic Mechanism ◽  
Video Camera ◽  
Flow Speed ◽  
Test Method ◽  
Natural Mode ◽  
Excited Oscillation ◽  
Set Up

A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.

Metabolic power, mechanical power and efficiency during wind tunnel flight by the European starlingSturnus vulgaris

2001 ◽  
Vol 204 (19) ◽  
pp. 3311-3322 ◽  
Author(s):  
S. Ward ◽  
U. Möller ◽  
J. M. V. Rayner ◽  
D. M. Jackson ◽  
D. Bilo ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Flight Muscle ◽  
Carbon Dioxide Production ◽  
Flight Speed ◽  
Mechanical Power ◽  
Metabolic Power ◽  
Aerodynamic Model ◽  
Flight Costs ◽  
High Speed Cinematography

SUMMARYWe trained two starlings (Sturnus vulgaris) to fly in a wind tunnel whilst wearing respirometry masks. We measured the metabolic power (Pmet) from the rates of oxygen consumption and carbon dioxide production and calculated the mechanical power (Pmech) from two aerodynamic models using wingbeat kinematics measured by high-speed cinematography. Pmet increased from 10.4 to 14.9 W as flight speed was increased from 6.3 to 14.4 m s–1 and was compatible with the U-shaped power/speed curve predicted by the aerodynamic models. Flight muscle efficiency varied between 0.13 and 0.23 depending upon the bird, the flight speed and the aerodynamic model used to calculate Pmech. Pmet during flight is often estimated by extrapolation from the mechanical power predicted by aerodynamic models by dividing Pmech by a flight muscle efficiency of 0.23 and adding the costs of basal metabolism, circulation and respiration. This method would underestimate measured Pmet by 15–25 % in our birds. The mean discrepancy between measured and predicted Pmet could be reduced to 0.1±1.5 % if flight muscle efficiency was altered to a value of 0.18. A flight muscle efficiency of 0.18 rather than 0.23 should be used to calculate the flight costs of birds in the size range of starlings (approximately 0.1 kg) if Pmet is calculated from Pmech derived from aerodynamic models.

Numerical Investigation of Drag and Lift Forces on a Sedan Car using Computational Fluid Dynamics

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
M.F. Mohamed ◽  
P.L. Madhavan ◽  
E. Manoj ◽  
K. Sivakumar
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Numerical Investigation ◽  
High Speed ◽  
The Body ◽  
Sharp Edge ◽  
Wind Tunnel Simulation ◽  
Lift Forces ◽  
Drag And Lift

The purpose of this work is to cut back the drag, lift and aerodynamic in-stability of a sedan car at high speed levels. In early times, the cars accustomed have a flat faces, sharp edge, conjointly had higher mileage and potency. However later because of the emergence of fuel crisis, scientists improved the model of cars with regard to dynamics of the fluid around the body. Thus, it changes the structure of cars with respect to aeromechanics. Simulation of a vehicle had been done using computational fluid dynamics to obtain the coefficient of drag and coefficient of lift. Finally, these coefficients from computational fluid dynamics are compared wind tunnel simulation.

Forewing asymmetries during auditory avoidance in flying locusts

1997 ◽  
Vol 200 (17) ◽  
pp. 2323-2335 ◽  
Author(s):  
J Dawson ◽  
K Dawson-Scully ◽  
D Robert ◽  
R. M. Robertson
Keyword(s):  
High Speed ◽  
Stimulus Onset ◽  
Wingbeat Frequency ◽  
Motor Patterns ◽  
Wing Kinematics ◽  
Roll Torque ◽  
High Speed Cinematography ◽  
Left And Right ◽  
The Asymmetry ◽  
Stroke Amplitude

Flying locusts orient to sounds in their environment. Sounds similar to those produced by echolocating bats cause a flying locust to change its flight path. We used high-speed cinematography and videography to study changes in body posture and wing kinematics of tethered locusts in response to stimulation with bat-like sounds. Locusts showed both negative and positive phonotaxis to this stimulus. Within a few wingbeats of stimulus onset (between 126 and 226ms), locusts deflected their abdomens to one side, and the angle of the left and right forewings with respect to the dorsal­ventral body axis became asymmetrical during the downstroke. This forewing asymmetry, in which the forewing on the inside of the turn became more depressed, ranged from 20 to 45° (37±9.7°, mean ± s.d.) and was correlated with the direction and magnitude of abdomen deflection, a measure of steering in tethered, flying locusts. Hindwing stroke angle asymmetries were minimal or non-existent after stimulation. Coincident with changes in forewing asymmetry and abdomen deflection was a decrease in stroke amplitude (19±6.5°) of the forewing on the inside of the attempted turn. Motor patterns from forewing first basalar (M97) muscles showed an asymmetry in the timing of left and right depressor activation that ranged from 10.4 to 1.6ms (4.23±2.85ms). The number of spikes per depressor burst increased to a maximum of three spikes in the muscle on the inside of the attempted turn, and depressor frequency (wingbeat frequency) increased by approximately 2Hz (2.17±0.26Hz). We suggest that the asymmetry in forewing first basalar activity is causally related to the asymmetry in the timing of the initiation of the downstroke, resulting in an asymmetry in the ranges of the stroke angles of the forewings, which would impart a roll torque to the locust. This would augment the steering torques generated by concurrent changes in the angle of attack of the fore- and hindwings and changes in abdomen position to effect rapid avoidance manoeuvres.

scholarly journals COLLISION AVOIDANCE OF FLYING LOCUSTS: STEERING TORQUES AND BEHAVIOUR

1993 ◽  
Vol 183 (1) ◽  
pp. 35-60 ◽  
Author(s):  
R. M. Robertson ◽  
A. G. Johnson
Keyword(s):  
Wind Tunnel ◽  
Avoidance Response ◽  
Collision Avoidance ◽  
Flight Path ◽  
Field Of View ◽  
Strain Gauges ◽  
Time To Collision ◽  
Leaf Springs ◽  
Forward Translation ◽  
The Right

1. Obstacles approaching in the flight path trigger postural and wing kinematic adjustments in tethered flying locusts. We sought to confirm that these behaviours were steering behaviours by measuring the changes in the flight forces associated with their execution. We also investigated the coordination of these behaviours in the execution of collision avoidance manoeuvres and the effect of speed or size of the obstacle on the timing and magnitude of the response. 2. Locusts were tethered and suspended in a wind tunnel from orthogonally arranged leaf springs mounted with strain gauges. Lift and yaw torque could be monitored unambiguously. We also monitored a forward translation force which combined pitch and thrust. During flight, the locusts were videotaped from behind while targets of different sizes (5 cmx5 cm, 7 cmx7 cm, 9 cmx9cm, 11 cmx11 cm) were transported towards the head at different speeds (1, 2, 3 or 4 m s-1). 3. Angular asymmetry of the forewings during the downstroke with the right forewing high, and abdomen and hindleg movement to the left, were temporally associated with an increase in yaw torque to the left. With the left forewing high, abdomen and hindleg movement to the right were temporally associated with a decrease in yaw torque to the left. Obstacle avoidance behaviours could be associated with either an increase or a decrease in the pitch/thrust component. 4. Leg, abdomen and wingbeat alterations in response to the approach of an obstacle were independent but tightly coordinated. Slower approaches increased the magnitude of the responses. However, the size of the obstacle had no effect on the magnitude of the response. Slower and larger targets generated earlier reactions (i.e. locusts reacted when the targets were further from the head). 5. We conclude that the behaviours we have described were steering behaviours which would have directed the animal around an obstacle in its flight path, and that there were at least two strategies for collision avoidance associated with slowing or speeding flight. Leg, abdomen and wingbeat alterations formed a coherent avoidance response, the magnitude of which was dependent upon the time available for it to develop. We further conclude that the manoeuvre was not initiated at a constant time to collision and we propose that the avoidance strategy was to initiate the manoeuvre when the targets subtended more than 10 s in the insect's field of view.

Horizontal flight of a swallow (Hirundo rustica) observed in a wind tunnel, with a new method for directly measuring mechanical power

2000 ◽  
Vol 203 (11) ◽  
pp. 1755-1765 ◽  
Author(s):  
C.J. Pennycuick ◽  
A. Hedenstrom ◽  
M. Rosen
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Time Course ◽  
The Body ◽  
Mechanical Power ◽  
Vertical Position ◽  
Vertical Acceleration ◽  
Minimum Drag ◽  
Horizontal Flight ◽  
The Moment

A swallow flying in the Lund wind tunnel was observed from the side and from behind, by two synchronised high-speed video cameras. The side-view camera provided a record of the vertical position of a white mark, applied to the feathers behind and below the eye, from which the vertical acceleration was obtained. The rear-view camera provided measurements of the mean angle of the left and right humeri above horizontal. From these data, the force acting on the body, the moment applied by each pectoralis muscle to the humerus and the rotation of the humerus were estimated and used to analyse the time course of a number of variables, including the work done by the muscles in each wing beat. The average mechanical power turned out to be more than that predicted on the basis of current estimates of body drag coefficient and profile power ratio, possibly because the bird was not flying steadily in a minimum-drag configuration. We hope to develop the method further by correlating the mechanical measurements with observations of the vortex wake and to apply it to birds that have been conditioned to hold a constant position in the test section.

Gliding flight: drag and torque of a hawk and a falcon with straight and turned heads, and a lower value for the parasite drag coefficient

2000 ◽  
Vol 203 (24) ◽  
pp. 3733-3744 ◽  
Author(s):  
V.A. Tucker
Keyword(s):  
Wind Tunnel ◽  
Mathematical Models ◽  
Drag Coefficient ◽  
High Speed ◽  
Aerodynamic Drag ◽  
The Body ◽  
Head Turning ◽  
Drag Coefficients ◽  
Spiral Path ◽  
Gliding Flight

Raptors - falcons, hawks and eagles in this study - such as peregrine falcons (Falco peregrinus) that attack distant prey from high-speed dives face a paradox. Anatomical and behavioral measurements show that raptors of many species must turn their heads approximately 40 degrees to one side to see the prey straight ahead with maximum visual acuity, yet turning the head would presumably slow their diving speed by increasing aerodynamic drag. This paper investigates the aerodynamic drag part of this paradox by measuring the drag and torque on wingless model bodies of a peregrine falcon and a red-tailed hawk (Buteo jamaicensis) with straight and turned heads in a wind tunnel at a speed of 11.7 m s(−)(1). With a turned head, drag increased more than 50 %, and torque developed that tended to yaw the model towards the direction in which the head pointed. Mathematical models for the drag required to prevent yawing showed that the total drag could plausibly more than double with head-turning. Thus, the presumption about increased drag in the paradox is correct. The relationships between drag, head angle and torque developed here are prerequisites to the explanation of how a raptor could avoid the paradox by holding its head straight and flying along a spiral path that keeps its line of sight for maximum acuity pointed sideways at the prey. Although the spiral path to the prey is longer than the straight path, the raptor's higher speed can theoretically compensate for the difference in distances; and wild peregrines do indeed approach prey by flying along curved paths that resemble spirals. In addition to providing data that explain the paradox, this paper reports the lowest drag coefficients yet measured for raptor bodies (0.11 for the peregrine and 0.12 for the red-tailed hawk) when the body models with straight heads were set to pitch and yaw angles for minimum drag. These values are markedly lower than value of the parasite drag coefficient (C(D,par)) of 0.18 previously used for calculating the gliding performance of a peregrine. The accuracy with which drag coefficients measured on wingless bird bodies in a wind tunnel represent the C(D,par) of a living bird is unknown. Another method for determining C(D,par) selects values that improve the fit between speeds predicted by mathematical models and those observed in living birds. This method yields lower values for C(D,par) (0.05-0.07) than wind tunnel measurements, and the present study suggests a value of 0.1 for raptors as a compromise.

Structural Dynamics and Response of Roof Tiles Under Wind Loading

2006 ◽  
Author(s):  
Satoru Okamoto
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Natural Frequencies ◽  
Basic Mechanism ◽  
Video Camera ◽  
Flow Speed ◽  
Test Method ◽  
Wind Loading ◽  
Natural Mode ◽  
Set Up

A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.

RATIO OF THE SPEED COMPONENTS OF SKI RACERS AT SPORTS TRAINING STAGES IN TIME TRIALS

2020 ◽  
Vol 8 (4) ◽  
pp. 20-25
Author(s):  
Elena Reutskaya ◽  
Tamara Poltoratskaya
Keyword(s):  
High Speed ◽  
Time Trial ◽  
Video Camera ◽  
The Body ◽  
Movement Speed ◽  
Sports Training ◽  
Cycle Frequency ◽  
Training Stage ◽  
Motor Actions ◽  
Ski Racers

The purpose: a study of the rationality of motor actions of ski racers at different sports training stages. Methods and organization of the research. 202 female skiers and 201 male skiers participated in the study. The authors carried out video shooting with a Sony HDR-CX360E video camera with a maximum resolution of 1920x1080 and a shooting speed of 50 frames per second, in order to assess motion techniques. Results and discussion. The comparative characteristics of the speed components of ski racers in time-trial competitions has shown that ski racers have a significant decrease in cycle frequency and cycle length at sports training stages. Consequently, movement speed decreases from the first to the last lap of the race. Conclusion. The research has revealed that ski racers choose the quick start tactics at every sports training stage, and then they try to maintain a high-speed rate until the end of the race. Meanwhile, the skiers maintain high speed due to the power component of movement techniques at the beginning of the race, while the main energy systems of the body cope with fatigue and ensure speed maintenance. The study of ski racers at different sports training stages has demonstrated that the high movement speed is maintained by the speed component of movement techniques.

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