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.

The mechanics of flight in the hawkmoth Manduca sexta. I. Kinematics of hovering and forward flight.

1997 ◽  
Vol 200 (21) ◽  
pp. 2705-2722 ◽  
Author(s):  
A P Willmott ◽  
C P Ellington
Keyword(s):  
Manduca Sexta ◽  
High Speed ◽  
Time Course ◽  
The Body ◽  
Forward Speed ◽  
Plane Angle ◽  
Free Flight ◽  
Body Angle ◽  
Distal Half ◽  
Angle Of Rotation

High-speed videography was used to record sequences of individual hawkmoths in free flight over a range of speeds from hovering to 5 ms-1. At each speed, three successive wingbeats were subjected to a detailed analysis of the body and wingtip kinematics and of the associated time course of wing rotation. Results are presented for one male and two female moths. The clearest kinematic trends accompanying increases in forward speed were an increase in stroke plane angle and a decrease in body angle. The latter may have resulted from a slight dorsal shift in the area swept by the wings as the supination position became less ventral with increasing speed. These trends were most pronounced between hovering and 3 ms-1, and the changes were gradual; there was no distinct gait change of the kind observed in some vertebrate fliers. The wing rotated as two functional sections: the hindwing and the portion of the forewing with which it is in contact, and the distal half of the forewing. The latter displayed greater fluctuation in the angle of rotation, especially at the lower speeds. As forward speed increased, the discrepancy between the rotation angles of the two halfstrokes, and of the two wing sections, became smaller. The downstroke wing torsion was set early in the halfstroke and then held constant during the translational phase.

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.

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.

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.

scholarly journals Reduction of the head-up pitching moment of small quad-rotor unmanned aerial vehicles in uniform flow

2017 ◽  
Vol 10 (1) ◽  
pp. 85-105 ◽  
Author(s):  
Hikaru Otsuka ◽  
Daisuke Sasaki ◽  
Keiji Nagatani
Keyword(s):  
Wind Tunnel ◽  
Unmanned Aerial Vehicles ◽  
Uniform Flow ◽  
The Body ◽  
Pitching Moment ◽  
Aerial Vehicles ◽  
Flow Interactions ◽  
Wire Method ◽  
The Moment ◽  
Cruise Flight

Multi-rotor unmanned aerial vehicles are unstable in headwind because of nose-up pitching moment generation and thrust degradation. Reducing the pitching moment generation could enhance the tolerance of the unmanned aerial vehicles to wind and improve cruise flight speed. In this study, a canted rotor configuration was proposed to reduce the moment in uniform flow and examined. The objective of the study is to evaluate the effect of moment reduction by canted rotors. First, flow interactions between rotors of the quad-rotor were visualized using a smoke wire method. Second, the moment reduction by canted rotors was estimated based on isolated rotor performance. Third, the moment of the quad-rotor varying the body pitching angle was examined using a wind tunnel. At an 8 m/s wind, when the body pitching angle is horizontal, slanting the rotor by 20° to outside the body degraded the moment by 26% compared with the parallel rotor configuration.

scholarly journals Dynamic influence of the plane curve radius on vertical- circular overlapping lines of high-speed railway

2021 ◽  
Vol 248 ◽  
pp. 03033
Author(s):  
Xianghui Fan ◽  
Bin Li ◽  
Yongfu Zhang ◽  
Guoqiang Du ◽  
Hua Liu
Keyword(s):  
High Speed ◽  
Plane Curve ◽  
Simulation Software ◽  
The Body ◽  
Dynamics Simulation ◽  
Vertical Acceleration ◽  
High Speed Railway ◽  
Starting Point ◽  
Train Operation ◽  
Curve Radius

In order to reasonably match the horizontal and vertical sections of high-speed railway lines, the vehicle-line spatial coupling model of the vertical-circular overlapping line is established, based on the multi-body dynamics simulation software SIMPACK,. The dynamic indexes of train passing through vertical-circular overlapping lines are calculated when the radii of different plane curves match the corresponding superelevation value. The results show that: on the vertical-circular overlapping line, it is suggested that the maximum plane curve radius is 9000m.The existence of the convex vertical-circular overlapping line worsens the safety of train operation and passenger comfort. The existence of the concave vertical-circular overlapping line is the opposite, but it increases rail wear and the workload of maintenance. The vertical-circular overlapping line has the most obvious influence on the vertical acceleration and the vertical Sperling index of the body. The vertical acceleration of the body is superimposed at the plane gentle circle point and the starting point of the vertical curve, which has a great impact on the stability of the train operation.

Estimates of circulation and gait change based on a three-dimensional kinematic analysis of flight in cockatiels (Nymphicus hollandicus)and ringed turtle-doves (Streptopelia risoria)

2002 ◽  
Vol 205 (10) ◽  
pp. 1389-1409 ◽  
Author(s):  
Tyson L. Hedrick ◽  
Bret W. Tobalske ◽  
Andrew A. Biewener
Keyword(s):  
Wind Tunnel ◽  
Vortex Ring ◽  
High Speed ◽  
Three Dimensional ◽  
Circulation Model ◽  
Whole Body ◽  
Vertical Acceleration ◽  
Streptopelia Risoria ◽  
Wide Range ◽  
Nymphicus Hollandicus

SUMMARYBirds and bats are known to employ two different gaits in flapping flight,a vortex-ring gait in slow flight and a continuous-vortex gait in fast flight. We studied the use of these gaits over a wide range of speeds (1-17 ms-1) and transitions between gaits in cockatiels (Nymphicus hollandicus) and ringed turtle-doves (Streptopelia risoria)trained to fly in a recently built, variable-speed wind tunnel. Gait use was investigated via a combination of three-dimensional kinematics and quasi-steady aerodynamic modeling of bound circulation on the distal and proximal portions of the wing. Estimates of lift from our circulation model were sufficient to support body weight at all but the slowest speeds (1 and 3 ms-1). From comparisons of aerodynamic impulse derived from our circulation analysis with the impulse estimated from whole-body acceleration,it appeared that our quasi-steady aerodynamic analysis was most accurate at intermediate speeds (5-11 ms-1). Despite differences in wing shape and wing loading, both species shifted from a vortex-ring to a continuous-vortex gait at 7 ms-1. We found that the shift from a vortex-ring to a continuous-vortex gait (i) was associated with a phase delay in the peak angle of attack of the proximal wing section from downstroke into upstroke and (ii) depended on sufficient forward velocity to provide airflow over the wing during the upstroke similar to that during the downstroke. Our kinematic estimates indicated significant variation in the magnitude of circulation over the course the wingbeat cycle when either species used a continuous-vortex gait. This variation was great enough to suggest that both species shifted to a ladder-wake gait as they approached the maximum flight speed (cockatiels 15 ms-1, doves 17 ms-1) that they would sustain in the wind tunnel. This shift in flight gait appeared to reflect the need to minimize drag and produce forward thrust in order to fly at high speed. The ladder-wake gait was also employed in forward and vertical acceleration at medium and fast flight speeds.

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.

Influence of stable iodine on the uptake of the thyroid – model vs. experiment

2001 ◽  
Vol 40 (01) ◽  
pp. 31-37 ◽  
Author(s):  
U. Wellner ◽  
E. Voth ◽  
H. Schicha ◽  
K. Weber
Keyword(s):  
Time Course ◽  
Compartment Model ◽  
The Body ◽  
Iodine Uptake ◽  
Model Calculations ◽  
Physiological Conditions ◽  
Iodine Supply ◽  
Predicted Values ◽  
The Individual ◽  
Stable Iodine

Summary Aim: The influence of physiological and pharmacological amounts of iodine on the uptake of radioiodine in the thyroid was examined in a 4-compartment model. This model allows equations to be derived describing the distribution of tracer iodine as a function of time. The aim of the study was to compare the predictions of the model with experimental data. Methods: Five euthyroid persons received stable iodine (200 μg, 10 mg). 1-123-uptake into the thyroid was measured with the Nal (Tl)-detector of a body counter under physiological conditions and after application of each dose of additional iodine. Actual measurements and predicted values were compared, taking into account the individual iodine supply as estimated from the thyroid uptake under physiological conditions and data from the literature. Results: Thyroid iodine uptake decreased from 80% under physiological conditions to 50% in individuals with very low iodine supply (15 μg/d) (n = 2). The uptake calculated from the model was 36%. Iodine uptake into the thyroid did not decrease in individuals with typical iodine supply, i.e. for Cologne 65-85 μg/d (n = 3). After application of 10 mg of stable iodine, uptake into the thyroid decreased in all individuals to about 5%, in accordance with the model calculations. Conclusion: Comparison of theoretical predictions with the measured values demonstrated that the model tested is well suited for describing the time course of iodine distribution and uptake within the body. It can now be used to study aspects of iodine metabolism relevant to the pharmacological administration of iodine which cannot be investigated experimentally in humans for ethical and technical reasons.

Sign in / Sign up

Export Citation Format

Share Document