scholarly journals Nectar vs. pollen loading affects the tradeoff between flight stability and maneuverability in bumblebees

2015 ◽  
Vol 112 (33) ◽  
pp. 10527-10532 ◽  
Author(s):  
Andrew M. Mountcastle ◽  
Sridhar Ravi ◽  
Stacey A. Combes
Keyword(s):  
Wind Tunnel ◽  
Unsteady Flow ◽  
Resource Selection ◽  
Center Of Mass ◽  
Equal Mass ◽  
Moment Of Inertia ◽  
Flight Performance ◽  
Rotational Moment ◽  
External Perturbations ◽  
Smooth Flow

Bumblebee foragers spend a significant portion of their lives transporting nectar and pollen, often carrying loads equivalent to more than half their body mass. Whereas nectar is stored in the abdomen near the bee’s center of mass, pollen is carried on the hind legs, farther from the center of mass. We examine how load position changes the rotational moment of inertia in bumblebees and whether this affects their flight maneuverability and/or stability. We applied simulated pollen or nectar loads of equal mass to Bombus impatiens bumblebees and examined flight performance in a wind tunnel under three conditions: flight in unsteady flow, tracking an oscillating flower in smooth flow, and flower tracking in unsteady flow. Using an inertial model, we estimated that carrying a load on the legs rather than in the abdomen increases a bee’s moment of inertia about the roll and yaw axes but not the pitch axis. Consistent with these predictions, we found that bees carrying a load on their legs displayed slower rotations about their roll and yaw axes, regardless of whether these rotations were driven by external perturbations or self-initiated steering maneuvers. This allowed pollen-loaded bees to maintain a more stable body orientation and higher median flight speed in unsteady flow but reduced their performance when tracking a moving flower, supporting the concept of a tradeoff between stability and maneuverability. These results demonstrate that the types of resources collected by bees affect their flight performance and energetics and suggest that wind conditions may influence resource selection.

Measurement Method Research on Inertial Parameters of Motor Assembly

2013 ◽  
Vol 437 ◽  
pp. 663-668
Author(s):  
Ling Sun ◽  
Peng Yu ◽  
Tong Zhang
Keyword(s):  
Measurement Method ◽  
Center Of Mass ◽  
Moment Of Inertia ◽  
Balance Method ◽  
Test Error ◽  
Inertial Parameters ◽  
Drive Motor ◽  
Weight Method ◽  
Mass Position

Inertial parameters of the motor assembly include its mass, CM (center of mass) position, moment of inertia and product of inertia. Taking one vehicle drive motor as the research object, its mass and CM position are measured by using weight method and moment balance method respectively. Its moment of inertia and product of inertia are measured by using three-wire pendulum. On the basis of analyzing the test error, this paper proposed specific measures to reduce the test error.

A COMPLETE VARIATIONAL WAVE FUNCTION FOR THE GROUND STATE OF 3H AND 3He

1966 ◽  
Vol 44 (9) ◽  
pp. 2095-2110 ◽  
Author(s):  
Marcel Banville ◽  
P. D. Kunz
Keyword(s):  
Wave Function ◽  
Coordinate System ◽  
Body Wave ◽  
Center Of Mass ◽  
Minimum Energy ◽  
Equal Mass ◽  
Radial Coordinate ◽  
Orthogonal Functions ◽  
Gaussian Shape ◽  
Three Body

The three-body wave function for particles of equal mass is expanded in a systematic way by making use of a hyperspherical coordinate system. Apart from the center-of-mass coordinates, three of the variables are the usual Euler angles describing the orientation of the plane defined by the three particles. The other three variables, which describe the shape of the triangle, are represented in terms of a radial coordinate and two angular coordinates. The kinetic energy for these last three coordinates is separable and allows one to expand the three-body wave function in a complete set of orthogonal functions based upon the angular variables. The particular symmetry of the internal part of the wave function under permutations of the three particles is easily represented in terms of the set of functions for one of the angular variables. By choosing a particular set of radial functions one can then obtain the upper limit on the binding energy for the three-body system through the Rayleigh–Ritz variational procedure. The advantage of this particular coordinate system is that all but a few of the variational parameters occur linearly in the wave function, and the minimum energy can be obtained by diagonalizing a small number of the energy matrices. The method is applied to find the lower limit to a standard spin-independent potential of Gaussian shape.

scholarly journals Introduction of Multi-fan Unsteady Flow Wind Tunnel

2021 ◽  
Vol 46 (1) ◽  
pp. 40-44
Author(s):  
Yumi IIDA ◽  
Daisuke SOMEKAWA
Keyword(s):  
Wind Tunnel ◽  
Unsteady Flow

11 Dimensions, Mass, Location of the Center of Mass, and Moment of Inertia of the Segments of the Human Body

2016 ◽  
Author(s):  
Paul Brinckmann ◽  
Wolfgang Frobin ◽  
Gunnar Leivseth ◽  
Burkhard Drerup
Keyword(s):  
Human Body ◽  
Center Of Mass ◽  
Moment Of Inertia

A Roundabout for Studying Sustained Flight of Locusts

1952 ◽  
Vol 29 (2) ◽  
pp. 211-219 ◽  
Author(s):  
AUGUST KROGH ◽  
TORKEL WEIS-FOGH
Keyword(s):  
Wind Tunnel ◽  
External Factors ◽  
Flight Performance ◽  
Average Speed ◽  
Preliminary Results ◽  
Air Resistance

A roundabout technique is described which makes it possible to study the flight performance of a small ‘swarm’ of locusts (up to thirty-two individuals) for hours at a time. The resistance of the roundabout was compensated by means of a mill so that the locusts only had to overcome their own air resistance. The speed of the revolving periphery therefore equalled the preferred average flying speed of the suspended locusts. The average speed during a period, as well as the variation in speed in the course of an experiment, were found to be the same in the roundabout and in experiments where single locusts flew in front of a wind tunnel. In the latter case the insects flew in completely normal flight posture. It was concluded that the results obtained with the roundabout were as valid as the results obtained with a wind tunnel. Some preliminary results are given on the influence of different external factors on the flying speed and the ability to endure sustained flight.

Development of a 6-DOF Testing Platform for Multirotor Flying Vehicles with Suspended Loads

Aerospace ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 355
Author(s):  
Saad M. S. Mukras ◽  
Hanafy M. Omar
Keyword(s):  
Degrees Of Freedom ◽  
Center Of Mass ◽  
Performance Testing ◽  
Flight Performance ◽  
Testing Platform ◽  
Six Degrees Of Freedom ◽  
Mass Properties ◽  
Test Platform ◽  
Suspended Loads

The development of multirotor vehicles can often be a dangerous and costly undertaking due to the possibility of crashes resulting from faulty controllers. The matter of safety in such activities has primarily been addressed through the use of testbeds. However, testbeds for testing multirotor vehicles with suspended loads have previously not been reported. In this study, a simple yet novel testing platform was designed and built to aid in testing and evaluating the performances of multirotor flying vehicles, including vehicles with suspended loads. The platform allows the flying vehicle to move with all six degrees of freedom (DOF). Single or three-DOF motions can also be performed. Moreover, the platform was designed to enable the determination of the mass properties (center of mass and moments of inertia) of small multirotor vehicles (which are usually required in the development of new control systems). The applicability of the test platform for the in-flight performance testing of a multirotor vehicle was successfully demonstrated using a Holybro X500 quadcopter with a suspended load. The test platform was also successfully used to determine the mass properties of the vehicle.

scholarly journals Quantification of vibrissal mechanical properties across the rat mystacial pad

2019 ◽  
Vol 121 (5) ◽  
pp. 1879-1895 ◽  
Author(s):  
Anne En-Tzu Yang ◽  
Hayley M. Belli ◽  
Mitra J. Z. Hartmann
Keyword(s):  
Mechanical Properties ◽  
Center Of Mass ◽  
Distal Region ◽  
Density Variation ◽  
Average Density ◽  
Proximal Region ◽  
Moment Of Inertia ◽  
Radius Of Gyration ◽  
Mass Moment ◽  
Mass Moment Of Inertia

Recent work has quantified the geometric parameters of individual rat vibrissae (whiskers) and developed equations that describe how these parameters vary as a function of row and column position across the array. This characterization included a detailed quantification of whisker base diameter and arc length as well as the geometry of the whisker medulla. The present study now uses these equations for whisker geometry to quantify several properties of the whisker that govern its mechanical behavior. We first show that the average density of a whisker is lower in its proximal region than in its distal region. This density variation appears to be largely attributable to the presence of the whisker cuticle rather than the medulla. The density variation has very little effect on the center of mass of the whisker. We next show that the presence of the medulla decreases the deflection of the whisker under its own weight and also decreases its mass moment of inertia while sacrificing <1% stiffness at the whisker base compared with a solid whisker. Finally, we quantify two dimensionless parameters across the array. First, the deflection-to-length ratio decreases from caudal to rostral: caudal whiskers are longer but deflect more under their own weight. Second, the nondimensionalized radius of gyration is approximately constant across the array, which may simplify control of whisking by the intrinsic muscles. We anticipate that future work will exploit the mechanical properties computed in the present study to improve simulations of the mechanosensory signals associated with vibrissotactile exploratory behavior. NEW & NOTEWORTHY The mechanical signals transmitted by a whisker depend critically on its geometry. We used measurements of whisker geometry and mass to quantify the center of mass, mass moment of inertia, radius of gyration, and deflection under gravity of the whisker. We describe how variations in these quantities across the array could enhance sensing behaviors while reducing energy costs and simplifying whisking control. Most importantly, we provide derivations for these quantities for use in future simulation work.

Lift and Measurements in an Aerofoil in Unsteady Flow

1973 ◽  
Author(s):  
D. W. Holmes
Keyword(s):  
Wind Tunnel ◽  
Unsteady Flow ◽  
Pressure Distribution ◽  
Pressure Fluctuations ◽  
Separation Region ◽  
Vortex Theory

A wind tunnel is described which is capable of producing both “transverse” and “streamwise” gusts. An account is given of the lift and pressure fluctuations measured on an isolated aerofoil tested in the tunnel. The response to a transverse gust compares well with Kemp’s (1) theory although the pressure distribution is not as predicted. The results suggest that the wake behavior and in particular the existence of a separation region can in practice seriously affect the validity of applying the now classical unsteady vortex theory.

Morphing wing with skin discontinuity – kinematic concept

2017 ◽  
Vol 89 (4) ◽  
pp. 535-546 ◽  
Author(s):  
Andrzej Tarnowski
Keyword(s):  
Wind Tunnel ◽  
Performance Optimization ◽  
Numerical Optimization ◽  
Design Methodology ◽  
Control Allocation ◽  
Flight Performance ◽  
Content Type ◽  
Original Contribution ◽  
Wing Morphing ◽  
Kinematic Solution

Purpose This paper aims to describe the concept of morphing tailless aircraft with discontinuous skin and its preliminary kinematic solution. Project assumptions, next steps and expected results are briefly presented. Design/methodology/approach Multidisciplinary numerical optimization will be used to determine control allocation for wing segments rotation. Wing demonstrator will be fabricated and tested in wind tunnel. Results will be used in construction of flying model and design of its control system. Flight data of morphing demonstrator and reference aircraft will result in comparative analysis of both technologies. Findings Proposed design combines advantages of wing morphing without complications of wing’s structure elastic deformation. Better performance, stability and maneuverability is expected due to wing’s construction which is entirely composed of unconnected wing segments. Independent control of each segment allows for free modeling of spanwise lift force distribution. Originality/value Nonlinear multipoint distribution of wing twist as the only mechanism for control and flight performance optimization has never been studied or constructed. Planned wind tunnel investigation of such complex aerodynamic structure has not been previously published and will be an original contribution to the development of aviation and in particular to the aerodynamics of wing with discontinuous skin.

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