Measurement on Camber Deformation of Wings of Free-flying Dragonflies and Beating-flying Dragonflies

The knowledge of wing orientation and deformation during flapping flight is necessary for a complete aerodynamic analysis, but to date those kinematic features have not been simultaneously quantified for free-flying insects. A projected comb-fringe (PCF) method has been developed for measuring spanwise camber changes on free-flying dragonflies and on beating-flying dragonflies through the course of a wingbeat, which bases on projecting a fringe pattern over the whole measurement area and then measuring the wing deformation from the distorted fringe pattern. Experimental results demonstrate substantial camber changes both along the wingspan and through the course of a wingbeat. The ratio of camber deformation to chord length for hind wing is up to 0.11 at 75% spanwise with a flapping angle of -0.66 degree for a free-flying dragonfly.

Flexible Wing Kinematics of a Free-Flying Beetle （Rhinoceros Beetle Trypoxylus Dichotomus）

Detailed 3-Dimensional （3D） wing kinematics was experimentally presented in free flight of a beetle, Trypoxylus dichotomus, which has a pair of elytra （forewings） and flexible hind wings. The kinematic parameters such as the wing tip trajectory, angle of attack and camber deformation were obtained from a 3D reconstruction technique that involves the use of two synchronized high-speed cameras to digitize various points marked on the wings. Our data showed outstanding characteristics of deformation and flexibility of the beetle＇s hind wing compared with other measured insects, especially in the chordwise and spanwise directions during flapping motion. The hind wing produced 16% maximum positive camber deformation during the downstroke. It also experienced twisted shape showing large variation of the angle of attack from the root to the tip during the upstroke.

Flow Visualization of Rhinoceros Beetle （Trypoxylus dichotomus） in Free Flight

Aerodynamic characteristics of the beetle, Trypoxylus dichotomus, which has a pair of elytra （forewings） and flexible hind wings, are investigated. Visualization experiments were conducted for various flight conditions of a beetle, Trypoxylus di- chotomus： free, tethered, hovering, forward and climbing flights. Leading edge, trailing edge and tip vortices on both wings were observed clearly. The leading edge vortex was stable and remained on the top surface of the elytron for a wide interval during the downstroke of free forward flight. Hence, the elytron may have a considerable role in lift force generation of the beetle. In addition, we reveal a suction phenomenon between the gaps of the hind wing and the elytron in upstroke that may improve the positive lift force on the hind wing. We also found the reverse clap-fling mechanism of the T. dichotomus beetle in hovering flight. The hind wings touch together at the beginning of the upstroke. The vortex generation, shedding and interaction give a better understanding of the detailed aerodynamic mechanism of beetle flight.

How Could Beetle＇s Elytra Support Their Own Weight during Forward Flight？

The aerodynamic role of the elytra during a beetle＇s flapping motion is not well-elucidated, although it is well-recognized that the evolution of elytra has been a key in the success of coleopteran insects due to their protective function. An experimental study on wing kinematics reveals that for almost concurrent flapping with the hind wings, the flapping angle of the elytra is 5 times smaller than that of the hind wings. Then, we explore the aerodynamic forces on elytra in free forward flight with and without an effect of elytron-hind wing interaction by three-dimensional numerical simulation. The numerical results show that vertical force generated by the elytra without interaction is not sufficient to support even its own weight. However, the elytron-hind wing interaction improves the vertical force on the elytra up to 80%; thus, the total vertical force could fully support its own weight. The interaction slightly increases the vertical force on the hind wind by 6% as well.

Metabolic cost of flight and aerobic efficiency in the rose chafer,Protaetia cuprea(Cetoniinae)

Rose chafer beetles(Protetia cuprea)are pollinators as well as agricultural pests,flying between flowers and trees while foraging for pollen and fruits.Calculating the energy they expend on flying during foraging activity faces the challenge of measuring the metabolic rate(MR)of free-flying insects in an open space.We overcame this challenge by using the bolus injection of ^(13)C Na-bicarbonate technique to measure their metabolic energy expenditure while flying in a large flight arena.Concurrently,we tracked the insects with high-speed cameras to extract their flight trajectory,from which we calculated the mechanical power invested in flying for each flight bout.We found that the chemical(metabolic)energy input converted to mechanical flight energy output at a mean efficiency of 10.4%±5.2%,with a trend of increased efficiency in larger conspecifics(efficiency scaled with body mass to the power of 1.4).The transition in the summer from a diet of pollen to that of fruits may affect the energy budget available for foraging.Starved P.cuprea,feeding on apples ad libitum,increased their body mass by an average of 6%in 2 h.According to our calculations,such a meal can power a 630-m flight(assuming a carbohydrate assimilation efficiency of 90%).Pollen,with a low water and carbohydrate content but rich in proteins and lipids,has a higher caloric content and should assimilate differently when converting food to flight fuel.The high cost of aerial locomotion is inherent to the foraging behavior of rose chafers,explaining their short flight bouts followed by prolonged feeding activity.

Improved Flight Conflict Detection Algorithm Based on Gauss-Hermite Particle Filter

In order to improve the accuracy of free flight conflict detection and reduce the false alarm rate, an improved flight conflict detection algorithm is proposed based on Gauss-Hermite particle filter（GHPF）. The algorithm improves the traditional flight conflict detection method in two aspects：（i） New observation data are integrated into system state transition probability, and Gauss-Hermite Filter（GHF） is used for generating the importance density function.（ii） GHPF is used for flight trajectory prediction and flight conflict probability calculation. The experimental results show that the accuracy of conflict detection and tracing with GHPF is better than that with standard particle filter. The detected conflict probability is more precise with GHPF, and GHPF is suitable for early free flight conflict detection.