Can scalable design of wings for flapping wing micro air vehicle be inspired by natural flyers?

Lift production is constantly a great challenge for flapping wing micro air vehicles (MAVs). Designing a workable wing, therefore, plays an essential role. Dimensional analysis is an effective and valuable tool in studying the biomechanics of flyers. In this paper, geometric similarity study is firstly presented. Then, the pw−AR ratio is defined and employed in wing performance estimation before the lumped parameter is induced and utilized in wing design. Comprehensive scaling laws on relation of wing performances for natural flyers are next investigated and developed via statistical analysis before being utilized to examine the wing design. Through geometric similarity study and statistical analysis, the results show that the aspect ratio and lumped parameter are independent on mass, and the lumped parameter is inversely proportional to the aspect ratio. The lumped parameters and aspect ratio of flapping wing MAVs correspond to the range of wing performances of natural flyers. Also, the wing performances of existing flapping wing MAVs are examined and follow the scaling laws. Last, the manufactured wings of the flapping wing MAVs are summarized. Our results will, therefore, provide a simple but powerful guideline for biologists and engineers who study the morphology of natural flyers and design flapping wing MAVs

Adaptive evolution of butterfly wing shape: from morphology to behaviour

International audienceButterflies display extreme variation in wing shape associated with tremendous ecological diversity. Disentangling the role of neutral versus adaptive processes in wing shape diversification remains a challenge for evolutionary biologists. Ascertaining how natural selection influences wing shape evolution requires both functional studies linking morphology to flight performance, and ecological investigations linking performance in the wild with fitness. However, direct links between morphological variation and fitness have rarely been established. The functional morphology of butterfly flight has been investigated but selective forces acting on flight behaviour and associated wing shape have received less attention. Here, we attempt to estimate the ecological relevance of morpho-functional links established through biomechanical studies in order to understand the evolution of butterfly wing morphology. We survey the evidence for natural and sexual selection driving wing shape evolution in butterflies, and discuss how our functional knowledge may allow identification of the selective forces involved, at both the macro-and micro-evolutionary scales. Our review shows that although correlations between wing shape variation and ecological factors have been established at the macro-evolutionary level, the underlying selective pressures often remain unclear. We identify the need to investigate flight behaviour in relevant ecological contexts to detect variation in fitness-related traits. Identifying the selective regime then should guide experimental studies towards the relevant estimates of flight performance. Habitat, predators and sex-specific behaviours are likely to be major selective forces acting on wing shape evolution in butterflies. Some striking cases of morphological divergence driven by contrasting ecology involve both wing and body morphology, indicating that their interactions should be included in future studies investigating co-evolution between morphology and flight behaviour

Experimental and computational analysis for insect inspired flapping wing micro air vehicles

Many creatures in nature have evolved the ability to fly and some seem to do so effortlessly with captivating movement. The flight characteristics of these natural fliers have greatly fascinated biologists and engineers for a long time that to this day researchers continue to actively work in this field of science with the aim of one day developing a Flapping Wing Micro Aerial Vehicle (FWMAV) which can replicate the flight of nature's creatures. These types of autonomous robotic vehicles can fulfil tasks which are not suitable for manned vehicles especially when risks to human safety are present. Flight techniques such as control, stability and manoeuvrability are flight characteristics which an FWMAV must possess if such a device is employed for various rescue missions. With this in mind symmetrical and asymmetrical wing motions are studied experimentally in the current research programme in such a way that the methodology employed for this type of flight can be implemented into future FWMAVs. In summary, the research performed during the course of this project produced innovative results in the form of the creation of two micro air vehicles with a thorough explanation of the development process and examination under experimental tests. Various parameters were analysed during the experimental tests such as force, moment, power and wing position measurements. The tests were performed on both models, one of which has the functionality to perform asymmetrical flapping and successfully generate moments about two different axes. A unique wing motion which favoured the upward vertical force production was investigated under various scenarios. The wings keep a fixed angle of attack during the downwards flapping motion and are allowed to passively rotate during the upstroke motion. Computational simulations were performed to investigate the hovering fluid dynamics, forces, moments and power required for various chordwise rotational positions and durations of wing rotation. This investigation aided in understanding the full effects of altering these parameters under hovering conditions for a rectangular wing. The valuable results found from this research program provide a better insight into various topics involving micro air vehicles in addition to developing future flight worthy insect inspired vehicles

Plant Quality Mediates the Response of Disease to Global Environmental Change

A major challenge for ecology rests in understanding how direct and indirect effects of abiotic and biotic drivers combine to influence organisms under rapid environmental change. The local environment of both hosts and parasites can have profound impacts on disease dynamics, but the major mechanisms underlying these changes remain largely unresolved. In this dissertation, I combine a series of manipulative experiments to assess the effects of an ongoing and pervasive driver of global environmental change, elevated CO2, on a plant-phytophagous host-parasite system. In Chapter II, I investigated the effects of elevated CO2 on the defensive and nutritional chemistry of milkweeds and the subsequent impacts of those phytochemical changes on monarch tolerance and parasite virulence. I found that high-cardenolide milkweeds lost their medicinal properties under elevated CO2; monarch tolerance to infection decreased, and parasite virulence increased. Declines in foliar medicinal quality were associated with declines in foliar concentrations of lipophilic cardenolides. In Chapter III, I examined how those same phytochemical changes induced by elevated CO2 influence the defensive phenotype of monarchs against predation, e.g. toxin sequestration and flight ability. I found that monarchs maintained the concentration and composition of cardenolides that they sequestered despite changes in the phytochemistry of milkweed under elevated CO2. Additionally, feeding on high cardenolide milkweed was associated with the formation of rounder, thinner wings, which are less efficient at gliding flight. In Chapter IV, I evaluated changes in monarch cellular and humoral immunity in response to phytochemical shifts induced by elevated CO2. I found that the immune enzyme activity of early-instar monarchs declined under parasite infection but was “rescued” by consuming foliage grown under elevated CO2. Additionally, infection and a diet of foliage from elevated CO2 increased the hemocyte concentrations of early-instar monarchs. In late-instar monarchs, the immune response against parasitoids declined on “medicinal” milkweed, suggesting a potential tradeoff between resistance against parasitoids and resistance against agents of disease. Finally, in Chapter V, I examined how elevated CO2 might alter plant resistance traits and regrowth tolerance and the subsequent relationship between these defense strategies. I found that elevated CO2 altered the resistance of regrowth foliage in a species-specific manner. However, the tradeoff between resistance and regrowth tolerance varied only among milkweed species. Taken together, my research illustrates that anthropogenic changes in abiotic and biotic factors operate in complex combinations, and at multiple scales, to influence the outcome of host-parasite interactions in our changing world.PHDEcology and Evolutionary BiologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/145914/1/lesldeck_1.pd