Many drone platforms have matured to become nearly optimal flying machines with only modest improvements in efficiency possible. “Chimera” craft combine fixed wing and rotary wing characteristics while being substantially less efficient than both. The increasing presence of chimeras suggests that their mix of vertical takeoff, hover, and more efficient cruise is invaluable to many end users. We discuss the opportunity for flapping wing drones inspired by large insects to perform these mixed missions. Dragonflies particularly are capable of efficiency in all modes of flight. We will explore the fundamental principles of dragonfly flight to allow for a comparison between proposed flapping wing technological solutions and a flapping wing organism. We chart one approach to achieving the next step in drone technology through systems theory and an appreciation of how biomimetics can be applied. New findings in dynamics of flapping, practical actuation technology, wing design, and flight control are presented and connected. We show that a theoretical understanding of flight systems and an appreciation of the detail of biological implementations may be key to achieving an outcome that matches the performance of natural systems. We assert that an optimal flapping wing drone, capable of efficiency in all modes of flight with high performance upon demand, might look somewhat like an abstract dragonfly.

The development of flapping wing systems has been restricted by high power density requirements, comparatively large forces and the requirement for light weight. The use of linear electromagnetic actuators has had a small presence in the flapping wing literature when compared to other actuator types. This has been due to the high power consumption and low power output of this system when compared to resonant systems. This work assesses linear electromagnetic actuators presented in the literature and demonstrates the performance improvements achieved when the mechanism natural frequency is appropriately tuned. This process shows a reduction of input power consumption to 13% of the original power consumption. This improvement, combined with appropriate power electronic design, can reduce the perceived gap between linear electromagnetic actuators and solid-state actuators.

The actuated abdomens of insects such as dragonflies have long been suggested to play a role in optimisation and control of flight. We have examined the effect of this type of actuation in the simplified case of a small fixed wing aircraft to determine whether energetic advantages exist in normal flight when compared to the cost of actuation using aerodynamic control surfaces. We explore the benefits the abdomen/tail might provide to balance level flight against trim changes. We also consider the transient advantage of using alternative longitudinal control effectors in a pull up flight maneuver. Results show that the articulated abdomen significantly reduces energy consumption and increase performance in isolated manoeuvres. The results also indicate a design feature that could be incorporated into small unmanned aircraft under particular circumstances. We aim to highlight behaviours that would increase flight efficiency to inform designers of micro aerial vehicles and to aid the analysis of insect flight behaviour and energetics.

We present a method for generating feedback and controlling multi-coil linear electromagnetic actuators for flapping wing systems. This has been achieved with a system capable of self-lifting, constructed using 3D-printed structures and miniaturised electromagnetic actuators with a combined weight of 3.07 g. Combining multiple magnets and coils into a single actuator with onboard feedback sensors has improved power densities upon existing linear electromagnetic systems present in the literature. The use of closed-loop control of the dynamics of the flapping profile allows for independent control of both flapping frequency and amplitude, which is differentiated from open-loop and resonance-based systems. This change will allow relatively precise control over the flapping dynamics of future systems while improving actuation efficiency.

A constraining factor in the development of flapping wing micro air vehicles (MAVs) is the power density and efficiency of actuators. Piezoelectric and rotary electromagnetic actuators have been shown to have functional power densities but can require mechanically complex transmissions to create flapping motion. Electromagnetic Linear actuators (ELAs) have unique characteristics, allowing them to be controlled and implemented similarly to muscles but demonstrated much lower efficiency. This study presents configurations of ELA consisting of multiple coils and magnets that have the potential to improve efficiency. The use of lightweight conductors in the form of copper clad aluminium (CCA) is explored as a method to improve power density. A numerical method of optimising the geometry and mass distribution of the magnetic and conductive material is presented. The results show the power consumption of these actuators can range between 910-260 W/kg. The inclusion of an additional magnet and coil can improve efficiency by up to 3.5 times over typical flapping wing ELAs.