Development of the Nano Hummingbird: A Tailless Flapping Wing Micro Air Vehicle

Nomenclature Ar = rotor disk area CD = sectional drag coefficient CD0 = zero-lift drag coefficient Clα = lift-curve slope CP = power coefficient CPi = induced power coefficient CP0 = profile power coefficient CT = thrust coefficient c = chord length D = drag force D.L . = disk loading L = lift force m = mass P.L . = power loading SF = separated flow T = rotor thrust V = local wind velocity perceived by flap W = weight W f = final weight Wo = gross takeoff weight α = blade section angle of attack η = efficiency μ = dynamic viscosity ρ = air density σ = rotor solidity = flapping amplitude (peak to peak)

Challenges Facing Future Micro-Air-Vehicle Development

▪ Abstract In this review we describe the aerodynamic problems that must be addressed in order to design a successful small aerial vehicle. The effects of Reynolds number and aspect ratio (AR) on the design and performance of fixed-wing vehicles are described. The boundary-layer behavior on airfoils is especially important in the design of vehicles in this flight regime. The results of a number of experimental boundary-layer studies, including the influence of laminar separation bubbles, are discussed. Several examples of small unmanned aerial vehicles (UAVs) in this regime are described. Also, a brief survey of analytical models for oscillating and flapping-wing propulsion is presented. These range from the earliest examples where quasi-steady, attached flow is assumed, to those that account for the unsteady shed vortex wake as well as flow separation and aeroelastic behavior of a flapping wing. Experiments that complemented the analysis and led to the design of a successful ornithopter are also described.

Aerodynamics of small vehicles

Autonomous unmanned air vehicle ∞ight control systems require robust path generation to account for terrain obstructions, weather, and moving threats such as radar, jammers, and unfriendly aircraft. In this paper, we outline a feasible, hierarchal approach for real-time motion planning of small autonomous flxed-wing UAVs. The approach divides the trajectory generation into four tasks: waypoint path planning, dynamic trajectory smoothing, trajectory tracking, and low-level autopilot compensation. The waypoint path planner determines the vehicle’s route without regard for the dynamic constraints of the vehicle. This results in a signiflcant reduction in the path search space, enabling the generation of complicated paths that account for pop-up and dynamically moving threats. Kinematic constraints are satisfled using a trajectory smoother which has the same kinematic structure as the physical vehicle. The third step of the approach uses a novel tracking algorithm to generate a feasible state trajectory that can be followed by a standard autopilot. Monte-Carlo simulations were done to analyze the performance and feasibility of the approach and determine real-time computation requirements. A planar version of the algorithm has also been implemented and tested in a low-cost micro-controller. The paper describes a custom UAV built to test the algorithms.

/pdf/autonomous-vehicle-technologies-for-small-fixed-wing-uavs-1lr64kzlwl.pdf

Autonomous Vehicle Technologies for Small Fixed-Wing UAVs

Light-weight, autonomous ornithopters form a promise to observe places that are too small or too dangerous for humans to enter In this article, we discuss the DelFly project, in which we follow a top-down approach to ever smaller and more autonomous ornithopters Top-down signifies that the project always focuses on complete flying systems equipped with camera We give arguments for the approach by explaining which findings on the DelFly I and DelFly II recently led to the development of the DelFly Micro: a 307-gram ornithopter carrying a camera and transmitter onboard These findings concern the design, aerodynamics, and vision-based control of the DelFly In addition, we identify main obstacles on the road to fly-sized ornithopters

https://journals.sagepub.com/doi/pdf/10.1260/175682909789498288

Design, Aerodynamics, and Vision-Based Control of the DelFly:

This paper describes the development of the Black Widow Micro Air Vehicle (MAV) over the past 4 years. An MAV has generally been defined as having a span of less than 6 inches, and a mass of less than 100 grams. The Black Widow is a 6-inch span, fixed-wing aircraft with a color video camera that downlinks live video to the pilot. It flies at 30 mph, with an endurance of 30 minutes, and a maximum communications range of 2 km. The vehicle has an autopilot, which features altitude hold, airspeed hold, heading hold, and yaw damping. The electronic subsystems are among the smallest and lightest in the world, including a 2gram camera, a 2-gram video downlink transmitter, and a 5-gram fully proportional radio control system with 0.5-gram actuators. A Multidisciplinary Design Optimization methodology with a genetic algorithm was used to integrate the MAV subsystems and optimize the vehicle for maximum endurance. Some of the potential missions for MAVs are visual reconnaissance, situational awareness, damage assessment, surveillance, biological or chemical agent sensing, and communications relay. In addition to these military missions, there are several commercial applications, such as search and rescue, border patrol, air sampling, police surveillance, and field research.

/pdf/development-of-the-black-widow-micro-air-vehicle-3sxdcw9qfl.pdf

Development of the Black Widow Micro Air Vehicle

Development of Two MAVs and Vision of the Future of MAV Design

Multifunctional materials are material-systems capable of performing two or more functions, simultaneously or sequentially in time. This paper presents multifunctional structure-plus-power developments being pursued under DARPA sponsorship with the focus on structure-battery components for unmanned air vehicles (UAV). New design strategies, analysis methods, performance indices, and prototypes for multifunctional structure-battery materials are described along with the development of two UAV prototypes with structure-battery implementation. Together, these efforts seek to explore and demonstrate performance enhancement in UAV systems by integrating multiple functions into a single material entity.

Multifunctional structure-plus-power concepts

This paper presents multifunctional structure-plus-power developments being pursued under DARPA sponsorship with the focus on structure-battery components for unmanned air vehicles (UAV). New design strategies, analysis methods, performance indices, and prototypes for multifunctional structure-battery materials are described along with the development of two UAV prototypes with structure-battery implementation.

Joel Grasmeyer

Papers

Development of the Black Widow Micro Air Vehicle

Development of Two MAVs and Vision of the Future of MAV Design

Multifunctional structure-plus-power concepts

Structure-Power Multifunctional Materials for UAV's