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This paper proposes a control method to remotely operate cooperative multiple heterogeneous slave unmanned aerial vehicles (UAVs) via a single master robot to perform different tasks on different targets in one mission. The UAV team is formed by different automated aircrafts. They are equipped with a vehicle-task-target pairing algorithm to be assigned their proper tasks and targets when moving in a leader-follower formation to track and perform assigned targets and tasks, respectively. The proposed leader-follower formation control method is modified based on a potential field algorithm to guide the UAV team or sub-team. In the UAV team, only a single leader vehicle is teleoperated by a human operator while all other follower vehicles autonomously form the formation regarding the leader movement. Therefore, the number of long distance transmission links between UAVs is reduced to minimize the possibility of occurrences of large communication delays.

Many Small Unmanned Aerial Vehicles (SUAV) are driven by small scale, fixed blade propellers. Flow produced by the propeller can have a significant impact on the aerodynamics of a SUAV. Therefore, in Computational Fluid Dynamic (CFD) simulations, it is often necessary to simulate the SUAV and propeller coupled together. For computational efficiency, the propeller can be modeled in a steady-state view by using momentum source terms to add the thrust and swirl produced by the propeller to the flow field. Many momentum source term models are based on blade element theory. Blade element theory divides the blade into element sections in the spanwise direction and assumes each element to operate independently as a two-dimensional (2D) airfoil.

Recent advances in small unmanned air vehicles (UAV) lead to robust on-board stabilized platforms ready to use for real-world problems. As a result, many different autonomy functions have been demonstrated, which allow controlling the UAVs at high level. However, the great variety of platforms also poses new challenges when adapting these autonomy functions to new platforms. For instance modifying a trajectory planning algorithm, which was designed for a rotary-aircraft with a moving camera, to work on a fixed-wing aircraft with a static camera is not a trivial task. Often such algorithmic solutions are tailored so specifically to a certain platform that it becomes very complicated to reuse algorithms. This results in a variety of many different approaches trying to solve the same task. We therefore encourage designing algorithms for UAVs autonomy function to be more generic. As an example, we focus on the task to autonomously follow a moving ground object using an UAV.

A Hybrid Projectile (HP) is a round that transforms into a UAV after being launched. Some HP's are fired from a rifled barrel and must be de-spun and wings-level for lifting surfaces to be deployed. Control surfaces and controllers for de-spinning and wings-leveling were required for initial design of an HP 40 mm. Wings, used as lifting surfaces after transformation, need to be very close to level with the ground when deployed. First, the tail surface area needed to de-spin a 40 mm HP was examined analytically and simulated. Next, a controller was developed to maintain a steady de-spin rate and to roll-level the projectile in preparation of wing deployment. The controller was split into two pieces, one to control de-spin, and the other for roll-leveling the projectile. An adaptable transition point for switching controllers was identified analytically and then adjusted by using simulations.

Since the recognition of the influence of human activity on climate change due to increasing use of fossil fuel energy, significant efforts are being devoted towards the development and implementation of renewable energy technologies that are harmless to the environment. One of the abundant energy sources is the sun. There are currently two primary ways of harvesting energy from the sun: through photovoltaic (PV) panels and through thermal collectors. With the evolution of unmanned air vehicles (UAV), as well as the growing interest in “Green Aviation,” the interest in investigating the usage of PV solar panels in certain category of aircrafts has increased in the last two decades. In a small UAV or low speed personal transportation aircraft, the wings of the airplane could possibly be covered with photovoltaic panels to harness sun's energy for propulsion.

In this work a new design of a liquid fuelled combustion engine is proposed for small and light weight unmanned air vehicles (<10kg and 15-200N thrust). Ethanol and gasoline were selected as the potential fuels while pressurized air and hydrogen peroxide were used as the oxidizer. The engine combines features of both a common rocket and turbojet engine. The main features of the engine are the restart ability during flight, low cost, easy manufacturability, light weight, long operation time and high durability. The main difficulties that come along with this engine are the need for proper engine cooling (long term operation) and start-up ability at atmospheric conditions. The low temperatures and injection pressures are not favorable for the fuel atomization and ignition. The paper focuses on the design on low pressure injectors and a start-up mechanism for micro UAV's without the use of a large amount of additional fueling circuits or components.

In this paper the regulatory and standardization aspects regarding the light UAV segment are described reporting main steps and activities carried out during the FP7 European SkyMedia funded project. With respect to the Unmanned Aircraft Vehicle regulation achievements, a detailed process conducted beside the Italian Flight Regulation Authority (ENAC) is reported emphasizing the key points that led to receive multiple Permit to Fly for Nimbus novel hybrid UAV platform, the first case in Italy in the category of “light UAV”. With specific reference to the UAV segment, after showing the complex procedure defined with such Authority to receive authorization to fly for project final demo, some light on the future perspectives for light UAV regulation will be provided underlining efforts and contributions to define a clear track on the UAV development in civil applications.

The present paper is focused on techniques aimed at including control law dynamics into linear flutter equations. An UAV in an unconventional joined wing configuration has been taken as test case for setting up the methodology. For this test case the pitch control law is included in the flutter equations, obtaining a model to perform closed loop flutter calculations. The extra degrees of freedom of control surfaces and additional terms due to the control law have been modeled by means of dynamic sub-structuring approach. The equations governing the dynamics of the control law are added to the aeroelastic stability equations after a suitable manipulation based on a derivative approach. The interesting aspect of the work is that the control law can be modeled as six external matrices to be properly assembled into the aeroelastic system. This is advantageous when already written codes for flutter evaluation are available since the requested modifications are minimal.

Unmanned Aerial Vehicles (UAVs) provide the ability to perform a variety of experimental tests of systems and unproven research technologies, including new autopilot systems and obstacle avoidance capabilities, without risking the lives of human pilots. This paper describes the activities of design, optimization, and flight operations of a UAV conceived at Clarkson University (USA) and equipped to perform wind speed measurements to support wind farmsite planning. The UAV design has been assisted and validated by the use of an automatic virtual environment for the assisted design of civil UAVs. This tool can be used as a “computing machine” for civil UAVs. The operator inputs the mission profile and other generic parameters and data about performance, aerodynamics, and weight breakdown are extracted. A mathematical model of the UAV for flight simulation and its dynamic computations, along with automatic drawing is also produced.

The target of this paper is to describe the SHM project developed at CIRA. In order to achieve the low weigh target in the MALE UAV structures, the SHM project has the target to setup a system that, being able to evaluate the current state of the structure, will enable minus conservative assumption in the composite structural design. A lamb wave based procedure has been developed in order to analyze the presence of a barely visible impact defect (BVID). The techniques for the damage detections of composite and metallic structures have been developed through extensive numerical-experimental analysis based on lambwave investigation by using piezoelectric sense- actuators. The use of SHM technology and methodology has shown the possibility to have a significant reduction in the structural weight. The technology has achieved a TRL level between 4 and 5 and in order to achieve a higher TRL a test on a component in relevant environment is planned at the end of 2014.

Weight reduction in structural aerospace configuration is based both on specific material selection and on the selection of specific shape and sections. UAS structures need both the introduction of new advanced composites and the definition of light weight construction based on thin walled configuration. With this idea in mind, Stiffening concepts are frequently used to increase structural performance, i.e. buckling characteristics, of a thin plates. Manufacturing of composite stiffened structures can give rise to the presence specific damaged situations such as skin/stiffener de-bonding. Such kind of defect can cause buckling prior to the designed critical condition and can cause a reduction in global strength. The presence of cyclical loading and fatigue effect can have important consequence on damage propagation and structural integrity. The static structural behavior of a damaged stiffened composite panel is summarized from previous research investigation and presented.

There has been an increased interest in low speed aerodynamics for Unmanned Aerial Vehicles (UAVs) and Micro Aerial Vehicles (MAVs). These vehicles which are increasingly being used for reconnaissance purposes operate in the Root Chord Reynolds number range of 104 to around 105 and thus, the flow regime encountered is in the low Reynolds number transitional flow range. Computational Fluid Dynamics (CFD) methods which employ eddy viscosity based RANS turbulence models that are formulated for high Reynolds number flow are not well suited for such low Reynolds number range as they cannot accurately model the formation of laminar separation bubble and subsequent onset of transition. In this paper, the transition k-ω SST model is assessed for aerodynamics prediction for the SD7003 airfoil for Reynolds number ranging from 104 to 9 × 104 and angle of attack ranging from 0° to 8°. The assessment is carried out against available experimental and Large Eddy Simulation results.

The use of a magnetic field applied to a gaseous conducting boundary layer flow as been proposed as a mean to control boundary layer losses. The solution of the Navier-Stokes equations together with the induction equation for the magnetic field was numerically obtained using a Finite Volume code. The effects of the magnetic field are introduced into the momentum equations by means of a Lorentz force source term. Further, several turbulence models were modified in order to include the magnetic field perturbation. The computation of the transitional flow on a flat plate was made for several values of the magnetic field, and a relaminarization of the flow was obtained for sufficient high values of the magnetic field. The code was also applied for the computation of the flow around an airfoil as an example application of an high speed high-altitude UAV.

A Hybrid Projectile (HP) is a tube launched munition that transforms into a gliding UAV, and is currently being researched at West Virginia University. In order to properly transform, the moment of transformation needs to be controlled. A simple timer was first envisioned to control transformation point for maximum distance. The distance travelled or range of an HP can directly be modified by varying the launch angle. In addition, an internal timer would need to be reprogrammed for any distance less than maximum range due to the nominal time to deployment varying with launch angle. A method was sought for automatic wing deployment that would not require reprogramming the round. A body angle estimation system was used to estimate the pitch of the HP relative to the Earth to determine when the HP is properly oriented for the designed glide slope angle. It also filters out noise from an inertial measurement unit (IMU).

The modal parameters of an aircraft structure are currently estimated from ground vibration tests (GVT). These tests are carried out on ground in order to estimate the frequency response functions first and then the modal parameters. Such estimates require one or more shakers to excite the structure together with simultaneous measurements of both the input and the output signals. Recent developments in operational modal analysis allowed such modal identification from the measurements of the output responses only, provided that the unmeasurable excitation is practically a white noise stochastic input in the frequency range of interest and is randomly exciting the different parts of the structure. In this paper the effects of the different test setup on the modal parameter estimates will be presented. Both input-output based experimental modal analysis and operational modal analysis are performed on an Unmanned Aerial Vehicle, the Clarkson University Golden Eagle.

UAS (Unmanned aircraft system), widely known to the general public as drones, are comprised of two major system elements: an Unmanned Aircraft (UA) and a Ground Control Station (GCS). UAS have a high mishap rate when compared to manned aircraft. This high mishap rate is one of several barriers to the acceptance of UAS for more widespread usage. Better awareness of the UA real time as well as long term health situation may allow timely condition based maintenance. Vehicle health and usage are two parts of the same solution to improve vehicle safety and lifecycle costs. These can be worked on through the use of two related aircraft management methods, these are: IVHM (Integrated Vehicle Health Management) which combines diagnosis and prognosis methods to help manage aircraft health and maintenance, and FOQA (Flight Operations Quality Assurance) systems which are mainly used to assist in pilot skill quality assurance.

This paper describes the design and development of a virtual environment conceived to support flight operations of an Unmanned Air Vehicle (UAV) used for wind mapping in the proximity of existing or planned wind farms. The virtual environment can be used in pre-flight briefings aiming to define a trajectory from a list of waypoints, to change and eventually re-plan the mission in case of intersection with no fly zones, to simulate the mission, and to preview images/videos taken from the UAV on-board cameras. During flight, the tool can be used to compute the wind speed along the trajectory by analyzing the data streaming from the UAV. The integration of Augmented Reality (AR) techniques in the flight environment provides assistance in remotely piloted landings, and allows visualizing flight and environmental information that are critical to the mission.

In this paper an automatic procedure aimed at preliminary designing an oleo-pneumatic landing gear strut for a light unmanned aircraft is presented. The whole work is motivated by the necessity to design the landing gear of the unmanned aircraft X-MALE, currently in development at the Italian Aerospace Research Center (CIRA SCpA), according to the Airworthiness Requirements NATO STANAG 4671 (USAR). The landing gear preliminary design is usually carried-out by responding to requirements of maximum overall dimensions, maximum weight and maximum attainable load factor. While the oleo-pneumatic mechanism depends essentially on the maximum vertical load factor and on the strut length, thus on the oleo-pneumatic efficiency, the structure is generally sized by combining the design vertical loads with the maximum expected horizontal loads.