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Unmanned aerial vehicle (UAV) design aspects are as broad as the missions they are used to support. In some cases, the UAV mission scope can impose design constraints that can be difficult to achieve. This paper describes recent work performed at West Virginia University (WVU) to support repeated flight testing of a single-use UAV platform with emphasis on the highly specialized wings required to help meet the overall airframe mass properties constrained by the project sponsor. The wings were fabricated using a molded polyurethane (PU) foam as the base material which was supported by several different types of rigid and flexible substructures, skins, and matrix-infused fiber elements. Different ratios of infused fiber mass to PU foam were tested and additional tungsten masses were added to the wings to achieve the correct total mass and mass distribution of the wings.

As unmanned aerial vehicle applications continue their rise in popularity in the public and private sectors, there is an increasing demand in many cases for smaller, more efficient low speed unmanned aerial vehicles (UAVs). Although the primary drivers for the continued performance improvement of smaller UAV platforms tend to be in the areas of electronics miniaturization and improved energy storage, aerodynamics, particularly in the low Reynolds number regime, still have a significant role in the overall performance enhancement of small UAVs. This paper focuses on the study of the nearfield aerodynamic effects of a low-power active flow enhancement technique known as dielectric barrier discharge (DBD) in very low speed/low Reynolds number flows most closely associated with small and micro unmanned aerial vehicles.

In this research, the magnetoplasmadynamic (MPD) effects of applying a toroidal magnetic field around an ionized exhaust plume were investigated to manipulate the exhaust profile of the plasma jet under near vacuum conditions. Tests for this experiment were conducted using the West Virginia University (WVU) Hypersonic Arc Jet Wind Tunnel. A series of twelve N52 grade neodymium magnets were placed in different orientations around a steel toroid mounted around the arc jet’s exhaust plume. Four different magnet orientations were tested in this experiment. Two additional configurations were run as control tests without any imposed magnetic fields surrounding the plume. Each test was documented using a set of 12 photographs taken from a fixed position with respect to the flow. The photographic data was analyzed by comparing images of the exhaust plume taken 10, 20, and 30 seconds after the plasma jet was activated.

The dielectric barrier discharge (DBD) has seen significantly increased levels of interest for its applications to various aerodynamic problems. The DBD produces stable atmospheric-pressure non-thermal plasma with highly energetic electrons and a variety of ions and neutral species. The resulting plasma often degrades the dielectric barrier between the electrodes of the device, ultimately leading to actuator failure. Several researchers have studied a variety of parameters related to degradation and time-dependent dielectric breakdown of various polymers such as PMMA or PVC that are often used in actuator construction. Many of these studies compare the degradation of these materials to that of borosilicate glass in which it is claimed that there is no observable degradation to the glass. Recent research at West Virginia University has shown that certain actuator operating conditions can lead to degradation of a glass barrier and can ultimately result in failure.

The dielectric barrier discharge (DBD) has been studied significantly in the past two decades for its applications to various aerodynamic problems. The most common aerodynamic applications have been stall/separation control and boundary layer modification. Recently several researchers have proposed utilizing the DBD in various configurations to act as viable propulsion systems for micro and nano aerial vehicles. The DBD produces stable atmospheric-pressure non-thermal plasma in a thin sheet with a preferred direction of flow. The plasma flow, driven by electrohydrodynamic body forces, entrains the quiescent air around it and thus develops into a low speed jet on the order of 10-1 to 101 m/s. Several researchers have utilized DBDs in an annular geometric setup as a propulsion device. Other researchers have used them to alter rectangular duct flows and directional jet devices. This study investigates 2-D duct flows for applications in micro plasma thrusters.

The design and testing of small unmanned aerial vehicle (sUAV) prototypes can provide numerous difficulties when compared to the same process applied to larger aircraft. In most cases, it is desirable to have a better understanding of the low Reynolds number aerodynamics and stability characteristics prior to completion of the final sUAV design. This paper describes the design, construction, and operational performance of a pneumatic launch apparatus that has been used at West Virginia University (WVU) for the development and early flight testing of transforming sUAV platforms. Although other launch platforms exist that can provide the safe launch of such prototypes, the particular launch apparatus constructed at WVU exhibits unmatched launch efficiency, and is far less expensive to operate per shot than any other launch system available.

The high demand for traditional air traffic as well as increased use of unmanned aerial systems (UAS) has resulted in researchers examining alternative technologies which would result in safer, more reliable, and better performing aircraft. Active methods of aerodynamic flow control may be the most promising approach to this problem. Research in the area of aerodynamic control is transitioning from traditional mechanical flow control devices to, among other methods, plasma actuators. Plasma actuators offer an inexpensive and energy efficient method of flow control. Dielectric Barrier Discharge (DBD), one of the most widely studied forms of plasma actuation, employs an electrohydrodynamic (EHD) device which uses dominant electric fields for actuation. Unlike traditional flow control methods, a DBD device operates without moving components or mass injection methods.

Significant efforts have been made in the research of Pulsed Detonation Engines (PDEs) to increase the reliability and longevity of detonation based propulsion systems for use in manned aircraft. However, the efficiency, durability, and low mechanical complexity of PDEs opens up potential for use in disposable unmanned-vehicles. This paper details the steps taken for producing a miniaturized pulse detonation engine at West Virginia University (WVU) to investigate the numerically generated constraining dimensions for Deflagration to Detonation Transition (DDT) cited in this paper. Initial dimensions for the WVU PDE Demonstrator were calculated using fuel specific DDT spatial properties featured in the work of Dr. Phillip Koshy Panicker, of The University of Texas at Arlington. The WVU demonstrator was powered using oxygen and acetylene mixed in stoichiometric proportions.

This paper documents the numerical and experimental investigation of a new type of wing section being developed at West Virginia University that shows good potential for use in wings in low Reynolds number flows. These wing sections have been designed with a minimum number of flat sides, or facets, which are arranged in such a way as to promote flow over the surface similar to traditional smooth airfoil shapes, but without the complexity of the typically highly contoured airfoil form. 2D numerical techniques have been employed to determine appropriate geometric limitations of the wing section facets, and finite span wings comprised of these faceted wing sections have been tested in wind tunnels in wing-only and wing-plus-body configurations to determine their basic aerodynamic performance. The latest results of these efforts, as well as some speculation as to the mechanisms at work are presented.

There is an ever growing need in the aircraft industry to increase the performance of a flight vehicle. To enhance performance of the flight vehicle one active area of research effort has been focused on the control of the boundary layer by both active and passive means. An effective flow control mechanism can improve the performance of a flight vehicle by eliminating boundary layer separation at the leading edge (as long as the energy required to drive the mechanism is not greater than the savings). In this paper the effectiveness of a novel active flow control technique known as dynamic roughness (DR) to eliminate flow separation in a stalled NACA 0012 wing has been explored. As opposed to static roughness, dynamic roughness utilizes small time-dependent deforming elements or humps with amplitudes that are on the order of the local boundary layer height to energize the local boundary layer. DR is primarily characterized by the maximum amplitude and operating frequency.

Tube Launched-Unmanned Air Vehicles (TL-UAV) are munitions that alter their trajectories during flight to enhance the capabilities by possibly extending range, increasing loiter time through gliding, and/or having guided targeting capabilities. Traditional munition systems, specifically the tube-launched mortar rounds, are not guided. Performance of these "dumb" munitions could be enhanced by updating to TL-UAV and still utilize existing launch platforms with standard propellant detonation firing methods. The ability to actively control the flight path and extend range of a TL-UAV requires multiple onboard systems which need to be identified, integrated, assembled, and tested to meet cooperative function requirements. The main systems, for a mortar-based TL-UAV being developed at West Virginia University (WVU), are considered to be a central hub to process information, aerodynamic control devices, flight sensors, a video camera system, power management, and a wireless transceiver.

Mortar weapons systems have existed for more than five hundred years. Though modern tube-launched rounds are far more advanced than the cannon balls used in the 15th century, the parabolic trajectory and inability to steer the object after launch remains the same. Equipping the shell with extending aerodynamic surfaces transforms the unguided round into a maneuverable munition with increased range [1] and precision [2]. The subject of this work is the experimental analysis of transient aerodynamic behavior of a transforming tube-launched unmanned aerial vehicle (UAV) during transition from a ballistic trajectory to winged flight. Data was gathered using a series of wind tunnel experiments to determine the lift, drag, and pitching moment exerted on the prototype in various stages of wing deployment. Flight models of the design were broken down into three configurations: “round”, “transforming”, and “UAV”.

West Virginia University's Mechanical and Aerospace Engineering Department is studying the benefits of continuous payload volume in transforming projectiles. Continuous payload volume is the single largest vacancy in a vehicle that may be utilized. Currently there is a market for transforming projectiles, which are gun launched (or tube launched) vehicles stowed in an initial configuration; which deploy wings once exiting the launcher to become small unmanned aircraft. WVU's proposed design uses a helical hinge, which allows the wing sections to be externally stowed outside the UAV's fuselage. Additionally, the design positions the vehicles wing sections sub-bore (or smaller than the guns internal diameter), and flush (smooth and planer) to the surface of the fuselage. The typical transforming winged projectile design considered, stores its wing sections along the center axis of the fuselage. This bisects the payload space and limits the continuous payload carrying potential.

Circulation Control (CC) by blowing over a rounded Coanda surface is capable of generating large lift forces while entraining the surrounding fluid. Its concept originates with Davidson in his 1960 British patent application. Within the sixties, CC was actively investigated for application on a high lift helicopter with elliptic rotors. The appeal of Circulation Control for high lift generation is its low blowing power required. However, supplying blowing air efficiently to the CC slot has proven to be an aerodynamic and structural engineering challenge. This delayed the first flight application of Circulation Control until a CC Technology Demonstrator STOL aircraft was completed in 1974. Elliptic airfoil based wings will not fly if blowing fails, so the airplane was designed with conventional wings. The engineering challenge was to provide in-flight transition from a rounded CC blown trailing edge to a conventional sharp trailing edge for low-drag cruise.