Artur Wolek

A novel unmanned aircraft with solid-state control surfaces: Analysis and flight demonstration

This article presents a completely servo-less, piezoelectric controlled, wind tunnel and flight tested, remotely piloted aircraft that has been developed by the 2010 Virginia Tech Wing Morphing Design Team (a senior design project between the Departments of Mechanical Engineering and Aerospace and Ocean Engineering). A type of piezocomposite actuator, the Macro-Fiber Composite, is used for changing the camber of all control surfaces on the aircraft. The aircraft is analyzed theoretically for its aerodynamic characteristics to aid the design of the piezoelectric control surfaces. A vortex lattice analysis complemented the database of aerodynamic derivatives used to analyze control response. Steady-state roll rates were measured in a wind tunnel and were compared to a similar aircraft with servomotor actuated control surfaces. The theoretical analysis and wind tunnel testing demonstrated the stability and control authority of the concept, culminating in the first flight of the completely Macro-Fiber Composite controlled aircraft on 29 April 2010. An electric motor-driven propulsion system is used to generate thrust, and all systems are powered with a single lithium polymer battery. This vehicle became the first completely Macro-Fiber Composite controlled, flight tested aircraft. It is also known to be the first fully solid-state piezoelectric material controlled, nontethered, flight tested fixed-wing aircraft.

Developmental Flight Testing of the SPAARO UAV

The Department of Aerospace and Ocean Engineering of Virginia Tech designed and built a new fleet of UAVs for use in augmenting the aircraft flight mechanics curriculum for undergraduates. This paper describes the flight testing of this new UAV. Issues associated with autonomous UAV flight testing are discussed and compared to traditional manned flight testing. Lessons learned during testing and data reduction are presented. Analysis results include specific excess power for a large portion of the UAV’s flight envelope, stability derivatives derived from experimental test, and airspeed for best range in a glide. Further the short period, dutch roll, and roll modes are excited and then characterized for the UAV.

The Educational Impact of Creating a New UAV for Curriculum Enhancement

The Department of Aerospace and Ocean Engineering of Virginia Tech requires a new fleet of UAVs for use in augmenting the aircraft flight mechanics curriculum for undergraduates. This paper describes a project that was undertaken by a mixture of graduate and undergraduate students to meet that requirement. The pedagogical methods employed in designing this experience are discussed. The aircraft’s requirements and the design methodologies used to meet those requirements are discussed. The construction of the aircraft, and a preliminary flight test summary are also detailed. Included in this report are data that can be used to create a 6-DOF simulation of the UAV discussed in this paper. This project was used to create educational opportunities for students to design, build, and flight test a UAV in a production environment that goes beyond a traditional DBF project.

Stability and performance of underwater gliders

Underwater gliders are efficient mobile sensor platforms that can be deployed for months at a time, traveling thousands of kilometers. As with any vehicle, different applications impose different mission requirements which impact vehicle design. In this paper, we consider a conventional glider configuration and investigate the relationship between geometry and the stability and performance characteristics. We consider two specific flight conditions: minimum drag and maximum horizontal speed. Configuration parameters of interest include the fineness ratio of the hull; the wing position, wingspan, and aspect ratio; and the area and position of the vertical stabilizer.

A maneuverable, pneumatic underwater glider

A coastal (100 meter depth) underwater glider has been developed to serve as a platform for testing advanced perception, planning, and control algorithms to improve glider efficiency and performance. The gliders buoyancy engine is pneumatically powered, and capable of generating large changes in buoyancy. Powerful and fast moving mass actuators allow the vehicle to achieve a large range of pitch attitudes and an unrestricted range of roll angles. The ability to complete a full 360 degree roll permits the use of asymmetric geometries like wing camber or dihedral and to assess their performance benefits. In this paper, the mechanical and electrical design of the glider is discussed in detail.

Time-Optimal Path Planning for a Kinematic Car with Variable Speed

This paper investigates the minimum-time path-planning problem for a kinematic car with variable speed and turn rate controls. The speed is strictly positive, ranging from a lower to an upper limit, and the turn rate limits are symmetric about zero. The minimum principle is used to characterize the extremal controls and, using additional geometric arguments, a finite and sufficient set of candidate optimal controls is derived. It is found that, in addition to straight and maximum rate turning segments at maximum-speed, minimum-time paths may include “cornering” turns at the minimum forward speed and the maximum turn rate. A procedure is proposed for solving the path synthesis problem of constructing the minimum-time path between two “oriented points” in the plane.

Testing a pneumatic underwater glider in shallow water

In this paper we discuss the testing of a novel underwater glider designed to be fast and maneuverable for operation in the littorals. The gliders pneumatic buoyancy engine was shown to operate reliably and provide large, rapid displacements. However, the compressibility of the bladder and associated change in tank weight (from exhausting air with each dive) presented significant challenges in trimming the vehicle. Several design considerations unique to a glider with unlimited roll control (and a cylindrical moving mass actuator) were identified through testing. The performance of a long baseline acoustic positioning system was characterized, and the challenges associated with deploying this system in a shallow-water, rocky-bottom lake are discussed.