Morphing wings are of great interest in the aerospace community. Control surfaces with continuously variable geometry increases the efficiency of aircraft aerodynamics. In order to prove efficacy and feasibility, this project focused on replacing a small chord-wise section of the trailing edge in a pre-existing wing for a small unmanned air vehicle (UAV). The flaps use flexible matrix composite (FMC) actuators, rather than hinged control surfaces, to create a local aerodynamic control force whose effect can be measured using the UAV’s onboard flight control system. After multiple design iterations, in which the FMC actuator material and structure were varied, the final design incorporates a carbon fiber frame with an actuator system embedded in a foam matrix. Two actuators are currently being integrated into Virginia Tech’s eSPAARO UAV in preparation for flight tests in Spring 2015.
Inspired by the fibrillar network in plant cell walls and the helical fibers found in soft bodied hydrostats (e.g. worms, squid, elephant trunks, and octopus arms), fluidic flexible matrix composites (F2MCs) are composite tubes that consist of multiple layers of oriented, high performance fibers, such as carbon, precisely placed in a flexible matrix resin to form high-mechanical advantage actuators and variable stiffness materials. Unique to the F2MC tube is its ability to generate high pressures and volume change with a small external load as a result of the stiff reinforcement fiber orientation in the wall of the tube and the soft supporting elastomer. When a load is applied to the tubes, the volume of the composite pump is reduced and fluid is forced out of the tube by the reinforcing fibers. The objective of this research is to design, fabricate and characterize F2MCs for use in wave energy conversion where ocean waves provide the axial load to drive fluid through the pumps. F2MCs pumps are tested in a water basin and mechanically cycled between 0 Hz and 2 Hz at up to 17 percent strain. Instantaneous input power is found by measuring the displacement and applied force to the actuators, while output power values are derived from pressure and flow rate measurements at the tube outlet. From these measurements the actuator efficiency is subsequently determined.
Morphing wings are of great interest in the aerospace community. Control surfaces with continuously variable geometry can increase the efficiency of aircraft aerodynamics. This research focuses on demonstrating a morphing flap on a small span-wise section of the trailing edge in a wing for a small unmanned air vehicle (UAV). The flaps used flexible matrix composite (FMC) actuators embedded in a flexible structure, rather than hinged control surfaces with conventional actuators. This created a local aerodynamic control force whose effect can be measured using the UAV’s on-board flight control system. After multiple design iterations, in which the FMC actuator material and structure were varied, the final design incorporates a carbon fiber frame with an actuator system embedded in a foam matrix. The FMC control surfaces were successfully demonstrated in flight tests on the eSPAARO unmanned aerial vehicle.
