Performance assessment of the atmospheric electric dowsing mechanism

The movement of the frame in the operator’s hand is provoked by the repulsion of the excess negative charge of air and the negative charge of the frame, equal in density to the charge of the Earth. A powerful increase in the repulsive forces is achieved due to the lever effect and is estimated by the ratio of the distance of the point on the horizontal knee to the radius of the vertical knee. Further strengthening is achieved by increasing the radius of the horizontal knee of the frame.

Simulation and Test of Discrete Mobile Surfaces for a RC-Aircraft

Morphing structures suitable for unmanned aerial vehicles (UAVs) have been investigated for several years. This paper presents a novel lightweight, morphing concept based on the exploitation of the “lever effect” of a bistable composite plate that can be integrated in an UAV horizontal tail. Flight dynamics equations are solved in Simulink environment, thus being able to simulate and compare different flight conditions with conventional and bistable command surfaces. Subsequently, bistable plates are built by using composite materials, paying particular attention to dimensions, asymmetric stacking sequence and total thickness needed to achieve bistability. NACA0011 airfoil is chosen for proving this concept. Wind tunnel tests demonstrate that the discrete surface is capable of withstanding the aerodynamic pressure. A remotely piloted vehicle is employed to test the discrete horizontal tail command during the take-off. The results show that, choosing a proper configuration of constraints, stacking sequence and aspect ratio for the bistable laminate, it is possible to tailor the snap-through mechanism. The proposed concept appears lighter and increases aerodynamic efficiency when compared to conventional UAV command surfaces.

Flanged Connections of Steel Tubular Sections under High Bending Stresses: A Comparison between Two Thickness Design Methods

This work presents a comparison of different possibilities of flange design of an aeolian tower structure, focusing the thickness determination, the critical connection parameter. The dimensioned structure is a fifteen-meter length tubular arm under bend stresses caused by wind loads and by gravitational loads, since the tubular arm might be horizontal or vertically positioned. The tubular sections connected by the flanges are all circular with external diameter varying from 270 to 360 mm and the flange modules are also circular shaped. Since the tubular diameters are relatively large, the lever effect plays a definitive role in the design. Most of the fluid conduits flange design criteria are not applicable for such diameters sizes and have a load case different from those of an aeolian tower. Two different approaches are presented and their flange thickness results compared.

Control Limitations on Static Unstable Airframe Using Two-Loop Acceleration Autopilot

An analysis for controlling a static-unstable tactical missile using two-loop acceleration autopilot was detailed. The rate feedback loop was firstly presented. The equivalent actuator dynamics was introduced and examined. Thus an overall stabilization condition combined with both low and high frequency cases was proposed. The lever effect led by inertial measurement unit was of benefit to a great controllable range. The results show that the autopilot control capacity is dominated by actuator bandwidth, and a compromise should be determined between the flight performance and the actuator requirement for a static unstable tactical missile.