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UAS Airframe Design
Published in R. Kurt Barnhart, Douglas M. Marshall, Eric J. Shappee, Introduction to Unmanned Aircraft Systems, 2021
Michael T. Most, Michael Stroup
In a conventionally designed aircraft, the vertical stabilizer is the primary source of directional control and stability. (Although a wing, especially one that is swept, will contribute to static directional stability, any effect is relatively slight.) Should the aircraft yaw, or sideslip, the change in angle of attack of the vertical stabilizer causes a side force (change in pressure differential acting on the major surfaces of the vertical stabilizer) to yaw the aircraft about the CG in a restoring moment that will turn the nose of the aircraft into the relative wind. The size of the vertical stabilizer and the arm (distance between the stabilizer and the CG, or x-axis) will determine the effectiveness of the stabilizer in creating a restoring force following any displacement of the nose in yaw.
Introduction
Published in Sergey E. Lyshevski, and Applied Mechatronics, 2018
As an example of the application of the mechatronic concept, consider the motion control problem as applied to advanced aircraft. The aircraft is controlled by flight control surfaces (aileron, canard, elevator, flap, rudder, stabilizer), and direct-drive servo-systems are used to actuate (displace) these control surfaces. A fly-by-wire control surface servo with stepper motor is illustrated in Figure 1.3. The desired angular displacement of the control surface (reference input) is assigned either by the pilot or aircraft flight computer. Using this reference signal (the specified angular displacement of the control surface), as well as the measured by sensors currents in the ab phase windings ias and bs, mechanical angular velocity ωrm and actual mechanical angular displacement of the control surface θrm, the controller develops signal-level signals that drive high-frequency switches, and the magnitude and frequency of the applied voltages to the ab phase windings uas and ubs of the permanent-magnet stepper motor are controlled by the PWM driver (amplifier) (see Figure 1.3).
New Avionics Systems: Airbus A330/A340
Published in Cary R. Spitzer, Uma Ferrell, Thomas Ferrell, Digital Avionics Handbook, 2017
The flight control system of the A330/A340 is essentially the same as that of the A320, with five computers of two different types allowing the pilot to control the aircraft in pitch, roll, and yaw. The layout of the pilot controls is essentially the same as that of the A320 series, as are the handling qualities. The technology features are also essentially the same, with extensive use of dissimilarity in the hardware and in the software, and extensive segregation in the hydraulic and electrical power supplies and signaling lanes. As with the A320 series, mechanical signaling is used for the rudder and for the horizontal stabilizer trim backup.
Stabilization of expansive soils using nontraditional chemical additives
Published in Mechanics of Advanced Materials and Structures, 2023
Tahar Ayadat, Ammar Noui, Layal Jradi, Danish Ahmed, Muhammad Ajmal, Andi Asiz
Researchers have conducted extensive research on different stabilizing agents like cement, industrial waste, fly ash, and lime for stabilizing expansive soils. Stabilizers can be classified into three types: traditional, by-product, and nontraditional. By-product stabilizers are made using cement dust, lime kiln dust, and slag as stabilizers. Traditional stabilizers include Portland cement, fly ash, and hydrated lime. The nontraditional stabilizers include potassium compounds, polymers, ammonium chloride, sulfonated oils, and enzymes [7–11]. In order to select the right stabilizer, several factors need to be considered, such as soil classification, soil mineralogy, and soil content (sulfates and organics), treatment objectives, additive mechanism, materials properties (modulus, strength), environmental conditions (water table, drainage), design life, and desired engineering, as well as economic constraints (cost-effectiveness) [12].