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Climb and descent
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
Whenever the vertical forces (lift plus vertical component of engine thrust) are less than aircraft weight, aircraft will lose height and descend. Descent can be simply viewed as a negative climb. If the engine is turned off during a descending flight, this flight operation is called gliding flight. An extreme case is when the descent angle is 90° and this flight program is referred to as dive. The diving is a beautiful part of a maneuvering flight usually carried out by an acrobatic aircraft. Due to the downward direction of a dive, the flight is often accelerating.
Fluid-structure interaction simulation for performance prediction and design optimization of parafoils
Published in Engineering Applications of Computational Fluid Mechanics, 2023
Hong Zhu, Qinglin Sun, Jin Tao, Hao Sun, Zengqiang Chen, Xianyi Zeng, Damien Soulat
The schematic of the parafoil system in a steady gliding state is shown in Figure 1. The aerodynamic lift force and drag force of the parafoil system are obtained by decomposing the total aerodynamic force along the incoming flow direction and its vertical direction (Knacke, 1987). According to the force balance of the system, we can obtain where is the total mass of the system (including ropes), g is the gravity acceleration, and γ is the glide angle. Equation (1) can be transformed into: where Equation (3) is the formula for aerodynamic efficiency in gliding flight. The smaller the glide angle, the larger the lift-to-drag ratio and the better the gliding performance. and are the lift coefficient and drag coefficient, respectively. ρ is the air density, and is the reference area of the parafoil canopy.
Fault-tolerant control of flexible air-breathing hypersonic vehicles in linear ODE-beam systems
Published in International Journal of Control, 2020
Dong Zhao, Bin Jiang, Hao Yang, Gang Tao
Air-breathing hypersonic vehicle (AHV) is one kind of modern aerospace vehicles that is critical to the development of new technologies in affordable space access and speedy global reach (Moses, Rausch, Nguyen, & Hill, 2004), such a vehicle makes hypersonic speed flight in the atmosphere, spreads through the atmosphere and make the gliding flight (Xu, 2009). An effective control scheme is typically required to ensure the desired system performance, especially in the presence of unknown effect of the flexibility and process/actuator faults.