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Takeoff and landing
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
The aircraft primary takeoff performance is often determined by the required runway. The shorter the runway, the better is the aircraft takeoff performance. In aircraft carriers, other techniques and devices such as catapult are provided to make takeoff and landing feasible and make takeoff run and landing run shorter. An aircraft that could take off and land in a runway with a length of less than 500 ft is called STOL (short takeoff and landing). The aircraft that is able to take off and land vertically are referred to as VTOL (vertical takeoff and landing). These two groups of aircraft are referred to as V/STOL aircraft. Most fighters are of V/STOL type. V-22 Osprey, Harrier AV-8B, and Bell XV-15 are examples of VTOL aircraft.
Gradient method using pseudospectral collocation scheme for two-stage optimal control with an unspecified switching time
Published in International Journal of Control, 2021
Liang Yang, Jin Yang, Xiaoming Liu, Wanchun Chen, Hao Zhou
Gradient Method (GM) is an iterative algorithm for solving trajectory optimisation problem and became popular since the 1960s. A detailed description on the gradient method is provided in the literature (Bryson & Ho, 1969). Because GM is very easy to implement, it has been successfully applied in many aerospace engineering problems. Bryson has applied the conjugate gradient method to solve the minimum time path problem for the climb phase of a V/STOL aircraft (Mehra & Bryson, 1969). Yiyuan Zhao investigated the optimal aircraft take-off trajectory in a down-burst using Gradient Method (Zhao & Bryson, 1990). Eun Jung Song used the first-order gradient method to provide the optimal solution for the ground-air intercept problem (Song & Tahk, 1998). However, traditional GM has low computational efficiency due to lack of an efficient way to determine the influence function, therefore, few researches focus on complicated multi-stage nonlinear systems. In spite of this, because GM is characterised by iteratively providing the improvement of control histories so as to satisfy the first-order necessary condition, we still believe that it has great potential to be regarded as baseline algorithm to solve the two-stage nonlinear optimal control problem in an efficient manner.
Design and analysis of Coanda effect nozzle with two independent streams
Published in International Journal of Ambient Energy, 2020
From the analysis done on various design, we can find an increase in deflection angle for increase in the length of sharp edge. The sixth design produced more deflection than any other models in both directions. It produced a higher angle of about 24° in an upward direction and 22° in a downward direction. Also, we can see that applying the same velocity in both the inlets will produce no deflection. From the figures plotted for each analysis, we can see that the pressure was the same in all the cases (i.e. pressure drop till certain position; after that, we can see the increase in pressure). Similarly, the velocity plot showed that there was an increase in velocity for the cases having higher velocity in Inlet 1; it results in producing deflection in an upward direction. If the velocity in Inlet 2 is higher, then it produces deflection in a downward direction. These upward and downward directions only belong in case of using conventional aircraft. In case of V/STOL aircraft, we can say that it is sideward force (i.e. left and right directions), for example, if it produced deflection along left side, the aircraft turns rightward. Similarly, if it produced force in right side, it deflects along the left side.
Experimental and numerical study of turbulent flow around a Fanwings profile
Published in Engineering Applications of Computational Fluid Mechanics, 2019
Slimane Benferhat, Tayeb Yahiaoui, Bachir Imine, Omar Ladjedel, Ondřej Šikula
For several years, the improved performance of rotorcrafts and rotary wing aircrafts capable of vertical take-off and landing (VTOL) or a short takeoff and landing (STOL), has led research to innovation and the Fanwing is one. He requires a short runway. The novelty of this type of propulsion is to move an aircraft using a cylindrical fan. Fanwing is a rare concept, working at low Reynolds numbers, developed and patented by Peebles (2001); it was inspired by the paddle steamers that sailed the Mississippi River. This type of aircraft with motorized lift uses a turbine engine mounted on the entire wingspan of a wing similar to a rigid wing. This is a different mode of operation from the conventional aircraft. This type of turbomachine is called cross-flow fan. It was patented by Mortier (1893). The rotation of the fan is used to accelerate the air flow on the profile.