The Experts below are selected from a list of 96 Experts worldwide ranked by ideXlab platform
Agneta M. Balint - One of the best experts on this subject based on the ideXlab platform.
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numerical analysis of the oscillation susceptibility along the path of longitudinal flight equilibria of a reentry vehicle
Nonlinear Analysis-real World Applications, 2010Co-Authors: St Balint, Eva Kaslik, Agneta M. BalintAbstract:Abstract In this paper, it is shown that when the automatic flight control system (AFCS) is decoupled, then on the path of longitudinal flight equilibria of the ALFLEX reentry vehicle, there exist saddle–node bifurcations resulting in oscillations: when the Elevator Angle exceeds the bifurcation value, the Angle of attack and pitch rate oscillate with the same period, while the pitch Angle increases or decreases infinitely. Hence, the orbit of the system is spiraling. It is also shown that a mild (non-catastrophic) stability loss occurs due to the bifurcations. Based on this analysis, an automatic flight control design is developed.
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oscillation susceptibility analysis along the path of the longitudinal flight equilibriums in admire model
Journal of Aerospace Engineering, 2009Co-Authors: Stefan Balint, Agneta M. Balint, Achim IoniţăAbstract:Our goal is the oscillation susceptibility analysis in the framework of a nonlinear mathematical model in the so-called ADMIRE or Aero Data Model in a Research Environment. First, we analyze the oscillation susceptibility along the path of the longitudinal flight equilibriums when the flight control system (FCS) is decoupled. After that, a similar analysis is undertaken in the case when the FCS is coupled. For decoupled FCS, it is shown that on the path of the longitudinal flight equilibriums there exists a saddle-node where stability is lost and fold bifurcation occurs. Maneuvers are simulated showing the effect of an instantaneous change of the Elevator Angle, and the evolution of the unstable equilibriums (due to the maneuvers) to the corresponding exponentially stable equilibriums. It is shown numerically that at the saddle-node oscillations occur when the Elevator Angle is less than the critical value and the start is from the saddle-node. More precisely, it is shown that if the plane state parameters coincide with the saddle-node coordinates and the Elevator Angle is changed instantaneously from the critical value to a value which is less than this value, then two of the state parameters (α,q) begin to oscillate with the same period and the third parameter (θ) increases, tending to infinity. Thus, the orbit of the system evolves spiraling. It is shown also, that if the Elevator Angle is reset, the plane returns to a stable equilibrium. Therefore, a soft or no catastrophic stability loss takes place. When the FCS is coupled, the plane for every value of the amplification factor has a unique equilibrium which is exponentially stable and attracts all the equilibriums which exist in decoupled case. In this case, there are no bifurcation points on the equilibrium path. The dependence of the equilibrium and of the relaxation period on the amplification factor value is found numerically. Finally, it is concluded that when the FCS is decoupled, then along the path of the longitudinal equilibriums oscillations can occur, but when the FCS is coupled and the pilot can modify (instantaneously) only the amplifier factor value, then the vehicle, defined by the considered numerical data, is not anymore susceptible to oscillation.
Wahyu Kuntjoro - One of the best experts on this subject based on the ideXlab platform.
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A blended wing body airplane with a close-coupled, tilting tail
IOP Conference Series: Materials Science and Engineering, 2016Co-Authors: Rizal Effendy Mohd Nasir, Wahyu Kuntjoro Wirachman Wisnoe, Z. M. Ali, Nur Syazwani Mazlan, Wahyu KuntjoroAbstract:This paper highlights a novel approach to stabilizing and controlling pitch and yaw\r\nmotion via a set of horizontal tail that can act as Elevator and rudder. The tail is incorporated\r\ninto a new design of blended wing body (BWB) aircraft, known as Baseline-V, located just aft\r\nof the trailing edge of its inboard wing. The proposed close-coupled tail is equipped with\r\nElevators that deflect in unison, and can tilt – an unusual means of tilting where if starboard\r\nside is tilted downward at k degree, and then the portside must be tilted upward at k degree too.\r\nA wind tunnel experiment is conducted to investigate aerodynamics and static stability of\r\nBaseline-V BWB aircraft. The model is being tested at actual flight speed of 15 m/s (54 km/h)\r\nwith varying Angle of attack for five Elevator Angle cases at zero tilt Angle and varying sideslip\r\nAngle for four tilt Angle cases at one fixed Elevator Angle. The result shows that the aircraft’s\r\nhighest lift-to-drag ratio is 32. It is also found that Baseline-V is statically stable in pitch and\r\nyaw but has no clear indication in terms of roll stability.
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Experimental investigation of center Elevator deflection on aerodynamics of UiTM's Baseline-I Blended Wing Body (BWB) unmanned aerial vehicle (UAV)
CSSR 2010 - 2010 International Conference on Science and Social Research, 2010Co-Authors: Wahyu Kuntjoro Wirachman Wisnoe, Rizal Effendy M Nasir, M. A. Zurriati, R. Nor Fazira, Mohd Firdaus, Wahyu KuntjoroAbstract:This paper describes the wind tunnel testing of a Blended Wing Body (BWB)-Baseline I with Elevator developed in Universiti Teknologi MARA (UiTM). The experiment work was carried out in UiTM low speed wind tunnel using 1:7 scaled model of BWB at Mach 0.1. The testing is conducted for center Elevator Angle between -10° to +10° until stall Angle. The result show similar trends with zero Elevator deflection case in terms of lift curve, drag curve and pitching moment curves.
St Balint - One of the best experts on this subject based on the ideXlab platform.
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numerical analysis of the oscillation susceptibility along the path of longitudinal flight equilibria of a reentry vehicle
Nonlinear Analysis-real World Applications, 2010Co-Authors: St Balint, Eva Kaslik, Agneta M. BalintAbstract:Abstract In this paper, it is shown that when the automatic flight control system (AFCS) is decoupled, then on the path of longitudinal flight equilibria of the ALFLEX reentry vehicle, there exist saddle–node bifurcations resulting in oscillations: when the Elevator Angle exceeds the bifurcation value, the Angle of attack and pitch rate oscillate with the same period, while the pitch Angle increases or decreases infinitely. Hence, the orbit of the system is spiraling. It is also shown that a mild (non-catastrophic) stability loss occurs due to the bifurcations. Based on this analysis, an automatic flight control design is developed.
Norazila Othman - One of the best experts on this subject based on the ideXlab platform.
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CEC - Time-series optimization methodology and knowledge discovery of descend trajectory for civil aircraft
2016 IEEE Congress on Evolutionary Computation (CEC), 2016Co-Authors: Masahiro Kanazaki, Norazila OthmanAbstract:Optimal control of aircraft descent is important to efficiency, safety and environmental impact near airports. This paper presents an approach to time-series flight trajectory optimization for a civil aircraft. The equations of motion are resolved by evaluating aerodynamic force prediction at each time step. The microburst effect during descent is considered in the equations of motion, and the results of the optimal trajectory are compared to those that do not account for the microburst effect. The optimization problem is solved using a Kriging model based a multi-objective evolutionary algorithm (MOEA). The optimization problem consists of two objective functions: minimization of a cost function that indicates trajectory efficiency, and minimization of the maximum acceleration to reduce the impact load to payloads and passengers. Initial values of Angle of attack, Mach number, pitch rate, and Elevator Angle are used as design variable optimization problem inputs. In this study, a 3-degree-of-freedom equation of motion (3-DoF) is solved to evaluate an aircraft's longitudinal motion. Optimization results reveal the trade-off between the two objective functions with and without account for microbursts. Non-dominated solutions without microbursts are advanced and compared with microburst cases. Results suggest that it is difficult to realise simultaneously trajectory efficiency and impact load reduction, especially with microbursts. Kriging model based analysis of variance (ANOVA) was used to discover the knowledge. From ANOVA results, it is also noted that the initial Elevator Angle is effective. Investigating the trajectory history, the differences in Elevator Angle history with versus without consideration of the microburst effect enables the largest solutions that achieve the lowest cost function to be selected.
Wahyu Kuntjoro Wirachman Wisnoe - One of the best experts on this subject based on the ideXlab platform.
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A blended wing body airplane with a close-coupled, tilting tail
IOP Conference Series: Materials Science and Engineering, 2016Co-Authors: Rizal Effendy Mohd Nasir, Wahyu Kuntjoro Wirachman Wisnoe, Z. M. Ali, Nur Syazwani Mazlan, Wahyu KuntjoroAbstract:This paper highlights a novel approach to stabilizing and controlling pitch and yaw\r\nmotion via a set of horizontal tail that can act as Elevator and rudder. The tail is incorporated\r\ninto a new design of blended wing body (BWB) aircraft, known as Baseline-V, located just aft\r\nof the trailing edge of its inboard wing. The proposed close-coupled tail is equipped with\r\nElevators that deflect in unison, and can tilt – an unusual means of tilting where if starboard\r\nside is tilted downward at k degree, and then the portside must be tilted upward at k degree too.\r\nA wind tunnel experiment is conducted to investigate aerodynamics and static stability of\r\nBaseline-V BWB aircraft. The model is being tested at actual flight speed of 15 m/s (54 km/h)\r\nwith varying Angle of attack for five Elevator Angle cases at zero tilt Angle and varying sideslip\r\nAngle for four tilt Angle cases at one fixed Elevator Angle. The result shows that the aircraft’s\r\nhighest lift-to-drag ratio is 32. It is also found that Baseline-V is statically stable in pitch and\r\nyaw but has no clear indication in terms of roll stability.
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Experimental investigation of center Elevator deflection on aerodynamics of UiTM's Baseline-I Blended Wing Body (BWB) unmanned aerial vehicle (UAV)
CSSR 2010 - 2010 International Conference on Science and Social Research, 2010Co-Authors: Wahyu Kuntjoro Wirachman Wisnoe, Rizal Effendy M Nasir, M. A. Zurriati, R. Nor Fazira, Mohd Firdaus, Wahyu KuntjoroAbstract:This paper describes the wind tunnel testing of a Blended Wing Body (BWB)-Baseline I with Elevator developed in Universiti Teknologi MARA (UiTM). The experiment work was carried out in UiTM low speed wind tunnel using 1:7 scaled model of BWB at Mach 0.1. The testing is conducted for center Elevator Angle between -10° to +10° until stall Angle. The result show similar trends with zero Elevator deflection case in terms of lift curve, drag curve and pitching moment curves.