The Experts below are selected from a list of 6057 Experts worldwide ranked by ideXlab platform
M Dileep - One of the best experts on this subject based on the ideXlab platform.
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minimum time ascent phase trajectory optimization using steepest descent method
Control theory & applications, 2016Co-Authors: Diksha Diva Singh, Vishnu G Nair, M DileepAbstract:In this paper, ascent phase gravity turn trajectory of a launch vehicle is taken into account. Minimum-time problem of optimization is considered for specifi ed structural and propulsive data. The objective is to achieve the target in minimum time and minimum error at terminal point by taking into account all the constraints. Trajectory generation is done for a single Stage Rocket in 2-D plane and computed for a given initial and fi nal conditions. Hamiltonian is formulated by converting the given problem into secure fi nal fl ight path angle problem and Pontryagin minimum principle is used to fi nd the necessary conditions. The non-linear equations are solved using gradient method. Ultimately, the numerical results are evaluated and validity of result is exhibited.
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trajectory optimization of launch vehicles using steepest descent method a novel approach
2014Co-Authors: M Dileep, Vishnu G Nair, K R Prahlad, Surekha KamathAbstract:Trajectory optimization of a generic launch vehicle is considered in this paper. The direct application of a nonlinear programming method is used in recent literature, which transforms the original problem into a nonlinear optimization problem.To study the Rocket motion under the influence of gravitational field, 2-D simulator is developed. The Rocket motion is analyzed for a gravity turn trajectory. The objective is to ensure desired terminal conditions as well as minimum control effort in the low dynamic pressure region. Design of optimal trajectory for a single Stage Rocket is a two point boundary problem. Trajectory is designed for a single Stage liquid Rocket.Trajectory is computed for a given initial and final condition using equations of motion of Rocket in 2-D plane. Hamiltonian is formulated for the given constraints. The non-linear equations are solved using steepest descent method.It is assumed that the launch vehicle is not experiencing any perturbations. Results are compared for Runge-kutta and Euler‟s integration methods,which clearly brings out the potential advantages of the proposed approach.
Virginia P Dawson - One of the best experts on this subject based on the ideXlab platform.
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taming liquid hydrogen the centaur upper Stage Rocket 1958 2002
2004Co-Authors: Mark D Bowles, Virginia P DawsonAbstract:During its maiden voyage in May 1962, a Centaur upper Stage Rocket, mated to an Atlas booster, exploded 54 seconds after launch, engulfing the Rocket in a huge fireball. Investigation revealed that Centaur's light, stainless-steel tank had split open, spilling its liquid-hydrogen fuel down its sides, where the flame of the Rocket exhaust immediately ignited it. Coming less than a year after President Kennedy had made landing human beings on the Moon a national priority, the loss of Centaur was regarded as a serious setback for the National Aeronautics and Space Administration (NASA). During the failure investigation, Homer Newell, Director of Space Sciences, ruefully declared: "Taming liquid hydrogen to the point where expensive operational space missions can be committed to it has turned out to be more difficult than anyone supposed at the outset." After this failure, Centaur critics, led by Wernher von Braun, mounted a campaign to cancel the program. In addition to the unknowns associated with liquid hydrogen, he objected to the unusual design of Centaur. Like the Atlas Rocket, Centaur depended on pressure to keep its paper-thin, stainless-steel shell from collapsing. It was literally inflated with its propellants like a football or balloon and needed no internal structure to give it added strength and stability. The so-called "pressure-stabilized structure" of Centaur, coupled with the light weight of its high- energy cryogenic propellants, made Centaur lighter and more powerful than upper Stages that used conventional fuel. But, the critics argued, it would never become the reliable Rocket that the United States needed.
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taming liquid hydrogen the centaur upper Stage Rocket
2004Co-Authors: Virginia P Dawson, Mark D BowlesAbstract:The Centaur is one of the most powerful Rockets in the world. As an upper-Stage Rocket for the Atlas and Titan boosters it has been a reliable workhorse for NASA for over forty years and has played an essential role in many of NASA's adventures into space. In this CD-ROM you will be able to explore the Centaur's history in various rooms to this virtual museum. Visit the "Movie Theater" to enjoy several video documentaries on the Centaur. Enter the "Interview Booth" to hear and read interviews with scientists and engineers closely responsible for building and operating the Rocket. Go to the "Photo Gallery" to look at numerous photos of the Rocket throughout its history. Wander into the "Centaur Library" to read various primary documents of the Centaur program. Finally, stop by the "Observation Deck" to watch a virtual Centaur in flight.
Mark D Bowles - One of the best experts on this subject based on the ideXlab platform.
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taming liquid hydrogen the centaur upper Stage Rocket 1958 2002
2004Co-Authors: Mark D Bowles, Virginia P DawsonAbstract:During its maiden voyage in May 1962, a Centaur upper Stage Rocket, mated to an Atlas booster, exploded 54 seconds after launch, engulfing the Rocket in a huge fireball. Investigation revealed that Centaur's light, stainless-steel tank had split open, spilling its liquid-hydrogen fuel down its sides, where the flame of the Rocket exhaust immediately ignited it. Coming less than a year after President Kennedy had made landing human beings on the Moon a national priority, the loss of Centaur was regarded as a serious setback for the National Aeronautics and Space Administration (NASA). During the failure investigation, Homer Newell, Director of Space Sciences, ruefully declared: "Taming liquid hydrogen to the point where expensive operational space missions can be committed to it has turned out to be more difficult than anyone supposed at the outset." After this failure, Centaur critics, led by Wernher von Braun, mounted a campaign to cancel the program. In addition to the unknowns associated with liquid hydrogen, he objected to the unusual design of Centaur. Like the Atlas Rocket, Centaur depended on pressure to keep its paper-thin, stainless-steel shell from collapsing. It was literally inflated with its propellants like a football or balloon and needed no internal structure to give it added strength and stability. The so-called "pressure-stabilized structure" of Centaur, coupled with the light weight of its high- energy cryogenic propellants, made Centaur lighter and more powerful than upper Stages that used conventional fuel. But, the critics argued, it would never become the reliable Rocket that the United States needed.
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taming liquid hydrogen the centaur upper Stage Rocket
2004Co-Authors: Virginia P Dawson, Mark D BowlesAbstract:The Centaur is one of the most powerful Rockets in the world. As an upper-Stage Rocket for the Atlas and Titan boosters it has been a reliable workhorse for NASA for over forty years and has played an essential role in many of NASA's adventures into space. In this CD-ROM you will be able to explore the Centaur's history in various rooms to this virtual museum. Visit the "Movie Theater" to enjoy several video documentaries on the Centaur. Enter the "Interview Booth" to hear and read interviews with scientists and engineers closely responsible for building and operating the Rocket. Go to the "Photo Gallery" to look at numerous photos of the Rocket throughout its history. Wander into the "Centaur Library" to read various primary documents of the Centaur program. Finally, stop by the "Observation Deck" to watch a virtual Centaur in flight.
Vishnu G Nair - One of the best experts on this subject based on the ideXlab platform.
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minimum time ascent phase trajectory optimization using steepest descent method
Control theory & applications, 2016Co-Authors: Diksha Diva Singh, Vishnu G Nair, M DileepAbstract:In this paper, ascent phase gravity turn trajectory of a launch vehicle is taken into account. Minimum-time problem of optimization is considered for specifi ed structural and propulsive data. The objective is to achieve the target in minimum time and minimum error at terminal point by taking into account all the constraints. Trajectory generation is done for a single Stage Rocket in 2-D plane and computed for a given initial and fi nal conditions. Hamiltonian is formulated by converting the given problem into secure fi nal fl ight path angle problem and Pontryagin minimum principle is used to fi nd the necessary conditions. The non-linear equations are solved using gradient method. Ultimately, the numerical results are evaluated and validity of result is exhibited.
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trajectory optimization of launch vehicles using steepest descent method a novel approach
2014Co-Authors: M Dileep, Vishnu G Nair, K R Prahlad, Surekha KamathAbstract:Trajectory optimization of a generic launch vehicle is considered in this paper. The direct application of a nonlinear programming method is used in recent literature, which transforms the original problem into a nonlinear optimization problem.To study the Rocket motion under the influence of gravitational field, 2-D simulator is developed. The Rocket motion is analyzed for a gravity turn trajectory. The objective is to ensure desired terminal conditions as well as minimum control effort in the low dynamic pressure region. Design of optimal trajectory for a single Stage Rocket is a two point boundary problem. Trajectory is designed for a single Stage liquid Rocket.Trajectory is computed for a given initial and final condition using equations of motion of Rocket in 2-D plane. Hamiltonian is formulated for the given constraints. The non-linear equations are solved using steepest descent method.It is assumed that the launch vehicle is not experiencing any perturbations. Results are compared for Runge-kutta and Euler‟s integration methods,which clearly brings out the potential advantages of the proposed approach.
Mahmut Reyhanoglu - One of the best experts on this subject based on the ideXlab platform.
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thrust vector control of a three axis stabilized upper Stage Rocket with fuel slosh dynamics
Acta Astronautica, 2014Co-Authors: Jaime Rubio Hervas, Mahmut ReyhanogluAbstract:Abstract This paper studies the thrust vector control problem for an upper-Stage Rocket with fuel slosh dynamics. The dynamics of a three-axis stabilized spacecraft with a single partially-filled fuel tank are formulated and the sloshing propellant is modeled as a multi-mass–spring system, where the oscillation frequencies of the mass–spring elements represent the prominent sloshing modes. The equations of motion are expressed in terms of the three-dimensional spacecraft translational velocity vector, the attitude, the angular velocity, and the internal coordinates representing the slosh modes. A Lyapunov-based nonlinear feedback control law is proposed to control the translational velocity vector and the attitude of the spacecraft, while attenuating the sloshing modes characterizing the internal dynamics. A simulation example is included to illustrate the effectiveness of the control law.
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thrust vector control of an upper Stage Rocket with multiple propellant slosh modes
Mathematical Problems in Engineering, 2012Co-Authors: Jaime Rubio Hervas, Mahmut ReyhanogluAbstract:The thrust vector control problem for an upper-Stage Rocket with propellant slosh dynamics is considered. The control inputs are defined by the gimbal deflection angle of a main engine and a pitching moment about the center of mass of the spacecraft. The Rocket acceleration due to the main engine thrust is assumed to be large enough so that surface tension forces do not significantly affect the propellant motion during main engine burns. A multi-mass-spring model of the sloshing fuel is introduced to represent the prominent sloshing modes. A nonlinear feedback controller is designed to control the translational velocity vector and the attitude of the spacecraft, while suppressing the sloshing modes. The effectiveness of the controller is illustrated through a simulation example.
