Flexible dynamics in launch vehicles have long been considered a disturbance for simulation purposes. Future launch vehicles may include real time estimation and possible real time control or attenuation of flexible dynamics. This is currently handled partially as part of gain-scheduled controllers, but future (slender) launch vehicles will require more detailed models and possibly actuation to control vibrational behavior. The engineer needs to know which parameters are critical and have confidence that all relevant features of the dynamics have been included so that the rocket will not encounter an unfavorable dynamic interaction.
Dynamics and Simulation of Flexible Rockets provides a full state, multi-axis treatment of large flexible rockets with propellant slosh and provides the state equations in a format that can be readily coded into a simulation environment. Presenting a vector formulation of rocket dynamics that is suitable for modern computer analysis, equations of motion are derived for a flexible rocket with sloshing fuel and moving nozzles. Various forms of the mass matrix for this system are also presented. This book also discusses the nature of various forms of coupling, such as between the nozzle motions and the flexible dynamics.
- Covers everything the structural and control engineer needs to analyze or improve launch vehicle stability when facing flexible dynamics
- Provides the derivation of the linear dynamics using Lagrange's equation plus a separate nonlinear Newton/Euler derivation, allowing the reader to assess the importance of nonlinear terms
- Presents a method for making a smooth transition from one finite element model to the next
2. Mass Matrix Using the Spring Slosh Model
3. Slosh Modeling
4. Pendulum Model
5. Forces and Torques
6. Engine Interactions
7. Linearized Analysis
8. Simulation Parameters
9. List of Symbols
Dr. Barrows has over 30 years of experience in analysis and simulation of complex mechanical systems for NASA and various agencies of the Department of Defense. His engineering expertise includes aerodynamics, multi-body dynamics, and simulation. A particular expertise is simulation of multibody systems. He has either directly created or supervised the construction of high fidelity simulations of several systems, including the attitude control of a satellite, a generalized robotic manipulator model, the space station mobile transporter, and the flight mechanics of precision guided airdrop systems. Other work has included successful airdrop tests of a gliding autogyro with folding rotor blades, and a concept definition of a large vehicle designed to fly in ground effect.
He has served as Section Chief of the Dynamical Systems Group at Draper, in which capacity he served as the engineering task leader of for the Space Station Dynamic Interaction program. During the past ten years, Dr. Barrows has focused on the development of rocket simulations. This has included a wide variety of rockets for both private and government sponsors, culminating in work on NASA's space launch system.
Dr. Jeb Orr has over 16 years of experience in mission-critical software engineering, flight mechanics, model-based design, flight control system architecture, guidance and navigation, structural dynamics, and related disciplines. He has authored or co-authored more than 30 peer-reviewed publications and technical reports and has conducted several invited lectures in the areas of dynamics and control. Dr. Orr has had a key role in various research initiatives supporting NASA and Department of Defense (DoD) emerging technologies. Dr. Orr was a principal designer of the Space Launch System Adaptive Augmenting Control (AAC) algorithm, and developed the FRACTAL software package, now the standard NASA design model for SLS flight control analysis. In 2013 Dr. Orr was awarded the NASA Exceptional Engineering Achievement Medal in recognition of his contributions to the SLS program. Dr. Orr serves as an officer of the SAE/IEEE Aerospace Control and Guidance Systems Committee (ACGSC), and conducts courses in aerospace dynamics and flight control for NASA Marshall Space Flight Center and the NASA Engineering and Safety Center (NESC).