Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722410049 Category : Languages : en Pages : 64
Book Description
The problem of minimization of fuel consumption during the atmospheric portion of an aeroassisted, orbital transfer with plane change is addressed. The complete mission has required three characteristic velocities, a deorbit impulse at high earth orbit (HEO), a boost impulse at the atmospheric exit, and a reorbit impulse at low earth orbit (LEO). A performance index has been formulated as the sum of these three impulses. Application of optimal control principles has led to a nonlinear, two-point, boundary value problem which was solved by using a multiple shooting algorithm. The strategy for the atmospheric portion of the minimum-fuel transfer is to start initially with the maximum positive lift in order to recover from the downward plunge, and then to fly with a gradually decreasing lift such that the vehicle skips out of the atmosphere with a flight path angle near zero degrees. Naidu, Desineni Subbaramaiah and Hibey, Joseph L. Unspecified Center...
Author: JENNIE RAE FREELAND JOHANNESEN Publisher: ISBN: Category : Languages : en Pages : 168
Book Description
Minimum-fuel orbital transfer between elliptical orbits is studied by first analyzing separately the three phases of aeroassisted orbital transfer (deorbit, atmospheric fly-through and post atmospheric maneuvers).
Author: Begum Senses Publisher: ISBN: Category : Languages : en Pages :
Book Description
ABSTRACT: In this study, minimum fuel solutions to finite thrust noncoplanar aeroassisted orbital transfers of a small spacecraft between two low-Earth orbits are found using General Pseudospectral Optimal Control Software (GPOPS) which applies an hp-adaptive pseudospectral method. Optimal trajectories, and final mass ratios of the small spacecraft that are obtained subject to various inclination changes, heating rate constraints, and number of atmospheric passes are compared. It is observed that, fuel consumption is proportional to the inclination change, on the other hand, it is inversely proportional to the heating rate constraint. Furthermore, for the cases where the heating rate is not constrained, the number of atmospheric passes does not affect the fuel consumption. For the cases where the heating rate is constrained, increasing number of atmospheric passes, however, decreases fuel consumption.
Author: Jean-Pierre Marec Publisher: Elsevier ISBN: 0444601074 Category : Technology & Engineering Languages : en Pages : 356
Book Description
Studies in Astronautics, Volume 1: Optimal Space Trajectories focuses on the concept of optimal transfer and the problem of optimal space trajectories. It examines the relative performances of the various propulsion systems (classical and electrical propulsions) and their optimization (optimal mass breakdown), along with parametric and functional optimizations and optimal transfers in an arbitrary, uniform, and central gravitational field. Organized into 13 chapters, this volume begins with an overview of optimal transfer and the modeling of propulsion systems. It then discusses the Hohmann transfer, the Hoelker and Silber bi-elliptical transfer, and the deficiencies of parametric optimization. The book explains the canonical transformation, optimization of the thrust law using the Maximum Principle, and optimal orbit corrections. The time-free orbital transfers and time-fixed orbital transfers and rendezvous are also discussed. Moreover, this volume explains the classical high-thrust and electric low-thrust propulsion systems and rendezvous between two planets. This book is written primarily for engineers who specialize in aerospace mechanics and want to pursue a career in the space industry or space research. It also introduces students to the different aspects of the problem of optimal space trajectories.
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722414306 Category : Languages : en Pages : 96
Book Description
The optimization and guidance of trajectories for coplaner, aeroassisted orbital transfer (AOT) from high Earth orbit (HEO) to low Earth orbit (LEO) are examined. In particular, HEO can be a geosynchronous Earth orbit (GEO). It is assumed that the initial and final orbits are circular, that the gravitational field is central and is governed by the inverse square law, and that at most three impulses are employed: one at HEO exit, one at atmospheric exit, and one at LEO entry. It is also assumed that, during the atmospheric pass, the trajectory is controlled via the lift coefficient. The presence of upper and lower bounds on the lift coefficient is considered. First, optimal trajectories are computed by minimizing the total velocity impulse (hence, the propellant consumption) required for AOT transfer. The sequential gradient-restoration algorithm (SGRA) is used for optimal control problems. The optimal trajectory is shown to include two branches: a relatively short descending flight branch (branch 1) and a long ascending flight branch (branch 2). Next, attention is focused on guidance trajectories capable of approximating the optimal trajectories in real time, while retaining the essential characteristics of simplicity, ease of implementation, and reliability. For the atmospheric pass, a feedback control scheme is employed and the lift coefficient is adjusted according to a two-stage gamma guidance law. Further improvements are possible via a modified gamma guidance which is more stable with respect to dispersion effects arising from navigation errors, variations of the atmospheric density, and uncertainties in the aerodynamic coefficients than gamma guidance trajectory. A byproduct of the studies on dispersion effects is the following design concept. For coplaner aeroassisted orbital transfer, the lift-range-to-weight ratio appears to play a more important role than the lift-to-drag ratio. This is because the lift-range-to-weight ratio controls mainly the minimum al...
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722334192 Category : Languages : en Pages : 68
Book Description
An actual geosynchronous Earth orbit-to-low Earth orbit (GEO-to-LEO) transfer is considered with reference to the aeroassisted flight experiment (AFE) spacecraft, and optimal trajectories are determined by minimizing the total characteristic velocity. The optimization is performed with respect to the time history of the controls (angle of attack and angle of bank), the entry path inclination and the flight time being free. Two transfer maneuvers are considered: direct ascent (DA) to LEO and indirect ascent (IA) to LEO via parking Earth orbit (PEO). By taking into account certain assumptions, the complete system can be decoupled into two subsystems: one describing the longitudinal motion and one describing the lateral motion. The angle of attack history, the entry path inclination, and the flight time are determined via the longitudinal motion subsystem. In this subsystem, the difference between the instantaneous bank angle and a constant bank angle is minimized in the least square sense subject to the specified orbital inclination requirement. Both the angles of attack and the angle of bank are shown to be constant. This result has considerable importance in the design of nominal trajectories to be used in the guidance of AFE and aeroassisted orbital transfer (AOT) vehicles. Miele, A. and Wang, T. and Deaton, A. W. Unspecified Center...
Author: National Aeronautics and Space Adm Nasa Publisher: Independently Published ISBN: 9781730754807 Category : Science Languages : en Pages : 68
Book Description
An actual geosynchronous Earth orbit-to-low Earth orbit (GEO-to-LEO) transfer is considered with reference to the aeroassisted flight experiment (AFE) spacecraft, and optimal trajectories are determined by minimizing the total characteristic velocity. The optimization is performed with respect to the time history of the controls (angle of attack and angle of bank), the entry path inclination and the flight time being free. Two transfer maneuvers are considered: direct ascent (DA) to LEO and indirect ascent (IA) to LEO via parking Earth orbit (PEO). By taking into account certain assumptions, the complete system can be decoupled into two subsystems: one describing the longitudinal motion and one describing the lateral motion. The angle of attack history, the entry path inclination, and the flight time are determined via the longitudinal motion subsystem. In this subsystem, the difference between the instantaneous bank angle and a constant bank angle is minimized in the least square sense subject to the specified orbital inclination requirement. Both the angles of attack and the angle of bank are shown to be constant. This result has considerable importance in the design of nominal trajectories to be used in the guidance of AFE and aeroassisted orbital transfer (AOT) vehicles. Miele, A. and Wang, T. and Deaton, A. W. Unspecified Center...
Author: National Aeronautics and Space Administration (NASA)
Author: Desineni S. Naidu
Author: JENNIE RAE FREELAND JOHANNESEN
Author: Peter Alexander Bidian
Author: Begum Senses
Author: Jean-Pierre Marec
Author: National Aeronautics and Space Administration (NASA)
Author: National Aeronautics and Space Administration (NASA)
Author: National Aeronautics and Space Adm Nasa
Author: Ya-Wen Shih