Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 24
Book Description
Aeroassisted Orbit Transfer Vehicle Trajectory Analysis
Author: The Effect of Trajectory and Vehicle Parameters on an Aeroassisted Orbital Transfer
Author: Shawn Andrew KerrAn Analysis of the Effect of Aeroassist Maneuvers on Orbital Transfer Vehicle Performance
Author: Singular Perturbation Analysis of Aotv-Related Trajectory Optimization Problems
Author: National Aeronautics and Space Administration (NASA)Publisher: Createspace Independent Publishing Platform
ISBN: 9781722741037
Category :
Languages : en
Pages : 54
Book Description
The problem of real time guidance and optimal control of Aeroassisted Orbit Transfer Vehicles (AOTV's) was addressed using singular perturbation theory as an underlying method of analysis. Trajectories were optimized with the objective of minimum energy expenditure in the atmospheric phase of the maneuver. Two major problem areas were addressed: optimal reentry, and synergetic plane change with aeroglide. For the reentry problem, several reduced order models were analyzed with the objective of optimal changes in heading with minimum energy loss. It was demonstrated that a further model order reduction to a single state model is possible through the application of singular perturbation theory. The optimal solution for the reduced problem defines an optimal altitude profile dependent on the current energy level of the vehicle. A separate boundary layer analysis is used to account for altitude and flight path angle dynamics, and to obtain lift and bank angle control solutions. By considering alternative approximations to solve the boundary layer problem, three guidance laws were derived, each having an analytic feedback form. The guidance laws were evaluated using a Maneuvering Reentry Research Vehicle model and all three laws were found to be near optimal. For the problem of synergetic plane change with aeroglide, a difficult terminal boundary layer control problem arises which to date is found to be analytically intractable. Thus a predictive/corrective solution was developed to satisfy the terminal constraints on altitude and flight path angle. A composite guidance solution was obtained by combining the optimal reentry solution with the predictive/corrective guidance method. Numerical comparisons with the corresponding optimal trajectory solutions show that the resulting performance is very close to optimal. An attempt was made to obtain numerically optimized trajectories for the case where heating rate is constrained. A first order state variable inequality constra...
Thermal Design of Aeroassisted Orbital Transfer Vehicles
Author: H. F. NelsonPublisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 592
Book Description
Design and Performance Analysis of an Aero-maneuvering Orbital-transfer Vehicle Concept
Author: Fuel-Optimal Trajectories of Aeroassisted Orbital Transfer with Plane Change
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...
Optimal Aeroassisted Coplanar Orbital Transfer Using an Energy Model
Author: National Aeronaut Administration (Nasa)Publisher: Createspace Independent Publishing Platform
ISBN: 9781722681548
Category :
Languages : en
Pages : 68
Book Description
The atmospheric portion of the trajectories for the aeroassisted coplanar orbit transfer was investigated. The equations of motion for the problem are expressed using reduced order model and total vehicle energy, kinetic plus potential, as the independent variable rather than time. The order reduction is achieved analytically without an approximation of the vehicle dynamics. In this model, the problem of coplanar orbit transfer is seen as one in which a given amount of energy must be transferred from the vehicle to the atmosphere during the trajectory without overheating the vehicle. An optimal control problem is posed where a linear combination of the integrated square of the heating rate and the vehicle drag is the cost function to be minimized. The necessary conditions for optimality are obtained. These result in a 4th order two-point-boundary-value problem. A parametric study of the optimal guidance trajectory in which the proportion of the heating rate term versus the drag varies is made. Simulations of the guidance trajectories are presented. Halyo, Nesim and Taylor, Deborah B. Unspecified Center...
Fuel-optimal Trajectories of Aeroassisted Orbital Transfer with Plane Change
Author: Desineni S. NaiduPublisher:
ISBN:
Category : Orbital transfer (Space flight)
Languages : en
Pages : 120
Book Description
Technology for Large Space Systems
Author: Publisher:
ISBN:
Category : Large space structures (Astronautics)
Languages : en
Pages : 676
Book Description