Download or read book Minimum fuel Finite Thrust Low earth Orbit Aeroassisted Orbital Transfer of Small Spacecraft written by Begum Senses and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book A Numerical Study of Fuel Optimal Low Earth Orbit Maintenance written by Lawrence E. Halbach and published by . This book was released on 2000-12-01 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis studies the fuel optimal periodic reboost profile required to maintain a spacecraft experiencing drag in low-earth-orbit (LEO). Recent advances in computational optimal control theory are employed, along with a Legendre-Gauss-Lobatto Pseudospectral collocation code developed at the Naval Postgraduate School, to solve the problem. Solutions obtained by this method are compared against a previous study. Key issues were checking the optimality of the solutions by way of the necessary conditions and the behavior of the solution to changes in the thruster size. The results confirmed Jensen's findings of propellant savings of one to five percent when compared against a middle altitude Forced Keplerian Trajectory (FKT). Larger savings are predicted if compared against a finite-burn Hohmann transfer with drag. The costates estimates compared favorably against necessary conditions of Pontryagin's Minimum Principle. Analysis of the switching flinction yielded periods of thrust-modulated arcs. The optimal thrust profile appears to be a thrust- modulated burn to raise the orbit followed by an orbital decay and a terminating thrust-modulated arc. For a sufficiently low thrust-control authority, the switching structure includes a maximum thrust arc. Indirect optimization techniques to confirm these findings were unsuccessful.

Download or read book Fuel Optimal Trajectories of Aeroassisted Orbital Transfer with Plane Change written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-07 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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...

Download or read book Minimum fuel Orbital Transfer Using Finite Thrust written by Jerry L. Mrozek (CAPT, USAF.) and published by . This book was released on 1975 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aeroassisted Orbit Transfer Vehicle Trajectory Analysis written by and published by . This book was released on 1988 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fuel Optimal Low Earth Orbit Maintenance written by Karl E. Jensen and published by . This book was released on 1998-06-01 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: First-order solutions indicate that a forced Keplerian trajectory (FKT) obtained by thrust-drag cancellation is as fuel-efficient as a Hohmann transfer. Further analysis has shown that the FKT is not Mayer-optimal. Therefore there must exist another trajectory that matches or exceeds the efficiency of the Hohmann transfer. The application of this result to the fuel- optimal orbit maintenance problem implies that periodic reboosts must be more efficient than an WT profile. This research begins with the formulation of an optimal periodic control (OPC) problem to determine the minimum fuel-reboost strategy. The problem is numerically solved by a spectral collocation method. The optimization code is further modified to increase accuracy and reduce sensitivity to initial guesses. The results of this effort identified a trajectory for a sample satellite that was 3.5% more efficient than an ideal impulsive Hohmann transfer over the same period of time. From the optimal code, a maximum thruster size is also identifiable for a set of initial conditions. The optimal trajectory can save as much as 10% of the propellant budget when compared to finite-bum Hohmann transfers.

Download or read book Minimum Fuel Continuous Low Thrust Orbital Transfer written by Eugene A. Smith and published by . This book was released on 1974 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Minimum fuel continuous low thrust orbit transfer is an optimal control problem which requires the application of iterative numerical methods to solve the resulting two point boundary value problem. A combination gradient- neighboring extremal algorithm gives accurate results when both the initial and terminal orbits are coplanar. These results are then used to extend the problem to include out-of-plane transfers between orbits of widely varying inclination. Control histories, in terms of thrust direction, are plotted as a function of time for both coplanar and non-coplanar transfers. Steering programs for coplanar transfers are characterized by a rapid thrust reversal which is dependent on eccentricity for the time of its occurrence. In the latter case, out-of-plane thrusting is primarily a function of the inclination change between orbits. On the basis of these results, the particular numerical approach used provides an effective method for generating optimal low thrust orbital transfer guidance.

Download or read book Optimal Aeroassisted Coplanar Orbital Transfer Using an Energy Model written by and published by . This book was released on 1989 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Piecewise Constant Guidance for Aeroassisted Orbit Transfer written by Peter Alexander Bidian and published by . This book was released on 1994 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1993 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Orbital Transfer with Minimum Fuel written by Willard Evan Bleick and published by . This book was released on 1963 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: An extension is made of the problem of scheduling the direction p of constant momentum thrust of a rocket, which loses mass at a constant rate, so that it transfers to a known earth satellite orbit in minimum time T after launching. A numerical solution was obtained, using rectangular coordinates, for the case of fixed launching conditions. The method is extended to solve the problem of orbital transfer of such a rocket with minimum fuel consumption. (Author).

Download or read book Decomposition Technique and Optimal Trajectories for the Aeroassisted Flight Experiment written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-06 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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...

Download or read book Investigation of Minimum Fuel Limited Thrust Orbital Transfer Trajectories written by Harold Dean Childers and published by . This book was released on 1969 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: The method of quasilinearization is applied to the solution of a system of lumped-parameter differential equations providing the necessary conditions for minimum-fuel finite-thrust transfers between coplanar orbits. A central gravitational field is assumed. The equations are derived from the basic equations describing the motion of a finite-thrust rocket. The method of optimization (a modification of quasilinearization for application to bang-bang control problems), and the computer program used to solve the problem are discussed. The method is found to be inapplicable to the problem as originally formulated, and reasons for the inapplicability are given. A new formulation is presented, and computer programming techniques relevant to its solution are discussed. A printout of the program is included. (Author).

Download or read book Minimum Fuel Continuous Low Thrust Orbital Transfer written by Eugene A. Smith (CAPT, USAF.) and published by . This book was released on 1974 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Decomposition Technique and Optimal Trajectories for the Aeroassisted Flight Experiment written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-11-03 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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...

Download or read book Optimization of Low thrust Spacecraft Trajectories by Direct Shooting Methods microform written by Christopher Rampersad and published by Library and Archives Canada = Bibliothèque et Archives Canada. This book was released on 2004 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The direct approach for trajectory optimization was found to be very robust. For most problems, solutions were obtained even with poor initial guesses for the controls. The direct approach was also found to be only slightly less accurate than the indirect methods found in the literature (within 0.7%). The present study investigates minimum-time and minimum-fuel low-thrust trajectory problems via a single shooting direct method. Various Earth-based and interplanetary case studies have been examined and have yielded good agreement with similar cases in the literature. Furthermore, new near-optimal trajectory problems have been successfully solved. A multiple-orbit thrust parameterization strategy was also developed to solve near-optimal very-low-thrust Earth-based transfers. Lastly, this thesis examines the use of the high-accuracy complex-step derivative approximation method for solving low-thrust transfer problems. For certain very nonlinear transfer problems, the complex-step derivative approximation was found to increase the robustness of the single shooting direct method.

Download or read book Optimum Low Thrust Elliptic Orbit Transfer Using Numerical Averaging written by Zahi Bassem Tarzi and published by . This book was released on 2012 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-thrust electric propulsion is increasingly being used for spacecraft missions primarily due to its high propellant efficiency. Since analytical solutions for general low-thrust transfers are not available, a simple and fast method for low-thrust trajectory optimization is of great value for preliminary mission planning. However, few low-thrust trajectory tools are appropriate for preliminary mission design studies. The method presented in this paper provides quick and accurate solutions for a wide range of transfers by using numerical orbital averaging to improve solution convergence and include orbital perturbations. Thus allowing preliminary trajectories to be obtained for transfers which involve many revolutions about the primary body. This method considers minimum fuel transfers using first order averaging to obtain the fuel optimum rates of change of the equinoctial orbital elements in terms of each other and the Lagrange multipliers. Constraints on thrust and power, as well as minimum periapsis, are implemented and the equations are averaged numerically using a Gaussian quadrature. The use of numerical averaging allows for more complex orbital perturbations to be added without great difficulty. Orbital perturbations due to solar radiation pressure, atmospheric drag, a non-spherical central body, and third body gravitational effects have been included. These perturbations have not ben considered by previous methods using analytical averaging. Thrust limitations due to shadowing have also been considered in this study. To allow for faster convergence of a wider range of problems, the solution to a transfer which minimizes the square of the thrust magnitude is used as a preliminary guess for the minimum fuel problem. Thus, this method can be quickly applied to many different types of transfers which may include various perturbations. Results from this model are shown to provide a reduction in propellant mass required over previous minimum fuel solutions. Minimum time transfers are also solved and compared to minimum fuel.