Download Free Rapid Near Optimal Trajectory Generation And Guidance Law Development For Single Stage To Orbit Airbreathing Vehicles Book in PDF and EPUB Free Download. You can read online Rapid Near Optimal Trajectory Generation And Guidance Law Development For Single Stage To Orbit Airbreathing Vehicles and write the review.

General problems associated with on-board trajectory optimization, propulsion system cycle selection, and with the synthesis of guidance laws were addressed for an ascent to low-earth-orbit of an air-breathing single-stage-to-orbit vehicle. The NASA Generic Hypersonic Aerodynamic Model Example and the Langley Accelerator aerodynamic sets were acquired and implemented. Work related to the development of purely analytic aerodynamic models was also performed at a low level. A generic model of a multi-mode propulsion system was developed that includes turbojet, ramjet, scramjet, and rocket engine cycles. Provisions were made in the dynamic model for a component of thrust normal to the flight path. Computational results, which characterize the nonlinear sensitivity of scramjet performance to changes in vehicle angle of attack, were obtained and incorporated into the engine model. Additional trajectory constraints were introduced: maximum dynamic pressure; maximum aerodynamic heating rate per unit area; angle of attack and lift limits; and limits on acceleration both along and normal to the flight path. The remainder of the effort focused on required modifications to a previously derived algorithm when the model complexity cited above was added. In particular, analytic switching conditions were derived which, under appropriate assumptions, govern optimal transition from one propulsion mode to another for two cases: the case in which engine cycle operations can overlap, and the case in which engine cycle operations are mutually exclusive. The resulting guidance algorithm was implemented in software and exercised extensively. It was found that the approximations associated with the assumed time scale separation employed in this work are reasonable except over the Mach range from roughly 5 to 8. This phenomenon is due to the very large thrust capability of scramjets in this Mach regime when sized to meet the requirement for ascent to orbit. By accounting for flight path angl...
Effort was directed toward the problems of the real time trajectory optimization and guidance law development for the National Aerospace Plane (NASP) applications. In particular, singular perturbation methods were used to develop guidance algorithms suitable for onboard, real time implementation. The progress made in this research effort is reported. Calise, A. J. and Corban, J. E. and Markopoulos, N. Unspecified Center NAG1-922
Much effort has been put into developing technologies for next generation re-usable launch vehicles. Fully re-usable launch vehicles include a booster stage that is designed to land, usually near the launch site, after it has released the upper-stage, which continues to orbit. The fuel reserve needed to turn the booster stage around will usually be minimal For this reason, once the booster stage has completed a rocket-back maneuver, it will typically be at a high altitude (exo-atmospheric) but with low kinetic energy and a steep flight path angle on re-entry. Traditional re-entry guidance is designed for vehicles with a high velocity, and shallow flight path angle, and thus these traditional approaches are not appropriate for a low energy re-entry (LOER). The current research presents a set of guidance algorithms that will successfully guide a vehicle to landing starting from LOER condition. The guidance algorithms are designed to ensure the vehicle can achieve near optimal range performance when required and also to execute a sharp pull-up maneuver that balances the load factor constraint against the need to pull-up quickly before the dynamic pressure constraint is exceeded. The guidance approach has been tested for a wide variety of vehicles and mission scenarios, including more traditional initial conditions that would occur at the end of a High Energy Re-entry (HIER) from orbit. Thus, the guidance approach we have developed can be used as a more robust version of Terminal Area Energy Management (TAEM) guidance, as well as for LOER and has been tested for a wide range of vehicles, including the Space Shuttle and vehicles with a wide variety of L/D capability. Significant development has also gone into the engineering considerations needed to implement the guidance algorithms on a real vehicle. Program execution time, application of vehicle constraints, trajectory repeatability and other factors are all addressed in order to meet this need.
The first step in the approach to developing guidance laws for a horizontal take-off, air breathing single-stage-to-orbit vehicle is to characterize the minimum-fuel ascent trajectories. The capability to generate constrained, minimum fuel ascent trajectories for a single-stage-to-orbit vehicle was developed. A key component of this capability is the general purpose trajectory optimization program OTIS. The pre-production version, OTIS 0.96 was installed and run on a Convex C-1. A propulsion model was developed covering the entire flight envelope of a single-stage-to-orbit vehicle. Three separate propulsion modes, corresponding to an after burning turbojet, a ramjet and a scramjet, are used in the air breathing propulsion phase. The Generic Hypersonic Aerodynamic Model Example aerodynamic model of a hypersonic air breathing single-stage-to-orbit vehicle was obtained and implemented. Preliminary results pertaining to the effects of variations in acceleration constraints, available thrust level and fuel specific impulse on the shape of the minimum-fuel ascent trajectories were obtained. The results show that, if the air breathing engines are sized for acceleration to orbital velocity, it is the acceleration constraint rather than the dynamic pressure constraint that is active during ascent. Mease, Kenneth D. and Vanburen, Mark A. Unspecified Center NAG1-907