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Aerospace Plane

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Kenneth D. Mease – One of the best experts on this subject based on the ideXlab platform.

  • Near-Optimal Control of Altitude and Path Angle During Aerospace Plane Ascent
    Journal of Guidance Control and Dynamics, 1997
    Co-Authors: Jean-paul Kremer, Kenneth D. Mease

    Abstract:

    Altitude and e ight-path-angle control during the posttransonic airbreathing segment of Aerospace Plane ascent is addressed, with objectives to minimize fuel usage and respect the vehicle e ight envelope. Based on a time-scale separation between energy/mass and altitude/path-angle dynamics, the altitude/path-angle control problem is viewedina singularperturbation framework asan initialboundary-layerproblem. Afeedbacklawapproximating theminimum-fuelinitialboundary-layercontrolisobtainedbysolvinganeighboring-optimalproblem.Tofacilitate this derivation, the state constraint that is active on the slow solution is modeled in the boundary layer using an appropriatepenaltyfunction.Theneighboring-optimalfeedbacklawperformswellaslongastemporaryconstraint violations are acceptable in the boundary layer. An alternate linear feedback law is derived with gains calculated to reduce constraint violations, but this law leads to increased fuel usage. Numerical results are presented for a lifting-body cone guration of an Aerospace Plane and a Mach 8 e ight condition. The results show that fuel usage and control activity are reduced when the peak dynamic pressure is allowed to increase. Differences in fuel usage are small for the vehicle model employed.

  • Aerospace Plane ascent guidance considering aeropropulsive interactions
    Guidance Navigation and Control Conference, 1995
    Co-Authors: Jean-paul Kremer, Kenneth D. Mease

    Abstract:

    The ascent guidance is considered for an Aerospace Plane vehicle with aeropropulsive interactions. The attention is on the control of the fast translational dynamics, altitude and flight-path angle. The objective is to continue the developments towards a fuel-efficient control of the fast dynamics during the ascent. The twopoint boundary value problem for the minimum-fuel ascent trajectory is decomposed into a slow part, and left and right boundary layer corrections. Hard or soft models are used for the maximum dynamic pressure constraint. Optimal left boundary layer solutions are calculated numerically at Mach 8, for the hard constraint and for different soft constraint shapes. The analysis of the solutions shows the existence of a tradeoff between peak dynamic pressure, fuel consumption, and control activity. Feedback solutions are obtained for the neighboring-optimal left boundary layer problem, and offer satisfactory performance for mild constraint modeling. For sharp constraint modeling, a different, sub-optimal linear feedback is proposed.

  • Geometric synthesis of Aerospace Plane ascent guidance logic
    Automatica, 1994
    Co-Authors: Kenneth D. Mease, Mark A. Van Buren

    Abstract:

    Abstract A single-stage vehicle using airbreathing propulsion holds promise for a more economical delivery of payloads to orbit. The utility of the vehicle is contingent on having a guidance capability for flying a near minimum-fuel ascent trajectory. In this paper, feedback guidance logic is developed for the hypersonic ascent phase. The two-time-scale behavior present in the vehicle translation dynamics allows the corresponding state space to be decomposed approximately into an invariant slow manifold and an invariant foliation of fast manifolds. Robust near-optimal guidance is synthesized as a composite of the minimum-fuel control on the slow manifold—as determined by the dynamic pressure and heat rate constraints—and a fast control for robust tracking of the slow manifold in the presence of atmospheric disturbances and modeling errors. The tracking problem is solved as a family of regulation problems on the fast foliation, using feedback linearization and a bandwidth-limited variable structure controller. Simulations indicate the effectiveness of the guidance logic.

A. R. Urbach – One of the best experts on this subject based on the ideXlab platform.

  • Slush Hydrogen Quantity Gaging and Mixing for the National Aerospace Plane
    Advances in Cryogenic Engineering, 1992
    Co-Authors: R. S. Rudland, I. M. Kroenke, A. R. Urbach

    Abstract:

    The National Aerospace Plane (NASP) design team has selected slush hydrogen as the fuel needed to power the high-speed ramjet/scramjet engines. Use of slush hydrogen rather than normal hydrogen provides significant improvements in density and cooling capacity for the aircraft. The loading of slush hydrogen in the NASP tank must be determined accurately to allow the vehicle size and weight to be kept to a minimum. A unique sensor developed at Ball to measure the slush density will be used in each region of the hydrogen tank to accurately determine the total mass of fuel loaded in the vehicle.

Mark A. Van Buren – One of the best experts on this subject based on the ideXlab platform.

  • Geometric synthesis of Aerospace Plane ascent guidance logic
    Automatica, 1994
    Co-Authors: Kenneth D. Mease, Mark A. Van Buren

    Abstract:

    Abstract A single-stage vehicle using airbreathing propulsion holds promise for a more economical delivery of payloads to orbit. The utility of the vehicle is contingent on having a guidance capability for flying a near minimum-fuel ascent trajectory. In this paper, feedback guidance logic is developed for the hypersonic ascent phase. The two-time-scale behavior present in the vehicle translation dynamics allows the corresponding state space to be decomposed approximately into an invariant slow manifold and an invariant foliation of fast manifolds. Robust near-optimal guidance is synthesized as a composite of the minimum-fuel control on the slow manifold—as determined by the dynamic pressure and heat rate constraints—and a fast control for robust tracking of the slow manifold in the presence of atmospheric disturbances and modeling errors. The tracking problem is solved as a family of regulation problems on the fast foliation, using feedback linearization and a bandwidth-limited variable structure controller. Simulations indicate the effectiveness of the guidance logic.

  • Aerospace Plane guidance using time-scale decomposition and feedback linearization
    Journal of Guidance Control and Dynamics, 1992
    Co-Authors: Mark A. Van Buren, Kenneth D. Mease

    Abstract:

    Single-stage vehicles using air-breathing propulsion hold promise for more economical delivery of payloads to orbit. Feedback guidance logic is developed for steering and accelerating such a vehicle along the superand hypersonic segments of a near-minimum-fuel ascent trajectory. Accurate solutions of the minimum-fuel ascent problem show the effects of dynamic pressure, acceleration, and heating constraints and establish a basis for the development and assessment of guidance logic. The two-time-scale behavior in the optimal solution allows the state space to be decomposed into a control-dependent slow manifold and a family of fast manifolds. Near-optimal guidance is obtained by constructing a composite control law from the control for flying the minimum-fuel reduced-order trajectory on the slow manifold and a control for tracking the optimal reduced-order trajectory. The tracking problem is solved as a family of regulation problems corresponding to the family of fast manifolds, using the feedback linearization methodology from nonlinear geometric control theory. A complete characterization is given of all state transformation-static feedback pairs that lead to exact linearization of the fast dynamics. Simulation shows that the composite control law produces a near-minimum-fuel ascent.

  • A geometric approach to regulator and tracker design for an Aerospace Plane
    3rd International Aerospace Planes Conference, 1991
    Co-Authors: Mark A. Van Buren, Kenneth D. Mease

    Abstract:

    The paper presents a nonlinear design approach drawing from singular perturbations, feedback linearization, and variable structure control, that leads to regulators with automatic gain scheduling which exhibit similar dynamic behavior over the entire flight envelope of the Aerospace Plane. Additionally, design approach provides for a systematic way to counter disturbance effects as well as modeling uncertainties. The unifying feature of the three nonlinear feedback control methodologies is that they all have a geometric interpretation. First, the translational dynamics are decomposed into reduced-order slow and fast dynamics by way of a formal singular perturbation analysis. After feedback linearization the fast dynamics are robustly stabilized via a variable structure control approach. The slow dynamics are stabilized using conventional proportional-integral compensation based on the nominal slow dynamics. A number of sample command and disturbance responses at opposite ends of the flight envelope are presented for a nonlinear Aerospace Plane model.