Launch vehicle load relief algorithms are concerned with realizing a reduction of transient bending moments near maximum dynamic pressure. Traditional approaches to load relief typically use inner-loop acceleration feedback to reduce the wind-induced angle of attack. When implemented in the inner loop, load relief bandwidth is necessarily limited by the achievable stability margins, and when acceleration feedback is employed, by the uncertainty associated with structural modes that couple with the body-mounted accelerometer. The structure of inner loop load relief increases the dimensionality of the flight control gain and filter optimization problem. Most importantly, classical load relief laws do not take advantage of high-rate and high-accuracy GPS-aided inertial velocity data that is readily available from modern strap down IMUs. In this paper, a novel load relief guidance scheme is described that uses direct angle-of-attack feedback in a clever mechanization. The steering commands are determined by examining the wind-perturbed dynamics of a launch vehicle with respect to a gravity turn ascent trajectory. An angle of attack estimate is derived from GPS-aided inertial data and pre-launch range wind measurements, and it is shown that a reduction worst-case rigid-body loads can be realized without requiring air data. The algorithm also includes a high-rate navigation data preprocessing scheme that operates directly on the IMU delta-theta and delta-velocity measurements in order to produce a filtered acceleration estimate at the vehicle center of mass. The outer-loop guidance scheme simplifies the design process for the classical inner-loop autopilot. Algorithm performance is demonstrated using Monte Carlo analysis of a representative liquid booster in a production high fidelity launch vehicle simulation.


    Access

    Access via TIB

    Check availability in my library


    Export, share and cite



    Title :

    A Modern Load Relief Guidance Scheme for Space Launch Vehicles


    Contributors:

    Conference:

    44th Annual AAS Guidance, Navigation and Control (GN&C) Conference ; 2022 ; Breckenridge, CO, US


    Type of media :

    Conference paper


    Type of material :

    No indication


    Language :

    English




    A MODERN LOAD RELIEF GUIDANCE SCHEME FOR SPACE LAUNCH VEHICLES

    Orr, Jeb S. / Russell, Colter W. | Springer Verlag | 2024



    An optimal Q-guidance scheme for satellite launch vehicles

    BHAT, M. SEETHARAMA / SHRASTAVA, SHASHI K. | AIAA | 1987


    LOAD RELIEF FOR LAUNCH VEHICLES USING AN ENGINE BIASING ECHNIQUE

    Dhuyvetter, Henry J. / Lam, Hieu T. | SAE Technical Papers | 1989


    "t1 compensation" guidance law for launch of space vehicles

    Chomak, S. / Haggerty, T. / Rothstein, H. | Engineering Index Backfile | 1963