Hypersonic Glide Research Articles

Coevolutionary Algorithm Applied to Skip Reentry Trajectory Optimization Design

This paper proposed a coevolutionary algorithm combining improved particle swarm optimization algorithm with differential evolution method and its application was provided. Adaptive position escapable mechanism is introduced in the particle swarm optimization to improve the diversity of population and guarantee to achieve the global optima. The differential algorithm is employed in a cooperative manner to maintain the characteristic of fast convergence speed in the later convergence phase. The coevolutionary algorithm is then applied to skip trajectory optimization design for crew exploration vehicle with low-lift-to-drag and several comparative cases are conducted, Results show that coevolutionary algorithm is quite effective in finding the global optimal solution with great accuracy.

Phugoid dynamic characteristic of hypersonic gliding vehicles

This paper focuses on the phugoid dynamic characteristic of hypersonic gliding vehicle. By regarding equilibrium glide as the fixed state of reentry trajectory, the dynamic equations are simplified and a hyper-geometric equation with a forcing function is deduced. Linearization theory is applied to analyze the characteristic of the motion, and the phugoid mode is found to be stable. An analytical solution of flight path angle as a function of speed is derived based on General Multiple Scale theory. The dynamic characteristic is analyzed, and the analytic solution is found to be in good agreement with the numerical simulation. When the initial states do not satisfy equilibrium glide condition or perturbation occurs, a damped oscillation along the equilibrium glide trajectory would occur. The damping diminishes as the speed decreases. The number of oscillations is decided by the lift-to-drag ratio, the initial altitude and the initial/final speed.

Trajectory optimization for hypersonic boost‐glide missile considering aeroheating

PurposeThe purpose of this paper is to optimize the downrange for hypersonic boost‐glide (HBG) missile under near‐real condition, and to validate the suitability of proposed wall cooling materials.Design/methodology/approachThe trajectory optimization problem is characterized by a boost phase followed by a glide phase. A multi‐phase trajectory optimization tool is adopted to optimize the downrange. The associated optimal control problem has been solved by selecting a direct shooting method. The dynamics has been transcribed to a set of nonlinear constraints and the arising nonlinear programming problem has been solved through a sequential quadratic programming solver. An aerothermodynamics analysis method is introduced to calculate the aerodynamic heating at nose, leading edge, and ventral centerline regions.FindingsHBG missile is suitable for long‐range attack, and the optimal trajectory solved is a novel boost‐glide‐skip trajectory, i.e. boost firstly, glide secondly, and skip at last. The proposed wall materials are valid.Originality/valueThis paper provides further study on the methods of trajectory design and aerothermodynamics analysis for HBG missile.

State-Dependent Riccati-Equation-Based Guidance Law for Impact-Angle-Constrained Trajectories

IN MANY advanced guidance applications, it is required to intercept the target from a particular direction: that is, to achieve a certain impact angle [1–3]. Closed-form solutions for energyoptimal impact-angle-constrained guidance laws have been proposed for a stationary target by Ryoo et al. [4], who used the linear quadratic regulator technique after linearizing the engagement kinematics. The guidance law proposed by them captures all impact angles from any initial launch angle in a planar engagement scenario. Lu et al. [5] solved the problem of guiding a hypersonic gliding vehicle in its terminal phase to a stationary target using adaptive proportional navigation guidance. Ohlmeyer and Phillips [6] extended the idea of explicit guidance (proposed by Cherry [7]) to include a terminal impact angle constraint. However, the simulations by Ohlmeyer and Phillips [6] are carried out only for a vertical impact against a stationary target, and the impact angle errors encountered are sensitive to the launch altitude.

Conceptual design assessment of a suborbital tourist space access vehicle

AbstractSpace transportation remains in the pioneering stages. What might this century bring if we had a ‘railroad to space’ that embodied the characteristics of the transcontinental undertaking? The X-33 and Venture Star projects were one attempt to achieve the characteristics of that transcontinental railroad. There are others, here and in other countries, but perhaps we need to begin with a smaller first step, a small, commercial reusable rocket with ballistic ascent to space altitude with a hypersonic glider return? Our challenge in space today is to develop vehicles that are in continuous use, maintained and operated on a fixed schedule despite weather or environmental hazards, which move payloads not only into space but back again. The X PRIZE was a $10 million prize awarded to Scaled Composites as the first privately financed spaceship that launched the equivalent of three persons to an altitude of at least 100 kilometers on two consecutive flights within two weeks. What about an analogous vehicle that flies two or three times a week, every week for a number of years? A major difference is that this challenge is to be accomplished without government support or government developed vehicles. The aerospace vehicle design (AVD) Laboratory team at the University of Texas at Arlington is developing a generic space access vehicle (SAV) design synthesis environment with focus on the conceptual design phase. The AVD Lab has applied elements of this toolbox to the study of a tourist aerospace vehicle under a grant from Rocketplane Limited, Inc. The development of a low-cost tourist vehicle based on the adaptation of a Learjet 25/35/45 series aircraft is the focus of this paper.

Adaptive Terminal Guidance for Hypervelocity Impact in Specified Direction

The problem of guiding a hypersonic gliding vehicle in the terminal phase to a target location is considered. In addition to the constraints on its final position coordinates, the vehicle must also impact the target from a specified direction with very high precision. The proposed 3-dimensional guidance laws take simple proportional forms. The analysis establishes that with appropriately selected guidance parameters the 3-dimensional guided trajectory will satisfy these impact requirements. We provide the conditions for the initial on-line selection of the guidance law parameters for the given impact direction requirement. The vehicle dynamics are explicitly taken into account in the realization of guidance commands. To ensure high accuracy in the impact angle conditions in an operational environment, we develop closed-loop nonlinear adaptation laws for the guidance parameters. We present the complete guidance logic and associated analysis. Simulation results are provided to demonstrate the effectiveness and accuracy of the proposed terminal guidance approach. I. Introduction Recent interests in developing on-demand global-reach payload delivery capability have brought to the forefront a number of underlying technological challenges. Such operations will involve responsive launch, autonomous entry flight, and precision terminal maneuvers. In certain scenarios the mission requirements call for the payload to impact the target location from a specific direction with supersonic speed. One example is to impact the target in a direction perpendicular to the tangent plane of the terrain at the target. The terminal guidance system will be responsible for directing the vehicle to the target and achieving the desired impact direction. The impact precision requirements under the scenarios considered are very high and stringent. For instance, the required Circular Error Probable (CEP) of the impact distance is just 3-meter. 1 The errors of the impact angles are desired to be within 0.5 deg. The very high speeds throughout the terminal phase only make it considerably more difficult to achieve these levels of precision. Yet cost considerations dictate that the terminal guidance algorithm should be relatively simple and computationally tractable for real-time operations. While a number of guidance methods can guide the vehicle to the target, not many address the unique need for impact from a specific direction. One method that can is the so-called “dive-line” guidance approach in Ref. 2. In this method one or more lines intersecting the Earth are established. The final dive-line intersects the target, and its direction can be set to the desired direction. The vehicle’s velocity vector is

Guidance law for hypersonic gliders based on piecewise constant control

A midcourse guidance law is developed for the descent of a hypersonic glider, initially in level flight, to a fixed target on the ground. It is based on an optimal piecewise constant control (N intervals) obtained from an approximate physical model (flat Earth, exponential atmosphere, parabolic drag polar, etc). The resulting optimal control equations can be integrated either analytically or by quadrature, and the guidance algorithm requires the solution of 2N + nonlinear algebraic equations. The guidance law is implemented in a realistic glider simulation, the intercept is achieved, and final velocities within 14% of the true values are obtained for the downrange and crossranges considered.

Guidance law for hypersonic descent to a point

A neighboring optimal control problem is formulated for a hypersonic glider to execute a maximumterminal-velocity descent to a stationary target. The resulting two-part, feedback control scheme initially solves a nonlinear algebraic problem to generate a nominal trajectory to the target altitude. Second, a neighboring optimal path computation about the nominal provides the lift and side-force perturbations necessary to achieve the target downrange and crossrange. On-line feedback simulations of the proposed scheme and a form of proportional navigation are compared with an off-line parameter optimization method. The neighboring optimal terminal velocity compares very well with the parameter optimization solution and is far superior to proportional navigation. A variety of targeting geometries are possible,

Optimal heading change with minimum energy loss for a hypersonic gliding vehicle

A three state model is presented for analyzing the problem of optimal changes in heading with minimum energy loss for a hypersonic gliding vehicle. A further model order reduction to a single state model is examined using singular perturbation theory. The optimal solution for the reduced problem defines an optimal altitude profile dependent on the current energy of the vehicle, and the corresponding optimal lift and bank angle. A separate boundary layer analysis, based on an expansion of the necessary conditions about the reduced solution, is used to account for altitude and flight path angle dynamics and to derive a guidance law in feedback form. The guidance law is evaluated for a hypothetical vehicle.

Chemical energy accommodation at catalyst surfaces. Flow reactor studies of the association of nitrogen atoms on metals at high temperatures

The fate of the energy release in highly exoergic surface-catalysed chemical reactions is of considerable fundamental interest and influences catalyst volatilization/sintering, the aerodynamic heating of hypersonic glide vehicles subject to bombardment by atomic nitrogen and atomic oxygen, etc. To provide the first available high temperature data (T > 800 K) on what fraction (β) of the equilibrium (bond) dissociation energy is delivered to the catalyst per atom association event, a coaxial filament flow reactor (CFFR) has been developed, well-suited to both precise atom mass balance and isothermal calorimetric measurements. Experimental results for the chemical energy accommodation (CEA) coefficient β, and the corresponding N-atom recombination probabilities, γ, are presented for the metals Pt, Ir, Rh, Pd, Co, W and Re at temperatures up to 2600 K. Catalyst energy deposition can be an order of magnitude less than the equilibrium reaction energy. However, since this is not true at all surface temperatures, simple rankings of β-values for metals (at, say, room temperature) or correlations based only on one or two relevant system parameters (e.g. bulk Debye temperature) are of limited application. Alternatively, for N/Re, N/W a Langmuir-type mass-action analysis of the operative elementary steps, combined with a simple postulate (viz. Rideal-produced molecules leave excited whereas Langmuir—Hinshelwood (LH) produced molecules do not) provides a semi-quantitative understanding of β-trends in terms of the adatom binding energy, the equilibrium bond dissociation energy of the product molecule and an elementary Rideal reaction probability. However, high β-values can be observed at low temperatures if the system admits LH-reaction, or Rideal-formed excited molecules are rapidly quenched prior to desorption. We postulate that low catalyst energy deposition occurs at high temperatures (N/Pt, N/Ir) if LH-reaction occurs prior to the complete accommodation of the reactant (atom) chemisorption energy.

Energy transfer effects of excited molecule production by surface-catalyzed atom recombination

Surface-catalyzed atom recombination often yields internally excited molecules. If these molecules are not quenched, by or in the vicinity of the surface, there can be an appreciable reduction in the rate of energy transfer to that surface. To assess the importance of homogeneous and heterogeneous quenching on the wall energy transfer under continuum diffusion conditions, we examine a simple physicochemical model leading to closed-form predictions of the quenching and energy transfer effects and relevant dimensionless parameters. This model, together with available experimental data on the selective production and quenching of electronically excited O2 molecules during heterogeneous O-atom recombination, are used to estimate: (i) the importance of gas phase and wall quenching in experimental determinations of atom recombination coefficients or the apparent heat of atom recombination at catalyst surfaces, and (ii) the likelihood of appreciable reductions in the aerodynamic heating of hypersonic glide vehicles.

Optimal lift control of a hypersonic glider.

Optimal lift control of a hypersonic glider.

Determination of Lift or Drag Programs to Minimize Re-Entry Heating

A study of single-pass re-entry from escape speed and from circular satellite speed is made to determine the lift program for a hypersonic glider and the drag-modulation program for a nonlifting vehicle that minimize the heating of the vehicles within acceleration or range constraints. A new of numerical solution is used, similar to Kelley's method of gradients, that permits rapid convergence to the optimum lift program starting with an original good estimate. This avoids the twopoint boundary-value problem of the calculus-of-variations formulation, and is applicable to any optimum-programing problem. An acceleration-tolerance limit is introduced which describes the human pilot's capability to withstand acceleration more accurately than a simple acceleration limit. at tack program, must be determined in order to minimize the total heat and satisfy the desired terminal constraints. The straightforward approach to solving such complicated problems has not met with any significant success, despite the fact t ha t the formulation is clear.7 Recently Kelley and the present authors developed, almost simultaneously, a steepest descent technique which is capable of solving such complicated variational problems in a practical way using highspeed digital computers. This technique is presented in the next section and then it is applied to the two problems described above.