Supersonic Maneuvering Research Articles

Field-to-View Constrained Integrated Guidance and Control for Hypersonic Homing Missiles Intercepting Supersonic Maneuvering Targets

An integrated guidance and control (IGC) scheme considering the field-of-view (FOV) constraint is proposed in this paper for hypersonic skid-to-turn (STT) missiles with a strapdown seeker intercepting a high-speed maneuvering target, which is based on the backstepping control (BC), barrier Lyapunov function (BLF), sliding mode control (SMC), dynamic surface control (DSC), and reduced-order extended state observer (ESO). First, a fifth-order strict feedback IGC model considering the rudder delay dynamics is derived, which also considers the drag effect on the axial velocity. Second, the missile guidance control system based on the BC consists of seeker, guidance, angle-of-attack, attitude, and rudder subsystems. The seeker subsystem was designed based on the BLF, and the other four subsystems were designed based on the SMC. The system-lumped disturbances, including unknown target maneuvers, unmodeled parts, perturbations caused by aerodynamic parameter variations, and external disturbances, were estimated and compensated for using the reduced-order ESO. The DSC prevented the “differential explosion” caused by virtual control commands introduced by the BC. Subsequently, the stability of the closed-loop system was strictly proven using the Lyapunov theory, and the boundedness of the FOV angle was strictly derived. Finally, the simulation results demonstrated the effectiveness and robustness of the proposed IGC scheme.

Design and performance study of a parametric diverterless supersonic inlet

Diverterless supersonic inlet integration for a flight vehicle requires a three-dimensional compression surface (bump) design with an acceptable shock structure and boundary layer diversion; this results in a low drag induction system with acceptable propulsive efficiency. In this investigation, a computational fluid dynamics-based-generated bump is used to design an integrated diverterless supersonic inlet without any bleed mechanism on a forebody with a large wetted area. Numerical solution of the Navier–Stokes equations simulates the flow pattern of the configuration. The forebody design analysis includes simulating the effects of angle of attack and sideslip by dependent computational domains. Results demonstrate the ability of the bump surface to keep the shock structures in an operational mode even at high supersonic angles of attack. Analysis of shock structures and shock wave boundary layer interactions at supersonic maneuver conditions indicate that the aerodynamic efficiency of the diverterless supersonic inlet in conditions with a thick boundary layer and high angles of attack is sufficient to ensure operation throughout the supersonic flight envelope.

Failure Analyses of Polymer Matrix Composite (PMC) Honeycomb Sandwich Joint Panels

The objective of this paper is to investigate the structural behavior and material failure characteristics of polymer-matrix composite (PMC) honeycomb sandwich joint panels under several transverse loads which resulted in web bending as typically experienced by aircraft wing skin. Several PMC honeycomb sandwich joint panels were fabricated as part of the demonstration test elements to provide structural concepts for the High-Speed Civil Transport (HSCT) wing. Test elements were preliminarily designed and sized under design-integration trade studies (DITS) task. Test elements selected for this study included two PMC honeycomb sandwich joint panels; one panel consisted of a honeycomb sandwich wing skin bolted joint by two fiber-reinforced composite spar caps to a honeycomb sandwich spar web; the other panel had the same structural concept except that the composite spar caps were replaced with the titanium ones. Essential components in the sandwich construction were composite face sheets, honeycomb cores, and core-to-facing bonding material. By statically loaded test elements to failure in room temperature, the test was designed to simulate flight load condition of 15 psi fuel over pressurization against the wing spar during supersonic maneuver. Geometric linear and nonlinear finite element models were constructed to simulate the structural behaviors of these test panels. Failure theories such as the Yeh-Stratton, Tsai-Wu, Tsai-Hill, and Maximum Stress and Strain criteria were utilized to predict the first ply failure and the results were compared with experimental data.

Controlled focused sonic booms from maneuvering aircraft

In April 1994, the USAF Armstrong Laboratory, in cooperation with USAF Test Pilot School, conducted an experimental study of controlled focus boom generated by supersonic maneuvers. The objective of this study was to collect focus and postfocus booms and to assess the ability of aircrews to control the placement of the focal region during basic maneuvers. Forty-nine supersonic passes were flown and included level linear acceleration, level turn, accelerating dives, and climbout-pushover maneuvers. These flights were flown under calm and turbulent atmospheric conditions. Turbulent conditions had a defocusing effect which caused distortions in the focus region and resulted in smaller maximum overpressures. Sonic booms were collected by up to 25 boom event analyzer recorders (BEARs) placed in a 13 000-ft linear array. The BEAR units were spaced 500–2000 ft apart with the denser spacing at the expected focal region. This spacing was chosen to evaluate the thickness of both the focal and postfocal regions. The target location varied from 2000–5000 from the uptrack end of the array. Of the 49 flights, a focus boom was placed within the array 37 times and within ±3000 feet of the target point 27 times, demonstrating the ability to place controlled focus booms.

USAF flight test investigation of focused sonic booms

In April 1994, the USAF Armstrong Laboratory in cooperation with USAF Test Pilot School conducted a measurement study of controlled focus booms generated by supersonic maneuvers. The objective of this study was to collect focus and post‐focus booms and to assess the ability of aircrews to control the placement of the focal region during basic maneuvers. Forty‐nine flights were performed and included level linear acceleration, level turn, accelerating dives, and climbout/pushover maneuvers. Sonic booms were collected by up to 25 boom event analyzer recorders (BEARs) placed in a 13 000‐ft linear array. The BEAR units were spaced 500 to 2000 ft apart with the denser spacing at the expected focal region. This spacing was chosen to evaluate the thickness of both the focal and post‐focal regions. Of the 49 flights, a focus boom was successfully placed within the array 35 times which demonstrated the ability to place controlled focus booms. This ability of the aircrew can be employed to avoid collateral damage to noise sensitive receptors. Along with capturing focus U waves, complex N–U signatures were recorded at distances away from the foci. Turbulent conditions had a defocusing effect, resulting in smaller maximum overpressures.

USAF single event sonic boom prediction model: PCBOOM

The United States Air Force is required to analyze the environmental impact from sonic booms produced by supersonic maneuvering aircraft. To meet this need, a single event prediction model PCBOOM3 has been developed. This model uses full ray tracing propagation theory and includes the effects of aircraft maneuvers, non-standard atmospheric profiles, and winds. Calculations include focused superbooms when they occur. Input parameters are flexible to allow general supersonic maneuvers. The program accepts user-defined F functions, and has F functions built in for current USAF aircraft. The model predicts the location and waveforms of sonic booms on the ground. Predicted sonic boom footprints are in the form of contours (psf, CSEL, etc.) and isopemps, or as tabular values at specific points. Signature output is provided in either graphical or tabular format for arbitrary points within the footprint. This program will enhance the ability to predict sonic booms for operational planning or for incident investigation. It will also be used as a research tool to investigate sonic boom generation and propagation. [Work supported by USAF AL/OEBN.]

Evaluation of NCOREL, PAN AIR, and W12SC3 for supersonic wing pressures

The ability of three recently developed computer programs to predict pressures on a supersonic maneuver wing has been evaluated. The NCOREL program was the only code capable of predicting the nonlinear leeward leading edge supercritical crossflow and resultant shock wave formation at the higher angles of attack Both linear panel methods, PAN AIR and W12SC3, performed reasonably well at the lower angles of attack Im plementing the freestream axis as the compressibility axis, PAN AIR overpredicted the windward pressures in comparison to the W12SC3 program at higher angles of attack

Effects of Airframe-Inlet Integration on Half -Axisymmetric and Two-Dimensional Supersonic Inlet Performance

Diagnostic data from large-scale, airframe-inlet model wind-tunnel tests have been analyzed to facilitate understanding of both axisymmetric and two-dimensional inlet performance in different installation configurations of highly maneuverable supersonic aircraft. Distortion pattern shifts have been used to identify duct swirl, apparently due to duct offset and loft. Examinations of total pressure surveys through the ducts of various inlet installations have been used to show the influence of flow separation at the inlet aperture and in the throat on performance degradation in various inlet configurations. Benefits and limitations of inlet shielding in supersonic maneuvering flight have been explored, showing performance advantages of half-axisymmetric inlets over two-dimensional inlets in the wing-shielded flowfields and more general performance advantages associated with fuselage shielding. Data comparisons have incorporated total pressure recovery, duct turbulence, and compressor face steady-state and dynamic flow distortion index showing, in particular, the importance of dynamic flow distortion measurement and sophisticated, high-speed analysis capability.