On the low speed longitudinal stability of hypersonic waveriders

The development of hypersonic civilian transport aircraft requires solutions to a number of challenging problems in the areas of aerothermodynamics, control, aeroelasticity, propulsion and others encountered at high Mach number flight. The desire for good aerodynamic performance at high Mach numbers results in slender vehicle designs called waveriders. The stability and handling of waverider shapes at the low speeds at the take-off and landing phases of flight is not well studied. This thesis covers static and dynamic CFD simulations of the Hexafly-Int glider which have been used to obtain longitudinal stability derivatives at low speeds. Complementary static and free-to-pitch dynamic wind tunnel testing, are used to validate the CFD computations. A final chapter on the optimisation of waverider designs including low speed longitudinal stability is presented to show the impacts of this additional requirement on the hypersonic design space. The static wind tunnel testing has identified stability issues relating to the location of the centre of gravity. The design centre of gravity which is suitable for the Hexafly-Int vehicle at Mach 7.2 is found to be too far aft which results in instability at low speeds. In addition, the dynamic testing in the wind tunnel shows that the pitch damping is inadequate at low speeds. The CFD simulations agree well with the wind tunnel test results validating the use of CFD tools for determining dynamic stability derivatives of this class of slender vehicle in the design process. To alleviate the low speed stability issue of hypersonic vehicles, a waverider shape optimisation study has been carried out to understand what shapes will produce better low speed stability behaviour. These shapes are found to produce lower aerodynamic efficiency at high speeds which suggests that a design compromise between low speed stability and high speed performance is required at the outset of hypersonic waverider design

A Parametric Study of Hypersonic Waverider Flight Mechanics in Optimized Trajectories during Atmospheric Entry

Over the years, many aerospace corporations and agencies have attempted to develop hypersonic vehicles. However, until recently, they have only achieved very limited success due to a lack of air-breathing hypersonic propulsion technology. Now, as technology is advancing and funds are becoming more available, aviation is once again shifting its focus towards hypersonic flight. One of many hypersonic applications is atmospheric reentry, whether reentry into Earth's atmosphere or entry into another planetary body's atmosphere. While basic theories on hypersonic reentry flight mechanics are already in use, these analyses have yet to be applied to optimizing trajectories for hypersonic waveriders in skip-glide atmospheric entry trajectories. The purpose of this research project was to provide a brief analysis of unpowered skip and glide entry trajectories and to present an optimized hypersonic waverider trajectory for a simple atmospheric reentry scenario. Five main types of unpowered glide trajectories—constant flight path angle, constant sinking speed, constant flight speed, constant dynamic pressure, and constant heating rate—were analyzed using MATLAB to model the altitude, velocity, flight path angle, and lift modulation profiles. Additionally, constant aerodynamic efficiency skip trajectories were analyzed for their ability to extend reentry ranges. The results of these analyses were then used to optimize a combined skip-glide atmospheric reentry trajectory for hypersonic waveriders about the Earth's equator. This research utilized a classical optimization approach, using MATLAB to graph the applicable design spaces for the analysis. The resulting trajectory maximizes the range of the reentry trajectory while conforming to applied maximum aerodynamic heating and maximum dynamic pressure constraints. The findings of this research will benefit the aerospace community by providing insight into hypersonic waverider performance during Earth reentry after completed space missions. This information can be used to inform flight vehicle design decisions for optimizing hypersonic waverider performance. Moreover, beyond just Earth atmospheric reentry, the analyses used in this research can also be applied to atmospheric entry into other planetary atmospheres, aiding in vehicle design and planning for interplanetary missions.The Ohio State University College of EngineeringNo embargoAcademic Major: Aerospace Engineerin

Hypersonic Vehicles

Some sixty years after the experimental flights of the North American X-15 hypersonic rocket-powered aircraft, sustained hypervelocity travel is still the next frontier in high-speed transportation. Today, there is much excitement and interest regarding hypersonic vehicles. In fact, many aerospace agencies, large industries, and several start-ups are involved in design activities and experimental campaigns both in wind tunnels and in-flight with full-scale experimental flying test beds and prototypes to make hypersonic travel almost as easy and convenient as airliner travel. Achieving this goal will radically revolutionize the future of civil transportation. This book contains valuable contributions that focus on various design issues related to hypersonic aircraft

Guidance, flight mechanics and trajectory optimization. Volume 14 - Entry guidance equations

Entry guidance equations, reference trajectories, and guidance system mechanizatio

Aeronautical engineering: A continuing bibliography with indexes (supplement 277)

This bibliography lists 467 reports, articles, and other documents introduced into the NASA scientific and technical information system in Mar. 1992. Subject coverage includes: the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines); and associated aircraft components, equipment, and systems. It also includes research and development in ground support systems, theoretical and applied aspects of aerodynamics, and general fluid dynamics

A prototype computerized synthesis methodology for generic space access vehicle (SAV) conceptual design.

This dissertation presents the development steps required towards a generic (configuration independent) hands-on flight vehicle conceptual design synthesis methodology. This process is developed such that it can be applied to any flight vehicle class if desired. In the present context, the methodology has been put into operation for the conceptual design of a tourist Space Access Vehicle. The case study illustrates elements of the design methodology & algorithm for the class of Horizontal Takeoff and Horizontal Landing (HTHL) SAVs. The HTHL SAV design application clearly outlines how the conceptual design process can be centrally organized, executed and documented with focus on design transparency, physical understanding and the capability to reproduce results. This approach offers the project lead and creative design team a management process and tool which iteratively refines the individual design logic chosen, leading to mature design methods and algorithms. As illustrated, the HTHL SAV hands-on design methodology offers growth potential in that the same methodology can be continually updated and extended to other SAV configuration concepts, such as the Vertical Takeoff and Vertical Landing (VTVL) SAV class. Having developed, validated and calibrated the methodology for HTHL designs in the 'hands-on' mode, the report provides an outlook how the methodology will be integrated into a prototype computerized design synthesis software AVDS-PrADOSAV in a follow-on step.Today's and especially tomorrow's competitive launch vehicle design environment requires the development of a dedicated generic Space Access Vehicle (SAV) design methodology. A total of 115 industrial, research, and academic aircraft, helicopter, missile, and launch vehicle design synthesis methodologies have been evaluated. As the survey indicates, each synthesis methodology tends to focus on a specific flight vehicle configuration, thus precluding the key capability to systematically compare flight vehicle design alternatives. The aim of the research investigation is to provide decision-making bodies and the practicing engineer a design process and tool box for robust modeling and simulation of flight vehicles where the ultimate performance characteristics may hinge on numerical subtleties. This will enable the designer of a SAV for the first time to consistently compare different classes of SAV configurations on an impartial basis

Aeronautical Engineering: A special bibliography with indexes, supplement 48

This special bibliography lists 291 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1974

Compendium of NASA Langley reports on hypersonic aerodynamics

Reference is made to papers published by the Langley Research Center in various areas of hypersonic aerodynamics for the period 1950 to 1986. The research work was performed either in-house by the Center staff or by other personnel supported entirely or in part by grants or contracts. Abstracts have been included with the references when available. The references are listed chronologically and are grouped under the following general headings: (1) Aerodynamic Measurements - Single Shapes; (2) Aerodynamic Measurements - Configurations; (3) Aero-Heating; (4) Configuration Studies; (5) Propulsion Integration Experiment; (6) Propulsion Integration - Study; (7) Analysis Methods; (8) Test Techniques; and (9) Airframe Active Cooling Systems

Aeronautical engineering: A continuing bibliography with indexes (supplement 322)

This bibliography lists 719 reports, articles, and other documents introduced into the NASA scientific and technical information system in Oct. 1995. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Trajectory optimization and performance sensitivity studies of NASA Langley\u27s proposed small satellite launch system

Optimal ascent and booster glide back trajectories were determined for NASA Langley\u27s proposed small satellite launcher, SSL-1, for a given polar mission, vehicle configuration, propulsion system, aerodynamic characteristics, structural characteristics and trajectory constraints. The optimal ascent and glide back trajectories were determined for a launch from Vandenberg Air Force Base launch pad SLC-2W and booster glide back to Vandenberg Air Force Base runway 30. The SSL-1 ascent and glide back trajectories were simulated and optimized in POST, Program to Optimize Simulated Trajectories. Inertial pitch angles relative to a inertial launch frame were specified as independent variables in the ascent trajectory and optimized to yield maximum weight to orbit. Aerodynamic angles were specified as independent variables in the booster glide back trajectory and optimized to yield maximum altitude at a heading alignment cylinder six nautical miles south of runway 30. The SSL-1 could not perform an ascent trajectory that satisfies the constraint of gliding the booster back to a heading alignment cylinder for runway 30. The optimal SSL-1 ascent trajectory results in 1022 lb of total weight and 384 lb of payload being inserted into a 150 nautical mile polar orbit. However, a booster glide back that achieves a desired altitude goal of 18800 ft at a heading alignment cylinder for runway 30 could not be performed from the separation point of the optimal ascent for the given aerodynamic and structural limits. The separation Mach number could not be reduced to a point where the booster could attain a desired glide back altitude using reductions in booster size alone since the booster size could not be reduced more than 3% and meet the dynamic pressure at separation constraint of 300 Ib/ft2. The glide back altitude goal can be obtained if the structural normal force limit is increased to 3g loads or the aerodynamic constraint on dynamic pressure at separation is increased to 400 Ib/ft2. The altitude goal will likely be obtained if a high angle of attack drag maneuver is performed between Mach numbers 3.2 and 1.2. The maximum allowable angle of attack for stable flight in this speed range and the corresponding lift/drag characteristics are needed to quantify the obtainable altitude. To achieve the desired altitude goal, modifications in the aerodynamic and/or structural limitations are needed. Weight to orbit performance is influenced by the dynamic pressure at separation constraint but is not sensitive to it. The weight to orbit ranges from 384 lb to 400 lb for dynamic pressure limits of 300 Ib/ft2 to 500 Ib/f2. The glide back altitude is sensitive to the dynamic pressure at separation constraint. Glide back altitude at the HAC ranges from 11995 ft to 24600 ft for dynamic pressure limits of 300 Ib/ft2 to 500 Ib/ft2. Both ascent and glide back performance is insensitive to atmospheric winds. Mean winds reduce payload by 2 lb and increase altitude at the heading alignment cylinder 515 ft. The SSL-1 weight to orbit performance is insensitive to movements in the vehicle\u27s C.G. Movements up to 7% of the reference length result in a 2 lb change in payload. The glide back is sensitive to structural normal force limits Increasing the limit from 2.5g to 5.0g increases altitude at the heading alignment cylinder from 11995 ft to 23410 ft