Browsing by Author "Smith, Howard"

Now showing 1 - 20 of 49
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    Aircraft conceptual design decision through operational modelling
    (Cranfield University, 2005) Harasani, W.; Smith, Howard
    Aircraft manufacturing is not only a difficult business but also a very competitive one, the consequences of any drop in sales would cost billions, loss of jobs, and maybe an economical failure. Therefore, concentrating on just flight performance and adding new technologies just because they exit is not enough to win the airlines attention, especially the flow cost carriers. Manufactures must be able to convince operators that the application of a new design or technology will produce a favourable change in the bottom line of their balance sheets and not just a reduction in fuel burn. Aircraft designers must put more emphasis on what happens to the aircraft after it leaves the assembly line, through the designed life operation cycle of the aircraft with the airline customer, quality should be built in to the aircraft. Knowing what are the airline's concerns, how the aircraft with a given design behaves, and the issues that the airline has, is vital. Firstly, it is important to know what are the issues that the airline has, the costumer (airlines) needs are identified, and, since fleet planning is the top level decision making department in the airline in which a decision is made to buy one aircraft over the other, it is important to understand the process and the elements that are involved in fleet planning. So fleet planning was studied. Second different technologies for the design have been looked at and selected. Then the aircraft, airline, airport, and air traffic control are studied, as well as the interaction between them. A key element of the research is a simulation program DEBOS that has been built to see the impact of the different design technologies and concepts through the operation of a simulation fleet size of 23 aircraft. The Boeing777 aircraft has been chosen to be the base line of the study. Finally, it was found that a given technology with improved performance, or a new concept, would improve the aircraft attractiveness only if it has better life cycle behaviour characteristics.
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    Airliner conceptual designs for the application of alternative fuels
    (AIAA, 2023-06-08) Chan, Joseph; Sun, Yicheng; Smith, Howard
    This paper investigates the application of alternative fuels in conventional tube-and-wing aircraft configuration. Potential alternative fuel choices include biofuel, liquid hydrogen, liquefied natural gas, ammonia and methanol. A comprehensive mission range starting from 2000 nautical miles to 8500 nautical miles is explored, designed and analysed using GENUS, an in-house built multidisciplinary design analysis and optimization platform. It is expected to see a progressive change for each fuel type and capacity combination over different mission ranges. The gradient of these trends should be different which potentially demonstrates the additional benefits of using alternative fuels. The aim of this study is 1) to determine how different fuel properties will affect the designs and performance of aircraft, 2) to quantify the reduction of GHG emission by utilising alternative fuel. The results show cryogenic fuel, which required fuselage fuel tanks and external fuel tanks, will noticeably increase energy consumption due to drag and weight penalties. Meanwhile, the use of hydrogen and biofuel can significantly reduce life cycle GHG emissions if only the fuel is produced in sustainable pathways.
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    Bioinspired genetic-algorithm optimized ground-effect wing design: flight performance benefits and aircraft stability effects
    (World Scientific and Engineering Academy and Society (WSEAS), 2024-05-02) Zammit, Karl; Smith, Howard; Lobo, Noel Sierra; Giannopoulos, Ioannis K.
    This paper presents a bioinspired, genetic-algorithm evolutionary process for Ground-Effect vehicle wing design. The study made use of a rapid aerodynamic model generation and results evaluation computational fluid dynamics vortex lattice method software, supervised by a genetic algorithm optimization Python script. The design space for the aircraft wing parametric features drew inspiration from seabirds, under the assumption of their wings being naturally evolved and partially optimized for proximity flight over water surfaces. A case study was based on the A-90 Orlyonok Russian Ekranoplan, where alternative bioinspired wing variations were proposed. The study objective was to investigate the possible increased flight aircraft performance when using bioinspired wings, as well as verify the static and dynamic aircraft stability compliance for Ground-Effect flight. The methodology presented herein along with the study results, provided an incremental step towards advancing Ground-Effect aircraft conceptual designs using computational fluid dynamics.
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    Blended wing body with boundary layer ingestion conceptual design in a multidisciplinary design analysis optimization environment
    (AIAA, 2020-01-05) Gao, Ziang; Smith, Howard
    This paper introduces the GENUS multidisciplinary concept level aircraft design and analysis environment developed by Cranfield University in recent years and it has been applied to the conceptual design of blended wing body (BWB) aircraft. Analytical disciplines include a variety of low-to-medium fidelity, physics-based and empirical methods, and aerodynamic analysis of high-order panel method. Boundary layer ingestion (BLI), as a special module, has been incorporated into the aerodynamic and propulsion analysis. The results of the Cranfield BW-11 are presented. In the highly-constrained design space, a type of highly fuel- efficient BWB concept can be studied, and the advantages of the BLI concept can also be explored based on this framework.
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    The comparison of aerodynamic and stability characteristics between conventional and blended wing body aircraft
    (Cranfield University, 2012-01) Wang, Faliang; Smith, Howard
    Aircraft with advanced wing geometry, like the flying wing or blended wing body configuration, seems to be the seed candidate of future aircraft. Compared with conventional aircraft, there are significant aerodynamic performance improvements because of its highly integrated wing and fuselage configuration. On the other hand, due to its tailless configuration, the stability characteristics are not as good as conventional aircraft. The research aims to compare the aerodynamic and stability characteristics of conventional, flying wing and blended wing body aircraft. Based on the same requirement—250 passenger capability and 7,500 nautical miles range, three different configurations—conventional, flying wing and blended wing body options were provided to make direct comparison. The research contains four parts. In the first part, the aerodynamic characteristics were compared using empirical equation ESDU datasheet and Vortex-Lattice Method based AVL software. In the second part, combined with the aerodynamic data and output mass data from other team member, the stability characteristics were analysed. The stability comparison contains longitudinal, lateral-directional static stability and dynamic stability. In the third part, several geometry parameters were varied to investigate the influence on the aerodynamic and stability characteristics of blended wing body configuration. In the last part, a special case has been explored in an attempt to improve the static stability by changing geometry parameters. The process shows that the design of blended wing body is really complex since the closely coupling of several parameters.
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    Conceptual and preliminary design methods for use on conventional and blended wing body airliners
    (Cranfield University, 2019-02-19 11:40) Smith, Howard; Fielding, John
    Transcript of John Fielding and Howard Smith's 1999 lecture to Court, Cranfield University.
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    Conceptual design methodologies appropriate to supersonic business jets
    (2018-11) Sun, Yicheng; Smith, Howard; Fielding, John
    This project aims to study the status of the issues related to Supersonic Business Jet (SSBJ) conceptual design, to develop design methodologies appropriate to SSBJs, and to explore the design space of low-boom low-drag supersonic transport concepts. The design model appropriate to SSBJs is developed in the Cranfield multidisciplinary design analysis and optimization environment – GENUS. The mass breakdown, engine model, aerodynamic analysis, stability and control, and sonic boom prediction methods are developed in the GENUS framework. Optimizers help to explore the design space based on the model. Through the research, the current supersonic transport concepts are analysed and the supersonic natural laminar flow wing concept is found to leave little space for sonic boom mitigation. The most significant finding is the low-boom solution through the geometry shaping to the volume and lift effects. The low-drag requirement is not necessarily contradicted by the low-boom requirement. The low-boom optimization achieves a sonic boom reduction from 2.6 psf to 0.6 psf and the L/D increase from 8.96 to 10.67. The low-drag optimization achieves a L/D increase from 8.96 to 10.81 and sonic boom reduction from 2.6 psf to 1.0 psf. A low-boom low-drag SSBJ and a low-boom low-drag supersonic airliner concepts are designed in a multidisciplinary view. Pdf available on request and Howard Smith's permission.
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    Conceptual design methodology for blended wing body aircraft
    (Cranfield University, 2016-05) Okonkwo, Paulinus Peter Chukwuemeka; Smith, Howard
    The desire to create an environmentally friendly aircraft that is aerodynamically efficient and capable of conveying large number of passengers over long ranges at reduced direct operating cost led aircraft designers to develop the Blended Wing Body(BWB) aircraft concept. The BWB aircraft represents a paradigm shift in the design of aircraft. The design offers immense aerodynamics and environmental benefits and is suitable for the integration of advanced systems and concepts like laminar flow technology, jet flaps and distributed propulsion. However, despite these benefits, the BWB is yet to be developed for commercial air transport. This is due to several challenges resulting from the highly integrated nature of the configuration and the attendant disciplinary couplings. This study describes the development of a physics based, deterministic, multivariate design synthesis optimisation for the conceptual design and exploration of the design space of a BWB aircraft. The tool integrates a physics based Athena Vortex Lattice aerodynamic analysis tool with deterministic geometry sizing and mass breakdown models to permit a realistic conceptual design synthesis and enables the exploration of the design space of this novel class of aircraft. The developed tool was eventually applied to the conceptual design synthesis and sensitivity analysis of BWB aircraft to demonstrate its capability, flexibility and potential applications. The results obtained conforms to the pattern established from a Cranfield University study on the BlendedWing Body Aircraft and could thus be applied in conceptual design with a reasonable level of confidence in its accuracy.
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    Conceptual design of a fifth generation unmanned strike fighter
    (AIAA, 2018-01-06) Sepulveda, Eduardo; Smith, Howard
    Unmanned aircraft have significantly transformed aerial warfare through a combination of new technologies, extended operational capabilities, and reduced risks and costs. Similarly, computational modelling techniques have accelerated the rate of development for aircraft by being able to explore a large number of design options from the earliest design stages, further reducing time, risks, and costs. The near future will see the proliferation of unmanned combat aerial vehicles under a variety of roles such as unmanned tankers, strike aircraft, and even air - to - air fighters. In this paper the GENUS aircraft design framework is used to develop an unmanned weapons carrying platform able to partially match the performance of 5th generation fighters such as the Joint Strike Fighter F-35A. The vision of future joint operations is for a single lead manned fighter to command and designate targets to its various loyal wingmen unmanned aircraft, extending the combat capabilities and significantly multiplying force and air superiority.
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    Conceptual design of low-boom low-drag supersonic transports
    (AIAA, 2020-06-08) Sun, Yicheng; Smith, Howard; Chen, Haixin
    This paper introduces a supersonic aircraft design model developed in a multidisciplinary design analysis and optimization (MDAO) environment. Low- to medium- fidelity methods are applied to the conceptual design model. A family of different classes supersonic aircraft are designed with similar general layout, including a single seat supersonic demonstrator, a 10-passenger supersonic business jet and a 50-seat supersonic airliner. These concepts prove the feasibility of low-boom low-drag supersonic transport designs in a multidisciplinary perspective. There are some challenges to balance the volume with packaging and control requirements. The low-boom design for configuration with nacelles are also very challenging.
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    Conceptual design of sonic boom stealth supersonic transports
    (Springer, 2022-01-13) Sun, Yicheng; Smith, Howard
    This paper introduces a supersonic transport aircraft design model developed in the GENUS aircraft conceptual design environment. A conceptual design model appropriate to supersonic transports with low-to-medium-fidelity methods are developed in GENUS. With this model, the authors reveal the relationship between the sonic boom signature and the lift and volume distributions and the possibility to optimise the lift distribution and volume distribution together so that they can cancel each other at some region. A new inspiring design concept—sonic boom stealth is proposed by the authors. The sonic boom stealth concept is expected to inspire the supersonic aircraft designers to design low-boom concepts through aircraft shaping and to achieve low ground impacts. A family of different classes of supersonic aircraft, including a single-seat supersonic demonstrator (0.47 psf), a 10-passenger supersonic business jet (0.90 psf) and a 50-seat supersonic airliner (1.02 psf), are designed to demonstrate the sonic boom stealth design principles. Although, there are challenges to balance the volume with packaging and control requirements, these concepts prove the feasibility of low-boom low-drag design for supersonic transports from a multidisciplinary perspective.
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    Conceptual design synthesis and multidisciplinary optimisation of unmanned combat aerial vehicles.
    (2019-12) Sepulveda Palacios, Eduardo; Smith, Howard; Fielding, John
    The purpose of this research is to investigate and develop conceptual design methodologies and computational tools appropriate to the design and analysis of low-observable Unmanned Combat Aerial Vehicles (UCAVs), performing a wide variety of missions, with various payload and performance requirements, as well as a wide range of operational constraints, from subsonic to high supersonic flight regimes. Undoubtedly, unmanned aircraft have transformed many aspects of aeronautics and aviation, with military applications often leading these transformational efforts. UCAVs have emerged as a potential strategy to counter technological, operational, and economical challenges to the future of aerial warfare. These challenges include an aging fleet of 4th generation fighters, the deployment of new, advanced 4+ and 5th generation platforms, the reported high vulnerability of current unmanned aerial vehicles, as well as the future development of hypersonic vehicles and weapons. In order to investigate future aircraft configurations, the GENUS aircraft design environment was envisioned by Prof. Howard Smith at Cranfield University’s Aircraft Design Group in 2012. This framework relies on a central architecture with high degrees of modularity and flexibility capable of designing, analysing, and optimising several species of aircraft with similar analysis tools, revealing the real differences and potential advantages of new designs. Mass estimation, propulsion, aerodynamics, performance, radar cross section estimation, and aero-thermal analysis tools have been integrated into the GENUS framework in order to investigate the design space of UCAVs. Validation of these methods has been hampered due to the often restricted access to quality data of UCAVs and similar configurations against which to compare and from which to generate higher fidelity models. Specific steps for improving the accuracy of the methods in the future have been identified and proposed in §9.2. Design space explorations performed in this research include a mission parameter trade study for subsonic UCAVs in Hi-Lo-Hi missions, the conceptual and preliminary design of a UCAV platform with performance matching that of current 5th generation fighters, a fully supersonic deep-interdiction mission trade study, and a high-supersonic (M ≥ 3.0) carrier-based UCAV for time-critical strike missions.
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    Conceptual design synthesis and optimization for new generations of combat aircraft
    (Cranfield University, 1996-03-28) Siegers, Frank; Smith, Howard
    A numerical design synthesis methodology for new generations of combat aircraft has been developed. It incorporates advanced technology in the form of design for low observables. Aircraft capable of being modelled with this methodology will have internal or external Weapons carriage, side mounted intakes, a straight-tapered trapezoidal wing, aft-mounted tail with the option of single or twin ns, and one or two engines with rectangular or axisymmetric nozzles. The design methodology incorporates sufficiently accurate and realistic algorithms for the calculation of the geometry and the estimation of the aerodynamic, mass and performance properties of the aircraft. The inherent flexibility of the design permits the examination of a wide range of configurations whilst maintaining the accuracy required to examine minor changes in the design requirements. A numerical optimization routine was linked to the synthesis, allowing the determination of optimum aircraft design variables for a given set of mission and performance requirements. Results were obtained showing the usefulness of this design tool for setting up parametric trend studies. The numerical accuracy, flexibility of configuration options and high level of advanced aircraft technology of this synthesis make a significant contribution to the continuing development of automated design tools.
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    Damage tolerance of CFRP airframe bolted joints in bearing, following bolt pull-through failure
    (Elsevier, 2020-01-15) Giannopoulos, Ioannis K.; Grafton, Kaelan; Guo, Shijun; Smith, Howard
    The experimental study presented herein, investigated the residual strength of bolted joints on Carbon Fiber Reinforced Polymer (CFRP) airframe structures within the context of structural damage tolerance and airworthiness regulations. The damage scenario assumed, subjected a series of bolted joint CFRP laminate specimens to quasi-static bearing loading, following bolt pull-through failure events of different magnitude. Representative CFRP laminate specimens manufactured from AS7/8552 carbon fiber/epoxy matrix system were artificially damaged under bolt pull-through loading, following the herein proposed modifications to the current pull-through ASTM testing procedure. The specimens were subsequently tested in static bearing loading for examining the specimen residual bearing strength. The residual joint bearing strength was related to the displacement travelled passed the initial failure stage in pull-through mode and was measured up to a maximum of a 13% decrease for the tested samples and the maximum damage imposed. The study explored the safe utilization of bolted joints at higher operating loading levels, within the context of the current airworthiness regulations. The inherent damage arrest features of the joints were highlighted. The study concluded with comments and suggestions on the expansion of the current utilization spectrum of damaged bolted joints from pull-through loading in airframe design, bound by the current airworthiness certification requirements.
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    Dataset "Blended wing body design and analysis"
    (Cranfield University, 2024-05-23 12:45) Chan, Joseph; Sun, Yicheng; Smith, Howard
    Data collected from different simulations and analyses calculated using GENUS
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    Design and operational assessment of a low-boom low-drag supersonic business jet
    (Sage, 2021-04-09) Sun, Yicheng; Smith, Howard
    There has been a worldwide interest to develop a supersonic business jet (SSBJ) for a minimum range of 4,000 nm with low sonic boom intensity and high fuel efficiency. An SSBJ design model is developed in the GENUS aircraft conceptual design environment. With the design model, a low-boom low-drag SSBJ concept is designed and optimized. This paper studies the design concept for its operational performances. The sustained supersonic cruise flight is studied to find out the fuel-efficient Mach number and altitude combinations. The combined supersonic and subsonic cruise flight scenarios are studied to evaluate the feasibility of boom-free flight routes. The one-stop supersonic cruise flight scenario is studied to compare the fuel consumption and time advantage over subsonic airliners. The off-design sonic boom intensity is studied to explore the operational space assuming there would be a sonic boom intensity limit in the future. Through the studies, it is revealed that there is a corresponding most fuel-efficient operating altitude for a specific cruise Mach number. To operate the aircraft near the cut-off Mach number leads to both increases in the fuel consumption (6.3% - 8.1%) and the mission time (11.7% - 13.1%). The business-class supersonic transport (231 g/PAX/km) consumes nearly three times fuel as the economic-class supersonic transport (77 g/PAX/km), which is still far more than the economic-class subsonic transport (20 g/PAX/km). Off-design sonic boom intensity studies reveal different trends against the common understanding: the sonic boom intensity does not necessarily decrease as the altitude increases; the sonic boom intensity does not necessarily decrease as the Mach number decreases.
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    Design case of the E-19 AEOLUS supersonic business jet
    (AIAA, 2020-06-08) Smith, Howard; Sun, Yicheng
    This paper introduces the E-19 AEOLUS supersonic business jet designed by the authors (conceptual design) and a team of Staff and a team of graduate students (preliminary and detail design) from the Aerospace Vehicle Design MSc. The design is presented at the 50th anniversary of the first flight of Concorde and with growing interest from many aircraft design companies. An attractive design would still need the usual attributes of safety, security, comfort, reliability, performance and operational flexibility. This paper presents a design that attempts to address these issues. The details of cabin, structures, landing gear, systems, powerplants, etc. are designed. Low-boom low-drag technologies are applied to the design. The synthetic vision display and double drooping nose are introduced to increase the pilot’s field of view. The resulting concept is challenging but could result in an aircraft well suited to meet a new market opportunity
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    Development of design methodology for a small solar-powered unmanned aerial vehicle
    (Hindawi Publishing Corporation, 2018-03-27) Rajendran, Parvathy; Smith, Howard
    Existing mathematical design models for small solar-powered electric unmanned aerial vehicles (UAVs) only focus on mass, performance, and aerodynamic analyses. Presently, UAV designs have low endurance. The current study aims to improve the shortcomings of existing UAV design models. Three new design aspects (i.e., electric propulsion, sensitivity, and trend analysis), three improved design properties (i.e., mass, aerodynamics, and mission profile), and a design feature (i.e., solar irradiance) are incorporated to enhance the existing small solar UAV design model. A design validation experiment established that the use of the proposed mathematical design model may at least improve power consumption-to-take-off mass ratio by 25% than that of previously designed UAVs. UAVs powered by solar (solar and battery) and nonsolar (battery-only) energy were also compared, showing that nonsolar UAVs can generally carry more payloads at a particular time and place than solar UAVs with sufficient endurance requirement. The investigation also identified that the payload results in the highest effect on the maximum take-off weight, followed by the battery, structure, and propulsion weight with the three new design aspects (i.e., electric propulsion, sensitivity, and trend analysis) for sizing consideration to optimize UAV designs.
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    Effect of a fuselage boundary layer ingesting propulsor on airframe forces and moments
    (Elsevier, 2020-02-21) Fernández, Antonio Martínez; Smith, Howard
    The aim of this research project was to investigate the benefits of hybrid-distributed propulsion and boundary layer ingestion applied to an airliner similar in size, range and cruise velocity to an Airbus A320 or a Boeing 737-800. The power system selected consisted of two under-wing mounted conventional turbofans and an electrically driven boundary layer ingesting fan, located at the rear fuselage. The power required for the fan is extracted from both turbofans. The worked carried out and presented in this paper offers a new approach to modelling boundary layer ingestion configurations, consisting of using the sliding mesh method to simulate the rotation of the blades within the airflow. The simulations indicate that ingesting the boundary layer results in remarkable improvements reducing drag and increasing propulsive force, reaffirming the potential of this technology to reduce fuel consumption. However, the results also registered large changes in the pressure distribution, and hence in the pitching, rolling and yawing moment that need to be accounted for in the design phase.
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    The effects of the degree of hybridisation on the design of hybrid-electric aircraft considering the balance between energy efficiency and mass penalty
    (MDPI, 2023-01-23) Kang, Le; Sun, Yicheng; Smith, Howard; Mao, Junkui
    The growing interest in the application of the hybrid-electric concept demands a rigorous method applied to balancing the energy efficiency improvement with the mass penalty. In hybrid-electric aircraft (HEA) design, it is necessary to avoid excessive usage of energy, which is caused by deliberate hybridising in pursuit of high electrical energy conversion efficiency. This paper presents a design method to achieve multi-objective designs conducted within a framework of multi-disciplinary design exploration appropriate for HEA, meeting the requirement of minimising the maximum take-off mass (MTOM) and fuel saving. A theoretical analysis proposes the existence of the optimum design area of HEA. This is followed by a series of demand-focused numerical design experiments that have verified the existence and position of the optimum design area by taking the mission of a short-range narrow-body airliner as the design target, considering the predicted technology timeline until 2050. Compared to a fuel-powered twin-turbofan aircraft, 65.56% fuel-saving, 16.4% reduction in flight operation cost, 44.58% reduction in block CO2emission, and 75% improvement in the cost-specific air range (COSAR) are achieved via hybridisation using the proposed design optimisation method.