The impact of altitude, latitude, and endurance duration on the design of a high altitude, solar powered unmanned aerial vehicle

In this paper, a previously developed conceptual design tool has been used to study the impact of the latitude, altitude, and the flight duration on the weight estimation and the main characteristics of a high altitude, long endurance and solar powered unmanned aerial vehicle. The available solar energy during the daylight hours has been calculated at given locations and altitudes for specific periods to be used in the pre-conceptual design stage. The pre-conceptual design methodology is based on an analytical and continuous method, which consists of establishing the relationships between all the components with analytical functions using the component characteristics. This design approach can directly provide a unique and optimal design. This study is conducted for a solar aircraft designed for a surveillance mission over Iraq. It is concluded that increasing the operational altitude can lead to a heavier aircraft in spite of the high levels of the available solar energy that can be absorbed. Hence, at high altitude, the surface area required for solar power generation is less than that needed to obtain adequate lift. Increasing the maximum solar irradiance during the daylight hours can lead to further lowering of the aircraft weight. Moreover, an increase in the daylight hours can be beneficial if the charging and discharging losses of the fuel cells are considered

Aerofoil design for unmanned high-altitude aft-swept flying wings

In this paper, 12 new aerofoils with varying thicknesses for an aft-swept flying wing unmanned air vehicle have been designed using a MATLAB tool which has been developed in-house. The tool consists of 2 parts in addition to the aerodynamic solver XFOIL. The first part generates the aerofoil section geometry using a combination of PARSEC and Bezier-curve parameterisation functions. PARSEC parametrisation has been used to represent the camber line while the Bezier-curve has been used to select the thickness distribution. This combination is quite efficient in using an optimisation search process because of the capability to define a range of design variables that can quickly generate a suitable aerofoil. The second part contains the optimisation code using a genetic algorithm. The primary target here was to design a number of aerofoils with low pitching moment, suitable for an aft-swept flying wing configuration operating at low Reynolds number in the range of about 0.5 million. Three optimisation targets were set to achieve maximum aerodynamic performance characteristics. Each individual target was run separately to design several aerofoils of different thicknesses that meet the target criteria. According to the set of result obtained so far, the initial observation of the aerodynamic performance of the newly designed aerofoils is that the lift/drag ratio in general is higher than that of the existing ones used in many current-generation highaltitude long-endurance aircraft. Another observation is that increasing the maximum thickness of the aerofoil leads to a decrease in the maximum lift/drag ratio. In addition, as expected, this ratio sharply drops after the maximum value of some of these aerofoils

Design of a swept-wing High-Altitude Long-Endurance Unmanned Air Vehicle (HALE UAV)

High-altitude aircraft flying in the stratosphere (around 17-30 km altitude) can provide a useful platform for sensors to support a range of military and civilian surveillance tasks. The main topic of the thesis concerns the analysis of solar powered unmanned aerial vehicles designed for extended flight operations at high altitudes. An aft-swept flying wing configuration has been adopted for high altitude applications. Specific topics that were considered focussed on the development of a conceptual design tool and a multi-disciplinary optimisation tool able to converge on the layout for a solar powered HALE UAV. A true aft-swept flying wing is perhaps the most aerodynamically efficient aircraft configuration but, to date, has not been investigated in any detail for possible application to high-altitude UAVs. Such a configuration would require a moderate amount of wing sweep in order to generate the necessary stability in flight and to provide adequate control power for manoeuvring purposes. All systems and elements can now be placed inside the wing without compromising the weight distribution. This avoids the need for drag inducing mass balancing pods and/or reflexed trailing edge associated with unswept (straight) flying wings. Such features can either increase structural weight and/or overall drag whilst reducing the maximum lift that can be achieved. However, the design, in common with the other more conventional aircraft, represents a substantial challenge due to the simultaneous addressing of numerous inter-related engineering disciplines required for a fairly comprehensive analysis. The innovative aspect of this study was dedicated to the conceptual and preliminary design of a high altitude long endurance solar powered aft-swept flying wing and study in detail the design challenges along with the general problems associated with flying at high altitudes. Moreover, these aims were achieved by the author developing new design tools. The conceptual design tool was created to include all the aircraft elements and the expected power losses in addition to representing the drag estimation of the wing section rather than using a general expression as only a function of Reynolds number regardless the aerofoil performance. The preliminary design tool, also written by the author, represented by the composite structure model and the quasi 3D aerodynamic solver combined in a multidisciplinary optimisation framework, proved its capability in determining the aircraft geometry, its weight and its aerodynamic and structural performance capabilities

Composite structural analysis of a high altitude, solar powered unmanned aerial vehicle

In this paper, a development of a low order composite structure module has been introduced. This module can design the wing structure for the given aerodynamic load. The wing structure is broken down into non-spar elements and spars. The weight of non-spar elements is estimated by using empirical equations that were used by NASA for solar powered high altitude UAVs. The Spar is sized by using a numerical approach, which is developed in this paper. The spar is modelled as a composite rectangular wing-box and assumed to withstand the entire load with no contribution from the secondary wing components. The required numbers of laminate on each side of the spar are found iteratively until no failure or buckling is detected. The orientation of laminate of each side of spar was inspired by the existing high altitude aircraft structure. A linear finite beam element is used to evaluate the wing-box deflection under the internal and the aerodynamic loads while only a quasi-static equilibrium is considered during the sizing process. The module has been written in MATLAB. This tool can be used either in the conceptual design stage or in an optimisation process because it facilitates rapid computation. This module has been validated with a high order commercial package (ANSYS). The deflection calculation shows excellent agreement with less than 0.25 % error. The stress calculations show a reasonable agreement with ANSYS with maximum error margin of about 4% at the maximum shear stress level. However, this amount of error could be unimportant as a high factor of safety is usually taken in the design of composite structures. The weight prediction function also has been validated using reference to a NASA Pathfinder aircraft. The predicted weight seems reasonable with a 1.6 % difference from the expected weight of the case study

Design of a high altitude long endurance flying-wing solar-powered unmanned air vehicle

The low-Reynolds number environment of high-altitude flight places severe demands on the aerodynamic design and stability and control of a high altitude, long endurance unmanned air vehicle (HALE UAV). The aerodynamic efficiency of a flying-wing configuration makes it an attractive design option for such an application and is investigated in the present work. The proposed configuration has a high-aspect ratio, swept-wing planform, the wing sweep being necessary to provide an adequate moment arm for outboard longitudinal and lateral control surfaces. A design optimization framework is developed under a MATLAB environment, combining aerodynamic, structural and stability analysis. Low-order analysis tools are employed to facilitate efficient computations, which is important when there are multiple optimization loops for the various engineering analyses. In particular, a vortex-lattice method is used to compute the wing planform aerodynamics, coupled to a two-dimensional panel method to derive aerofoil sectional characteristics. Integral boundary-layer methods are coupled to the panel method in order to predict flow separation boundaries during the design iterations. A quasi-analytical method is adapted for application to flying-wing configurations to predict the wing weight and a linear finite-beam element approach is used for structural analysis of the wing-box. Stability is a particular concern in the low-density environment of high-altitude flight for flying-wing aircraft and so provision of adequate directional stability and control power forms part of the optimization process. At present, a modified Genetic Algorithm is used in all of the optimization loops. Each of the low-order engineering analysis tools is validated using higher-order methods, to provide confidence in the use of these computationally-efficient tools in the present design-optimization framework. This paper includes the results of employing the present optimization tools in the design of a high-altitude, long endurance, flying-wing unmanned air vehicle to indicate that this is a viable design configuration option

Proceedings of the CSE 2017 Annual PGR Symposium (CSE-PGSym17)

Welcome to the Proceedings of the second Annual Postgraduate Research Symposium of the School of Computing, Science and Engineering (CSE-PGSym 2017). After the success of the first symposium, the school is delighted to run its second symposium which is being held in The Old Fire Station on 17th March 2017. The symposium is organised by the Salford Innovation Research Centre (SIRC) to provide a forum for the PGR community in the school to share their research work, engage with their peers and staff and stimulate new ideas. In line with SIRC’s strategy, the symposium aims to bring together researchers from the six groups that make up the centre to engage in multidisciplinary discussions and collaborations. It also aims to contribute to the creation of a collaborative environment within the Research Centre and the Groups and share information and explore new ideas. This is also aligned with the University’s ICZ (Industrial Collaboration Zone) programme for creating cultural, physical and virtual environments for collaboration, innovation and learning