Experimental Effect of Sideslip Angle on the Dynamic Behaviour of Flared Folding Wingtips

A concept of growing interest in recent years is the Flared Folding Wingtip (FFWT), which can be used in-flight to reduce airframe loading due to gust encounters and augment the handling qualities of an aircraft. The performance of an FFWT is affected by the relative angle between the built-in hinge angle and the flow direction. Therefore, a critical concern is the behaviour of such a device at non-zero sideslip angles, such as experienced by aircraft in crosswind landings. In this paper, a specially designed wind tunnel model capable of large wingtip rotations, and a geometrically nonlinear numerical model, are utilised to explore how sideslip angle affects both the static and dynamic behaviour of such a system. It is shown that stable equilibrium positions exist up to and beyond a fold angle of 90 degrees, even when the effective flare angle is zero or switches sign. Additionally, to accurately capture the variation in the frequency of the wingtip with sideslip angle, it is shown factors such as the change in sweep angle of the wing must be accounted for. Furthermore, it is shown that these changes in frequency with sideslip angle can lead to a reduction in the flutter speed, but do not have a significant impact on the gust load alleviation of wings incorporating FFWTs, when exposed to one-minus-cosine gust encounters

Sizing of High-Aspect-Ratio Wings with Folding Wingtips

High-aspect-ratio wings are of particular interest to modern aircraft design due to the inherent reduction in induced drag that they provide. However, such wing configurations often come with problems such as increased structural weight and oversized wingspans for existing airport facilities. Unlike conventional folding wingtips, as used on the 777-X, this paper demonstrates the use of semi-aeroelastic hinge devices that enable aircraft incorporating high-aspect-ratio wings not only to fit into airport gates, but also to alleviate aerodynamic loads by allowing floating wingtips to be used in-flight. This study establishes a preliminary design process for such a wing configuration and undertakes a comprehensive sizing process to investigate the impact of the device on wing weight and aircraft performance. For the cases considered, a reduction in wing weight of approximately 25% can be achieved by utilizing the semi-aeroelastic hinge, which can lead to more than 5% improvement in aircraft range

Experimental and Numerical Nonlinear Stability Analysis of Wings Incorporating Flared Folding Wingtips

Recent studies have considered the use of wings incorporating flared folding wingtips (FFWTs) to enable higher aspect ratios (reducing overall induced drag) while also reducing gust loading and meeting airport operational requirements. This paper presents the first experimental research into the nonlinear dynamic behavior of a wing incorporating an FFWT. Wind-tunnel tests were conducted at a range of velocities below and beyond the linear flutter boundary. The experimental findings are compared with results obtained from continuation and bifurcation analyses on a representative low-fidelity numerical model. The results show that beyond the linear flutter boundary, stable limit cycle oscillations form, which is dependent on the flare angle, are bounded by either geometric or aerodynamic nonlinearities. Also presented is the effect of a wingtip trim tab on the stability boundary of a wing incorporating FFWTs. It is found that the tab angle can significantly alter the stability boundary of the system, indicating that the choice of camber is an important parameter when considering the stability boundary of FFWTs and that a moveable control surface on an FFWT could be used “in flight” to extend the stability boundary of an aircraft

Sequencing and Welding of Molecular Single-Crystal Optical Waveguides

Molecular crystals are promising anisotropic optical transducing media for next-generation optoelectronic microdevices that will be capable of secure transduction of information and impervious to external electromagnetic interference. However, their full potential has not been explored yet due to their poor processability, low mechanical compliance, pronounced brittleness and high proneness to cracking that often result in irrecoverable damage. These issues are detrimental to their ability to transduce light. Here, a novel strategy is presented based on 3D epitaxial crystal growth of organic/inorganic crystals based on charge-assisted hydrogen bonds that can be used to efficiently weld broken molecular single-crystalline optical waveguides and restore their light-transducing capability. This approach can also be applied to prepare asymmetric multidomain crystalline heterostructures starting from isostructural molecular tectons, resulting in novel opto/electro/mechanical functionalities in the hybrid materials. It also removes an important obstacle toward wider application of molecular crystals in the next-generation optoelectronics

Structure and function of the human Gly1619Arg polymorphism of M6P/IGF2R domain 11 implicated in IGF2 dependent growth

The mannose 6-phosphate/IGF 2 receptor (IGF2R) is comprised of 15 extra-cellular domains that bind IGF2 and mannose 6-phosphate ligands. IGF2R transports ligands from the Golgi to the pre-lysosomal compartment and thereafter to and from the cell surface. IGF2R regulates growth, placental development, tumour suppression and signalling. The ligand IGF2 is implicated in the growth phenotype, where IGF2R normally limits bioavailability, such that loss and gain of IGF2R results in increased and reduced growth respectively. The IGF2R exon 34 (5002A>G) polymorphism (rs629849) of the IGF2 specific binding domain has been correlated with impaired childhood growth (A/A homozygotes). We evaluated the function of the Gly1619Arg non-synonymous amino acid modification of domain 11. NMR and X-ray crystallography structures located 1619 remote from the ligand binding region of domain 11. Arg1619 was located close to the fibronectin type II (FnII) domain of domain 13, previously implicated as a modifier of IGF2 ligand binding through indirect interaction with the AB loop of the binding cleft. However, comparison of binding kinetics of IGF2R, Gly1619 and Arg1619 to either IGF2 or mannose 6-phosphate revealed no differences in ‘on’ and ‘off’ rates. Quantitative PCR, 35S pulse chase and flow cytometry failed to demonstrate altered gene expression, protein half-life and cell membrane distribution, suggesting the polymorphism had no direct effect on receptor function. Intronic polymorphisms were identified which may be in linkage disequilibrium with rs629849 in certain populations. Other potential IGF2R polymorphisms may account for the correlation with childhood growth, warranting further functional evaluation

Ontology-driven development of web services to support district energy applications

Current urban and district energy management systems lack a common semantic referential for effectively interrelating intelligent sensing, data models and energy models with visualization, analysis and decision support tools. This paper describes the structure, as well as the rationale that led to this structure, of an ontology that captures the real-world concepts of a district energy system, such as a district heating and cooling system. This ontology (called eedistrict ontology) is intended to support knowledge provision that can play the role of an intermediate layer between high-level energy management software applications and local monitoring and control software components. In order to achieve that goal, the authors propose to encapsulate queries to the ontology in a scalable web service, which will facilitate the development of interfaces for third-party applications. Considering the size of the ee-district ontology once populated with data from a specific district case study, this could prove to be a repetitive and time-consuming task for the software developer. This paper therefore assesses the feasibility of ontology-driven automation of web service development that is to be a core element in the deployment of heterogeneous district-wide energy management software