8 research outputs found
Span Morphing Using the Compliant Spar
This paper develops and models the Compliant Spar concept that allows the wing span to be varied to provide roll control and enhance the operational performance for a medium altitude long endurance (MALE) UAV. The wing semi-span is split into morphing partitions and the concept maybe incorporated in each partition; however only the tip partition is considered here. The Compliant Spar is made of compliant joints arrange in series to allow the partition to be flexible under axial (spanwise) loads but at the same time stiff enough to resist bending loads. Each compliant joint consists of two concentric overlapping AL 2024-T3 tubes joined together using elastomeric material. Under axial (spanwise) loading, the elastomeric material deforms in shear allowing the overlapping distance between the tubes to vary and hence the length (in the spanwise direction) of the joint/spar to vary. High fidelity modelling of the concept is performed. Then, structural optimisation studies are performed to minimise the axial stiffness and the structural mass of the concept for various design constraints. The flexible skin and actuation system to be used are also addressed
Broad-spectrum antiviral activity of 2-beta-D-ribofuranosylselenazole-4-carboxamide, a new antiviral agent
A new method for the determination of mobile phase volume in normal and reversed-phase liquid chromatography
A review of morphing aircraft
Aircraft wings are a compromise that allows the aircraft to fly at a range of flight conditions, but the performance at each condition is sub-optimal. The ability of a wing surface to change its geometry during flight has interested researchers and designers over the years as this reduces the design compromises required. Morphing is short for metamorphose: however, there is neither an exact definition nor an agreement between the researchers about the type or the extent of the geometrical changes necessary to qualify an aircraft for the title “shape morphing”. Geometrical parameters that can be affected by morphing solutions can be categorized into: planform alteration (span, sweep and chord), out-of-plane transformation (twist, dihedral/gull, spanwise bending) and airfoil adjustment (camber and thickness).Changing the wing shape or geometry is not new. Historically, morphing solutions always led to penalties in terms of cost, complexity or weight, although in certain circumstances these were overcome by system level benefits. The current trend for highly efficient and “green” aircraft makes such compromises less acceptable, calling for innovative morphing designs able to provide more benefits and fewer drawbacks. Recent developments in “smart” materials may overcome the limitations and enhance the benefits from existing design solutions. The challenge is to design a structure that is capable of withstanding the prescribed loads, but is also able to change its shape: ideally there should be no distinction between the structure and the actuation system. The blending of morphing and smart structures in an integrated approach requires multi-disciplinary thinking from the early development, which significantly increases the overall complexity, even at the preliminary design stage. Morphing is a promising enabling technology for future, next generation aircraft. However, manufacturers and end users are still too skeptical of the benefits to adopt morphing in the near future. Many developed concepts have a technology readiness level that is still very low. The recent explosive growth of satellite services means that UAVs are the technology of choice for many investigations on wing morphing.This paper presents a review of the state of the art on morphing aircraft and focuses on structural, shape changing morphing concepts for both fixed and rotary wings, with particular reference to active systems. Inflatable solutions have been not considered, and skin issues and challenges are not discussed in detail. Although many interesting concepts have been synthesized, few have progressed to wing tunnel testing, and even fewer have flown. Furthermore, any successful wing morphing system must overcome the weight penalty due to the additional actuation systems.<br/