In this review paper, several take-off techniques of different species of animal flyers and gliders, both extinct and extant, are analysed. The methods they use vary according to animal group and size. Smaller animals, such as insects, rely on the use of transient aerodynamic techniques or the use of stored elastic energy. Medium-size flyers such as birds, bats, and other mammal gliders initiate flight by a jump which involves leg and wing movement coordination. The largest animals to fly, the extinct pterosaurs, are believed to have used a combination of aerodynamic and mechanic techniques in order to become airborne. The information presented here can be used as a resource for novel biomimetic unmanned aircraft design.

In this review paper, different landing strategies of diverse species of animal flyers and gliders, both extinct and extant, are analysed. These methods vary depending on the animal group and the sensory system used by the animal to detect its landing site. In almost all species the use of delayed stall during the landing manoeuvre was observed. Sometimes wing flapping was used to aid in deceleration. With respect to guidance and navigation, most insect, bird and mammal gliders use their vision to guide them to landing via optical flow or motion parallax. Bats, which are nocturnal creatures, rely on their auditory system as they use echolocation to find their nesting site. Some butterfly and moth species guide themselves to landing using their olfactory sense as they follow pheromone trails. The information presented here can be used as a source of information for novel bio-inspired unmanned aircraft design.

This paper presents the development of a mathematical model for the implementation of flexible rotor blade dynamics in real-time helicopter aeromechanics applications. A Lagrangian approach is formulated for the rapid estimation of natural vibration characteristics of nonuniform rotor blades. A matrix/vector formulation is proposed for the treatment of elastic blade kinematics in the time-domain. In order to overcome the classical hurdles of time-accurate simulation and establish applicability in real-time, a novel, second-order accurate, finite-difference scheme is employed for the numerical discretisation of elastic blade motion. The proposed rotor dynamics model is coupled with a finite-state induced flow and an unsteady blade element aerodynamics model. The combined formulation is implemented in a helicopter flight mechanics simulation code. The integrated approach is deployed in order to investigate rotor blade resonant frequencies, trim control angles, oscillatory blade loads and induced vibration for a hingeless and an articulated helicopter rotor. Extensive comparisons are carried out with wind tunnel and flight test measurements, and non-real-time comprehensive analysis methods. Good agreement with measured data is exhibited considering primarily the low-frequency harmonic components of oscillatory loading. It is shown that, the developed methodology can be utilised for real-time simulation on a typical computer with sufficient modelling fidelity for accurate estimation of oscillatory blade loads.

The numerical simulations for cycloidal propellers based on five aerofoils with different thickness are presented in this paper. The CFD simulation is based on sliding mesh and URANS. The results of CFD simulation indicates that all test cases share similar flow pattern. There are leading edge vortex and trailing-edge vortex due to blade dynamic stall. Interaction between the vortices shed from upstream blade and the downstream blade can be observed. There is variation of blade relative inflow velocity due to downwash in the cycloidal rotor cage. These factors result in large fluctuations of the aerodynamics forces on the blade. The comparison of the forces and flow pattern indicates that the thickness and leading edge radius of the aerofoil can significantly influent the flow pattern and hence the performance of the cycloidal propeller.

In an effort to increase the air-breathing endurance capability of current hypersonic research aircraft (i.e. X-43, 7 seconds; X-51, 5 minutes), the authors have explored the technical and operational solution space for a 30 minute cruise endurance demonstrator operating in the Mach 6 to Mach 8 speed regime. The focus of this activity has been on exploration of the available solution space through a unique screening process to assess the implication and interplay between the (a) mission, (b) baseline vehicle, and (c) operational scenarios. This study concludes that an air-launched, liquid hydrogen fuelled, 30 minute duration Mach 6 demonstrator (with 10 min Mach 8 capability) provides the largest feasible solution space of the trades examined (i.e. largest design margins, lowest technical risk) when compared to a kerosene-powered equivalent.

The impact point dispersion of mortar missiles can be drastically reduced with a control ring of lateral pulse jets located around the centre of gravity and a homing head to measure or to derive estimates of appropriate missile-target states, e.g. the line-of-sight rates. A simulation model including a missile as a six-degree-of-freedom vehicle, a jet pulse flight control system, and a relative missile-to-target motion was used for the comparison of four guidance laws i.e. proportional navigation guidance, augmented proportional navigation, augmented proportional navigation with rendezvous, and adaptive sliding-mode guidance. This paper focuses on the efficiency of pulse jet control on miss distance, and thus makes the assumption that sensor measurements and the guidance states required to apply each of the guidance laws are perfectly known. Proportional navigation and the adaptive sliding mode guidance exhibit a large miss distance due to limited control authority. Augmented proportional navigation is slightly better than augmented proportional navigation with rendezvous for the same design parameters and they both give small miss distances with limited control authority, but they both require a free gyro. A proper selection of the design parameters — the number of pulse jets and the magnitude of the individual pulse jet thrust for a particular dispersion of flight parameters and the instant of the guidance start — is required to achieve optimum dispersion reduction. The minimum intensity of the individual pulse jet impulse required for the ‘pin point’ accuracy (the circular error probable smaller than 1m) of the mortar missile was determined for all presented guidance laws considering dispersion from the nominal trajectory.