MATHEMATICAL MODEL OF SELF-REPAIRING FLIGHT CONTROL

The most prospective method for certain structural failures and damages that cannot employ redundancy is self-repairing techniques, to ensure especially the maximum flight safety. Based on the characters of self-repairing aircraft, this paper states some basic assumptions of the self-repairing aircraft, and puts forward some special new conceptions concerning the self-repairing aircraft: control input, operating input, command input, repair input and operating and control factor as well as their relationships. Thus it provides a simple and reliable mathematical model structure for the research on the self-repairing control of the aircraft.

Experimental Investigation of the Aerodynamic Flow in the Aircraft Carrier Ski-jump by means of PIV

Computational Fluid Dynamics （CFD） methods have opened a new field to perform aerodynamic studies saving money and time. The difficulties presented by this method to calculate complex flow field problems imply that CFD validation is needed to provide correct results. Experimental data have recently been used to validate the accuracy of CFD predictions. Particle Image Velocimetry （PIV） has shown to be a powerful tool in the investigation of complex flows. The aim of this paper is to present results from PIV experiments that would be interesting for CFD validation. Regarding aircraft operations, the short runway available implies the necessity of equipment which helps to take-off performances. Ski-jump ramp system improves aircraft performances by an increment of lift resulting in successful take-off operations. The ski-jump ramp presence generates a complex flow bounded by a turbulent shear layer and a low velocity recirculation bubble over the end of the flight deck. The adverse effects on the aircraft aerodynamics affect to pilot safe operations, so this region is an interesting problem to be studied by means of wind tunnel experimental tests.

复方小艾飞蜜膏抗炎作用研究

目的：观察复方小艾飞蜜膏乙醇提取物的抗炎作用。方法：分别采用二甲苯致耳肿胀、角叉菜胶致大鼠足肿胀、大鼠棉球肉芽肿、角叉菜胶致大鼠胸膜炎等炎症模型,观察复方小艾飞蜜膏抗炎活性;测定胸膜炎大鼠胸腔渗出液中总蛋白含量、血清中前列腺素E2（PGE2）与肿瘤坏死因子（TNF-α）含量,探讨其抗炎作用机制。结果：复方小艾飞蜜膏乙醇提取物在0.034~0.136g/kg的剂量范围内,能明显抑制二甲苯致耳肿胀和角叉菜胶诱导大鼠足肿胀,减轻肉芽肿的质量,有效降低胸膜炎大鼠胸腔渗出液中蛋白含量、血清中前列腺素E2（PGE2）与肿瘤坏死因子（TNF-α）含量,作用呈剂量依赖性。结论：复方小艾飞蜜膏乙醇提取物具有抗炎作用,其作用与降低PGE2和TNF-α含量有关。

LATERAL STABILITY VERIFICATION OF A CANARD AIRPLANE WITH AND WITHOUT A VERTICAL PANEL

The lateral stability of Velocity-173, canard-pusher type airplane, has been investigated with and without an extended vertical panel. It is well known that Velocity-173 has an excellent longitudinal stability but a relatively poor lateral stability. To improve the lateral stability, two types of composite sandwich panel have been designed and attached to the vertical tail of Velocity-173. A series of flight test has been performed to measure the effects of the extended vertical tail. Analytical methods, such as maximum likelihood estimation method and real-time parameter estimation method, have been used to extract lateral controllability/stability derivatives from flight test data. This work validates the effects of an extended panel to the lateral stability.

Effects of static aeroelasticity on composite wing characteristics under different flight attitudes

Composite wing static aeroelasticity was analyzed through a loosely coupled method and the effects on composite wing characteristics under different flight attitudes were presented. Structural analysis and aerodynamic analysis were carried out through finite element method (FEM) software NASTRAN and computational fluid dynamics (CFD) software FLUENT, respectively. Correlative data transfer and mesh regenerate procedure were applied to couple the results of computational structure dynamics (CSD) and CFD. After static aeroelasticity analysis under different flight attitudes, it can be seen that lift increases with the increase of flight speed and the incremental value enlarges gradually in both rigid and elastic wings. Lift presents a linear increment relationship with the increase of attack angle when the flight speed is 0.4Ma or 0.6Ma, but nonlinear increment in elastic wing when flight speed is 0.8Ma. On the effect of aeroelasticity, the maximum of deformation increases with the increase of flight speed and attack angle, and the incremental value decreases with the increase of flight speed while uniform with different attack angles. The results provide a reference for engineering applications.

Performance Analysis of Slowed Rotor Compound Helicopter

The performance of slowed-rotor compound aircraft,particularly at high-speed flight condition,is examined.The forward flight performance calculation model of the composite helicopter is established,and the appropriate wing and propeller parameters are determined.The predicted performance of isolated propeller,wing and rotor combination is examined.Three kinds of tip speed and a range of load share setting are investigated.Propeller bearing 80%of the thrust with wing sharing lift is found to be the best condition to have better performance and the maximum L/D for maximum forward speed.Detailed rotor,propeller,and wing performance are examined for sea level,1000 m,and 2000 m cruise altitude.Rotor,propeller,and wing power are found to be largely from profile drag,except at low speed where the wing is near stall.Increased elevation offloads lift from the rotor to the wing,dropping the total power required and increasing the maximum speed limit over 400 km/h.

Laser Doppler Measurements of Twin Impinging Jets Aligned with a Crossflow

This paper presents a detailed analysis of the complex flow beneath two impinging jets aligned with a low-velocity crossflow which is relevant for the future F-35 VSTOL configuration, and provides a quantitative picture of the main features of interest for impingement type of flows. The experiments were carried out for a Reynolds number based on the jet exit conditions of Rej = 4.3 × 10^4, an impingement height of 20.1 jet diameters and for a velocity ratio between the jet exit and the crossflow VR = V/Uo of 22.5. The rear jet is located at S = 6 D downstream of the first jet. The results show a large penetration of the first （upstream）jet that is deflected by the crossflow and impinges on the ground, giving rise to a ground vortex due to the collision of the radial wall and the crossflow that wraps around the impinging point like a scarf. The rear jet （located downstream） it is not so affected by the crossflow in terms of deflection, but due to the downstream wall jet that flows radially from the impinging point of the first jet it does not reach the ground. The results indicate a new flow pattern not yet reported so far, that for a VSTOL aircraft operating in ground vicinity with front wind or small forward movement may result in enhanced under pressures in the aft part of the aircraft causing a suction down force and a change of the pitching moment towards the ground.

Aeroelastic optimization on composite skins of large aircraft wings

This paper presents studies of aeroelastic optimization on composite skins of large aircraft wings subject to aeroelastic constraints and strength/strain constraints. The design variable for optimization was the ply thickness of the wing skin panels, and the structural weight was the objective function to be minimised. The impacts of three strength/strain constraints and the ply proportion of the wing skin panels on the optimization results are discussed. The results indicate that the optimal composite wings that satisfy different constraints have remarkable weight advantages over metal wing. High levels of stiffness can be achieved while satisfying the constraints regarding allowable design strains and failure criteria. The optimization results with variable-proportions indicate that wing skins with higher proportions of 0° plies from the root to the middle segment and ±45° plies outboard have a more efficient and reasonable stiffness distribution.

Composites recycling solutions for the aviation industry

Ten of thousands of aircraft are expected to retire in the next 20 years.Aircraft manufacturers are gearing up for a new wave of recycling challenges as these aircrafts contain significant higher amount of carbon fibre reinforced polymer composite,which cannot be recycled by the conventional processes designed for metallic alloys.Aircraft manufacturers have been working with the recycling industry to limit unsustainable dismantling that is harmful to the environment and the potential liability risk of re-entry of un-certified salvaged parts back to the aviation market.An organised recycling network and procedures have already been set up for the conventional metallic alloys and will soon be required to include the composite waste.This paper reports the existing aircraft recycling practice and reviews the key recycling technologies for thermoset composites.Energy consumptions of these technologies are sought from the literature and are reported in this paper.Progress in development of reuse options for the recycled fibre is also included with discussion of their advantages and drawbacks.The challenge of working with the fluffy fibre is considered and the benefit of fibre alignment is highlighted for encouraging a widespread use of the fibre.

Adhesive bonding of composite aircraft structures:Challenges and recent developments

In this review paper,the challenges and some recent developments of adhesive bonding technology in composite aircraft structures are discussed.The durability of bonded joints is defined and presented for parameters that may influence bonding quality.Presented is also,a numerical design approach for composite joining profiles used to realize adhesive bonding.It is shown that environmental ageing and pre-bond contamination of bonding surfaces may degrade significantly fracture toughness of bonded joints.Moreover,it is obvious that additional research is needed in order to design joining profiles that will enable load transfer through shearing of the bondline.These findings,together with the limited capabilities of existing non-destructive testing techniques,can partially explain the confined use of adhesive bonding in primary composite aircraft structural parts.