Short take-off and landing (STOL) systems can offer significant capabilities to warfighters and, for civil operators thriving on maximising efficiencies they can improve airspace use while containing noise within airport environments. In order to provide data for next generation systems, a wind tunnel test of an all-wing cruise efficient, short take-off and landing (CE STOL) configuration was conducted in the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) 14ft by 22ft Subsonic Wind Tunnel. The test’s purpose was to mature the aerodynamic aspects of an integrated powered lift system within an advanced mobility configuration capable of CE STOL. The full-span model made use of steady flap blowing and a lifting centerbody to achieve high lift coefficients. The test occurred during April through June of 2007 and included objectives for advancing the state-of-the-art of powered lift testing through gathering force and moment data, on-body pressure data, and off-body flow field measurements during automatically controlled blowing conditions. Data were obtained for variations in model configuration, angles of attack and sideslip, blowing coefficient, and height above ground. The database produced by this effort is being used to advance design techniques and computational tools for developing systems with integrated powered lift technologies.

According to multi-node model, the dynamics equations of conical parachute system for simulating shape deformation process of the flexible canopy in the opening process were established. With the combination of dynamics equations code and computational fluid dynamics (CFD) software, the fluid-structure interaction investigation of the conical parachute was carried out. Also the change of parachute shape and flow field, inflation time, the rate of descent, the distance of descent, and other relevant data were achieved. This paper has focused on analysing vortex structure of the flow field in the opening process of conical parachute, and laid the foundation for studying mechanics mechanism of flow field variation of conical parachute in future.

Experimental studies have been conducted on a NASA 17-percent thick supercritical aerofoil with a Coanda trailing edge at subsonic speeds in both the boundary-layer control and circulation control regimes. Detailed boundary-layer surveys were performed along the mid span on the suction surface and around the Coanda trailing edge. The wake located at 43% chord-length behind the aerofoil was measured with a single-component hotwire anemometer, and the profile drag coefficients were calculated from the integration of wake momentum deficit. Lift forces and pitching moments were recorded from –20deg to +20deg incidence using a 3-component force balance. In the circulation control regime, the boundary-layer results indicated that separation bubbles are not present at high incidences compared to the boundary-layer control regime, and that minimised the potential for flow separation delay around the Coanda trailing edge. The spectral analysis of the wake showed a significant reduction of wake fluctuations at high incidences and improvement of the stability at the edge of the wake. The study of aerodynamic forces suggested the need to increase the blowing momentum coefficient if the circulation control is used near the stalling angle-of-attack.

The health monitoring and damage prognosis of aerospace hotspots is important for reducing maintenance costs and increasing in-service capacity of aging aircraft. One of the leading causes of structural failure in aerospace vehicles is fatigue damage. Based on the physical mechanism of damage nucleation and growth, a physics-based multiscale model is considered for fatigue damage assessment in metallic aircraft structures. A guided-wave based sensing approach is utilised to enable effective damage detection in a common structural hotspot: a lug joint. Finite element analysis is carried out with piezoelectric wafers bonded to the host structure and the simulated sensor signals are analysed. A damage classification strategy is developed, which integrates physically motivated time-frequency approaches with advanced stochastic modelling techniques. In particular, a variational Bayesian learning scheme is used to estimate the optimal model complexity automatically from the data, adapting the classifier for real-time use. Classification performance is studied as a function of signal-to-noise ratio and results are reported for the detection of fatigue crack damage in the lug joint. An adaptive hybrid prognosis model is proposed, which estimates the residual useful life of structural hotspots using damage condition information obtained in real-time.

This paper investigates the performance of a flight control system, based on nonlinear dynamics inversion theory, whose aim is to maintain a given geometry of a formation of unmanned aerial vehicles. A fundamental aspect is the complete three dimensionality of the formation geometry that provides a substantial improvement over existing two-dimensional control laws. The designed control system has been implemented in a Simulink® environment and its effectiveness has been tested with a campaign of numerical simulations.

Inlet start/unstart detection is one of the most important issues of hypersonic inlets and is also the foundation of protection controls of scramjets. In ground and flight tests, it is inevitably to introduce the sensor noises to the measurement system. How to overcome or weaken the influence of the sensor noises and the outer disturbances is an important issue to the control system of the engine. To solve this problem, the 2D inner steady flow of hypersonic inlets was numerically simulated in different freestream conditions and backpressures, and two different inlet unstart phenomena were analysed. The membership function for hypersonic inlet start/unstart can be obtained by using probabilistic output support vector machine, and the algorithm of multiple classifiers fusion is introduced. The variations of the classification accuracy with the intensity of the sensor noises and the number of the classifier were discussed respectively. In conclusion, it is useful to introduce the algorithm of support vector machine and multiple classifiers fusion to overcome or weaken the influence of the sensor noises on the classification accuracy of hypersonic inlet start/unstart. The number of the practical fusion classifiers needs a tradeoff between the fusion classification accuracy and the complexity of the classification system.

Vascular structures are contemplated for cooling the skins and leading surfaces of future high speed aircraft. This paper evaluates the proposal to cool with a flow architecture shaped as trees (dendritic) a parallelepipedic body that is heated uniformly. The coolant enters the body through one face and exits through the opposite face. The vasculature connects the two faces, and consists of trees that alternate with upside down trees. The fields for fluid flow and heat transfer are determined numerically in three dimensions. The effect of local pressure losses at bends, junctions and entrances is documented. Designs with tree-shaped architectures having up to four levels of bifurcation are evaluated for fluid flow and heat transfer performance, and are compared with the performance of a design with a single sheet of fluid sweeping the upper surface of the body. The fluid flow conductance of the tree designs increases when the number of bifurcation levels increases. The thermal performance of tree designs can be improved by endowing the tree design with more freedom such that the bifurcations generate asymmetric daughter channels. The tree designs outperform the fluid sheet design dramatically: the global thermal resistance of the tree designs is roughly one tenth of the global thermal resistance of the fluid sheet design.

Recent studies show that analytical predictions of crack growth in rotating components can be used in conjunction with displacement measurement techniques to identify critical levels of fatigue damage. However, investigations of this type traditionally have focused on the detection of damage at known flaw locations. This paper addresses the related problem of estimating damage associated with flaws at unknown locations, through the combined use of analytical models and measured vibration signatures. Because the measured data are insufficient to identify a unique solution for the location and severity of fatigue cracks, the function of the analytical model is to bound the extent of damage occurring at life-limiting locations. The prediction of remaining life based on estimates of worst-case fatigue damage and crack locations also is discussed.

The interaction of multiple jets with the ground is of great importance for the design and operation of short take-off, vertical landing aircraft. The fountain upwash flow, generated by the impingement of two axisymmetric, compressible, turbulent jets onto a ground plane was studied using laser-based particle image velocimetry and laser Doppler velocimetry. Measurements were made with nozzle pressure ratios of between 1·05 and 4, nozzle height-to-diameter ratios of between 2·4 and 8·4, nozzle splay angles of between ±15 degrees and a nozzle spacing-to-diameter ratio of seven. The effect of varying these parameters on the fountain velocity decay, spreading rate and momentum flux ratio are discussed. Mean fountain upwash velocity profiles were found to be self-similar for all test conditions. A distinct frequency of fountain oscillation was identified but only at a nozzle height of 4·4 diameters.