The study presents results of experimental examination of a model representing a fragment of an aircraft wing structure with the skin made of a glass fibre/epoxy composite. For such a system, the deformation pattern has been found and the representative equilibrium path determined. The finite element method has been used to develop the corresponding numerical model, the correctness of which has been then verified by comparing the obtained results with the course of the relevant experiment. Conformity of the results allowed one to determine usefulness of the applied methods in the assessment of mechanical properties of modified solutions involving integral skin stiffening elements.
Flight testing is both vital for collecting data for aeronautic research and at the same time fascinating for its contributors. Taking a glider as a versatile test bed example, this paper presents a transnational measurement campaign within the framework of a collaborative project funded by the European Commission. This project Advanced In-Flight Measurement Techniques 2 (AIM²) is a follow-up of Advanced In-Flight Measurement Techniques (AIM) and dedicated to developing and enhancing promising optical metrology for various flight test applications up to an industrial level.The Image Pattern Correlation Technique (IPCT) and infrared thermography (IRT) are two of these modern non-intrusive measurement methods that were further developed and applied to the glider test bed within the scope of AIM². Focusing on optical deformation measurements with IPCT the experimental setup, the flight testing and results are summarily discussed. Gliders are not commonly used flight test platforms, which is why this contribution concludes with some lessons learned in general and especially related to the presented application. The experience to be shared with the flight testing community addresses equipment preparation, data collection and processing as well as how to meet official requirements and perform test flight operations in a dense controlled airspace.
The large, EU Supported ESPOSA (Efficient Systems and propulsion for Small Aircraft) project has developed new small gas turbines for small aircraft. One of the important tasks was the engine - airframe aero-thermal radiation integration that included task of minimizing the infrared radiation of the small aircraft, too. This paper discusses the factors influencing on the aircraft infrared radiation, its possible simulation and measurements and introduces the results of small aircraft infrared radiation measurements. The temperature of aircraft hot parts heated by engines were determined for validation of methodology developed and applied to engine - aircraft thermal integration.
Abstract. Gyroscopes established one of the fundamental references for attitude and heading in aerospace applications. The information about angular velocities gives input not only for autopilot, but also damping devices, such as yaw or pitch dampers for example. The MEMS (micro-electro-mechanical system) gyroscopes are much less reliable than their laser or fibre-optic cousins. Nevertheless, the availability and low price of MEMS components make this a growing area of application in avionics for general aviation aeroplanes. This paper presents certain results of flight data analysis registered during the flight testing campaign of the new experimental lowpower single-engine turbo-propeller utility aeroplane I-31T. The research was focused on identification of oscillation modes, distinctive for the new aeroplane, such as engine precession or shimmy. The data came from a three-axis MEMS gyroscope and accelerometer recorder, placed near to the centre of gravity. Wavelet transform, which was used for analysis, gave better precision in time domain than Fourier transform, especially for signals of low frequency.
Scarf repair is widely used in the restoration of structural performance of damaged aircraft secondary structures. Such repairs result in reduced thickness sections which are significantly larger than those associated with typical fastener holes. Significant literature exists on the distribution of strain/stress concentration in fastener hole geometries, both straight sided and countersunk, but is lacking for the geometries associated with shallow scarf angles and thin laminates. Hence, herein three-dimensional finite element models are developed to understand the influence of stacking sequence and scarf angle on strain/stress concentrations. The results demonstrate and quantify for the first time that strain concentrations are not only dependant on the laminate membrane stiffness but also on laminate bending stiffness, due to the anisotropy created as a result of scarfing angle, hole geometry and laminate thickness. Scarfing is demonstrated, for typical repair geometry associated with foreign object damage (hole diameter 20 mm, scarf angles 3° to 7°), to elevate strains by up to 2.5 times when compared to equivalent diameter straight-sided holes in laminates of thickness ≈1 mm.
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