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    The Risk Observatory: Developing an Aviation Safety Information Sharing Platform in Europe
    (Macrothink Institute, 2016-12) Verstraeten, J. ; Baren, G.B. van ; Wever, R.
    In Europe the accident rate in commercial aviation has stagnated at around 40 accidents per ten million flights: forty times higher than Europe’s ambition. Currently safety management is done per organisation, focusing on an organisation’s own domain. European research institutions and the aviation sector have joined their expertise in the EU-funded Future Sky Safety Programme. One project within the programme aims to enable inter-organisation and inter-domain safety management. The four year project will deliver a tool, the Risk Observatory, which acquires safety data and translates it into actionable safety information. In the first year, more than 20 European stakeholder organisations have been consulted to express their needs for a Risk Observatory. The resulting requirements have been used to develop an early prototype: mock-ups of dashboards and a user interface. The Risk Observatory has four main elements. (1) Tracking of safety performance indicators distilled from input safety data. (2) Trend diagrams and visualisations of accident risk. Risk models will be developed to translate the input data into accident risk. The risk models also allow (3) assessment of the effects of mitigation measures. There is added value in sharing qualitative safety knowledge, such as identified hazards, therefore, (4) a searchable repository is included. The early prototype is successfully used to validate and further specify the requirements. The need for inter-organisation and inter-domain safety data dissemination was confirmed by the stakeholders. In the coming years the project will develop a fully functional prototype risk observatory, risk models and a business model.
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    Braking Capabilities on Flooded Runways: Flight Test Results Obtained with a Business Jet
    (AIAA, 2017) Es, G.W.H. van
    Statistics show that the likelihood of a runway excursion during takeoff or landing is much higher on flooded runways than on dry runways. Extreme loss of tyre braking can occur during rejected takeoffs and landings on flooded runways. As a result the stopping distance increases significantly and could exceed the available runway length. Most research in the past has focused on the braking capabilities of aircraft on wet runways instead of flooded runways. Most of the knowledge of aircraft braking performance on flooded runways was gained with older aircraft designs. This knowledge is still used to determine the takeoff and landing performance of today’s modern aircraft. During the development of the European Action Plan for the Prevention of Runway Excursions it was recognised that current aircraft designs may act differently when braking on water flooded runways from aircraft tested earlier, due to new tyres and anti-skid system designs. Also the water depths during these earlier tests were often just above the wet-flooded runway threshold. Flight tests with more modern aircraft designs were therefore scheduled as part of a research project under EU’s Horizon 2020 Research and Innovation Programme. This paper summarises the flight tests conducted with a Cessna Citation II aircraft on a flooded runway. Unbraked and braked tests were conducted in a specially constructed water pond at different ground speeds. Numerous parameters were recorded during each test run including accelerations, speeds, engine performance, etc. From the test data, effective braking friction for different grounds speeds were derived, contamination drag levels were established, and insight into the hydroplaning characteristics under unbraked and braked conditions were obtained.
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    Stopping performance flight test on a flooded runway
    (Society of Experimental Test Pilots, 2017-07) Tump, R.S. ; Mulder, T.J.
    One of the identified solutions for runway excursions is the research into the “Impact of fluid contaminants of varying depth on aircraft stopping performance”. For this, NLR has carried out water-pond flight testing with the NLR/TUD Cessna Citation research aircraft to assess braking performance of modern aircraft and tyres on water covered runways. Airbus Military performed the same test using an A400M. Both tests took place using the water-pond facility of NLR. Aircraft operating on runways that are contaminated by standing water or slush (> 3 mm, up to the AFM limit) are significantly affected in take-off and landing performance. Most data available today is bases on test carried out in the 60s and 70s of the last century. Improved aircraft braking systems and tires were only tested at small scale in recent years.
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    NLR’s experience with flight testing on wet and flooded runways
    (Society of Flight Test Engineers, 2017-09) Es, G.W.H. van ; Koks, P.
    Braking performance of aircraft is affected whenever a runway is wet or flooded. Aircraft manufacturers do wet runway braking tests during the certification of a civil transport aircraft. These are normally limited to tests on smooth runways. Additional tests are sometimes conducted on wet grooved or porous friction course runways when the manufacturer seeks for additional stopping performance credit for such runways. Braking tests on flooded runways are not conducted during certification. In the past such tests have been conducted in research programmes on runway friction. The Netherlands Aerospace Centre NLR has conducted braking tests on a highly textured runway under wet and flooded conditions. The wet runway tests were conducted to demonstrate an equivalent performance of the test surface with grooved and porous friction course runways under wet conditions. The flooded tests were conducted as part of an European Research project on the prevention of runway excursions. All tests were conducted in the autumn of 2016 at a former Air Force base in the Netherlands (Twente Airport). This paper discusses in detail the preparation, logistics, and execution of the flight tests conducted with NLR’s Cessna Citation test aircraft. The use of large water trucks to wet the runway and the construction of a water pond to conduct the flooded runway tests is discussed in detail. Difficulties encounter during the preparation and execution of the flight tests are briefed and finally lessons learned are shared with the reader.
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    A clustered and surrogate-based MDA use case for MDO scenarios in AGILE project
    (AIAA, 2018) Lefebre, T. ; Bartoli, N. ; Dubreuil, S. ; Panzeri, M. ; Lombardi, R. ; Lammen, W.F. ; Mengmeng, Z. ; Gent, I. van ; Ciampa, P.D.
    In this paper methodological investigations regarding an innovative Multidisciplinary Design and Optimization (MDO) approach for conceptual aircraft design are presented. These research activities are part of the ongoing EU-funded research project AGILE. The next generation of aircraft MDO processes is developed in AGILE, which targets significant reductions in aircraft development cost and time to market, leading to cheaper and greener aircraft solutions. The paper introduces the AGILE project structure and recalls the achievements of the first year of activities where a reference distributed MDO system has been formulated, deployed and applied to the design and optimization of a reference conventional aircraft configuration. Then, investigations conducted in the second year are presented, all aiming at making the complex optimization workflows easier to handle, characterized by a high degree of discipline interdependencies, multi-level processes and multi-partner collaborative engineering activities. The paper focuses on an innovative approach in which knowledge-based engineering and collaborative engineering techniques are used to handle a complex aircraft design workflow. Surrogate models replacing clusters of analysis disciplines have been developed and applied to make workflow execution more efficient. The paper details the different steps of the developed approach to set up and operate this test case, involving a team of aircraft design and surrogate modelling specialists, and taking advantage of the AGILE MDO framework. To validate the approach, different executable workflows were generated automatically and used to efficiently compare different MDO formulations. The use of surrogate models for clusters of design competences have been proved to be efficient approach not only to decrease the computational time but also to benchmark different MDO formulations on a complex optimization problem.
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    Low-Frequency Analysis of Multiconductor Transmission Lines for Crosstalk Design Rules
    (IEEE, 2018-09-18) Lansink Rotgerink, Jesper ; Schippers, Harmen ; Leferink, Frank
    For early risk assessment in the design of cabling in an aircraft, as well as cable bundle optimization, efficient crosstalk estimations, and dependency of crosstalk with respect to designable parameters are required. A low-frequency technique for analyzing crosstalk in multiconductor transmission lines is presented. The result of this analysis is a closed-form expression for crosstalk in a specific cabling configuration. The technique has been validated via measurements and is used in two examples comprising two wire pairs close to a ground plane and in free space. Low-frequency closed-form expressions for near-end crosstalk are derived for both situations, which directly relate any designable parameter to crosstalk levels. Moreover, these expressions clearly show differences between the cases with and without a ground plane. Specifically, with the ground plane, the decrease in crosstalk when doubling the separation distance is 24 dB for pairs close to the ground, while it is 12 dB in free space. The closed-form expressions are utilized to create an overview of sensitivities of crosstalk to all designable parameters for both configurations. Finally, the low-frequency approximations of the chain parameters are applied to more complex nonuniform transmission lines, yielding more than 20 times faster computations when compared with complete MTL simulations.
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    Learning curve: interpreting the results of four years of safety culture surveys
    (Flight Safety Foundation, 2018-12) Kirwan, B. ; Reader, T. ; Parand, A. ; Kennedy, R. ; Bieder, C. ; Balk, A.
    Safety culture is seen as a pillar of aviation safety and is a cornerstone in both the International Civil Aviation Organization’s and the European Aviation Safety Agency’s (EASA’s) safety management system (SMS) models. But what does this mean in practical terms? For aviation organizations, is there something credible, tangible and manageable they can work with, or is this simply meant to be an inspirational goal?
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    Soap bubbles for large-scale PIV in industrial wind tunnels
    (Universität der Bundeswehr München, 2019) Engler Faleiros, D. ; Tuinstra, Marthijn ; van Rooijen, Bart D. ; Scarano, F. ; Sciacchitano, A.
    This work evaluates the use of helium-filled soap bubbles (HFSB) for Particle Image Velocimetry (PIV) measurements at high Reynolds numbers (up to 3.2 million) in aeronautics. The measurements are performed in the Low Speed Tunnel (LST) of the German-Dutch Wind Tunnels (DNW) using a high-lift airfoil in close-to-stall conditions up to 70 m/s. Experiments using Di-ethylhexyl- sebacat (DEHS) particles are performed for a comparison of the two seeding techniques. The signal to noise ratio of HFSB images was two orders of magnitude larger than that of DEHS, which strongly reduced the unwanted effects of background reflections and light intensity spatial variations, compared to DEHS particle images. The mean velocity field obtained with HFSB exhibits differences typically within 1% of the free stream velocity, when compared to DEHS measurements.
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    Advancing safety in organisations: application via the Luton Safety stack
    (MATEC Web of Conferences, 2019) Smeltink, J. ; Stroeve, S. ; Kirwan, B.
    Controlling and improving safety in organisations is achieved using a Safety Management System (SMS). Notwithstanding the variety of components considered in SMS standards, including human factors and safety culture, safety management systems are sometimes observed by those at the ‘sharp end’ as being bureaucratic, distinct from actual operations, and being too focused on the prevention of deviations from procedures, rather than on the effective support of safety in the real operational context. The soft parts of advancing safety in organisations, such as the multitude of interrelations and the informal aspects in an organisation that influence safety, are only considered to a limited extent in traditional safety management systems. The research in Future Sky Safety Project 5 (FSS P5) focused on improving these human-related, informal organisational aspects. Since every organisation is unique, in the operations it conducts, its history, and its organisational culture, there cannot be a one-size-fits-all standard for advancing safety in organisations. Rather, this needs to be based on the organisation at hand, leading to tailored solutions. This has been applied to a safety culture assessment and enhancement approach applied for six key organisations at London Luton Airport, and the approach has become known as the Luton Safety Stack. The six organisations decided to share the detailed results of their individual safety culture assessments. They formed a group that holds quarterly meetings, which always include a workshop element. From this approach, the organisations were stimulated to develop harmonised procedures for all ground-handling operators at Luton, and for each operation, creating a simple one-page procedure with diagrams, to keep it simple and safe. The Luton Safety Stack shows that when organisations share a place, such as at an airport, they need the opportunity to meet to discuss both potential safety threats, and opportunities to advance safety, because even through organisations are interdependent, safety issues in one organisation often have implications for others.
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    Wind tunnel flutter testing on a highly flexible wing for aeroelastic validation in the transonic regime within the HMAE1 project
    ( 2019-06) Govers, Yves ; Mai, Holger ; Arnold, Juergen ; Dillinger, Johannes K.S. ; Pereira, Allan K.A. ; Breviglieri Jr., Carlos ; Takara, Edgard K. ; Correa, Manoela S. ; Mello, Olympio A.F. ; Marques, Rodrigo F.A. ; Geurts, E.G.M. ; Creemers, R.J.C. ; Timmermans, H.S. ; Habing, R. ; Kapteijn, K.
    The aircraft manufacturer Embraer, the German Aerospace Center (DLR), the Netherlands Aerospace Centre (NLR) and German–Dutch Wind Tunnels (DNW) have tested an innovative highly flexible wing within an aeroelastic wind tunnel experiment in the transonic regime. The HMAE1 project was initiated by Embraer to test its numerical predictions for wing flutter under excessive wing deformations in the transonic regime. A highly elastic fiberglass wingbody pylon nacelle wind tunnel model (see Figure 1), which is able to deform extensively, was constructed for the experiment. The model was instrumented with a large number of pressure orifices, strain gauges, stereo pattern recognition (SPR) markers and accelerometers. The wing was tested from Ma = 0.4 to Ma = 0.9 for different angles of attack and stagnation pressures. The static and dynamic behavior of the wing model was monitored and a new method to analyze its eigenfrequencies and damping ratios was used. In the past, the large amounts of data acquired during such experiments could only be evaluated with a time lag. An efficient method developed by DLR now allows performing the data analysis in real time [1, 2]. As a result, it was possible during the test to identify exactly which safety margins remained before the onset of flutter and the resulting possible destruction of the model.
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    Design and validation of a numerical high aspect ratio aeroelastic wind tunnel model (HMAE1)
    ( 2019-06) Timmermans, H.S. ; Tongeren, J.H. van ; Geurts, E.G.M. ; Marques, R.F.A. ; Correa, M.S. ; Waitz, S.
    The aircraft manufacturer Embraer, the German Aerospace Center (DLR), the Netherlands Aerospace Centre (NLR) and German–Dutch Wind Tunnels (DNW) have tested an innovative highly flexible wing within an aeroelastic wind tunnel experiment in the transonic regime. The HMAE1 project was initiated by Embraer to test its numerical predictions for wing flutter under excessive wing deformations in the transonic regime. A highly elastic fiberglass wing-body pylon nacelle wind tunnel model, which is able to deform extensively, was constructed for the experiment. The model was instrumented with a large number of pressure orifices, strain gauges, stereo pattern recognition markers and accelerometers. The wing was tested from M = 0.4 till M = 0.9 for different angles of attack and stagnation pressure. The HMAE1 model was tested in two different test campaigns in which the Mach number was increased. This paper will focus on the first test campaign of the HMAE1 project in which the windtunnel model is tested up to M = 0.7 and will describe the development of the physical numerical structural dynamic MSC Nastran model representing the manufactured windtunnel model in order to perform numerical aeroelastic analyses.
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    A Large-Scale European Union Study of Aircrew Fatigue During Long Night and Disruptive Duties
    (Aerospace Medical Association, 2020) Dijk, H. van ; Maij, A. ; Sallinen, M. ; Aeschbach, D. ; Akerstedt, T.
    We examined aircrew fatigue during the following flight duty periods (FDPs) mentioned in the European Union (EU) Flight Time Limitations (FTLs): night FDPs longer than 10 h and FDPs typical of disruptive schedules (early starts, late finishes, and nights). An alternative way of classifying night FDPs was also examined to reveal possible subcategories that warrant special attention.
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    CLAIRPORT - Environmental impact assessments at airport level in Clean Sky 2 TE
    (CEAS, 2021) Eenige, M.J.A. van
    Building on the first Clean Sky Programme, the Clean Sky 2 Programme aims to make a substantial contribution to the ACARE 2050 environmental goals by accelerating the introduction of new aircraft technology in the timeframe 2025-2035. Cross-positioned within this programme, the Technology Evaluator is a dedicated evaluation platform with the key role of assessing the environmental impact of technologies developed in Clean Sky 2 and their level of success towards these ACARE environmental goals. It conducts assessments at three complementary levels: aircraft, airport, and air-transport system level. This paper addresses the environmental-impact assessment at airport level for fixed-wing aircraft, as performed in the CLAIRPORT project.
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    New Generation of Counter UAS Systems to Defeat of Low Slow and Small (LSS) Air Threats
    (NATO, 2021) Dominicus, J.W.
    Detecting, classifying, identifying, tracking and defeating low, slow and small air threats presents a major challenge for existing sensor and effector systems. So-called first generation C-UAS systems often rely on detecting the datalink from the controller to the drone which provides limited capability against current threats. However, this means of detecting drones is a challenge when operators manipulate standard datalinks and will not work at all against current and future autonomous drones. Other current methods of detecting and neutralising drones include for example combining radar with optical sensors. These systems are not always reliable, can generate large numbers of false alerts and are often manpower intensive to operate. The NATO SCI-301 Research Task Group (RTG) has been working on specifying what second generation C-UAS systems should entail. The paper will outline the findings of this RTG over the past three years.
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    Icing characteristics on NGCTR engine inlet for relevant certification conditions
    (ERF, 2021) Hoff, S.C. van 't ; Ven, H. van der ; Norde, E. ; Spek, F. ; Weide, E. van der
    Rotorcraft engine air intakes are known to be particularly sensitive to inflight and ground icing and snow conditions. To allow early identification of geometrical features of the inlet that are sensitive to ice accumulation, the design can benefit from early icing analyses through numerical methods. This paper is focused on the icing assessment and optimisation of the engine intake duct of the Next Generation Civil Tilt Rotor (NGCTR) which is being developed by Leonardo Helicopters. Results for catching efficiency and water catch rates are presented for test cases that have been defined with respect to the operational envelope of the NGCTR and the requirements for atmospheric icing as defined in the EASA certification specifications for large aeroplanes, large rotorcraft and engines. It was found that both the water catch rate and the total water catch are lower for the NGCTR in conversion flight compared to the NGCTR in airplane flight conditions. Additionally, ground operations of the NGCTR are not found to be critical for icing in/on the engine inlet due to supercooled droplets.
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    Performance Based Training : White Paper for RNLAF
    (Netherlands Aerospace Centre NLR, 2021) Nabben, A.C. ; Benthem, G.J. van ; Pal, J. van der ; Eaglestone, J.
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    Advanced landing gear fibre Bragg grating sensing and monitoring system
    ( 2022) Grooteman, F.P. ; Goutagny, R. ; Davies, C. ; Leest, T. van ; Platt, I. ; Symons, J.
    In this paper an advanced optical-based landing gear load sensing and monitoring system is presented. The system measures strains using fibre Bragg grating sensor that are converted into loads and torque at the landing gear wheels and provides this data for use by the aircraft systems for integration with aircraft health monitoring, hard landing detection, flight management, flight controls and ground controls. A complete sensing system was developed in the European Union Clean Sky 2 Joint Technology Initiative Advanced Landing Gear Sensing and Monitoring (ALGeSMo), described herein. This involved: the integration of optical fibres into a composite structure, the development of an optical harness (cabling and connectors) meeting aircraft installation requirements, the readout of the optical fibre sensors with state-of-the-art miniature optoelectronics and the processing and communication of the data. Apart from specific tests on the various components, a bespoke test rig was developed to rigorously test the whole sensing and monitoring system on an A320 main landing gear slider tube to validate the performance of the system. The system-level tests performed on the test rig showed a very good correlation with applied actuator loads and additional conventional strain and temperature sensors. It demonstrates that loads along all three axis of the landing gear and the torque about the wheel axle can be accurately measured. Tests performed at cold and elevated temperatures, however, revealed that the generally applied one-dimensional temperature compensation equation is not accurate enough for this application, due to the non-uniform non-stationary temperature field. The ALGeSMo research activities have advanced the state of the art in several key areas for the deployment of optical sensing systems for safety-critical applications, such as integration of optical fibres into composite material, robust optical connections, avionic-compliant optical interrogator and landing gear load measurement up to technology readiness level technology readiness level 5.
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    Metropolis II: Investigating the Future Shape of Air Traffic Control in Highly Dense Urban Airspace
    (IEEE, 2022) Patrinopoulou, N. ; Daramouskas, I. ; Lappas, V. ; Kostopoulos, V. ; Morfin Veytia, A. ; Badea, C.A. ; Ellerbroek, J. ; Hoekstra, J. ; Vries, V.J.F. de ; Ham, J.M. van ; Sunil, E. ; Menéndez-Ponte Alonso, P. ; Pedrero Gonzalez, J. ; Bereziat, D. ; Vidosavljevic, A.
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    Towards Innovative Ways to Assess Annoyance
    (Springer, 2022) Lavandier, C. ; Aalmoes, R. ; Dedieu, R. ; Marki, F. ; Grossarth, S. ; Schreckenberg, D. ; Gharbi, A. ; Kotzinos, D.
    Technological changes have driven the developments in the field of noise annoyance research. It helped to increase knowledge on the topic substantially. It also provides opportunities to conduct novel research. The introduction of the internet, the mobile phone, and miniaturisation and improved sensor technology are at the core of the three research examples presented in this chapter. The first example is the use of a Virtual Reality simulation to evaluate aircraft flyovers in different environments, and it examines how visual perception influences noise annoyance. The second example describes the use of a mobile application applying an Experience Sampling Method to assess noise annoyance for a group of people living near an airport. The third and final example is a study over social media discussions in relation to noise annoyance and quality of life around airports. These three examples demonstrate how novel technologies help to collect and analyse data from people who live around airports, and so improve our understanding of the effect of noise on humans.
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