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    A challenging high-end data acquisition system in a harsh wind tunnel environment at high rotational speed
    (3AF, 2023) Bardet, S.M. ; Zutphen, W.J.C.M. van ; Fontaine, F.M. ; Faasse, P.R.
    NLR developed an advanced, high-performance data acquisition system for a generic engine test rig. The test rig is intended for wind tunnel use. The RDAS and MDAS subsystems are bespoke developments, supporting a total of 120 rotating and almost 700 stationary measurement channels. All measurements are made under harsh environmental conditions: wide temperature range and high vibration levels. The rotating section tolerates rotation up to 16,000 rpm.
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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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    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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    An Assessment of STPA as Applied to the Scaled Flight Demonstrator Test Program
    (SFTE, 2024) MacCafferty, J.P. ; Bumgardner, W.R.
    Systems Theoretic Process Analysis (STPA) is a methodology for system development and safety assessment which builds on the System-Theoretic Accident Model and Processes (STAMP) causality model which approaches safety as a dynamic control problem. The STPA methodology addresses system analysis and safety assessment for systems that involve complex human interactions and high degrees of coupling. The purpose of this paper is to demonstrate the application of STPA to the remotely piloted Scaled Flight Demonstrator (SFD) aircraft test program, and assess the effectiveness for test planning and risk assessment relative to the traditional Test Hazards Analysis (THA) process. The SFD aircraft is a 1:8.5 scaled model of the Airbus A320 which has been modified into a distributed electric propulsion (DEP) configuration. The aircraft was developed in collaboration with members of the Clean Sky 2 program: The Royal Netherlands Aerospace Centre (NLR), Technische Universiteit Delft (TU Delft), The Office national d'études et de recherches aérospatiales (ONERA), Centro Italiano Ricerche Aerospaziali (CIRA), Airbus, and Orange Aerospace. This effort identifies multiple benefits for flight testers when applying STPA to a highly complex system, including: increased knowledge of the system under test, forced collaboration between the test team and system experts, and identification of risks and mitigations that may otherwise be missed. The team also identifies some drawbacks to applying STPA, including: the time investment required to learn and apply the process, and the challenge in identifying specific hardware or software failure modes. Lessons learned and recommendations are presented to help other flight test professionals determine how and when STPA can best be applied to their programs in the future.
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    Assessment of the cooperation between driver and vehicle automation: A framework
    (Elsevier, 2023) Tinga, A.M. ; Petermeijer, S.M. ; Reus, A.J.C. de ; Jansen, R.J. ; Waterschoot, B.M. van
    As long as the human driver is responsible for part(s) of the driving task during automated driving, the driver and automated driving system are sharing the driving task. Such a shared task is characterized by shared control, in which cooperation between the driver and vehicle automation is essential. However, means to holistically assess the quality of this cooperation are currently lacking. This work addresses how cooperation between driver and vehicle automation can be operationalized and assessed to gain insight into the quality of the shared driving task. Quality indicators and measurement methods are identified across seven dimensions reflective of the quality of cooperation between driver and automation. Based on previous empirical and theoretical studies a total of 34 quality indicators are identified. The methods to measure these quality indicators fall into four categories: 1) Subjective (such as questionnaires); 2) behavioral (such as reaction times, steering response); 3) neurophysiological (such as heart rate and pupil size); and 4) heuristic evaluation. The result is a first step in the development of a framework for the quantitative assessment of cooperation in the shared driving task. Yet, important knowledge gaps remain. For instance, the exact contribution of each quality indicator and their exact interrelationship are currently unclear. Moreover, all quality indicators reflect a requirement that should be met. Further research is needed to define exactly when each requirement is met. Additionally, it should be established to what degree each measurement method can validly and reliably provide insight into their quality indicator. Therefore, to ultimately ensure valid and reliable application of the framework in practice, the framework should continue to be developed and improved upon in future work.
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    Attention Guidance for Tower ATC using Augmented Reality Devices
    (IEEE, 2022) Teutsch, J. ; Bos, T.J.J. ; Apeldoorn, M.C. van ; Camara, L.
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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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    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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    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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    Concept Evaluation of Radical Short–Medium-Range Aircraft with Turbo-Electric Propulsion
    (MDPI, 2024) Vankan, W.J. ; Lammen, W.F. ; Scheers, E. ; Dewitte, P.A.R. ; Defoort, S.
    Ambitious targets for the coming decades have been set for further reductions in aviation greenhouse gas emissions. Hybrid electric propulsion (HEP) concepts offer potential for the mitigation of these aviation emissions. To investigate this potential in an adequate level of detail, the European research project IMOTHEP (Investigation and Maturation of Technologies for Hybrid Electric Propulsion) explores key technologies for HEP in close relation with developments of aircraft missions and configuration. This paper presents conceptual-level design investigations on radical HEP aircraft configurations for short–medium-range (SMR) missions. In particular, a blended-wing-body (BWB) configuration with a turbo-electric powertrain and distributed electric propulsion is investigated using NLR’s aircraft evaluation tool MASS. For the aircraft and powertrain design, representative top-level aircraft requirements have been defined in IMOTHEP, and the reference aircraft for the assessment of potential benefits is based on the Airbus A320neo aircraft. The models and data developed in IMOTHEP and presented in this paper show that the turbo-electric BWB configuration has potential for reduced fuel consumption in comparison to the reference aircraft. But in comparison to advanced turbofan-powered BWB configurations, which have the same benefits of the BWB airframe and advanced technology assumptions, this potential is limited. Keywords: hybrid electric propulsion; HEP; turbo-electric; blended-wing-body; energy efficiency
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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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    Design of a Tiltrotor Semi-Span Wind Tunnel Model for Whirl Flutter Investigations
    (Netherlands Aerospace Centre NLR, 2023) Hoff, S.C. van 't ; Vilsteren, J.G. van ; Cocco, A. ; Masarati, P.
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    Development of a production approach to build a titanium flaperon rib by directed energy deposition
    (Netherlands Aerospace Centre NLR, 2022) Montero - Sistiaga, M.L. ; Haagsma, R.L. ; Osinga, T. ; San Martin, U. ; Smit, M.J. de ; Nijhuis, P.
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    Enabling Technologies for the Navigation and Communication of UAS Operating in the Context of BVLOS
    (MDPI, 2024) Politi, E. ; Purucker, P. ; Larsen, M. ; Reis, R.J. Dos ; Rajan, R.T. ; Penna, S.D. ; Boer, J.F. ; Rodosthenous, P. ; Dimitrakopoulos, G. ; Varlamis, I.
    Unmanned Aerial Systems (UAS) have rapidly gained attraction in recent years as a promising solution to revolutionize numerous applications and meet the growing demand for efficient and timely delivery services due to their highly automated operation framework. Beyond Visual Line of Sight (BVLOS) operations, in particular, offer new means of delivering added-value services via a wide range of applications. This "plateau of productivity" holds enormous promise, but it is challenging to equip the drone with affordable technologies which support the BVLOS use case. To close this gap, this work showcases the convergence of the automotive and aviation industries to advance BVLOS aviation for UAS in a practical setting by studying a combination of Commercial Off-The-Shelf (COTS) technologies and systems. A novel risk-based approach of investigating the key technological components, architectures, algorithms, and protocols is proposed that facilitate highly reliable and autonomous BVLOS operations, aiming to enhance the alignment between market and operational needs and to better identify integration requirements between the different capabilities to be developed. Keywords: UAS; UAVs; BVLOS; communication systems; autonomous navigation
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    Engaging Communities in the Hard Quest for Consensus
    (Springer, 2022) Heyes, G. ; Hauptvogel, D. ; Benz, S. ; Schreckenberg, D. ; Hooper, P. ; Aalmoes, R.
    Mistrust, negative attitudes and the expectation of not having any voice against airport authorities can considerably impact on the perception of aircraft noise exposure, lead to increased annoyance and can even influence sleep quality of the noise affected residents. As a result, quality of life can reasonably be assumed to be reduced. This chapter focuses on measures to engage airport communities in aviation-related decision making by improving the information and communication of airports in order to enhance residents’ ‘competence’ and also trust in the airport noise authorities. The role of non-acoustical factors, including aviation-related media coverage in this process, is discussed and results from a media coverage analysis conducted in the ANIMA project are presented. Based on research on perceived fairness in communication, recommendations are given as to how to communicate and engage residents with the aim of building a neighbourly relationship between airport authorities and residents on an even footing and, thus, enable an improved exchange leading to deeper understanding and comprehension by both parties. Results from the ANIMA review on airport management strategies (including communication and engagement aspects) of several European airports are presented and conclusions are drawn about what characterises good (or bad) communication and community engagement strategies for the purpose of a neighbourly relationship between the airport and its residents.
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    Environmental-impact assessments at airport level of Clean Sky 2 technologies
    (IOPscience, 2023) Eenige, M.J.A. van ; Ommeren, T.E. van
    GREENPORT2050 is a project within Clean Sky 2 Technology Evaluator. Its objective is to assess the environmental impact up to 2050 at airport level of technologies developed in the Clean Sky 2 Programme for fixed-wing aircraft. With these assessments, it complements the environmental-impact assessments of those technologies at the other two levels in Clean Sky 2 Technology Evaluator: aircraft and air-transport system level. This paper provides an overview of the systematic approach for airport-level assessments in GREENPORT2050 and of the indicators to quantify impacts in these assessments.
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    Evaluating the climate impact of aviation emission scenarios towards the Paris agreement including COVID-19 effects
    (Springer Nature, 2022) Grewe, V. ; Rao, A.G. ; Gronstedt, T. ; Xisto, C. ; Linke, F. ; Melkert, J. ; Middel, J. ; Ohlenforst, B.A. ; Blakley, S. ; Christie, S. ; Matthes, S. ; Dahlmann, C.
    Aviation is an important contributor to the global economy, satisfying society’s mobility needs. It contributes to climate change through CO2 and non-CO2 effects, including contrail-cirrus and ozone formation. There is currently significant interest in policies, regulations and research aiming to reduce aviation’s climate impact. Here we model the effect of these measures on global warming and perform a bottom-up analysis of potential technical improvements, challenging the assumptions of the targets for the sector with a number of scenarios up to 2100. We show that although the emissions targets for aviation are in line with the overall goals of the Paris Agreement, there is a high likelihood that the climate impact of aviation will not meet these goals. Our assessment includes feasible technological advancements and the availability of sustainable aviation fuels. This conclusion is robust for several COVID-19 recovery scenarios, including changes in travel behaviour.
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    Hybrid inspection method using 3 dimensional scanning, lock-in thermography and laser shearography
    (NDTnet, 2024) Jansen, H.P. ; Platenkamp, D.J. ; Hwang, J.S.
    The proportion of composite materials (such as CFRP) to the metal used on the modern aircrafts is rising, imposing different kind of failure modes. Since the composite structures are known to be sensitive to the impact loading, there is need for means to assess the sub-surface damage in the structure rapidly. Royal Netherlands Aerospace Centre NLR has an extensive track record on contactless non-destructive inspection (NDI) methods based on optical sensors, such as 3D surface scanning, lock-in thermography and laser shearography. The combination of these methods (multi-domain inspection) enables us to assess the structural integrity of an aircraft outer surface in a short time, reducing inspection costs and the “down time” of the aircraft. Recently, NLR is working towards a 3D oriented mesh environment of an object, enhanced with NDI data, providing sub-surface damage information. By automatically stitching the 3D object images, it is possible to expand this method for a complete scan of an aircraft surface. Furthermore, the thermographic and shearography imaging information has been integrated into the 3D surface accounting for the image distortion from the different measurement angles. In this paper, the results from the various studies will be presented involving integration of the 2D measurements with the 3D scan mesh. Keywords: Thermography, Shearography, 3D scanning, Data fusion