Welcome to the NLR Reports Repository
Royal NLR conducts research, which is published in reports. Only a minor part of these reports is made public. This repository holds these public, so called Technical Publications (TP), mainly produced from 1996 up till now.
Technical publications published before 1996 may be obtained using the request-form. Other types of NLR-reports are Contract Reports (CR) and Technical Reports (TR), which in general are not public. You may however request a copy by using the request-form. In some cases permission may be granted, depending on specific properties and contractor of the report. Reports will be supplied as pdf-file.
Recent Submissions
Item type:Item, Promising First Deployments of Hydrogen-powered Aircraft Operations in the European Commercial Flight Network(NLR, 2026) Scheers, E.; Andringa, J.Y.Airlines require assurance of adequate infrastructure at airports before investing in hydrogen aircraft, while airports require confirmation of long-term airline commitments before investing in hydrogen infrastructure as both airlines and airports operate with small profit margins, creating a "chicken-or-egg problem". This challenge extends beyond airlines and airports alone, encompassing, amongst others, OEMs, hydrogen fuel suppliers, land-side supply chains, land-use planners and regulatory bodies. To address part of this stalemate, this study presents a methodology to identify promising origin-destination airport pairs for early deployment of hydrogen-powered aircraft operations in the European commercial flight network. The airport pair suitability is quantified using compatibility with the hydrogen TRANSCEND aircraft range and seat capacities, proximity to hydrogen infrastructure, potential number of hydrogen flights, effect on passenger volume, available airport area, production costs of hydrogen, availability of renewable electricity, and commitment of airlines and airports to hydrogen operations. The outcome of this study is a concise ranking of European origin-destination pairs, with comprehensive scorecards detailing their suitability for hydrogen operations across various criteria. The study identified ESSA-LFPG (Stockholm Arlanda Airport – Charles de Gaulle Airport) as the top-ranked origin-destination pair for hydrogen aircraft operations in the 2035 scenario using the TRANSCEND aircraft, while EETN-EVRA (Tallinn Airport – Riga International Airport) emerged as the best pair in the 2040 scenario, with routes from and to EHAM (Amsterdam Schiphol Airport) also featuring prominently in the top 10. The analysis is based on the 2023 flight network without adapting routes or demand to reflect the introduction of hydrogen aircraft. The methodology prioritises compatibility between airport pair flights and TRANSCEND aircraft characteristics and impacts on airline passenger-revenue-kilometre values when transitioning to hydrogen flights. The study demonstrated that the suitability of airport pairs depends on complex interaction of the identified factors, highlighting that there is no one-size-fits-all solution. This research is intended as a foundation for future evaluation that can inform relevant potential investments, ultimately contributing to addressing the chicken-or-egg problem in hydrogen aircraft adoption.Item type:Item, Developing a Qualification and Testing Framework for Cold Spray Repairs in Aerospace Applications(MDPI, 2026) Stamoulis, K.; Abouhamzeh, M.; Bosma, G.A.; Anderiessen, L.; Pascoe, J.-A.Cold spray is a solid-state deposition technology with great potential for coating and repair applications. This study examines the compliance of the cold spray repair process with a qualification and testing framework based on the requirements set by the European Union Aviation Safety Agency (EASA). As part of this effort, the case study of a repair of a Main Landing Gear (MLG) aluminium component is investigated to demonstrate the applicability of the proposed framework. This framework integrates mechanical and microstructural evaluations, including bond strength, hardness profiling and microstructural characterisation according to relevant ASTM and ISO standards. Experimental results from post-repair testing indicated promising performance, while ongoing testing is aligning reasonably with expected benchmarks and showing compliance with the EASA requirements.Item type:Item, Human–AI Teaming in the Cockpit: From Theory to Practice(MDPI, 2026) Kox, E.S.; Rooij, J.M. van; Zon, G.D.R.; Kirwan, B.Crew Resource Management (CRM) in aviation is grounded in principles derived from human–human teamwork, such as the Big Five model of Teamwork (B5T). With the advent of AI-based systems, which could one day take on increasingly complex roles in the cockpit, it remains unclear whether these principles will remain applicable or risk becoming outdated. This study examines how human teamwork concepts translate to use-case-based human–AI collaboration. Five contemporary aviation human–AI teaming use cases are examined by two groups (four Human Factors experts and four professional pilots who are also CRM experts) using B5T and CRM as frameworks. Although the two expert groups are small and are reviewing use cases rather than observing actual pilot behaviour, these early findings suggest that teamwork (B5T) elements and CRM core competencies can be useful for identifying potential positive and negative impacts of AI-based systems on human teamworking, and hence operational risk. Candidate augmentations to B5T are identified to increase its adaptation to human–AI teaming system assessment, and preliminary new CRM training avenues are proposed to enable pilots to better accommodate future AI assistance in the cockpit.Item type:Item, Sizing Uncertainty in Time-of-Flight Diffraction by Monte Carlo Modeling(MDPI, 2026) Goto, D.T.; Volker, A.W.F.; Maljaars, J.This study provides a method to estimate of the sizing error of Time-of-Flight Diffraction (TOFD) using a calibration/inspection procedure and a TOFD instrument in accordance with ISO 10863 and ISO 16828. This estimate is based on Monte Carlo simulations using distributions of the underlying error sources. The objective is to estimate the distribution of the flaw height sizing error and to rank the factors affecting the sizing error in a TOFD inspection. The proposed method is demonstrated on a T-shaped carbon steel welded connection with wall thickness 40 mm and flaws with flaw height 5 mm from the back wall. This is a common detail in welded bridges and TOFD is a frequently used inspection technique for fatigue cracks in such a detail. This demonstration case poses two practical challenges. First, for some old bridges, there are no reference blocks of the same material for calibration. This could possibly lead to errors propagated from the calibration. Second, the practice of inspecting the weld by scanning parallel to the weld bead may result in uncertainty of the flaw location relative to the instrument midplane. We found that the errors propagated from calibration are irrelevant for the case of study, and the major contributors to the flaw height sizing error are the uncertainty in picking time-of-flight on the ultrasonic signal and the position of the flaw with respect to the midplane of the TOFD instrument. This last factor is also the main contributor to the systematic underestimation of the flaw height (95% sizing error interval of −1.1 mm in the considered inspection scenario).Item type:Item, Spare mental capacity is related to oxyhemoglobin concentrations (HbO) in the prefrontal cortex and heart rate (variability) : Exploring the relationship between changes in spare mental capacity and multimodal (psycho)physiological measurements in a multitask environment(SfNIRS, 2022) Miltenburg, M.P.G. van; Zon, G.D.R.; Mohr, T.Exploring the relationship between changes in spare mental capacity and multimodal (psycho)physiological measurements in a multitask environment.