Aft Section Research Articles

Hydrogen, medium-range airplane design optimization for minimal global warming impact

This paper focuses on the conceptual design optimization of liquid hydrogen aircraft and their performance in terms of climate impact, cash operating cost, and energy consumption. An automated, multidisciplinary design framework for kerosene-powered aircraft is extended to design liquid hydrogen-powered aircraft at a conceptual level. A hydrogen tank is integrated into the aft section of the fuselage, increasing the operating empty mass and wetted area. Furthermore, the gas model of the engine is adapted to account for the hydrogen combustion products. It is concluded that for medium-range, narrow-body aircraft using hydrogen technology, the climate impact can be minimized by flying at an altitude of 6.0 km at which contrails are eliminated and the impact due to NOx\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {NO}_{\ extrm{x}}$$\\end{document} emissions is expected to be small. However, this leads to a deteriorated cruise performance in terms of energy and operating cost due to the lower lift-to-drag ratio (– 11%) and lower engine overall efficiency (– 10%) compared to the energy-optimal solutions. Compared to cost-optimal kerosene aircraft, the average temperature response can be reduced by 73–99% by employing liquid hydrogen, depending on the design objective. However, this reduction in climate impact leads to an increase in cash operating cost of 28–39% when considering 2030 hydrogen price estimates. Nevertheless, an analysis of future kerosene and hydrogen prices shows that this cost difference can be significantly decreased beyond 2030.

Experimental and CFD Investigation of Directional Stability of a Box-Wing Aircraft Concept

This study aimed to explore the directional stability issues of a previously studied light box-wing aircraft model with a pusher propeller engine in the fuselage aft section. Earlier configurations have included the use of fuselage together with a lifting system consisting of two wings joined together at their wingtips with vertical stabilizers. However, these side vertical surfaces failed to provide the aircraft with sufficient directional stability, thus prompting the quest in this study for novel solutions that would exclude the need for a fuselage extension and a typical fin. Solutions included the use of a ducted propeller and few configurations of small “fishtail” vertical fins, which formed part of the aft fuselage itself and coupled with vortex generators on the fuselage surface to improve their interference and heal flow separation at the fuselage aft cone. The results of wind tunnel testing were supported with CFD simulations to explain the flow behavior of each of the studied solutions. Tuft visualization and computed flow patterns allowed identification of the sources of the observed low efficiency in terms of directional stability of the fishtail against a simple idle duct without a propeller. A final configuration with a duct and a modified version of the fuselage fins was achieved that provides enough yaw stability margins for a safe flight.

Magnetohydrodynamic Experiments of Total Heat Flux Mitigation for Superorbital Earth Reentry

A set of experiments was conducted with the aim of evaluating total heat flux mitigation using magnetohydrodynamic flow control over ionized shock layers surrounding planetary entry vehicles. The University of Queensland’s X2 expansion tube was used to generate a flow condition representative of a Mars return trajectory. Spherical permanent magnets were fitted into a scaled test model based on NASA’s Stardust capsule. Thermocouples located at the stagnation point and shoulder of the test model, as well as thin-film heat transfer gauges located in the aft section, measured total heat flux for both magnetic and nonmagnetic experiments. High-speed imaging of the shock layer showed a significant increase in shock standoff when using the magnet, and polynomial fits were derived, describing standoff distance along the model’s forebody. Despite significant noise affecting the heat flux gauges signals for the magnetic experiments, a simple methodology allowed to compare heat flux during the useful test time. It was found that the applied magnetic field significantly reduces total heat flux at the stagnation point and shoulder of the test model, although heat flux to the aft section was found to significantly increase. Reasonable agreement with the numerical predictions was found for the aft section of the test model, but discrepancies were observed at the other locations.

Numerical simulation of the flow around a simplified vehicle with an upswept aft section

Numerical simulation of the flow around a simplified vehicle with an upswept aft section

Detailed velocity and heat transfer measurements of an advanced insert for impingement cooling

This work reports the results of paired experiments for the aft section of a complex internal cooling flow within a gas turbine vane using Magnetic Resonance Velocimetry (MRV) and steady-state Infrared (IR) thermography. The aft cooling insert for the vane with two-pass impingement was designed at a scale five times larger than the original and built using stereolithography (SLA) fabrication methods. The MRV technique was used to measure the three-dimensional, three-component velocity field for a test case with a Reynolds number range of 2,600 to 7,600 based on diameter of the impingement holes. Flow distribution, impingement hole performance, and cross flow effects are discussed for the experiment in which a dilute aqueous copper sulfate solution was used as the working fluid. A paired experiment with a geometrically similar design employed electrical heating of a thin stainless steel shim to model a constant heat flux boundary condition of an interior wall of the turbine vane. The modeled vane insert was then operated with air as the working fluid at two test conditions with Reynolds numbers in the range of approximately 1,200 to 7,600 based on the diameter of the impingement holes. An IR camera was used to measure the surface temperature of the shim. Using energy balances and the known heat flux, the temperature data were used to determine heat transfer characteristics of the impinging jets for the pressure and suction side surfaces, including the Nusselt number. The MRV and IR data sets provide detailed insight into the surface effects of the flow distribution and the result on the local and area-averaged heat transfer performance. A strong coupling between the velocity field and temperature data provide insight into design feature performance, and serve as a validation data set for matched computational simulations. Finally, a comparison with internal heat transfer correlations is presented using the data from Florschuetz et al. [1]. The results showed a lack of agreement with Florschuetz, leading to the development of a novel methodology for estimating the heat transfer performance of an impinging hole with crossflow. Measurement uncertainty was estimated to be ±5% for velocity and ±5% for the spatially averaged Nusselt number distributions.

Assessing Boundaries of AI Planning Models of Human-Robot Collaborative Riveting Processes in Industry-Like Conditions

<div class="section abstract"><div class="htmlview paragraph">Riveting is an essential process for the pre-assembly as well as the final assembly of aircrafts. In many cases, the riveting process fails to be fully automated, for instance, in parts with complex geometries. Thus, manual riveting is still widely common. Several works have been carried towards semi-automatic riveting solutions, namely in riveting the section barrel of the aft section to its pressure bulkhead. In [<span class="xref">1</span>], a method of communication-free semi-automated riveting is proposed where a partially autonomous robot performs counter-holding while a human worker rivets. The method has been modeled and tested extensively in simulation. However, although a demonstration prototype has been developed, models have been tested on it curtly. This paper investigates experimental evaluation of different model variations on demonstration. The aim is to identify the boundaries of the method in real world conditions. Experimental setups are tailored similarly to the ones used in simulation for comparability purposes. Multiple riveting tests are carried out to assess the applicability of the solution in an industry-like environment. These tests allow online tracking of the worker-robot dynamic. Additionally, they quantify the impact this solution on both task ergonomics and efficiency in a semi-automated process with respect to a manual one.</div></div>

МЕТОД ВИЗНАЧЕННЯ ОСНОВНИХ ПАРАМЕТРІВ ВАНТАЖНОГО ЛЮКА В ХВОСТОВІЙ ЧАСТИНІ ФЮЗЕЛЯЖУ ЛІТАКІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

A method has been developed for determining principal parameters for aft cargo door of transport aircraft. A list of input data is given and a technique for finding them is described. An example based on an existing transport aircraft is considered. The following has been used as source data: basic cargo nomenclature to be transported by the designed aircraft, cargo overall dimensions and weight, methods of loading and mooring, loading facilities. More over the design, operational and regulatory parameters are needed, such as landing gear configuration, its bottoming system, extension of rails of the upper equipment for loading/unloading, cargo trajectories during loading and airdropping, codes of the international regulatory bodies such as FAR, CS, AP. Based on the source data, the principle of determining the dimensions of the cargo compartment, cargo floor and the loading sites in the form of a ramp with a pressure bridge, and air stairs is given. The relation between the ramp length and the cargo floor length is described taking into account the loading, unloading and air dropping operations. Correct calculation of these parameters is the most important task, because performance of the future transport aircraft directly depends on the solution. The technique of determining the cargo door opening, development of the load-bearing structure of the transport aircraft fuselage aft section, its main strong elements – the cargo door beam, the ramp, the attachment units, the ramp locks – is given. The interconnection of the ramp load-bearing structure with the load-bearing structure of the fuselage aft part, the options for transferring loads perceived by the ramp to the frame are described. Examples of two types – flat and volumetric – of the cargo door beams, as well as the method of their assignment are considered. Trajectories of the extreme points of the in-gauge load are determined using graphical method for loading, unloading, and airdropping operations. Taking into account the positions of these trajectories makes it possible to select the desired cutout in the fuselage aft section. While designing the aft cargo doors the main features are highlighted. These features when considered make it possible to determine the most optimal parameters of the cutout, the cargo door type and its components.

A Communication-Free Human-Robot-Collaboration Approach for Aircraft Riveting Process Using AI Probabilistic Planning

<div class="section abstract"><div class="htmlview paragraph">In large scale industries attempts are continuously being made to automate assembly processes to not only increase productivity but also alleviate non-ergonomic tasks. However this is not always technologically possible due to specific joining challenges and the high number of special-purpose parts. For the riveting process, for example, semi-automated approaches represent an alternative to optimizing aircraft assembly and to reduce the exposure of workers to non-ergonomic conditions entailed by performing repetitive tasks.</div><div class="htmlview paragraph">In [<span class="xref">1</span>], a semi-automated solution is proposed for the riveting process of assembling the section barrel of the aft section to its pressure bulkhead. The method introduced a dynamic task sharing strategy between human and robot that implements interaction possibilities to establish a communication between a human and a robot in Human-Robot-collaboration fashion. Although intuitive, interacting with the robot constantly is still not natural for the worker as in the manual process no explicit communication between both workers is needed.</div><div class="htmlview paragraph">In this work a communication-free Human-Robot-collaboration solution is presented. The method developed not only enables sharing assembly missions by dividing tasks based on skills, but also offers the possibility of decision making to the robot. In this context, off-the-shelf Artificial Intelligence planning tools are used to model the work-flow of the human as well as the task of the robot handling alongside possible uncertainties yielding while perceiving the environment or the activity of the human.</div></div>

Numerical Analysis of Sweeping Jets for Active Flow Control Application

Abstract It has become apparent recently that the fluidic oscillators, also known as sweeping jets, can be used to create a combination of steady (streamwise vortices) and unsteady (spanwise vortices) forcing mechanisms which have the potential to fulfill many of the promises of active separation control. The fluidic oscillators contain no moving parts, but produce an unsteady component via a natural feedback loop inherent to their geometry. The oscillations are entirely self-induced and self-sustaining. Their simple and robust design and their effectiveness over a wide range of flow conditions make them more attractive than other flow control devices, such as synthetic jets and plasma actuators. Figure 1 shows the instantaneous jet generated in quiescent environment using the Improved Delayed Detached Eddy Simulation (IDDES) model, where the Large Eddy Simulation (LES) branch of the IDDES model is able to capture the turbulence structures properly. An instantaneous iso-surface of vorticity magnitude, colored by streamwise velocity for flow over a wall-mounted hump is depicted in Figure 2. As expected, a massive flow separation occurs behind the hump in the uncontrolled condition (Figure 2 (a)), with a nearly two-dimensional free shear layer at the edge of the separation line. Breakdown of the shear layer by an array of sweeping jets located slightly downstream of the separation line is seen in Figure 2 (b), which is followed by the elimination of the separation region behind hump. The three-dimensional structures generated by the sweeping jets are smaller and closer to the hump wall than those produced by the steady jets shown in Figure 2 (c). Presence of a large region of reversed flow near the hump wall in its aft section is also seen in the case of the steady jet. This study indicates a superior effectiveness of sweeping jets on separated flows.

Long Voyage Home: Eugene O'Neill's Plays of the Sea

Long Voyage Home: Eugene O'Neill's Plays of the Sea

Effect of three different codend designs on the size selectivity of juvenile cod in the Barents Sea shrimp trawl fishery

Shrimp trawlers often use a Nordmøre sorting grid ahead of a small mesh codend to avoid bycatch of juvenile fish while allowing shrimps to be efficiently caught. However, small fish can pass through the grid to enter the codend and risk being retained. The risk of retention for fish of different sizes depends the size selection in the Nordmøre grid and the size selection in the subsequent codend, which makes the process complex and often results in a bell-shaped size selection curve. In the Barents Sea shrimp fishery, cod (Gadus morhua) is one of the species of concern because of its great commercial value. We studied the size selection of juvenile cod when the trawl was equipped with the compulsory gear in the fishery: a 19 mm Nordmøre grid followed by a 35 mm diamond mesh codend. As expected, the size selection curve showed a bell-shaped signature, with a certain size range of juveniles having high retention risk, while the risk for smaller and bigger cod was smaller. The retention risk was highest for cod between 12 and 20 cm in length. We also tested two alternative designs in the aft section of the gear: a codend with 35 mm square mesh panels and a square mesh sorting cone section. Neither of these designs affected the size selection in the trawl significantly.

Aqueous copper bioavailability linked to shipwreck-contaminated reef sediments

Pollution from the grounding or sinking of ships can have long lasting effects on the recovery and dynamics of coastal ecosystems. Research on the impact of copper (Cu) pollution from the 2011 MV Rena shipwreck at the Astrolabe Reef (Otaiti), New Zealand, 5 years after the grounding, followed a multi-method and multi-disciplinary approach. Three independent measures of aqueous Cu using trace-element-clean-techniques substantiate the presence of high total, total dissolved (<2 µm) and elevated bioavailable Cu in the water column immediately above the aft section of the wreck where the highest sedimentary load of Cu was located. Intermittently elevated concentrations of strong Cu-binding ligands occurred in this location, and their binding strength was consistent with ligands actively produced by organisms in response to Cu induced stress. The recruitment of benthic invertebrates was modified at the high-Cu location. Taxonomic groups usually considered robust to pollution were restricted to this site (e.g. barnacles) or were the most abundant taxa present (e.g. foraminifera). Our results demonstrate that Cu-contaminated sediments can impose a persistent point source of Cu pollution in high-energy reef environments, with the potential to modify the composition and recovery of biological communities.

Collaboration in a Hybrid Team of Human and Robot for Improving Working Conditions in an Aircraft Riveting Process

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Aircraft production is facing various technical challenges, such as large product dimensions, complex joining processes, and organization of assembly tasks. Overcoming such challenges, as well as maintaining low tolerances and small batch sizes, is often difficult to achieve whilst retaining economic viability.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;ZeMA believes that a semi-automated approach is the most effective way to optimize aircraft section assembly. This can be achieved with a semi-automated riveting process for solid rivets, using Human-Robot-Collaboration in combination with an intuitive Human-Machine-Interaction operating concept.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;In the assembly of aircraft structures - in this scenario the aircraft aft section - the pressure bulk head is mounted to the section barrel. Two operators work collaboratively in uncomfortable, non-ergonomic positions, yet of course have to maintain exacting quality standards. In order to improve this process, a dynamic task sharing strategy between human and robot according to their respective skills, with due consideration given to ergonomic factors is proposed. The ideal solution involves placing a robot inside the section barrel. The robot’s workspace is expanded by mounting it on top of a lifting unit so that it can position the anvil properly. In the meantime, the human performs the more complex tasks of inserting the solid rivets and operating the riveting hammer from outside the section barrel.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;In order to carry out the assembly tasks efficiently, the following components must be implemented: Human-Robot-Collaboration based on natural and intuitive interaction possibilities, and smart mixed reality devices for communication between human and robot in the hybrid team. By implementing a modular control system for configuration and operation of the assembly station with a variety of interaction possibilities, human and robot can perform the collaborative riveting process more efficiently than human operators alone. Additionally, due to the high forces and vibrations applied by the riveting hammer, a process-specific tool has been developed to prevent damage to the robot system. The implementation of natural and intuitive interaction within the Human-Robot-Collaboration achieves operator acceptance, improves ergonomics and therefore effectively optimizes aircraft production.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;The results are part of the European Union’s Horizon 2020 research and innovation program, and present semi-automation as shown in the HRC riveting process.&lt;/div&gt;&lt;/div&gt;

Tolerance Management in a Semi-Automated and Collaborative Human-Robot Aircraft Riveting Process

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Large aircraft sizes with high precision requirements combined with complex joining tasks are typical challenges for aircraft production. To increase competitiveness and effectiveness, the automation of such production processes seems a viable solution for companies in the aircraft sector. When implementing automation, in order to handle small batch sizes and high variation while adhering to tight tolerances, the production equipment must meet high quality standards and flexibility requirements.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;To achieve the objectives above, tolerance management is essential: deviations are acceptable within limits, as long as they do not result in quality losses and expensive rework. For these reasons, all the interactions between the product, production process and production equipment used must be analyzed in detail. The importance of this analysis is evident in assembly where new technologies are used, such as (semi-)automation using Human-Robot-Collaboration. Despite its innovative value, this approach must be robust, within tolerances and have minimal deviations from the outset. However, current planning and optimization of deviations and tolerances lack properly developed methods and approaches.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;This paper proposes a method for securing and achieving proper tolerance in assembly processes: characteristic trees and tolerance chains are simple methods to make tolerance management more effective and attractive. The method combination promotes understanding of interactions and communication between all those involved in the development of products and the associated processes.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;The methods developed are validated using a semi-automated riveting process, with Human-Robot-Collaboration, to complete a joining process in the assembly of the aft section. In this scenario the pressure bulkhead is mounted to the section barrel by means of hundreds of rivets. The intention is to implement a semi-automated production process to improve ergonomics, increase process traceability and efficiency, and minimize rework while meeting tolerance requirements.&lt;/div&gt;&lt;/div&gt;

Experimental and numerical analyses of wedge effects on the rooster tail and porpoising phenomenon of a high-speed planing craft in calm water

This paper presents experimental and numerical investigation of stability and rooster tail of a mono-hull high-speed planing craft with a constant deadrise angle. Initially, a one-fifth scale model was tested in a towing tank, which showed porpoising phenomenon at 8 m/s (equal to the speed of sailing). Subsequently, two wedges of 5 and 10 mm heights, based on the boundary layer calculations, were mounted on the aft section of the planing hull. These wedges were shown to increase the lift at the aft section. These experiments were carried out at different speeds up to 10 m/s in calm water. The experimental results indicated that the installed wedges reduced the trim, drag, and the elapsed time for reaching the hump peak, and also eliminated the porpoising condition. All these test cases were also numerically simulated using Star CCM+ software. The free surface was modeled using the volume of fluid scheme in three-dimensional space. The examined planing craft had two degrees of freedom, and overset mesh technique was used for space discretization. The obtained numerical results were compared with experimental data and good agreement was displayed in the presented comparisons. Ultimately, the effect of the wedge on the rooster tail behind the planing craft was studied. The results of this investigation showed that by decreasing the trim at a constant speed, the height of the generated wake profile (rooster tail) behind the craft decreases, albeit its length increases.

Experimental and Computational Analysis of Model–Support Interference in Low-Speed Wind-Tunnel Testing of Fuselage-Boundary-Layer Ingestion

Junction flow caused by the aerodynamic interaction between a wind-tunnel model and the support structure can largely influence the flowfield and hence the experimental results. This paper discusses a combined numerical and experimental study which was carried out to mitigate the model–support interference in a wind-tunnel test setup for the study of fuselage boundary-layer ingestion. The setup featured an axisymmetric fuselage mounted through a support beam, covered by a wing-shaped fairing. The junction flow appearing at the fuselage–fairing connection produced undesired flow distortions at the fuselage aft section, due to the formation of an horseshoe vortex structure at the fairing leading edge. Numerical and experimental analysis were performed with the aim of reducing the distortion intensity by improving the fairing design. Results show that modifying the leading-edge shape of the fairing effectively decreased the flowfield distortions. Moreover, the addition of a dummy fairing diametrically opposed to the first one was found to be beneficial due to the enhancement of the configuration symmetry.

Method for Designing Three-Dimensional Swept Hybrid Wings for Icing Wind-Tunnel Tests

Hybrid-wing models are those that present the same leading-edge geometry of the full-scale aircraft wing and a redesigned aft section of reduced chord, such that models can be tested inside an icing wind tunnel. When properly designed, these models reproduce the full-scale flowfield and ice accretions on the leading edge, with reduced tunnel blockage. Although a method exists for designing hybrid airfoils, no systematic method is available in the literature for designing hybrid swept wings. This paper presents a method for designing three-dimensional swept hybrid wings using hybrid airfoils for the purpose of generating full-scale ice accretions, such as those on large commercial aircraft, in icing wind tunnels. An application example using the method is shown for the design of three hybrid wings representing different wing stations of a modern commercial aircraft. Investigations of the effects of tunnel walls, model sweep angle, model aspect ratio, model thickness, and wind-tunnel blockage are also presented. Attachment-line location was used as a first-order parameter for matching full-scale ice shapes, following the findings of previous investigations on hybrid airfoils. Methods for controlling the spanwise variation of attachment line due to flow three-dimensionality were assessed with the use of angle of attack, gap between the model and tunnel wall, aerodynamic twist, and segmented flaps. Finally, model design tradeoffs are presented from the perspective of the hybrid-wing designer between competing performance parameters, such as level of agreement in matching full-scale attachment-line location, wind-tunnel load/speed limits, and model manufacturing/operational complexity.

Method for Designing Hybrid Airfoils for Icing Wind-Tunnel Tests

The certification of modern commercial aircraft requires manufacturers to demonstrate flight safety under various scenarios, including icing conditions. Although computational tools play a key role in icing-related aircraft design and certification, icing wind-tunnel testing remains an important part of the process. The size of models that can be tested is limited by the dimensions of the existing icing wind-tunnel facilities. To obtain ice accretions on full-scale aircraft wings in icing wind tunnels, scaling methods must be applied. One attractive option is the use of hybrid airfoils. Hybrid airfoils present the same leading-edge geometry of the full-scale airfoil but replace the aft section with a redesigned geometry of reduced chord. When properly designed, these models generate the full-scale ice accretion on the leading edge, with reduced blockage and aerodynamic loads. This paper presents an investigation of the effects of different design parameters on the performance of hybrid airfoils, identifies the key design parameters to generate full-scale ice shapes, and puts the research findings in perspective with overall model design tradeoffs.

Investigating fish behavioural responses to LED lights in trawls and potential applications for bycatch reduction in the Nephrops-directed fishery

AbstractLight-emitting diodes (LEDs) have been tested in trawl fisheries to reduce the bycatch of unwanted species through behavioural stimulation. Previous studies used LED lights to either highlight escaping routes or increase the contact rate with square-mesh panels. However, phototactic responses (moving towards or away from light sources) to LED lights could also be exploited to separate species during the catching process. We investigated if either positive or negative phototaxis can be used to improve fish vertical separation from Nephrops (Nephrops norvegicus) in the aft section of a horizontally separated trawl codend. The aim was to increase the proportion of fish entering the upper compartment. We conducted two different experiments in front of the separation into compartments, inserting green LED lights in the upper and lower netting panel, respectively. Species vertical separation was analysed and compared in two identical trawls towed in parallel, one equipped with lights and one without. We obtained significant changes in vertical separation, but no clear species-specific phototactic response was identified. Neither of the light positions improved fish separation from Nephrops. However, the potential of LED lights as behavioural stimulators is confirmed, and a more mechanistic understanding of light and fish vision may improve the results of future applications.

Progress in Optimizing the Propulsive Fuselage Aircraft Concept

As a novel approach toward the realization of synergistic airframe–propulsion system integration, the characteristics of a propulsive fuselage aircraft concept targeting entry-into-service year 2035 are discussed in this paper. In previous work, the concept of a boundary-layer ingesting propulsor encircling the aft section of an axisymmetric fuselage was identified to be particularly promising for attaining a noticeable reduction in required propulsive power. After presenting the basic features of the concept, the methodological approach used for the assessment of the highly integrated boundary-layer ingesting propulsion system is reviewed. Using this set of methods, several parametric design studies as presented that are suitable for discussing the system- and aircraft-level implications. In addition, a best-and-balanced design point is selected, and the sensitivities of important design parameters associated with the concept are highlighted, thereby allowing for performing a technology-based scenario analysis. To round off, the impact of varying design cruise speeds on aircraft key parameters is compared and contrasted to the characteristics of an advanced twin-engine reference aircraft.