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The purpose of this paper is to present a novel hybrid engine concept for a multi-fuel blended wing body (MFBWB) aircraft and assess the performance of this engine concept.

The proposed hybrid engine concept has several novel features which include a contra-rotating fan for implementing boundary layer ingestion, dual combustion chambers using cryogenic fuel (liquefied natural gas [LNG] or liquid hydrogen [LH2]) and kerosene in the inter-turbine burner (in flameless combustion mode) and a cooling system for bleed air cooling utilizing the cryogenic fuel. A zero-dimensional thermodynamic model of the proposed hybrid engine is created using Gas Turbine Simulation Program to parametrically analyse the performance of various possible engine architectures. Furthermore, the chosen engine architecture is optimized at a cycle reference point using a developed in-house thermodynamic engine model coupled with genetic algorithm.

Using LH2 and kerosene, the hybrid engine can theoretically reduce CO₂ emissions by around 80 per cent. Using LNG and kerosene, the CO₂ emissions are reduced by more than 20 per cent as compared to the baseline engine.

The hybrid engine is being investigated in the AHEAD project co-sponsored by the European Commission. This unique aircraft and engine combination will enable aviation to use cryogenic fuels like LH2 or LNG, and will make aviation sustainable.

The MFBWB concept and the hybrid engine is a novel concept which has not yet been investigated before. The potential implications of this technology are far reaching and will shape the future development in aviation.

The purpose of this paper is to analyze and compare the performances of novel roadable personal air vehicle (PAV) concepts that meet established operational requirements with different types of engines.

The vehicle configuration was devised considering the dimensions and operational restrictions of the roads, runways and parking lots in South Korea. A folding wing design was adopted for road operations and parking. The propulsion designs considered herein use gasoline, diesel and hybrid architectures for longer-range missions. The sizing point of the roadable PAV that minimizes the wing area was selected, and the rate of climb, ground roll distance, cruise speed and service ceiling requirements were met. For various engine types and mission profiles, the performances of differently sized PAVs were compared with respect to the MTOW, wing area, wing span, thrust-to-weight ratio, wing loading, power-to-weight ratio, brake horsepower and fuel efficiency.

Unlike automobiles, the weight penalty of the hybrid system because of the additional electrical components reduced the fuel efficiency considerably. When the four engine types were compared, matching the total engine system weight, the internal combustion (IC) engine PAVs had better fuel efficiency rates than the hybrid powered PAVs. Finally, a gasoline-powered PAV configuration was selected as the final design because it had the lowest MTOW, despite its slightly worse fuel efficiency compared to that of the diesel-powered engine.

Although an electric aircraft powered only by batteries most capitalizes on the operating cost, noise and emissions benefits of electric propulsion, it also is most hampered by range limitations. Air traffic integration or any safety, and noise issues were not accounted in this study.

Aircraft sizing is a critical aspect of a system-level study because it is a prerequisite for most design and analysis activities, including those related to the internal layout as well as cost and system effectiveness analyses. The results of this study can be implemented to design a PAV.

This study can contribute to the establishment of innovative PAV concepts that can alleviate today’s transportation problems.

This study compared the sizing results of PAVs with hybrid engines with those having IC engines.

The purpose of this paper is to demonstrate how opting for multiple contributors to the lowC economy and introducing new intelligent solutions allows a smooth transition to renewable fuels. Undoubtedly, biofuels are no longer everybody's darling. This is partly owed to the need to produce bio fuels at the lowest possible price and absent sustainability regulations or their enforcement like the European parliament initiated by banning bio fuels with not sufficient evidence of saving CO₂. But on the other hand, the end of cheap oil is clearly visible and it is clear that second generation lowC fuels may by no means be able to replace all of the worlds growing fuel consumption in a few years.

The paper presents a tri‐fold approach which has originated of two EU‐projects (SUGRE and RECODRIVE) based on reduction of the propulsion demand, intelligent powertrain configuration and the use of residues and waste as feedstock. The RECODRIVE approach tested in the European project with the same name introduces a quality management in fleet management which comprises procurement, driving and maintenance. This approach comprising also logistics should be able to reduce the propulsion demand at least by 10 per cent targeting 30 per cent and more.

Hybrid power trains are regenerating the braking energy and are reducing the propulsion demand by 15‐25 per cent in stop'n go traffic in cities. Parallel or power split hybrids may operate with phlegmatized and thus more efficient combustion engines, but serial hybrid electric power trains drive this characteristics, the extreme which is helpful introducing alternative fuels. They decouple the production of energy from the throttle command and allow for a more steady operation of the internal combustion engine.

By employing a serial hybrid power train simpler low‐RPM engines may be used which are modified to run on plant oils and other alternative fuels which are difficult to use in modern highly performing diesel engines. By reducing the propulsion demand, a higher share of alternative fuels based on natural feedstock may be achieved. This feedstock may be also amended by better utilising waste. The paper describes two examples. In Graz, used frying oil is collected to feed a transesterification plant and in Linköping waste from the meat industry is collected to produce biogas.

The approach enables the transport sector to increase the independence on oil at short‐term without the risk of putting a lot of venture capital in the wrong fuel or engine technology. The serial hybrid electric concept remains the basis for future solutions working on different end energy like hydrogen.

The limited energy density of batteries generates the need for high-performance power sources for emerging eVTOL applications with radical operational improvement potential over traditional aircraft. This paper aims to evaluate on-design and off-design recuperated turbogenerator performances based on newly developed compression loaded ceramic turbines, the Inside-out Ceramic Turbine (ICT), in order to select the optimum engine configuration for sub-megawatt systems.

System-level thermal engine modeling is combined with electric generators and power electronics performance predictions to obtain the Pareto front between efficiency and power density for a variety of engine designs, both for recuperated and simple cycle turbines. Part load efficiency for those engines are evaluated, and the results are used for an engine selection based on a simplified eVTOL mission capability.

By operating with high turbine inlet temperature, variable output speed and adequately sized recuperator, a turbogenerator provides exceptional efficiency at both nominal power and part load operation for a turbomachine, while maintaining the high power density required for aircraft. In application with a high peak-to-cruise power ratio, such power source would provide eight times the range of battery-electric power pack and an 80% improvement over the state-of-the-art simple cycle turbogenerator.

The implementation of a recuperator would provide additional gains especially important for military and on-demand mobility applications, notably reducing the heat signature and noise of the system. The engine low-pressure ratio reduces its complexity and combined with the fuel savings, the system could significantly reduce operational cost.

Implementation of radically new ICT architecture provides the key element to make a sub-megawatt recuperated turbogenerator viable in terms of power density. The synergetic combination of a recuperator, high temperature turbine and variable speed electric generator provides drastic improvement over simple-cycle turbines, making such a system highly relevant as the power source for future eVTOL applications.

Europe has adopted the Flight Path 2050 (FP2050) challenge demanding that by 2050, 90 per cent of the travelers are able to reach door-to-door destinations in Europe within four hours. A hypothesis can be formulated that without the Small Air Transport (SAT) system, optimized for short distances and for multiple but narrow passenger flows, this challenge cannot be met.

This paper defines design goals and necessary research focused on small aircraft concepts, as a required condition to fulfil the FP2050 challenge “90 per cent d2d 4h”.

The new small aircraft concepts have been defined as SAT Aircraft Family Program. Three demonstrators with common modules could be proposed: two using the same turboprop engine (first, one engine, 9 passengers; second, two engines, 19 passengers) and third demonstrator could be with a diesel hybrid engine.

The SAT Aircraft Family Program depends on demand optimized for specific regional features (passenger flows, passenger time value spectrum and infrastructure) and a set of matured technologies as a result of Clean Sky 2 (CS2) devoted to SAT.

This practical implications consist of developing on SAT technologies in CS2, deploying the demonstrators by the small aviation industry and launching an SAT system pilot phase.

FP2050 has changed the approach to a citizen-oriented from an atomized technologies taxonomy-oriented one. The challenge “90 per cent d2d 4h” also covers the needs of remote regions. This niche could be filled by the SAT system using the small aircrafts family.

The paper value is in defining entry requirements, answering how to build the SAT Aircraft Family Program satisfying the FP2050 challenge “90 per cent d2d 4h”.

This paper is about how a command system allocated resources under profound uncertainty. The command system was the Soviet economy, the period was Stalin's dictatorship, and the resources were designated for military research & development. The context was formed by the limits of the existing aviation propulsion technology, the need to replace it with another, and uncertainty as to how to do so. We observe the formation of a quasi-market in which rival agents proposed projects and competed for funding to carry them out. We find rivalry and rent seeking, imperfectly regulated by principals. As rent seeking spread and uncertainty was reduced, the quasi-market was closed down and replaced by strict hierarchical allocation and monitoring. In theory, a dictator cannot commit to refrain from taxing the returns from today's effort tomorrow; therefore, we expect agents in a command system to seek only short-term returns from quasi-market activity. Agents’ willingness to invest in the Soviet quasi-market for inventions is ascribed to a reputation mechanism that enforced long-run returns.

The aim of the research is to conduct a study into a configuration of an aircraft system with a focus on aerodynamics. In addition, trim condition and static stability constraints were included. The main application of this system is suborbital space flights. The presented concept of a modular airplane system (MAS) consists of two vehicles: a Rocket Plane and a Carrier. Both are designed in tailless configurations but coupled formed a classic tail aircraft configuration, where the Rocket Plane works as the empennage. The most important challenge is to define the mutual position of those two tailless vehicles under the assumption that each vehicle will be operating alone in different flight conditions while joined in one object create a conventional aircraft. Each vehicle configuration (separated and coupled) must fulfil static stability and trim requirements.

Aircrafts’ aerodynamic characteristics were obtained using the MGAERO software which is a commercial computing fluid dynamics tool created by AMI Aero. This software uses the Euler flow model. Results from this software were used in the static stability and trim condition analysis.

The main outcome of this investigation is a mutual position of the Rocket Plane and the Carrier that fulfils project requirements. Also, the final configuration of both separated vehicles (Rocket Plane and Carrier) and the complete MAS were defined. In addition, it was observed that in the case of classic aircraft configuration which is created by connecting two tailless vehicles increasing horizontal tail arm reduces static stability. This is related to a significantly higher mass ratio of the horizontal tail (the Rocket Plane) with respect to the whole system. Moving backward, the Rocket Plane has a notable effect on a position of a centre of gravity of the whole system static stability. Moreover, the impact of the mutual vehicles’ position (horizontal tail arm) and inclination angle on the coupled vehicle lift to drag ratio was analysed.

In terms of aerodynamic computation, MGAERO software using an inviscid flow model, therefore, both a friction drag and breakdown of vortex are not considered. But the presented research is for the computation stage of the design, and the MGAERO software guarantees satisfactory accuracy with respect to the relatively low time of computations. The second limitation is that the presented results are for the conceptual stage of the design and dynamic stability constraints were not taken into account.

The ultimate goal of the coupled aircraft project is to conduct flying tests and the presented result is one of the milestones to achieve this goal.

A design process for a conventional aircraft configuration is well known however, there are not many examples of vehicles that consist of two coupled aircrafts where both vehicles have similar mass. The unique part of this paper includes results of the investigation of the mutual position of the vehicles that can fly alone, as well as in coupled form. The impact of the position of the centre of gravity on trim conditions and static stability of the coupled configuration was investigated.

This research examines what motivates professional truck drivers to engage in eco-driving by linking their self-reports with objective driving scores.

Theory of Planned Behavior (TPB) is illustrated in an embedded, single-case study of a Finnish carrier with 17 of its truck drivers. Data are obtained through in-depth interviews with drivers, their fuel-efficiency scores generated by fleet telematics and a focus group session with the management.

Discrepancies between drivers’ intentions and eco-driving behaviors are illustrated in a two-by-two matrix that classifies drivers into four categories: ideal eco-drivers, wildcards, wannabes and non-eco-drivers. Attitudes, subjective norms and perceived behavioral control are examined for drivers within each category, revealing that drivers’ perceptions did not always align with the reality of their driving.

This study strengthens the utility of TPB through data triangulation while also revealing the theory’s inherent limitations in elucidating the underlying causes of its three antecedents and their impact on the variance in driving behaviors.

Managerial insights are offered to fleet managers and eco-driving solution providers to stipulate the right conditions for drivers to enhance fuel-efficiency outcomes of transport fleets.

This is one of the first studies to give a voice to professional truck drivers about their daily eco-driving practice.

Flow induced by rotating disks is of great practical importance in several engineering applications such as rotating heat exchangers, turbine disks, pumps and many more. The present research has been freshly displayed regarding the implementation of an engine oil-based Casson tri-hybrid nanofluid across a rotating disk in mass and heat transferal developments. The purpose of this study is to contemplate the attributes of the flowing tri-hybrid nanofluid by incorporating porosity effects and magnetization and velocity slip effects, viscous dissipation, radiating flux, temperature slip, chemical reaction and activation energy.

The articulated fluid flow is described by a set of partial differential equations which are converted into one set of higher-order ordinary differential equations (ODEs) by using convenient conversions. The numerical solution of this transformed set of ODEs has been spearheaded by using the effectual bvp4c scheme.

The acquired results show that the heat transmission rate for the Casson tri-hybrid nanofluid is intensified by, respectively, 9.54% and 11.93% when compared to the Casson hybrid nanofluid and Casson nanofluid. Also, the mass transmission rate for the Casson tri-hybrid nanofluid is augmented by 1.09% and 2.14%, respectively, when compared to the Casson hybrid nanofluid and Casson nanofluid.

The current investigation presents an educative response on how the flow profiles vary with changes in the inevitable flow parameters. As per authors’ knowledge, no such scrutinization has been carried out previously; therefore, our results are novel and unique.