Aerospace

22 pages, 4777 KiB

Open AccessArticle

Advanced Passenger Movement Model Depending On the Aircraft Cabin Geometry

by Marc Engelmann, Tim Kleinheinz and Mirko Hornung

Aerospace 2020, 7(12), 182; https://doi.org/10.3390/aerospace7120182 - 20 Dec 2020

Cited by 4 | Viewed by 4342

The aircraft cabin and boarding procedures are steadily increasing focus points for both aircraft manufacturers and airlines, as they play a key part in the customer experience. In the German research project AVACON (AdVAnced Aircraft CONcepts), the boarding procedure is assessed using the [...] Read more.

The aircraft cabin and boarding procedures are steadily increasing focus points for both aircraft manufacturers and airlines, as they play a key part in the customer experience. In the German research project AVACON (AdVAnced Aircraft CONcepts), the boarding procedure is assessed using the PAXelerate boarding simulation. As the project demands an increased level of detail concerning the passenger movement model, this publication introduces an improved methodology. Additions to the model include the development of a method capable of describing the passenger walking speed in dependence of the surrounding objects, their proximity as well as the location of other passengers within the cabin. The validation of the model is performed using the AVACON research baseline and an Airbus A320. The model is then applied to an altered version of the Airbus A320 with an extended aisle and to a COVID-19 safe distance scenario. Regarding the results, an extended aisle width delivers boarding times reduced by up to 3%, whereas the COVID-19 assessment delivers a 67% increase in boarding times. Concluding, the integration of the newly developed model empowers PAXelerate to simulate a more detailed boarding process and enables a better understanding of the influence of cabin layout changes to an aircraft’s boarding performance. Full article

(This article belongs to the Special Issue 10th EASN International Conference on Innovation in Aviation & Space to the Satisfaction of the European Citizens)

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24 pages, 13554 KiB

Open AccessReview

Energy Transition in Aviation: The Role of Cryogenic Fuels

by Arvind Gangoli Rao, Feijia Yin and Henri G.C. Werij

Aerospace 2020, 7(12), 181; https://doi.org/10.3390/aerospace7120181 - 18 Dec 2020

Cited by 50 | Viewed by 8360

Abstract

Aviation is the backbone of our modern society. In 2019, around 4.5 billion passengers travelled through the air. However, at the same time, aviation was also responsible for around 5% of anthropogenic causes of global warming. The impact of the COVID-19 pandemic on [...] Read more.

Aviation is the backbone of our modern society. In 2019, around 4.5 billion passengers travelled through the air. However, at the same time, aviation was also responsible for around 5% of anthropogenic causes of global warming. The impact of the COVID-19 pandemic on the aviation sector in the short term is clearly very high, but the long-term effects are still unknown. However, with the increase in global GDP, the number of travelers is expected to increase between three- to four-fold by the middle of this century. While other sectors of transportation are making steady progress in decarbonizing, aviation is falling behind. This paper explores some of the various options for energy carriers in aviation and particularly highlights the possibilities and challenges of using cryogenic fuels/energy carriers such as liquid hydrogen (LH₂) and liquefied natural gas (LNG). Full article

(This article belongs to the Special Issue Selected Papers from 3rd ECATS Conference on Making Aviation Environmentally Sustainable)

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9 pages, 3175 KiB

Open AccessArticle

Deployment of Solar Sails by Joule Effect: Thermal Analysis and Experimental Results

by Gianluigi Bovesecchi, Sandra Corasaniti, Girolamo Costanza, Fabrizio Paolo Piferi and Maria Elisa Tata

Aerospace 2020, 7(12), 180; https://doi.org/10.3390/aerospace7120180 - 16 Dec 2020

Cited by 4 | Viewed by 3392

Abstract

Space vehicles may be propelled by solar sails exploiting the radiation pressure coming from the sun and applied on their surfaces. This work deals with the adoption of Nickel-Titanium Shape Memory Alloy (SMA) elements in the sail deployment mechanism activated by the Joule [...] Read more.

Space vehicles may be propelled by solar sails exploiting the radiation pressure coming from the sun and applied on their surfaces. This work deals with the adoption of Nickel-Titanium Shape Memory Alloy (SMA) elements in the sail deployment mechanism activated by the Joule Effect, i.e., using the same SMA elements as a resistance within suitable designed electrical circuits. Mathematical models were analyzed for the thermal analysis by implementing algorithms for the evaluation of the temperature trend depending on the design parameters. Several solar sail prototypes were built up and tested with different number, size, and arrangement of the SMA elements, as well as the type of the selected electrical circuit. The main parameters were discussed in the tested configurations and advantages discussed as well. Full article

(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)

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31 pages, 5697 KiB

Open AccessArticle

Trajectory Design of Perseus: A CubeSat Mission Concept to Phobos

by Ravi teja Nallapu, Graham Dektor, Nalik Kenia, James Uglietta, Shota Ichikawa, Mercedes Herreras-Martinez, Akshay Choudhari, Aman Chandra, Stephen Schwartz, Erik Asphaug and Jekanthan Thangavelautham

Aerospace 2020, 7(12), 179; https://doi.org/10.3390/aerospace7120179 - 15 Dec 2020

Cited by 2 | Viewed by 5868

Abstract

The Martian satellites Phobos and Deimos hold many unanswered questions that may provide clues to the origin of Mars. These moons are low

Δ v

stopover sites to Mars. Some human missions to Mars typically identify Phobos and Deimos as staging bases for [...] Read more.

The Martian satellites Phobos and Deimos hold many unanswered questions that may provide clues to the origin of Mars. These moons are low

Δ v

stopover sites to Mars. Some human missions to Mars typically identify Phobos and Deimos as staging bases for Mars surface exploration. Astronauts could base initial operations there in lieu of repeated voyages to and from the planet surface, to refuel transiting spacecraft, to teleoperate robotics and other critical machinery, and to develop habitable infrastructure ahead of human landings. Despite their strategic and scientific significance, there has been no successful dedicated mission to either moon. For this reason, we propose Perseus, a geological imaging CubeSat mission to Phobos. Perseus, a

27 U

,

54 kg

CubeSat will return thermal and visible images at resolutions better than currently available over most of Phobos’ surface. This includes visible images at

5 m / pixel

and thermal images at

25 m / pixel

of Phobos’ surface. The Perseus mission is nominally intended to be a co-orbital mission, where the spacecraft will encounter Phobos on its Martian orbit. However, a hyperbolic rendezvous mission concept, to image Phobos on a hyperbolic flyby, is also considered to reduce the risks associated with orbit capture and to reduce mission costs. This paper presents the preliminary feasibility, science objectives, and technological development challenges of achieving these science goals. We then formulate two rendezvous concepts as a series of three nonlinear optimization problems that span the design tree of mission concepts. The tree’s root node is the heliocentric cruise problem, which identifies the near-optimal launch and arrival windows for the Perseus spacecraft. The leaf nodes of the design tree are the two rendezvous concepts that identify near-optimal co-orbital and hyperbolic trajectories for Phobos’ reconnaissance. The design problems are solved using evolutionary algorithms, and the performance of the selected mission concepts is then examined. The results indicate that a co-orbital encounter allows about one encounter per day with about 6 min per encounter. The hyperbolic encounter, on the other hand, allows a single encounter where the spacecraft will spend about 2 min in the imaging region with respect to Phobos. The spacecraft will obtain higher resolution images of Phobos on this feasible region than have ever been seen for most of the surface. These detailed images will help identify candidate landing sites and provide critical data to derisk future surface missions to Phobos. Full article

(This article belongs to the Special Issue Small Satellite Technologies and Mission Concepts)

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28 pages, 1594 KiB

Open AccessArticle

Analysis of Aircraft Maintenance Related Accidents and Serious Incidents in Nigeria

by Khadijah Abdullahi Habib and Cengiz Turkoglu

Aerospace 2020, 7(12), 178; https://doi.org/10.3390/aerospace7120178 - 11 Dec 2020

Cited by 11 | Viewed by 8744

Abstract

The maintenance of aircraft presents considerable challenges to the personnel that maintain them. Challenges such as time pressure, system complexity, sparse feedback, cramped workspaces, etc., are being faced by these personnel on a daily basis. Some of these challenges cause aircraft-maintenance-related accidents and [...] Read more.

The maintenance of aircraft presents considerable challenges to the personnel that maintain them. Challenges such as time pressure, system complexity, sparse feedback, cramped workspaces, etc., are being faced by these personnel on a daily basis. Some of these challenges cause aircraft-maintenance-related accidents and serious incidents. However, there is little formal empirical work that describes the influence of aircraft maintenance to aircraft accidents and incidents in Nigeria. This study, therefore, sets out to explore the contributory factors to aircraft-maintenance-related incidents from 2006 to 2019 and accidents from 2009 to 2019 in Nigeria, to achieve a deeper understanding of this safety critical aspect of the aviation industry, create awareness amongst the relevant stakeholders and seek possible mitigating factors. To attain this, a content analysis of accident reports and mandatory occurrence reports, which occurred in Nigeria, was carried out using the Maintenance Factors and Analysis Classification System (MxFACS) and Hieminga’s maintenance incidents taxonomy. An inter-rater concordance value was used to ascertain research accuracy after evaluation of the data output by subject matter experts. The highest occurring maintenance-related incidents and accidents were attributed to “removal/installation”, working practices such as “accumulation of dirt and contamination”, “inspection/testing”, “inadequate oversight from operator and regulator”, “failure to follow procedures” and “incorrect maintenance”. To identify the root cause of these results, maintenance engineers were consulted via a survey to understand the root causes of these contributory factors. The results of the study revealed that the most common maintenance-related accidents and serious incidents in the last decade are “collision with terrain” and “landing gear events’’. The most frequent failures at systems level resulting in accidents are the “engines” and “airframe structure”. The maintenance factors with the highest contribution to these accidents are “operator and regulatory oversight”, “inadequate inspection” and “failure to follow procedures”. The research also highlights that the highest causal and contributory factors to aviation incidents in Nigeria from 2006 to 2019 are “installation/removal issues”, “inspection/testing issues”, “working practices”, “job close up”, “lubrication and servicing”, all of which corresponds to studies by other researchers in other countries. Full article

(This article belongs to the Special Issue Civil and Military Airworthiness: Recent Developments and Challenges (Volume II))

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19 pages, 6048 KiB

Open AccessArticle

Application of the HPCMP CREATE^TM-AV Kestrel to an Integrated Propeller Prediction

by Pooneh Aref, Mehdi Ghoreyshi, Adam Jirasek and Jürgen Seidel

Aerospace 2020, 7(12), 177; https://doi.org/10.3390/aerospace7120177 - 11 Dec 2020

Cited by 4 | Viewed by 3528

Abstract

This article presents the results of a computational investigation of an integrated propeller test case using the HPCMP CREATE

^{TM}

-AV Kestrel simulation tools. There is a renewed interest in propeller-driven aircraft for unmanned aerial vehicles, electric aircraft, and flying taxies. Computational resources [...] Read more.

This article presents the results of a computational investigation of an integrated propeller test case using the HPCMP CREATE

^{TM}

-AV Kestrel simulation tools. There is a renewed interest in propeller-driven aircraft for unmanned aerial vehicles, electric aircraft, and flying taxies. Computational resources can significantly accelerate the generation of aerodynamic models for these vehicles and reduce the development cost if the prediction tools can accurately predict the aircraft/propeller aerodynamic interactions. Unfortunately, limited propeller experimental data are available to validate computational methods. An American Institute of Aeronautics and Astronautics (AIAA) workshop was therefore established to address this problem. The objective of this workshop was to generate an open access-powered wind tunnel test database for computational validation of propeller effects on the wing aerodynamics, specifically for wing-tip-mounted propellers. The propeller selected for the workshop has four blades and a diameter of 16.2 in. The wing has a root and tip chord of 11.6 and 8.6 in, respectively. Two different simulation approaches were used: one using a single grid including wind tunnel walls and the second using a subset grid overset to an adaptive Cartesian grid that fills the space between the near-body grid and wind tunnel walls. The predictions of both approaches have been compared with available experimental data from the Lockheed Martin low-speed wind tunnel to investigate the grid resolution required for accurate prediction of flowfield data. The results show a good agreement for all tested conditions. The measured and predicted data show that wing aerodynamic performance is improved by the spinning tip-mounted propeller. Full article

(This article belongs to the Special Issue Computational Aerodynamic Modeling of Aerospace Vehicles (Volume II))

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Graphical abstract

20 pages, 5016 KiB

Open AccessArticle

Modelling Flexibility and Qualification Ability to Assess Electric Propulsion Architectures for Satellite Megaconstellations

by Massimo Panarotto, Olivia Borgue and Ola Isaksson

Aerospace 2020, 7(12), 176; https://doi.org/10.3390/aerospace7120176 - 11 Dec 2020

Cited by 7 | Viewed by 3277

Abstract

The higher satellite production rates expected in new megaconstellation scenarios involve radical changes in the way design trade-offs need to be considered by electric propulsion companies. In relative comparison, flexibility and qualification ability will have a higher impact in megaconstellations compared to traditional [...] Read more.

The higher satellite production rates expected in new megaconstellation scenarios involve radical changes in the way design trade-offs need to be considered by electric propulsion companies. In relative comparison, flexibility and qualification ability will have a higher impact in megaconstellations compared to traditional businesses. For these reasons, this paper proposes a methodology for assessing flexible propulsion architectures by taking into account variations in market behavior and qualification activities. Through the methodology, flexibility and qualification ability can be traded against traditional engineering attributes (such as functional performances) in a quantitative way. The use of the methodology is illustrated through an industrial case related to the study of xenon vs. krypton architectures for megaconstellation businesses. This paper provides insights on how to apply the methodology in other case studies, in order to enable engineering teams to present and communicate the impact of alternative architectural concepts to program managers and decision-makers. Full article

(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)

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22 pages, 8010 KiB

Open AccessArticle

Traffic Network Identification Using Trajectory Intersection Clustering

by Ingrid Gerdes and Annette Temme

Aerospace 2020, 7(12), 175; https://doi.org/10.3390/aerospace7120175 - 10 Dec 2020

Cited by 5 | Viewed by 3030

Abstract

The current airspace route system consists mainly of pre-defined routes with a low number of intersections to facilitate air traffic controllers to oversee the traffic. Our aim is a method to create an artificial and reliable route network based on planned or as-flown [...] Read more.

The current airspace route system consists mainly of pre-defined routes with a low number of intersections to facilitate air traffic controllers to oversee the traffic. Our aim is a method to create an artificial and reliable route network based on planned or as-flown trajectories. The application possibilities of the resulting network are manifold, reaching from the assessment of new air traffic management (ATM) strategies or historical data to a basis for simulation systems. Trajectories are defined as sequences of common points at intersections with other trajectories. All common points of a traffic sample are clustered, and, after further optimization, the cluster centers are used as nodes in the new main-flow network. To build almost-realistic flight trajectories based on this network, additional parameters such as speed and altitude are added to the nodes and the possibility to take detours into account to avoid congested areas is introduced. As optimization criteria, the trajectory length and the structural complexity of the main-flow system are used. Based on these criteria, we develop a new cost function for the optimization process. In addition, we show how different traffic situations are covered by the network. To illustrate the capabilities of our approach, traffic is exemplarily divided into separate classes and class-dependent parameters are assigned. Applied to two real traffic scenarios, the approach was able to emulate the underlying route systems with a difference in median trajectory length of 0.2%, resp. 0.5% compared to the original routes. Full article

(This article belongs to the Collection Air Transportation—Operations and Management)

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17 pages, 4497 KiB

Open AccessArticle

Validation of Numerical Models of a Rotorcraft Crashworthy Seat and Subfloor

by Paolo Astori, Mauro Zanella and Matteo Bernardini

Aerospace 2020, 7(12), 174; https://doi.org/10.3390/aerospace7120174 - 10 Dec 2020

Cited by 14 | Viewed by 6405

Abstract

The present work explores some critical aspects of the numerical modeling of a rotorcraft seat and subfloor equipped with energy-absorbing stages, which are paramount in crash landing conditions. To limit the vast complexity of the problem, a purely vertical impact is considered as [...] Read more.

The present work explores some critical aspects of the numerical modeling of a rotorcraft seat and subfloor equipped with energy-absorbing stages, which are paramount in crash landing conditions. To limit the vast complexity of the problem, a purely vertical impact is considered as a reference scenario for an assembly made of a crashworthy helicopter seat and a subfloor section, including an anthropomorphic dummy. A preliminary lumped mass model is used to drive the design of the experimental drop test. Some additional static and dynamic tests are carried out at the coupon and sub-component levels to characterize the seat cushion, the seat pan and the honeycomb elements that were introduced in the structure as energy absorbers. The subfloor section is designed and manufactured with a simplified technique, yet representative of this structural component. Eventually, a finite element model representing the full drop test was created and, together with the original lumped mass model, finally validated against the experimental test, outlining the advantage of using both the numerical techniques for design assistance. Full article

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18 pages, 1951 KiB

Open AccessArticle

Design Space Exploration of a Jet Engine Component Using a Combined Object Model for Function and Geometry

by Jakob R. Müller, Massimo Panarotto and Ola Isaksson

Aerospace 2020, 7(12), 173; https://doi.org/10.3390/aerospace7120173 - 8 Dec 2020

Cited by 5 | Viewed by 4357

Abstract

The design of aircraft and engine components hinges on the use of computer aided design (CAD) models and the subsequent geometry-based analyses for evaluation of the quality of a concept. However, the generation (and variation) of CAD models to include radical or novel [...] Read more.

The design of aircraft and engine components hinges on the use of computer aided design (CAD) models and the subsequent geometry-based analyses for evaluation of the quality of a concept. However, the generation (and variation) of CAD models to include radical or novel design solutions is a resource intense modelling effort. While approaches to automate the generation and variation of CAD models exist, they neglect the capture and representation of the product’s design rationale—what the product is supposed to do. The design space exploration approach Function and Geometry Exploration (FGE) aims to support the exploration of more functionally and geometrically different product concepts under consideration of not only geometrical, but also teleological aspects. The FGE approach has been presented and verified in a previous presentation. However, in order to contribute to engineering design practice, a design method needs to be validated through application in industrial practice. Hence, this publication reports from a study where the FGE approach has been applied by a design team of a Swedish aerospace manufacturers in a conceptual product development project. Conceptually different alternatives were identified in order to meet the expected functionality of a guide vane (GV). The FGE was introduced and applied in a series of workshops. Data was collected through participatory observation in the design teams by the researchers, as well as interviews and questionnaires. The results reveal the potential of the FGE approach as a design support to: (1) Represent and capture the design rationale and the design space; (2) capture, integrate and model novel solutions; and (3) provide support for the embodiment of novel concepts that would otherwise remain unexplored. In conclusion, the FGE method supports designers to articulate and link the design rationale, including functional requirements and alternative solutions, to geometrical features of the product concepts. The method supports the exploration of alternative solutions as well as functions. However, scalability and robustness of the generated CAD models remain subject to further research. Full article

(This article belongs to the Special Issue Aircraft Design (SI-2/2020))

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12 pages, 1845 KiB

Open AccessArticle

Assessing the Climate Impact of Formation Flights

by Katrin Dahlmann, Sigrun Matthes, Hiroshi Yamashita, Simon Unterstrasser, Volker Grewe and Tobias Marks

Aerospace 2020, 7(12), 172; https://doi.org/10.3390/aerospace7120172 - 8 Dec 2020

Cited by 12 | Viewed by 4472

Abstract

An operational measure that is inspired by migrant birds aiming toward the mitigation of aviation climate impact is to fly in aerodynamic formation. When this operational measure is adapted to commercial aircraft it saves fuel and is, therefore, expected to reduce the climate [...] Read more.

An operational measure that is inspired by migrant birds aiming toward the mitigation of aviation climate impact is to fly in aerodynamic formation. When this operational measure is adapted to commercial aircraft it saves fuel and is, therefore, expected to reduce the climate impact of aviation. Besides the total emission amount, this mitigation option also changes the location of emissions, impacting the non-CO₂ climate effects arising from NO_x and H₂O emissions and contrails. Here, we assess these non-CO₂ climate impacts with a climate response model to assure a benefit for climate not only due to CO₂ emission reductions, but also due to reduced non-CO₂ effects. Therefore, the climate response model AirClim is used, which includes CO₂ effects and also the impact of water vapor and contrail induced cloudiness as well as the impact of nitrogen dioxide emissions on the ozone and methane concentration. For this purpose, AirClim has been adopted to account for saturation effects occurring for formation flight. The results of the case studies show that the implementation of formation flights in the 50 most popular airports for the year 2017 display an average decrease of fuel consumption by 5%. The climate impact, in terms of average near surface temperature change, is estimated to be reduced in average by 24%, with values of individual formations between 13% and 33%. Full article

(This article belongs to the Special Issue Selected Papers from 3rd ECATS Conference on Making Aviation Environmentally Sustainable)

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22 pages, 4117 KiB

Open AccessArticle

Using Convolutional Neural Networks to Automate Aircraft Maintenance Visual Inspection

by Anil Doğru, Soufiane Bouarfa, Ridwan Arizar and Reyhan Aydoğan

Aerospace 2020, 7(12), 171; https://doi.org/10.3390/aerospace7120171 - 7 Dec 2020

Cited by 46 | Viewed by 9080

Abstract

Convolutional Neural Networks combined with autonomous drones are increasingly seen as enablers of partially automating the aircraft maintenance visual inspection process. Such an innovative concept can have a significant impact on aircraft operations. Though supporting aircraft maintenance engineers detect and classify a wide [...] Read more.

Convolutional Neural Networks combined with autonomous drones are increasingly seen as enablers of partially automating the aircraft maintenance visual inspection process. Such an innovative concept can have a significant impact on aircraft operations. Though supporting aircraft maintenance engineers detect and classify a wide range of defects, the time spent on inspection can significantly be reduced. Examples of defects that can be automatically detected include aircraft dents, paint defects, cracks and holes, and lightning strike damage. Additionally, this concept could also increase the accuracy of damage detection and reduce the number of aircraft inspection incidents related to human factors like fatigue and time pressure. In our previous work, we have applied a recent Convolutional Neural Network architecture known by MASK R-CNN to detect aircraft dents. MASK-RCNN was chosen because it enables the detection of multiple objects in an image while simultaneously generating a segmentation mask for each instance. The previously obtained

F_{1}

and

F_{2}

scores were 62.67% and 59.35%, respectively. This paper extends the previous work by applying different techniques to improve and evaluate prediction performance experimentally. The approach uses include (1) Balancing the original dataset by adding images without dents; (2) Increasing data homogeneity by focusing on wing images only; (3) Exploring the potential of three augmentation techniques in improving model performance namely flipping, rotating, and blurring; and (4) using a pre-classifier in combination with MASK R-CNN. The results show that a hybrid approach combining MASK R-CNN and augmentation techniques leads to an improved performance with an

F_{1}

score of (67.50%) and

F_{2}

score of (66.37%). Full article

(This article belongs to the Special Issue Application of Multiagent Systems and Artificial Intelligence Techniques in Aviation (Volume II))

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22 pages, 2870 KiB

Open AccessArticle

The Contrail Mitigation Potential of Aircraft Formation Flight Derived from High-Resolution Simulations

by Simon Unterstrasser

Aerospace 2020, 7(12), 170; https://doi.org/10.3390/aerospace7120170 - 5 Dec 2020

Cited by 13 | Viewed by 3921

Abstract

Formation flight is one potential measure to increase the efficiency of aviation. Flying in the upwash region of an aircraft’s wake vortex field is aerodynamically advantageous. It saves fuel and concomitantly reduces the carbon foot print. However,

C O_{2}

emissions are only [...] Read more.

Formation flight is one potential measure to increase the efficiency of aviation. Flying in the upwash region of an aircraft’s wake vortex field is aerodynamically advantageous. It saves fuel and concomitantly reduces the carbon foot print. However,

C O_{2}

emissions are only one contribution to the aviation climate impact among several others (contrails, emission of

H_{2} O

and

N O_{x}

). In this study, we employ an established large eddy simulation model with a fully coupled particle-based ice microphysics code and simulate the evolution of contrails that were produced behind formations of two aircraft. For a large set of atmospheric scenarios, these contrails are compared to contrails behind single aircraft. In general, contrails grow and spread by the uptake of atmospheric water vapour. When contrails are produced in close proximity (as in the formation scenario), they compete for the available water vapour and mutually inhibit their growth. The simulations demonstrate that the contrail ice mass and total extinction behind a two-aircraft formation are substantially smaller than for a corresponding case with two separate aircraft and contrails. Hence, this first study suggests that establishing formation flight may strongly reduce the contrail climate effect. Full article

(This article belongs to the Special Issue Selected Papers from 3rd ECATS Conference on Making Aviation Environmentally Sustainable)

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18 pages, 2348 KiB

Open AccessArticle

How Well Can Persistent Contrails Be Predicted?

by Klaus Gierens, Sigrun Matthes and Susanne Rohs

Aerospace 2020, 7(12), 169; https://doi.org/10.3390/aerospace7120169 - 2 Dec 2020

Cited by 51 | Viewed by 10249

Abstract

Persistent contrails and contrail cirrus are responsible for a large part of aviation induced radiative forcing. A considerable fraction of their warming effect could be eliminated by diverting only a quite small fraction of flight paths, namely those that produce the highest individual [...] Read more.

Persistent contrails and contrail cirrus are responsible for a large part of aviation induced radiative forcing. A considerable fraction of their warming effect could be eliminated by diverting only a quite small fraction of flight paths, namely those that produce the highest individual radiative forcing (iRF). In order to make this a viable mitigation strategy it is necessary that aviation weather forecast is able to predict (i) when and where contrails are formed, (ii) which of these are persistent, and (iii) how large the iRF of those contrails would be. Here we study several data bases together with weather data in order to see whether such a forecast would currently be possible. It turns out that the formation of contrails can be predicted with some success, but there are problems to predict contrail persistence. The underlying reason for this is that while the temperature field is quite good in weather prediction and climate simulations with specified dynamics, this is not so for the relative humidity in general and for ice supersaturation in particular. However we find that the weather model shows the dynamical peculiarities that are expected for ice supersaturated regions where strong contrails are indeed found in satellite data. This justifies some hope that the prediction of strong contrails may be possible via general regression involving the dynamical state of the ambient atmosphere. Full article

(This article belongs to the Special Issue Selected Papers from 3rd ECATS Conference on Making Aviation Environmentally Sustainable)

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40 pages, 63213 KiB

Open AccessArticle

Sensitivity Analysis and Flight Tests Results for a Vertical Cold Launch Missile System

by Robert Głębocki and Mariusz Jacewicz

Aerospace 2020, 7(12), 168; https://doi.org/10.3390/aerospace7120168 - 28 Nov 2020

Cited by 9 | Viewed by 6432

Abstract

In vertical cold launch the missile starts without the function of the main engine. Over the launcher, the attitude of the missile is controlled by a set of lateral thrusters. However, a quick turn might be disturbed by various uncertainties. This study discusses [...] Read more.

In vertical cold launch the missile starts without the function of the main engine. Over the launcher, the attitude of the missile is controlled by a set of lateral thrusters. However, a quick turn might be disturbed by various uncertainties. This study discusses the problem of the influences of disturbances and the repeatability of lateral thrusters’ ignition on the pitch maneuver quality. The generic 152.4 mm projectile equipped in small, solid propellant lateral thrusters was used as a test platform. A six degree of freedom mathematical model was developed to execute the Monte-Carlo simulations of the launch phase and to prepare the flight test campaign. The parametric analysis was performed to investigate the influence of system uncertainties on quick turn repeatability. A series of ground laboratory trials was accomplished. Thirteen flight tests were completed on the missile test range. The flight parameters were measured using an onboard inertial measurement unit and a ground vision system. It was experimentally proved that the cold vertical launch maneuver could be realized properly with at least two lateral motors. It was found that the initial roll rate of the projectile and the lateral thrusters ‘igniters’ uncertainties could affect the pitch angle achieved and must be minimized to reduce the projectile dispersion. Full article

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29 pages, 12770 KiB

Open AccessArticle

Constructive Aerodynamic Interference in a Network of Weakly Coupled Flutter-Based Energy Harvesters

by Emmanuel Beltramo, Martín E. Pérez Segura, Bruno A. Roccia, Marcelo F. Valdez, Marcos L. Verstraete and Sergio Preidikman

Aerospace 2020, 7(12), 167; https://doi.org/10.3390/aerospace7120167 - 24 Nov 2020

Cited by 9 | Viewed by 3471

Abstract

Converting flow-induced vibrations into electricity for low-power generation has received growing attention over the past few years. Aeroelastic phenomena, good candidates to yield high energy performance in renewable wind energy harvesting (EH) systems, can play a pivotal role in providing sufficient power for [...] Read more.

Converting flow-induced vibrations into electricity for low-power generation has received growing attention over the past few years. Aeroelastic phenomena, good candidates to yield high energy performance in renewable wind energy harvesting (EH) systems, can play a pivotal role in providing sufficient power for extended operation with little or no battery replacement. In this paper, a numerical model and a co-simulation approach have been developed to study a new EH device for power generation. We investigate the problem focusing on a weakly aerodynamically coupled flutter-based EH system. It consists of two flexible wings anchored by cantilevered beams with attached piezoelectric layers, undergoing nonlinear coupled bending–torsion limit cycle oscillations. Besides the development of individual EH devices, further issues are posed when considering multiple objects for realizing a network of devices and magnifying the extracted power due to nonlinear synergies and constructive interferences. This work investigates the effect of various external conditions and physical parameters on the performance of the piezoaeroelastic array of devices. From the viewpoint of applications, we are most concerned about whether an EH can generate sufficient power under a variable excitation. The results of this study can be used for the design and integration of low-energy wind generation technologies into buildings, bridges, and built-in sensor networks in aircraft structures. Full article

(This article belongs to the Special Issue Aeroelasticity, Volume II)

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