Advances in Aerospace Sciences and Technology

A special issue of Aerospace (ISSN 2226-4310).

Deadline for manuscript submissions: closed (31 March 2021) | Viewed by 68348

Special Issue Editor


E-Mail Website
Guest Editor
School of Engineering, University of Glasgow, James Watt Building South, University Avenue, Glasgow G12 8QQ, Scotland, UK
Interests: aerodynamic technologies; flow and flight control systems; shock physics; aerospace design and optimization; flow diagnostics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue collects feature papers (original research articles or comprehensive review papers) in aerospace research fields. Highly experienced practitioners from various fields within the journal’s scope (https://www.mdpi.com/journal/aerospace/about) are welcome to contribute papers, highlighting the latest developments in their research area or a detailed summary of their own work done thus far. All papers to be published in this collection will be solicited and selected by the guest editor; a very high standard will be set in the selection of prospective authors and submitted papers, and those papers will be published, free of charge, in Open Access after peer review on condition that no valid rejection report is received during the peer-review process.

The submission deadline for this round of call for papers is 31 March 2021.

Prof. Dr. Konstantinos Kontis
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Aerospace is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue polices can be found here.

Related Special Issues

Published Papers (14 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

12 pages, 1194 KiB  
Article
Aeroelastic Stability Analysis of Electric Aircraft Wings with Distributed Electric Propulsors
by Mohammadreza Amoozgar, Michael I. Friswell, Seyed Ahmad Fazelzadeh, Hamed Haddad Khodaparast, Abbas Mazidi and Jonathan E. Cooper
Aerospace 2021, 8(4), 100; https://doi.org/10.3390/aerospace8040100 - 2 Apr 2021
Cited by 10 | Viewed by 4308
Abstract
In this paper, the effect of distributed electric propulsion on the aeroelastic stability of an electric aircraft wing was investigated. All the electric propulsors, which are of different properties, are attached to the wing of the aircraft in different positions. The wing structural [...] Read more.
In this paper, the effect of distributed electric propulsion on the aeroelastic stability of an electric aircraft wing was investigated. All the electric propulsors, which are of different properties, are attached to the wing of the aircraft in different positions. The wing structural dynamics was modelled by using geometrically exact beam equations, while the aerodynamic loads were simulated by using an unsteady aerodynamic theory. The electric propulsors were modelled by using a concentrated mass attached to the wing, and the motor’s thrust and angular momentum were taken into account. The thrust of each propulsor was modelled as a follower force acting exactly at the centre of gravity of the propulsor. The nonlinear aeroelastic governing equations were discretised using a time–space scheme, and the obtained results were verified against available results and very good agreement was observed. Two case studies were considered throughout the paper, resembling two flight conditions of the electric aircraft. The numerical results show that the tip propulsor thrust, mass, and angular momentum had the most impact on the aeroelastic stability of the wing. In addition, it was observed that the high-lift motors had a minimal effect on the aeroelastic stability of the wing. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

25 pages, 2676 KiB  
Article
On the Handling Qualities of Two Flying Wing Aircraft Configurations
by Luís M. B. C. Campos and Joaquim M. G. Marques
Aerospace 2021, 8(3), 77; https://doi.org/10.3390/aerospace8030077 - 16 Mar 2021
Cited by 4 | Viewed by 3512
Abstract
The coupling of the longitudinal and lateral stability modes of an aeroplane is considered in two cases: (i) weak coupling, when the changes in the frequency and damping of the phugoid, short period, dutch roll, and helical modes are small, i.e., the square [...] Read more.
The coupling of the longitudinal and lateral stability modes of an aeroplane is considered in two cases: (i) weak coupling, when the changes in the frequency and damping of the phugoid, short period, dutch roll, and helical modes are small, i.e., the square of the deviation is negligible compared to the square of the uncoupled value; (ii) strong coupling, when the coupled values may differ significantly from the uncoupled values. This allows a comparison of three values for the frequency and damping of each mode: (i) exact, i.e., fully coupled; (ii) with the approximation of weak coupling; (iii) with the assumption of decoupling. The comparison of these three values allows an assessment of the importance of coupling effects. The method is applied to two flying wing designs, concerning all modes in a total of eighteen flight conditions. It turns out that lateral-longitudinal coupling is small in all cases, and thus classical handling qualities criteria can be applied. The handling qualities are considered for all modes, namely the phugoid, short period, dutch roll, spiral, and roll modes. Additional focus is given to the pitch axis, considering the control anticipation parameter (CAP). The latter relates to the two kinds of manouever points, where damping vanishes, that are calculated for minimum speed, take-off, and initial and final cruise conditions. The conclusion compares two flying wings designs (the “long narrow” and “short wide” fuselage concepts) not only from the point of view of flight stability, but also from other viewpoints. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

26 pages, 3628 KiB  
Article
Phasing Maneuver Analysis from a Low Lunar Orbit to a Near Rectilinear Halo Orbit
by Giordana Bucchioni and Mario Innocenti
Aerospace 2021, 8(3), 70; https://doi.org/10.3390/aerospace8030070 - 9 Mar 2021
Cited by 11 | Viewed by 3596
Abstract
The paper describes the preliminary design of a phasing trajectory in a cislunar environment, where the third body perturbation is considered non-negligible. The working framework is the one proposed by the ESA’s Heracles mission in which a passive target station is in a [...] Read more.
The paper describes the preliminary design of a phasing trajectory in a cislunar environment, where the third body perturbation is considered non-negligible. The working framework is the one proposed by the ESA’s Heracles mission in which a passive target station is in a Near Rectilinear Halo Orbit and an active vehicle must reach that orbit to start a rendezvous procedure. In this scenario the authors examine three different ways to design such phasing maneuver under the circular restricted three-body problem hypotheses: Lambert/differential correction, Hohmann/differential correction and optimization. The three approaches are compared in terms of ΔV consumption, accuracy and time of flight. The selected solution is also validated under the more accurate restricted elliptic three-body problem hypothesis. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

16 pages, 10605 KiB  
Article
A Study on Thermal Buckling and Mode Jumping of Metallic and Composite Plates
by Javier Gutiérrez Álvarez and Chiara Bisagni
Aerospace 2021, 8(2), 56; https://doi.org/10.3390/aerospace8020056 - 21 Feb 2021
Cited by 8 | Viewed by 3844
Abstract
Composite plates in post-buckling regime can experience mode jumping in their buckling shape, suddenly increasing the number of half-waves. This phenomenon can be advantageous, because the shape change could be used for local morphing or structural adaptability in future aerospace structures. A study [...] Read more.
Composite plates in post-buckling regime can experience mode jumping in their buckling shape, suddenly increasing the number of half-waves. This phenomenon can be advantageous, because the shape change could be used for local morphing or structural adaptability in future aerospace structures. A study of this phenomenon under heating is here presented, combining numerical and experimental techniques. At first, a set of parametric analysis was conducted to identify composite panels that present a mode jump when heated. Three plates were selected, one in aluminum alloy 2024T3, and two in AS4/8552 composite material, with layup [30/30/5/5]s and [35/35/10/10]s. The plates were tested in a new test setup for thermal buckling based on low thermal expansion fixtures. The mode jumping was successfully obtained experimentally for both composite plates. Numerical simulations predicted the general trends for all plates, and the mode jumps for the composite plates. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

23 pages, 1786 KiB  
Article
On Probabilistic Risk of Aircraft Collision along Air Corridors
by Luís M. B. C. Campos and Joaquim M. G. Marques
Aerospace 2021, 8(2), 31; https://doi.org/10.3390/aerospace8020031 - 27 Jan 2021
Cited by 5 | Viewed by 3091
Abstract
The separation of aircraft in cruising flight in air corridors is based on the assurance of an extremely low probability of collision due to position inaccuracy caused by navigation errors, atmospheric disturbances, or other factors. The appropriate standard is the International Civil Aviation [...] Read more.
The separation of aircraft in cruising flight in air corridors is based on the assurance of an extremely low probability of collision due to position inaccuracy caused by navigation errors, atmospheric disturbances, or other factors. The appropriate standard is the International Civil Aviation Organization (ICAO) Target Level of Safety (TLS) of frequency of collision less than 5 × 10−9 per flight hour. An upper bound for the collision probability per unit distance is the probability of coincidence, in the case of aircraft flying at the same speed along parallel tracks in the same direction. This leads to the case of two aircraft flying at a constant separation, for which at least three probabilities of coincidence can be calculated: (i) the maximum probability of coincidence at the most likely point; (ii) the cumulative probability of coincidence integrated along the flight path; and (iii) the cumulative probability of coincidence integrated over all space. These three probabilities of coincidence are applied to the old standard and new reduced vertical separations of 2000 ft and 1000 ft respectively, for comparison with the ICAO TLS, and also to assess their suitability as safety metrics. The possibility is raised of complementing the ICAO TLS 5 × 10−9 per hour, which is suitable for the cumulative probability of collision, by two additional safety metrics: (i) one per hour flown squared, which is suitable for comparison with the maximum joint probability density of collision; and (ii) another times hour flown, for comparison with the three-dimensional cumulative probability of coincidence. These three metrics (i) to (iii) have distinct dimensions, give different information, and could be alternatives or supplements. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

16 pages, 17667 KiB  
Article
Synthesis and Experimental Characterization of a MWCNT-Filled Bio-Based Adhesive
by Konstantinos Tserpes and Vasileios Tzatzadakis
Aerospace 2021, 8(2), 26; https://doi.org/10.3390/aerospace8020026 - 21 Jan 2021
Cited by 2 | Viewed by 2757
Abstract
In the present paper, a novel epichlorohydrin/cardanol adhesive was reinforced by multi-walled carbon nanotubes (MWCNTs) and characterized experimentally. The adhesive was reinforced by MWCNTs in weight ratios (wt %) of 0.5%, 1.0% and 2.0%. The bulk properties of the reinforced adhesive were characterized [...] Read more.
In the present paper, a novel epichlorohydrin/cardanol adhesive was reinforced by multi-walled carbon nanotubes (MWCNTs) and characterized experimentally. The adhesive was reinforced by MWCNTs in weight ratios (wt %) of 0.5%, 1.0% and 2.0%. The bulk properties of the reinforced adhesive were characterized through dynamic mechanical analysis tests, tension tests, and fracture toughness tests, while its shear behavior was characterized through single-lap shear tests on aluminum and composite bonded specimens. The morphology of the reinforced adhesive was characterized using scanning electron microscopy tests. Due to the high viscosity of the bio-based adhesive, special efforts were placed on the dispersion of the MWCNTs into the adhesive, which was achieved through mechanical mixing. The results from the tests show that the presence of the MWCNTs increases the glass transition temperature, the Young’s modulus and the fracture toughness of the reinforced bio-based adhesive, while it decreases its tensile strength. This contradictory finding is attributed to the formation of MWCNT agglomerates into the adhesive. For the content of 2.0 wt %, the shear strength of the reinforced adhesive is increased by 57% for the aluminum joints and by 10.4% for the composite joints. The findings of the study reveal that the reinforcement of the bio-based adhesive by MWCNTs is feasible from a manufacturing viewpoint and may increase the efficiency of the adhesive in structural applications. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

12 pages, 3273 KiB  
Article
A Conceptional Approach of Resin-Transfer-Molding to Rosin-Sourced Epoxy Matrix Green Composites
by Sicong Yu, Xufeng Zhang, Xiaoling Liu, Chris Rudd and Xiaosu Yi
Aerospace 2021, 8(1), 5; https://doi.org/10.3390/aerospace8010005 - 28 Dec 2020
Cited by 3 | Viewed by 3680
Abstract
In this concept-proof study, a preform-based RTM (Resin Transfer Molding) process is presented that is characterized by first pre-loading the solid curing agent onto the preform, and then injecting the liquid nonreactive resin with an intrinsically low viscosity into the mold to infiltrate [...] Read more.
In this concept-proof study, a preform-based RTM (Resin Transfer Molding) process is presented that is characterized by first pre-loading the solid curing agent onto the preform, and then injecting the liquid nonreactive resin with an intrinsically low viscosity into the mold to infiltrate and wet the pre-loaded preform. The separation of resin and hardener helped to process inherently high viscosity resins in a convenient way. Rosin-sourced, anhydrite-cured epoxies that would normally be regarded as unsuited to liquid composite molding, were thus processed. Rheological tests revealed that by separating the anhydrite curing agent from a formulated RTM resin system, the remaining epoxy liquid had its flowtime extended. C-scan and glass transition temperature tests showed that the preform pre-loaded with anhydrite was fully infiltrated and wetted by the liquid epoxy, and the two components were diffused and dissolved with each other, and finally, well reacted and cured. Composite laminates made via this approach exhibited roughly comparable quality and mechanical properties with prepreg controls via autoclave or compression molding, respectively. These findings were verified for both carbon and ramie fiber composites. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

9 pages, 3175 KiB  
Article
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 3404
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)
Show Figures

Figure 1

20 pages, 5016 KiB  
Article
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 3289
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)
Show Figures

Figure 1

17 pages, 1333 KiB  
Article
Neuro-Fuzzy Network-Based Reduced-Order Modeling of Transonic Aileron Buzz
by Rebecca Zahn and Christian Breitsamter
Aerospace 2020, 7(11), 162; https://doi.org/10.3390/aerospace7110162 - 13 Nov 2020
Cited by 1 | Viewed by 2892
Abstract
In the present work, a reduced-order modeling (ROM) framework based on a recurrent neuro-fuzzy model (NFM) that is serial connected with a multilayer perceptron (MLP) neural network is applied for the computation of transonic aileron buzz. The training data set for the specified [...] Read more.
In the present work, a reduced-order modeling (ROM) framework based on a recurrent neuro-fuzzy model (NFM) that is serial connected with a multilayer perceptron (MLP) neural network is applied for the computation of transonic aileron buzz. The training data set for the specified ROM is obtained by performing forced-motion unsteady Reynolds-averaged Navier Stokes (URANS) simulations. Further, a Monte Carlo-based training procedure is applied in order to estimate statistical errors. In order to demonstrate the method’s fidelity, a two-dimensional aeroelastic model based on the NACA651213 airfoil is investigated at different flow conditions, while the aileron deflection and the hinge moment are considered in particular. The aileron is integrated in the wing section without a gap and is modeled as rigid. The dynamic equations of the rigid aileron rotation are coupled with the URANS-based flow model. For ROM training purposes, the aileron is excited via a forced motion and the respective aerodynamic and aeroelastic response is computed using a computational fluid dynamics (CFD) solver. A comparison with the high-fidelity reference CFD solutions shows that the essential characteristics of the nonlinear buzz phenomenon are captured by the selected ROM method. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

19 pages, 3477 KiB  
Article
A Novel Holistic Index for the Optimization of Composite Components and Manufacturing Processes with Regard to Quality, Life Cycle Costs and Environmental Performance
by Christos V. Katsiropoulos and Spiros G. Pantelakis
Aerospace 2020, 7(11), 157; https://doi.org/10.3390/aerospace7110157 - 30 Oct 2020
Cited by 12 | Viewed by 3556
Abstract
In the present work, a novel holistic component and process optimization index is introduced. The Index is aimed to provide a decision support tool for the optimization of aircraft composite components and manufacturing processes as well as for the selection of the appropriate [...] Read more.
In the present work, a novel holistic component and process optimization index is introduced. The Index is aimed to provide a decision support tool for the optimization of aircraft composite components and manufacturing processes as well as for the selection of the appropriate manufacturing technique of a component when various techniques are considered as manufacturing options. The criteria involved in the index are quality, cost and environmental footprint functions which are considered to be interdependent. In the present concept quality is quantified through measurable technological features which are required for the component under consideration. Cost has been estimated by implementing the Activity Based Concept (ABC) using an in house developed tool. Environmental footprint is assessed by exploiting the ReCiPe method using the ‘open LCA’ software. The weight factor of each of the above criteria in the Index is calculated by using the Multi Criteria Decision (MCD) method Analytic Hierarchy Process (AHP). The Index developed has been applied to support the selection of the appropriate production technique for a typical aeronautical composite part. The alternative manufacturing options considered have been the Automated Fiber Placement (AFP) as well as the classical Autoclave manufacturing technique. By considering quality as the prevailing factor for meeting a decision the index confirms the advantage of the Autoclave process. Yet, by considering the environmental footprint and/or cost to be of equal or higher significance to quality, the implementation of the index demonstrates the clear advantage of AFP process. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Graphical abstract

25 pages, 10057 KiB  
Article
A Performance-Based Airspace Model for Unmanned Aircraft Systems Traffic Management
by Nichakorn Pongsakornsathien, Suraj Bijjahalli, Alessandro Gardi, Angus Symons, Yuting Xi, Roberto Sabatini and Trevor Kistan
Aerospace 2020, 7(11), 154; https://doi.org/10.3390/aerospace7110154 - 28 Oct 2020
Cited by 32 | Viewed by 5887
Abstract
Recent evolutions of the Unmanned Aircraft Systems (UAS) Traffic Management (UTM) concept are driving the introduction of new airspace structures and classifications, which must be suitable for low-altitude airspace and provide the required level of safety and flexibility, particularly in dense urban and [...] Read more.
Recent evolutions of the Unmanned Aircraft Systems (UAS) Traffic Management (UTM) concept are driving the introduction of new airspace structures and classifications, which must be suitable for low-altitude airspace and provide the required level of safety and flexibility, particularly in dense urban and suburban areas. Therefore, airspace classifications and structures need to evolve based on appropriate performance metrics, while new models and tools are needed to address UTM operational requirements, with an increasing focus on the coexistence of manned and unmanned Urban Air Mobility (UAM) vehicles and associated Communication, Navigation and Surveillance (CNS) infrastructure. This paper presents a novel airspace model for UTM adopting Performance-Based Operation (PBO) criteria, and specifically addressing urban airspace requirements. In particular, a novel airspace discretisation methodology is introduced, which allows dynamic management of airspace resources based on navigation and surveillance performance. Additionally, an airspace sectorisation methodology is developed balancing the trade-off between communication overhead and computational complexity of trajectory planning and re-planning. Two simulation case studies are conducted: over the skyline and below the skyline in Melbourne central business district, utilising Global Navigation Satellite Systems (GNSS) and Automatic Dependent Surveillance-Broadcast (ADS-B). The results confirm that the proposed airspace sectorisation methodology promotes operational safety and efficiency and enhances the UTM operators’ situational awareness under dense traffic conditions introducing a new effective 3D airspace visualisation scheme, which is suitable both for mission planning and pre-tactical UTM operations. Additionally, the proposed performance-based methodology can accommodate the diversity of infrastructure and vehicle performance requirements currently envisaged in the UTM context. This facilitates the adoption of this methodology for low-level airspace integration of UAS (which may differ significantly in terms of their avionics CNS capabilities) and set foundations for future work on tactical online UTM operations. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

29 pages, 997 KiB  
Article
The Two-Point Boundary-Value Problem for Rocket Trajectories
by Luís M. B. C. Campos and Paulo J. S. Gil
Aerospace 2020, 7(9), 131; https://doi.org/10.3390/aerospace7090131 - 2 Sep 2020
Cited by 4 | Viewed by 4235
Abstract
The two dimensional gravity turn problem is addressed allowing for the effects of variable rocket mass due to propellant consumption, thrust and thrust vector angle, lift and drag forces at an angle-of-attack and atmospheric mass density varying with altitude; Coriolis and centrifugal forces [...] Read more.
The two dimensional gravity turn problem is addressed allowing for the effects of variable rocket mass due to propellant consumption, thrust and thrust vector angle, lift and drag forces at an angle-of-attack and atmospheric mass density varying with altitude; Coriolis and centrifugal forces are neglected. Three distinct analytical solutions are obtained for constant: propellant flow rate, thrust, thrust vector angle, angle-of-attack and acceleration of gravity; the lift and drag are assumed to be proportional to the square of velocity, and the mass density is assumed to decrease exponentially with altitude. The method III uses power series of time for the horizontal (downrange) and vertical (altitude) coordinates; the method II replaces the altitude as variable by the atmospheric mass density and method I by its inverse. Thus the three solutions have distinct properties, e.g., I and III converge best close to lift-off and II close to burn-out. The three solutions: I, II, III, can be applied in isolation (or matched in combination) to the single-point boundary-value problem (SPBVP) of finding the trajectory with given initial conditions at launch. They can also be used as pairs in six distinct ways (I + II, I + III, II + III or reverse orders) to solve the two-point boundary-value problem (TPBVP), viz.: from given conditions at launch achieve one (not more) specified condition at burn-out, e.g., ã desired horizontal velocity for payload release. Each of the six distinct combinations of methods of addressing the TPBVP shares three features: (i) it can determine if there is a solution, viz. if the rocket has enough performance to reach the desired burn-out condition; (ii) if the desired burn-out condition is achievable it can calculate the complete trajectory from launch to burn-out; (iii) it can determine the range of achievable burn-out conditions, e.g., the minimum and maximum possible horizontal velocity at burn-out for given initial conditions at launch. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

Review

Jump to: Research

18 pages, 1306 KiB  
Review
Large Constellations of Small Satellites: A Survey of Near Future Challenges and Missions
by Giacomo Curzi, Dario Modenini and Paolo Tortora
Aerospace 2020, 7(9), 133; https://doi.org/10.3390/aerospace7090133 - 7 Sep 2020
Cited by 141 | Viewed by 14681
Abstract
Constellations of satellites are being proposed in large numbers; most of them are expected to be in orbit within the next decade. They will provide communication to unserved and underserved communities, enable global monitoring of Earth and enhance space observation. Mostly enabled by [...] Read more.
Constellations of satellites are being proposed in large numbers; most of them are expected to be in orbit within the next decade. They will provide communication to unserved and underserved communities, enable global monitoring of Earth and enhance space observation. Mostly enabled by technology miniaturization, satellite constellations require a coordinated effort to face the technological limits in spacecraft operations and space traffic. At the moment in fact, no cost-effective infrastructure is available to withstand coordinated flight of large fleets of satellites. In order for large constellations to be sustainable, there is the need to efficiently integrate and use them in the current space framework. This review paper provides an overview of the available experience in constellation operations and statistical trends about upcoming constellations at the moment of writing. It highlights also the tools most often proposed in the analyzed works to overcome constellation management issues, such as applications of machine learning/artificial intelligence and resource/infrastructure sharing. As such, it is intended to be a useful resource for both identifying emerging trends in satellite constellations, and enabling technologies still requiring substantial development efforts. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology)
Show Figures

Figure 1

Back to TopTop