Aerotecnica Missili & Spazio最新文献

Advanced avionics and automation technologies have significantly transformed cockpit operations, resulting in a gradual reduction of the crew members on-board. Single-pilot operations (SPO) concept is gaining significant attention in the aviation industry due to its potential for cost savings and to cope with the anticipated pilot shortage and the increasing air traffic demand. This paper conducts a scoping literature review on SPOs, serving as an initial step to map the scientific peer-reviewed content on the subject. The survey focuses on three thematic domains, which are, respectively, operations, automation, and the emerging field of digital and cognitive flight assistants. The methodology involved the use of Google Scholar and IEEE Xplore databases. Sources were selected adapting the search criteria to the proposed sub-topics and prioritizing either the most cited and recent contributions. The analysis of the literature reveals a growing body of work in the recent years. This review also highlights interest in the human-centered design for automation solutions which are responsive to cognitive and behavioral states of the pilot. While acknowledging the potential safety and operational challenges associated with SPOs and the pilot-automation cooperation, this work suggests that great research efforts should be made on the human factor and regulatory subjects to pave the way for a feasible and safe implementation of the single-pilot paradigm in commercial aviation.

Due to their simplicity and relative ease of manufacture, single-stage centrifugal and mixed flow micro gas turbine (MGT) engines are preferred in thrust-based remotely piloted aerial vehicles. A single-stage mixed-flow compressor upgrade for the 200 N CAT250TJ MGT engine is numerically evaluated and presented. An in-house developed mean line application and commercial CFD software is used for the design and performance evaluation of the proposed upgrade configurations. The CAT250TJ – Gen1 engine features a single-stage centrifugal compressor, annular combustor, and single stage axial turbine. Apart from an upgraded impeller, a new crossover diffuser configuration is introduced to replace the wedge-type, straight outlet diffuser configuration of the Gen1 engine. The new single vane crossover diffuser configuration provides a design point total-to-total efficiency and pressure ratio increase of 8.3% and 12.1%, respectively. A disadvantage of a single-vaned crossover diffuser compared to legacy diffusers is a narrower operating range. To alleviate this issue, various combinations of tandem and splitter vane crossover diffuser configurations are proposed. These provide an enhanced operating range, comparable with the operating range displayed by the Gen1 configuration. A turbine power matching analysis is additionally completed to ensure proper compressor integration. Gas turbine cycle software is used to evaluate the on-engine performance of the upgraded compressor configurations. It is shown that the new baseline, single vane crossover diffuser configuration provides a 10.74% increase in design point static thrust.

In this paper, the problem of guiding a vehicle from the entry interface to the ground is addressed. The Space Shuttle Orbiter is assumed as the reference vehicle and its aerodynamics data are interpolated to properly simulate its dynamics. The transatmospheric guidance is based on an open-loop optimal strategy which minimizes the total heat input absorbed by the vehicle while satisfying all the constraints. Instead, the terminal phase guidance is achieved through a multiple-sliding-surface technique, which is able to drive the vehicle toward a specified landing point with desired heading angle and vertical velocity at touchdown, even in the presence of nonnominal initial conditions. The terminal guidance strategy is successfully tested through a Monte Carlo campaign, in the presence of stochastic winds and wide dispersions on the initial conditions at the terminal area energy management, in more critical scenarios with respect to the orbiter safety criteria.

Stellar in-flight calibrations have a relevant impact on the capability of space optical instruments, such as telescopes or cameras, to provide reliable scientific products, i.e., accurately calibrated data. Indeed, by using the in-flight star images, instrument optical performance can be checked and compared with the on-ground measurements. The analysis of star images carried out throughout the entire lifetime of the instrument in space will enable tracking changes in instrument performance and sensitivity due to degradation or misalignment of the optical components. In this paper, we present the concept, the necessary input and the available outputs of the simulations performed to predict the stars visible in the field of view (FoV) of a specific space instrument. As an example of the method, its application to two specific cases, the Metis coronagraph onboard Solar Orbiter and the stereo camera STereo Channel (STC) onboard BepiColombo, are given. Due to their proximity to the Sun, and to Mercury for STC, both instruments operate under harsh environmental conditions in terms of radiation exposure ((e.g., cosmic rays and SEP), high temperatures and significant temperature variations. Therefore, it is crucial to monitor their optical performances.

In the last few years, the number of orbiting satellites has increased exponentially, in particular due to the development of the New Space Economy. Even if this phenomenon makes the space more accessible, bringing a great contribution to the scientific, economic and technological fields, on the other hand it contributes to the overpopulation of the space background. Therefore, it is necessary to develop new techniques to manage the space environment, such as in orbit servicing, which is a procedure that aims to refuel and repair satellites to extend their operational life. A first step to reach this goal is to inspect closely the object of interest to study its features. In this framework, the Space Rider Observer Cube (SROC) mission is being developed. SROC is a payload that will be deployed by Space Rider (SR), an uncrewed and reusable robotic spacecraft designed by ESA (European Space Agency). SROC is a 12U CubeSat, whose goal is to carry out inspection manoeuvres around SR, then re-enter on board using a safe docking system to come back to Earth. The feasibility of a mission similar to SROC has been simulated during a university class, starting from the definition of the system requirements with particular focus on the analysis of the payloads and subsystems, to ensure the achievement of the mission goals. In particular, the CubeSat is equipped with an imaging payload to capture high resolution images of Space Rider surface and a docking mechanism. Then, the design of the orbit and the simulation of the effects of the space environment on the CubeSat have been studied using GMAT, SYSTEMA, MATLAB and other numerical tools. The results of the study are useful for future missions, aiming to inspect orbiting objects, such as operative satellites for in orbit servicing, space debris and dead satellites to study their geometries and plan their removal.

The utilization of liquid oxygen/liquid methane couple ((LOX/LCH_4)) as a potential candidate to substitute hypergolic propellants and hydrazine in the next future propulsion systems has arisen an increasing interest due to the advantages offered in terms of low environmental impact, re-usability, cooling capabilities and relatively high specific impulse (Schuff et al. in Integrated modeling and analysis for a lox/methane expander cycle engine: Focusing on regenerative cooling jacket design, p. 4534, 2006 ). In this perspective, the Italian Aerospace Research Center manages the “HYPROB” research program, cofunded by the Italian Research and University Ministry, that has the objective to improve the national capabilities into developing engines, fed by hydrocarbons, that could be successfully applied as propulsion units for third stages of launchers for space exploration. The “HYPROB” program led to the realization of a (LOX/LCH_4) engine named “DEMO-0A”, a 30 kN thrust class demonstrator, technologically representative of a regenerative thrust chamber assembly of an expander engine (Ricci et al. in Energies, p. 2190, 2022). The present paper describes the results of the numerical simulations performed by means of the EcosimPro software, aimed at reproducing the operative conditions, both cold flow and firing, of the regenerative thrust chamber “DEMO-0A”. An assessment of the capabilities of the software in predicting the behaviour of the demonstrator by modelling it with a 1-D approach and by considering different wall heat exchange semiempirical correlations has been done by comparing numerical results and the available experimental data gathered during both cold flow both firing test campaigns.

Ferrofluid-based systems provide an opportunity for increasing the durability and reliability of systems, where mechanical parts are prone to wear and tear. Conventional reaction control systems are based on mechanically mounted rotating disks. Due to inherent friction, they suffer from degradation, which may eventually lead to failure. This problem is further intensified due to the limited possibility for repair and maintenance. Ferrofluid-based systems aim to replace mechanical components by exploiting ferrofluidic suspended motion. Ferrofluids consist of magnetic nanoparticles suspended in a carrier fluid and can be manipulated by external magnetic fields. This paper describes the working principle, design, and integration of a working prototype of a ferrofluid-based attitude control system (ACS), called Ferrowheel. It is based on a stator of a brushless DC motor in combination with a rotor on a ferrofluidic bearing. The prototype will be verified in a microgravity environment on the International Space Station, as part of the Überflieger 2 student competition of the German Aerospace Center. First ground tests deliver positive results and confirm the practicability of such a system.

This paper presents the evaluation of various model reduction techniques as possible candidates for building a virtual testing simulation environment of the ESA’s Micro Vibrations Measurement System (MVMS). The resulting tool would represent a key enabling technology for optimization of the tests to be carried out by the facility for the characterization of potential microvibration sources and environments. The present investigation involves both component mode synthesis and state-space based methods. In particular, an enhanced version of the Craig–Bampton (CB) method with substructuring and a hybrid two-stage approach involving a preliminary CB reduction step followed by a balanced truncation are presented and discussed. The number of dominant vibration modes to be retained in each substructure is determined according to the effective interface mass criterion. The different model reduction methods are compared in terms of performance and computational effort. It is shown that some preferable techniques can be identified for the specific purposes of the virtual testing environment of the MVMS.

The advent of Automated Fiber Placement (AFP) in aerospace composites lay-up and manufacturing has allowed orientations to vary along pre-defined curved directions rather than being forced to remain constant within the lamina. These composites are called Variable Angle Tow (VAT) or Variable Stiffness Composites (VSC). Despite the enhancements in mechanical performance offered by VAT, constraints from the manufacturing process hinder their full potential. This paper explores the effect of primary defects, i.e., gaps and overlaps, on optimal design and fundamental frequency optimization. For doing so, the Carrera Unified Formulation (CUF) and the Defect Layer Method (DLM) are integrated directly into the optimization process to provide an efficient and cost-effective framework for modeling the structural behavior and manufacturing process of VSCs. Particular attention is given to manufacturing and tow-steering simulation to quantify and map defects for each laminate layer. This research serves a dual purpose: (i) examining the impact of process-induced defects on achieving an optimal design and (ii) exploring how the choice of structural theory may affect the optimal solution.

Spacecraft fragmentation due to collisions with space debris is a major concern for space agencies and commercial entities, since in the next years the production of collisional fragments is expected to become the major source of space debris. Experimental studies have shown that the fragmentation process is highly complex and influenced by various factors, such as the satellite design, the material properties, the velocity and angle of the debris impact, and the point of collision (e.g., central, glancing, on spacecraft appendages). This paper summarizes the current state of research in spacecraft fragmentation, including the methods and techniques used to simulate debris impacts, the characterization of fragment properties and the analysis of the resulting debris cloud. It provides an overview of the main experiments performed, underlining the most critical issues observed. Moreover, it presents a set of experiments performed at the University of Padova and proposes some future directions for this research.