Aerotecnica Missili & Spazio最新文献

This paper addresses the development of an attitude determination and control system (ADCS) for a sounding rocket using thrust vector control (TVC). To design the ADCS, a non-linear 6 degrees-of-freedom (DoF) model for the rocket dynamics and kinematics is deduced and implemented in simulation environment. An optimal attitude controller is designed using the linear quadratic regulator (LQR) with an additional integral action (LQI), and relying on the derived linear, time-varying, state-space representation of the rocket. The controller is tested in the simulation environment, demonstrating satisfactory attitude tracking performance, and robustness to model uncertainties. A navigation system is designed, based on measurements available on-board, to provide accurate real-time estimates on the rocket’s state and on the aerodynamic forces and moments acting on the vehicle. These aerodynamic estimates are used by an adaptive version of the controller that computes the gains in real time after correcting the state-space model. Finally, the ADCS is the result of the integration of the attitude control and navigation systems, with the complete system being implemented and tested in simulation, and demonstrating satisfactory performance.

Mixed flow compressor stage designs are becoming increasingly popular for use in Micro Gas Turbine (MGT) engines. Due to manufacturing constraints and structural considerations, such compressors typically feature unshrouded impeller designs. A numeric investigation of the effect of impeller-shroud tip clearance on the performance of a MGT mixed flow compressor stage fitted with a crossover diffuser is presented. Three baseline test compressors are designed using an in-house-developed application based on one-dimensional mean line theory. These cover a wide range of design mass flow rates, design speeds, and impeller meridional exit (mixed flow) angles. The performance of each of the test compressors are evaluated at an impeller-shroud tip clearance of 0.1 mm, 0.3 mm, and 0.6 mm. Commercial CFD software is used to verify the performance results of the various test compressor configurations. It is found that an increase in impeller tip clearance negatively impacts both compressor performance (total-to-total pressure ratio and efficiency) and choke margin. Conversely, stall margin increases with an increase in impeller tip clearance.

The technologies and demonstrators for space exploration (TEDS) Program is an essential part of the Italian Aerospace Research Program (PRORA), for which execution was assigned to the Italian Aerospace Research Centre (CIRA) by the Italian Minister of Research. It was conceived in 2020 as a technology program aimed to mature several technologies, demonstrators, and engineering tools considered enabling for future space exploration and colonization missions. Indeed, Martian colonization and lunar colonization are foreseen to be the next steps in human space exploration, and long-term manned spaceflight and extra-terrestrial planet settlement are the inevitable trends of space technologies and will enhance human knowledge in several scientific fields, leading to better understanding of the wider universe and our place within it. But the robotic and manned exploration, for both short- and long-term missions and, above all, the possible habitation and the future colonization of the Moon, require to overcome numerous critical challenges e.g., protection from radiation and micro-meteorites, energy supply, extraction and recycling of water, food production, and much more. Moreover, the environmental issues that could negatively impact lunar surface missions include temperature fluctuations, triboelectrification, airless conditions, energetic particle exposure, and the lunar regolith dust particles. The present paper gives an overview of the (CIRA) development plan related to the (TEDS) program, focusing on the development of enabling technologies, both actual achievements and future perspectives.

This paper presents a novel approach to developing 2D structural theories for composite shells. The proposed approach uses the capabilities of the Carrera Unified Formulation (CUF) in conjunction with the Axiomatic/Asymptotic Method (AAM) to obtain the best theories for given structural layouts. Different structural cases are considered to analyze the influence of factors such as boundary conditions, lamination, and thickness on the accuracy of a model. The parameter chosen to evaluate a model’s performance is based on the Failure Indexes (FI) defined by the Hashin Failure criteria for unidirectional fiber composites. The outcome of this procedure is the Best Theory Diagram (BTD), containing the graphical representation of the highest accuracy as a function of the number of adopted unknowns. The results show the importance of higher-order terms to capture stress fields and the influence of thickness on the definition of the best theories.

On August 22, 2014, the first two Full Operational Capacity satellites of the Galileo constellation were launched from Kourou on a Soyuz ST-B rocket. Shortly after the insertion into the final orbit, the on-board telemetry showed the achieved orbit was different from the target highly inclined circular orbit, due to a failure in the Fregat upper stage attitude control system. This anomaly precluded nominal operations in the Galileo constellation, as well as introducing limitations in the use of several of on-board subsystems. A recovery campaign took place in the winter of 2014 to change the two satellites’ trajectories, so to reduce the entity of operative constraints and provide better communication with the ground segment. With no dedicated orbital thruster available, attitude thrusters were used effectively to modify and enhance the orbit and recover from a multi-system failure, making reinsertion in a GNSS constellation possible. This work investigates, by means of a numerical model, the best combination and sequence of maneuvers that could have been implemented in the recovery campaign to satisfy most proposed drivers with the given (Delta v) budget. The results show that different final orbits with the same resonance but lower eccentricity could have been achieved.

A common issue for long-duration balloon flights in the polar area is high bit rate data transferring. Just a few hours after launch balloons are nor reachable with direct radio link, and often satellite links are not fast enough to allow the necessary transfer rate or, simply, too expensive. For this reason, stratospheric balloon borne experiments carry out on-board data recording. Data recorded need to be recovered after termination, which is, sometimes, a slow, difficult and expensive task. Not always it is easy or possible to reach the landing site, especially during the polar winter. The aim of the project is to provide an autonomous glider capable of physically carrying the data from the stratospheric platform to a recovery point on the ground. This can also transport physical objects (like air samples) collected at float or along the flight. We estimate that an electrical motorglider released in the stratosphere can fly for several hundreds of kilometers. The glider is installed on the balloon payload through a remotely controlled release system, and connected with the main computer to receive data and the geographic coordinates of the recovery point. The glider trajectory can be monitored with Iridium SBD (Short Burst Data), and simple commands can be issued as well as using Iridium.

An extension has been made with the popular Rayleigh–Ritz method by integrating the Lagrangian functional of a nonlinear vibration equation of motion over one period of vibrations to eliminate harmonics from the simplification. A set of successive nonlinear equations of coupled higher order amplitudes of deformation is obtained, and a nonlinear eigenvalue problem is presented for the frequency–amplitude dependence of nonlinear vibrations of successive displacements. The subsequent solutions of vibration frequencies and deformation are actually consistent with other successive approximate methods such as the harmonics balance method. This is an extension of the powerful Rayleigh–Ritz method which has broad applications for approximate solutions for vibration problems in solid mechanics. This extended Rayleigh–Ritz method can now be utilized for the analysis of free and forced nonlinear vibrations of structures as a new technique with significant advantages.

Since the introduction of Regulation (EU) No 376/2014 of the European Parliament and of the Council in 2014, [1], EU Member States and EASA have been required to publish the Annual Safety Review (ASR). The ASR contains an overview of the safety statistics in each Member State, reporting numerical indicators and graphical representations. Its goal is to describe national aviation safety scenarios on which appropriate preventive measures can be based. Among the diversity of reporting practices within the EU Member States, it is possible to find a common set of criteria for the analysis of ASRs, to design homogeneous and data-driven safety measures across the continent. Currently, the main obstacles to our approach arise from the wide variety of reporting styles and the lack of shared guidelines for ASRs. This paper proposes a template to assist EU Member States in the process of producing their ASRs and presents a comparative analysis of a selected subset of these documents.

The measurement of the Cosmic Microwave Background (CMB) polarization and the spectral distortions produced on this radiation field by clusters of galaxies (Sunyaev-Zeldovich Effect, SZE) are the current frontiers in cosmology. In this paper, we report on two stratospheric balloon experiments aimed to study the research fields mentioned above. OLIMPO is a mm/submm waves telescope, with 2.6 m primary mirror coupled to four arrays of Kinetic Inductance Detectors (KID), centered at 150, 250, 350, and 460 GHz, to match the SZ spectrum, and operating at 0.3 K. The payload, flown in 2018 producing a very successful technology demonstration, includes a plug-in Differential Fourier-Transform Spectrometer. LSPE (Large Scale Polarization Explorer) is a combined balloon-borne and ground-based program dedicated to the measurement of the CMB polarization at large angular scales. LSPE/SWIPE (Short Wavelength Instrument for the Polarization Explorer), the balloon-borne instrument, includes a refractive telescope with a 50 cm optical aperture feeding three arrays of 330 multi-mode TES bolometers at 145, 210, e 240 GHz. The polarization of the incoming radiation will be modulated by a rotating Half Wave Plate (HWP), that is maintained levitating by an innovative magnetic suspension system. The detectors and the optical elements are cooled at cryogenic temperatures. The cryogenic system is designed to have a duration of 14 days with a flight performed during the polar night, to allow a coverage of a large fraction of the sky. In the paper, we describe the configuration of the two instruments, the modifications to be implemented on OLIMPO for a second scientific flight and the status of the different sub-system for LSPE/SWIPE.