1,721,087 research outputs found
Design of solar powered high altitude long endurance unmanned biplanes
No full textIn the last few years, the interest regarding solar powered aircraft has increased significantly and, in particular, the attention has been focused on Unmanned Aerial Vehicles (UAV), able to perform High Altitude and Long Endurance (HALE) missions for telecommunication, remote sensing, surveillance and control, both for civil and military applications. The present book shows the results of a research about Solar Powered Biplanes (SPBs), dealing with the definition of a design methodology and the introduction of new design tools for this kind of aircraft. The potential benefits of choosing a biplane architecture are explained and mission requirements are introduced in order to define two types of mission, conceived to perform the two main tasks of such kind of UAVs: Telecommunication (TLC) and Intelligence, Reconnaissance and Surveillance (IRS) operations. The design procedure is illustrated and a method for the preliminary aircraft sizing, based on design curves, is proposed. The optimization method adopted for the UAV design is presented, together with the models used to study aerodynamics, flight mechanics, energy balance, structures and propulsion systems
Mission architecture for Mars exploration based on small satellites and planetary drones
Full text linkPurpose: The purpose of this paper is to deal with the study of an innovative unmanned mission to Mars, which is aimed at acquiring a great amount of detailed data related to both Mars’ atmosphere and surface. Design/methodology/approach: The Mars surface exploration is conceived by means of a fleet of drones flying among a set of reference points (acting also as entry capsules and charging stations) on the surface. The three key enabling technologies of the proposed mission are the use of small satellites (used in constellation with a minimum of three), the use of electric propulsion systems for the interplanetary transfer (to reduce the propellant mass fraction) and lightweight, efficient, drones designed to operate in the harsh Mars environment and with its tiny atmosphere. Findings: The low-thrust Earth-Mars transfer is designed by means of an optimization approach resulting in a duration of slightly more than 27 months with a propellant amount of about 125 kg, which is compatible with the choice of considering a 500 kg-class spacecraft. Four candidate drone configurations have been selected as the result of a sensitivity analysis. Flight endurance, weight and drone size have been considered as the driving design parameters for the selection of the final configuration, which is characterized by six rotors, a total mass of about 6.5 kg and a flight endurance of 28 minutes. In the mission scenario proposed, the drone is assumed to be delivered on the Mars surface by means of a passive entry capsule, which acts also as a docking station and charging base. Such a capsule has been sized both in terms of mass (68 kg) and power (80 W), showing to be compatible with 500 kg-class spacecraft. Research limitations/implications: As a general conclusion, the study shows the mission concept feasibility. Practical implications: The concept would return incomparable scientific data and can be also be potentially implemented with a relatively low budget exploiting of the shelf components to the larger extent, small identical spacecraft buses and modular low-cost drones. Originality/value: The innovative mission architecture proposed in this study aims at providing a complete coverage of the surface and lowest atmospheric layers. The main innovation factor of the proposed mission consists in the adoption of small multi-copter UAVs, also called “drones,” as remote-sensing platforms
Ottimizzazione aerodinamica del sistema portante di un velivolo ultraleggero di tipo PrandtlPlane
No full textIl presente documento riporta l’attività di sviluppo della configurazione aerodinamica di un velivolo ultraleggero con una configurazione alare non convenzionale, nota come “PrandtlPlane”. Tale attività è inserita in un progetto più ampio il cui obiettivo è la realizzazione di un prototipo
IDINTOS: the first prototype of an amphibious PrandtlPlane-shaped aircraft
Full text linkThis paper summarizes the main activities conducted to design, optimize and build a prototype of an innovative light amphibian. This aircraft is a “PrandtlPlane”, a particular box-wing configuration which introduces relevant advantages as increased aerodynamic efficiency and safety of flight; the research project, called IDINTOS, has been co-funded by the Regional Government of Tuscany (Italy), coordinated by the University of Pisa and carried out in 30 months by a consortium of public bodies and small private firms, starting from 2011. In this contribution an overview is given also on several aspects concerning the design, as the aerodynamic optimization, the construction and tests of three scaled models for towing tank wind tunnel and, flight tests, respectively
Aerodynamic design of a light amphibious PrandtlPlane: wind tunnel tests and CFD validation
Full text linkAs part of the activities carried out during the "IDINTOS" project, wind tunnel tests have been performed on a 1⁄4 scaled model of a two seats amphibious PrandtlPlane. The present paper deals with the CFD analyses performed after such experimental activities, with the main goal of solving lateral-directional stability problems observed during wind tunnel tests.
In the first part of the paper, an overview of the wind tunnel test performed is provided and some of the achieved results are discussed, underlining the aforementioned directional stability problems.
The second part of the paper concerns the CFD model validation activities, consisting in the search of the models whichbest represent the wind tunnel conditions. The results of several simulations are discussed, taking the influence of the scale factor, the turbulence models and the presence of wind tunnel structures, such as the walls and the strut, into account. A detailed description of the implementation procedure adopted of the κ-ω turbulence model with fixed transition is provided.
Finally, in the third part of the paper, the chosen CFD model is used to find a solution for the improvement of the directional stability. The achieved result are presented and some information about the adoption of the selected solution on a scaled radio-controlled flying model are reported
Preliminary stability analysis methods for PrandtlPlane aircraft in subsonic conditions
Full text linkPurpose
The present paper aims to assess the reliability and the limitations of analysing flight stability of a box-wing aircraft configuration known as PrandtlPlane by means of methods conceived for conventional aircraft and well known in the literature.
Design/methodology/approach
Results obtained by applying vortex lattice methods to PrandtlPlane configuration, validated previously with wind tunnel tests, are compared to the output of a “Roskam-like” method, here defined to model the PrandtlPlane features.
Findings
The comparisons have shown that the “Roskam-like” model gives accurate predictions for both the longitudinal stability margin and dihedral effect, whereas the directional stability is always overestimated.
Research limitations/implications
The method here proposed and related achievements are valid only for subsonic conditions. The poor reliability related to lateral-directional derivatives estimations may be improved implementing different models known from the literature.
Practical implications
The possibility of applying a faster method as the “Roskam-like” one here presented has two main implications: it allows to implement faster analyses in the conceptual and preliminary design of PrandtlPlane, providing also a tool for the definition of the design space in case of optimization approaches and it allows to implement a scaling procedure, to study families of PrandtlPlanes or different aircraft categories.
Social implications
This paper is part of the activities carried out during the PARSIFAL project, which aims to demonstrate that the introduction of PrandtlPlane as air transport mean can fuel consumption and noise impact, providing a sustainable answer to the growing air passenger demand envisaged for the next decades.
Originality/value
The originality of this paper lies in the attempt of adopting analysis method conceived for conventional airplanes for the analysis of a novel configuration. The value of the work is represented by the knowledge concerning experimental results and design methods on the PrandtlPlane configuration, here made available to define a new analysis tool
WAGNER: a new code for parametrical structural study of fuselages of civil transport aircraft
Full text linkIn the present paper, a new code (named WAGNER) for a parametric and automatic Finite Element mesh generation of fuselages of civil transport aircraft is presented. The code aims at providing a time saving and reliable tool in the conceptual design phase in order to evaluate stresses and deformations in the whole fuselage structure; these data allows us a preliminary structural sizing to be used as a baseline for deeper investigations and to determine the empty weight of the fuselage in view of a preliminary prediction of the maximum take-off weight of the aircraft. As an example of application, two layouts have been analysed: a non conventional two aisle single-deck (SD) with 2-4-2 passengers abreast
and a double-deck (DD) with 3-3 passengers abreast/deck. FEM results for two different load cases (combined loads at limit load factor and ultimate pressurization) with geometrical linear and non-linear solutions, are finally discussed
SNODO PER ALI
No full textil brevetto illustra l'invenzione per cui è possibile ripiegare le ali di un velivolo di aviazione leggera e aviazione generale da parte di una sola persona in modo che il velivolo possa essere posto in hangar occupando minime dimensioni
Design of a prototype of light amphibious PrandtPlane
No full textThe paper deals with the activities to design and manufactoring a prototype of a PrandtlPlane aircraft; the aspects of aerodynamic optimization, of the structural design and technology, and the descriptions of the tests on scaled models (wind tunnel tests, water tank tests and flying tests) are addresse
A new ultralight amphibious PrandtlPlane: preliminary CFD design of the hull
Full text linkThis paper describes the preliminary CFD analyses of a ultralight amphibious PrandtlPlane, performed in order to the define the hull configurations to be studied in a subsequent towing tank test campaign. By taking the Italian regulations on ultralight aircraft into account, the effects of the main design parameters on take-off manoeuvre are studied and two hull configurations are defined. Finally, the achieved results are discussed in order to define the scale factor of towing tank test models
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