We developed a global model aiming to study discharges in CO<sub>2</sub> under various conditions, pertaining to a large spectrum of pressure, absorbed energy, and feeding values. Various physical conditions and form factors have been investigated. The model was applied to a case of radiofrequency discharge and to helicon type devices functioning in low and high feed conditions. In general, main charged species were found to be <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.313601pt" id="M1" height="14.5635pt" version="1.1" viewBox="-0.0498162 -11.2499 30.845 14.5635" width="30.845pt"><g transform="matrix(.0135,0,0,-0.0135,0,0)"><path id="g190-68" d="M614 175C564 76 510 21 408 21C256 21 146 149 146 336C146 488 235 629 402 629C510 629 570 586 597 480L626 488C620 541 614 582 606 638C578 643 510 665 429 665C206 665 44 527 44 316C44 157 153 -15 402 -15C474 -15 558 5 586 11C604 45 629 119 643 165L614 175Z"/></g><g transform="matrix(.0135,0,0,-0.0135,9.105,0)"><path id="g190-80" d="M381 665C170 665 44 498 44 318C44 125 188 -15 369 -15C552 -15 703 117 703 333C703 534 550 665 381 665ZM359 629C491 629 601 517 601 306C601 114 502 21 390 21C249 21 146 158 146 346S248 629 359 629Z"/></g><g transform="matrix(.0095,0,0,-0.0095,19.297,3.264)"><path id="g50-51" d="M414 144C384 79 371 75 317 75H135L276 221C367 316 408 376 408 465C408 570 327 635 237 635C179 635 131 609 100 575L42 494L67 471C94 510 138 565 205 565C277 565 321 517 321 435C321 348 258 270 195 195C146 137 88 81 33 26V0H411C423 44 433 88 446 135L414 144Z"/></g><g transform="matrix(.0095,0,0,-0.0095,24.431,-5.984)"><path id="g54-36" d="M556 236V289H337V504H275V289H56V236H275V-4H337V236H556Z"/></g></svg> for sufficiently low pressure cases and O<sup>&#x2212;</sup> for higher pressure ones, followed by <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.313601pt" id="M2" height="14.5635pt" version="1.1" viewBox="-0.0498162 -11.2499 30.845 14.5635" width="30.845pt"><g transform="matrix(.0135,0,0,-0.0135,0,0)"><use xlink:href="#g190-68"/></g><g transform="matrix(.0135,0,0,-0.0135,9.105,0)"><use xlink:href="#g190-80"/></g><g transform="matrix(.0095,0,0,-0.0095,19.297,3.264)"><use xlink:href="#g50-51"/></g><g transform="matrix(.0095,0,0,-0.0095,24.431,-5.984)"><use xlink:href="#g54-36"/></g></svg>, CO<sup>+</sup>, and <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.313601pt" id="M3" height="14.5635pt" version="1.1" viewBox="-0.0498162 -11.2499 21.7065 14.5635" width="21.7065pt"><g transform="matrix(.0135,0,0,-0.0135,0,0)"><use xlink:href="#g190-80"/></g><g transform="matrix(.0095,0,0,-0.0095,10.158,3.264)"><use xlink:href="#g50-51"/></g><g transform="matrix(.0095,0,0,-0.0095,15.292,-5.984)"><use xlink:href="#g54-36"/></g></svg> in the latter case. Dominant reaction is dissociation of CO<sub>2</sub> resulting into CO production. Electronegativity, important for radiofrequency discharges, increases with pressure, arriving up to 3 for high flow rates for absorbed power of 250&#x2009;W, and diminishes with increasing absorbed power. Model results pertaining to radiofrequency type plasma discharges are found in satisfactory agreement with those available from an existing experiment. Application to low and high flow rates feedings cases of helicon thruster allowed for evaluation of thruster functioning conditions pertaining to absorbed powers from 50&#x2009;W to 1.8&#x2009;kW. The model allows for a detailed evaluation of the CO<sub>2</sub> potential to be used as propellant in electric propulsion devices.

Chloe Berenguer

Konstantinos Katsonis

Global Modeling of CO<sub>2</sub> Discharges with Aerospace Applications

The purpose of the paper is to investigate the effects of low pressure plasma treatment on wettability of carbon fibre reinforced polymer samples and on shear properties of adhesive bonded joints based on these substrates. In particular, two plasma process parameters, exposure time and power input, were optimized, performing contact angle evaluation on lap-shear tests. The plasma treatment was also compared with a conventional mechanical abrasion and untreated and only degreased specimens. The experimental results show that choosing the optimal parameters is possible to improve the wettability of composite substrates and reduce the contact angle.

Chiara Mandolfino

Enrico Lertora

Carla Gambaro

Cold Plasma Pretreatment of Carbon Fibre Composite Substrates to Improve Adhesive Bonding Performance

A review of the literature pertaining to hypergolic fuel systems, particularly using hydrazine or its derivatives and hydrogen peroxide, has been conducted. It has been shown that a large effort has been made towards minimizing the risks involved with the use of a toxic propellant such as the hydrazine. Substitution of hydrazines for nontoxic propellant formulations such as the use of high purity hydrogen peroxide with various types of fuels is one of the major areas of study for future hypergolic propellants. A series of criteria for future hypergolic propellants has been recommended, including low toxicity, wide temperature range applicability, short ignition delay, high specific impulse or density specific impulse, and storability at room temperature.

Stephen M. Davis

Nadir Yilmaz

Advances in Hypergolic Propellants: Ignition, Hydrazine, and Hydrogen Peroxide Research

Mobility control is one of the most essential parts of planetary rovers&#x2019; research and development. The goal of this research is to let the planetary rovers be able to achieve demand of motion from upper level with satisfied control performance under the rough and deformable planetary terrain that often lead to longitudinal slip. The longitudinal slip influences the mobility efficiency obviously, especially on the major deformable slopes. Compared with the past works on normal stiff terrains, properties of soil and interaction between wheels and soil should be considered additionally. Therefore, to achieve the final goal, in this paper, wheel-soil dynamic model for six-wheel planetary rovers while climbing up deformable slopes with longitudinal slip is first built and control based in order to account for slip phenomena. These latter effects are then taken into account within terramechanics theory, relying upon nonlinear control techniques; finally, a robust adaptive fuzzy control strategy with longitudinal slip compensation is developed to reduce the effects induced by slip phenomena and modeling error. Capabilities of this control scheme are demonstrated via full scale simulations carried out with a six-wheel robot moving on sloped deformable terrain, whose real time was computed relying uniquely upon RoSTDyn, a dynamic software.

Li Zhengcai

Wang Yang

Robust Adaptive Fuzzy Control for Planetary Rovers While Climbing up Deformable Slopes with Longitudinal Slip

GPS is a satellite-based navigation system that is able to determine the exact position of objects on the Earth, sky, or space. By increasing the velocity of a moving object, the accuracy of positioning decreases; meanwhile, the calculation of the exact position in the movement by high velocities like airplane movement or very high velocities like satellite movement is so important. In this paper, seven methods for solving navigation equations in very high velocities using least squares method and its combination with the variance estimation methods for weighting observations based on their qualities are studied. Simulations on different data with different velocities from 100&#x2009;m/s to 7000&#x2009;m/s show that proposed method can improve the accuracy of positioning more than 50&#x25;.

N. Rahemi

M. R. Mosavi

A. A. Abedi

S. Mirzakuchaki

Accurate Solution of Navigation Equations in GPS Receivers for Very High Velocities Using Pseudorange Measurements

A Micro air vehicle (MAV) is defined as class of unmanned air vehicle (UAV) having a linear dimension of less than 15 centimeters and a mass of less than 100 grams with flight speeds of 6 to 12 meters per second. MAVs fall within a Reynolds number (Re) range of 50,000 and 120,000, in which many causes of unsteady aerodynamic effects are not fully understood. The research field of low Reynolds number aerodynamics is currently an active one, with many defence organizations, universities, and corporations working towards a better understanding of the physical processes of this aerodynamic regime. In the present work, it is proposed to study the unsteady aerodynamic analysis of 2D airfoil using CFD software and Xfoil panel code method. The various steps involved in this work are geometric modelling using CATIA V5R17, meshing using ICEM CFD, and solution and postprocessing through FLUENT. The finite control volume analysis and Xfoil panel code method has been carried out to predict aerodynamic characteristics such as lift coefficients, drag coefficients, moment coefficients, pressure coefficients, and flow visualization. The lift and drag coefficients were compared for all the simulations with experimental results. It was observed that for the 2D airfoil, lift and drag both compared well for the midrange angle of attack from &#x2212;10 to 15 degree AOA.

Somashekar V

A Computational Investigation of Unsteady Aerodynamics of Insect-Inspired Fixed Wing Micro Aerial Vehicle&#x2019;s 2D Airfoil

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Advances in Aerospace Engineering