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Propulsion

About: Propulsion is a research topic. Over the lifetime, 24977 publications have been published within this topic receiving 200311 citations.


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Journal ArticleDOI
TL;DR: This model is presented and then compared to some experimental signatures for validation, and it is shown that this model can be used to study the field radiated by electrical propulsion motors.
Abstract: Magnetic silencing is required for specific naval applications, especially for some oceanographic or military ships It is therefore necessary to study the field radiated by electrical propulsion motors This can be achieved using a numerical modeling based on magnetic moments In the present paper, this model is presented and then compared to some experimental signatures for validation

45 citations

01 Jan 2003
Abstract: There has been recent interest in unmanned air vehicles with a largest linear dimension no greater than 6 inches. Micro sized air vehicles (µAV) are intended to operate close to a point of interest without detection and provide surveillance teams with critical information in life threatening situations that is currently not available in a rapid-deployment urban-environment mission scenario. This paper studies the importance of aerodynamics, propulsion, and mission requirements on the design of a µAV. A Multi-Disciplinary Optimization method is used to size µAV’s for a baseline mission. Sensitivity studies of the optimized designs identify features that most strongly affect its performance. Electric and internal combustion engine propulsion are compared. Results of these analyses show that large energy density, power density, and maximum lift capability are the most important features of successful µAV’s and that ICE power is superior to electric because of its larger power density. The results also show that increases in parasite drag due to low Reynolds number is of minor importance so long as lift capability is maintained. Maneuverability constraints have the strongest influence on µAV size because smaller turn radii require lower wing loadings and for a fixed weight this implies larger wing area and size. Three radio controlled prototypes of µAV’s were built and test flown based on the design study results. These vehicles are a 9 inch span electric powered fixed-wing, a 6 inch span ICE powered fixed-wing, and a 7 inch diameter ICE powered VTOL design. Each design has been flown successfully as a radio control aircraft and the flight test results revealed several unexpected difficulties relating to aircraft stability, control, and propulsion system integration. Further numerical analysis of the VTOL design shows that the size penalty for VTOL capability is negligible and that a 6 inch tail-sitter µAV can perform all of the mission requirements and operate in VTOL and translational flight modes.

45 citations

Proceedings ArticleDOI
13 Jul 1998
TL;DR: The first flight-worthy NSTAR 30 cm diameter xenon ion thrusters were designed and built by Hughes Electron Dynamics Division, with assistance from NASA's Lewis Research Center and Jet Propulsion Laboratory as mentioned in this paper.
Abstract: Deep Space 1 is a technology demonstration mission scheduled to be launched in October 1998. One of those technologies is the NSTAR 30 cm diameter xenon ion thruster which will provide the primary propulsion. Three Flight-design thrusters were designed and built by Hughes Electron Dynamics Division, with assistance from NASA's Lewis Research Center. The first thruster was a Pathfinder to finalize the fabrication and assembly procedures for the other thrusters. Two flight-worthy thrusters were then fabricated and tested to Protoflight Qualification levels at NASA's Lewis Research Center and Jet Propulsion Laboratory. Each thruster was performance tested before and after Vibration Tests, integrated with different flight power processors and digital control interface units, and underwent Thermal Vacuum Tests with engine starts from -97 °C. Performance tests included neutralizer, discharge chamber, and ion optics characterizations as well as measurements of thruster efficiency over the full 0.5 to 2.3 kW power throttle range. The performance, at both component and thruster levels, was as expected and found to be quite repeatable with negligible dispersion between thrusters. After final functional tests, one thruster was installed on the DS 1 spacecraft while the other was set aside as a flight spare.

45 citations

Journal ArticleDOI
TL;DR: In this article, a piezoelectric inertial rotary motor is designed to power the underwater vehicle, which is capable of forward swimming, rotating, rising and diving, and it can operate at a slip-slip mode by the saw-tooth type driving signal.
Abstract: With developments of micro-machining and advanced functional materials, smart actuators have been developed and applied in various micro underwater vehicles (MUVs) or micro underwater robots. Since there is a tradeoff between the miniature size and output performance for MUVs driven by traditional electromagnetic motors, piezoelectric motors with features of compact structure, large force or torque at small size and no electromagnetic interference provide another promising alternative for actuating MUVs. However, there is a few research to explore the possibility of utilizing piezoelectric motors to realize underwater actuations. In this paper, a novel piezoelectric inertial rotary motor is designed to power the underwater vehicle, which is capable of forward swimming, rotating, rising and diving. This motor consists of two rotors and one disk type stator. One piece of piezoelectric wafer adhered to the bottom face of the stator’s metal disk is used to excite the radial in-plane vibration mode of stator’s outer ring, which is converted into the revolved motion of the inner tube through the connection beams. To utilize the inertial driving mechanism, the motor works at a “slip-slip” mode by the saw-tooth type driving signal. One prototype motor with the appearance size of Φ 20 mm × 20 mm and weight of 3.6 g is designed, fabricated and characterized. Experimental results show that the prototype motor could rotate at a steady speed of 2200 r/min with 150 Vp-p driving voltage. In addition, the motor also performs well with a slightly decrease of operating speed in underwater environments when the silver electrode is coated by waterproof material. Consequently, sealing ring is not necessary for the proposed motor as immersed in water, which is different with conventional electromagnetic motors and enables the actuation unit to be smaller. And then, the prototype motor is coupled with a propeller to build a thruster, which could output the steady speed and maximum propulsion force of 1200 r/min and 4.6 mN, respectively. Finally, the thruster is installed in a spherical swimming robot, and the velocity of the robot could reach 80 mm/s. With merits of simple structure, compact size and great waterproof feasibility, the proposed piezoelectric inertial motor opens a new avenue for developing advanced and flexible MUVs.

45 citations

Proceedings ArticleDOI
11 Sep 2000
TL;DR: In this paper, the vehicle shape and main propulsion system were modified to use magnetic torque transfer through a seawater collar to eliminate a rotating shaft seal, which resulted in a four fold reduction in propulsion power at the same speed of the previous design, and an increase in maximum achievable speed by almost a factor of two.
Abstract: This paper details recent efforts on drag reduction, vehicle shape and propulsion system modifications, and propeller design for the REMUS class of autonomous underwater vehicles (AUV). Drag reduction was accomplished by tow-tank measurements of an existing design to itemize the sources of drag. The vehicle shape and main propulsion system were modified to use magnetic torque transfer through a seawater collar to eliminate a rotating shaft seal. Propeller design efforts consisted first of a trade-off analysis of blade number, RPM, vehicle speed and blade shape to determine an optimum design and then refinement of that design for production version. The combined effect of these efforts resulted in a four fold reduction in propulsion power at the same speed of the previous design, and an increase in maximum achievable speed by almost a factor of two. These propulsion system performance improvements combined with recent changes in energy capacity for the vehicle result in a total per mission range of 120 km at 1.5 m/s for an endurance of 20 hours.

45 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,085
20222,061
2021739
20201,050
20191,194
20181,187