Topic
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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TL;DR: The first planetary missions were based on conventional trajectories obtained with chemical engine rockets as mentioned in this paper, which could be considered 'impulsive' and clear limitations to the possible missions were set by the energy required to reach certain orbits.
Abstract: The design of spacecraft trajectories is a crucial part of a space mission design. Often the mission goal is tightly related to the spacecraft trajectory. A geostationary orbit is indeed mandatory for a stationary equatorial position. Visiting a solar system planet implies that a proper trajectory is used to bring the spacecraft from Earth to the vicinity of the planet. The first planetary missions were based on conventional trajectories obtained with chemical engine rockets. The manoeuvres could be considered 'impulsive' and clear limitations to the possible missions were set by the energy required to reach certain orbits. The gravity-assist trajectories opened a new way of wandering through the solar system, by exploiting the gravitational field of some planets. The advent of other propulsion techniques, as electric or ion propulsion and solar sail, opened a new dimension to the planetary trajectory, while at the same time posing new challenges. These 'low thrust' propulsion techniques cannot be considered 'impulsive' anymore and require for their study mathematical techniques which are substantially different from before. The optimisation of such trajectories is also a new field of flight dynamics, which involves complex treatments especially in multi-revolution cases as in a lunar transfer trajectory. One advantage of these trajectories is that they allow to explore regions of space where different bodies gravitationally compete with each other. We can exploit therefore these gravitational perturbations to save fuel or reduce time of flight. The SMART-1 spacecraft, first European mission to the Moon, will test for the first time all these techniques. The paper is a summary report on various activities conducted by the project team in these areas.
45 citations
01 Jan 2001
TL;DR: An intelligent fault tolerant flight control system that blends aerodynamic and propulsion actuation for safe flight operation in the presence of actuator failures is presented.
Abstract: This paper presents an intelligent fault tolerant flight control system that blends aerodynamic and propulsion actuation for safe flight operation in the presence of actuator failures. Fault tolerance is obtained by a nonlinear adaptive control strategy based on on-line learning neural networks and actuator reallocation scheme. The adaptive control block incorporates a recently developed technique for adaptation in the presence of actuator saturation, rate limits and failure. The proposed integrated aerodynamic/propulsion flight control system is evaluated in a nonlinear flight simulation environment.
45 citations
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31 Jul 1973
TL;DR: In this article, the authors describe an AC electric drive that allows a broad range of control of the power of actuating mechanisms with blower-type change of drag torque, e.g., in ship electric power systems, in powerful fan and pump units, etc.
Abstract: The report describes an invention that is one of the family of AC electric drives permitting a broad range of control of the power of actuating mechanisms with blower-type change of drag torque, e.g., in ship electric power systems, in powerful fan and pump units, etc.
45 citations
01 Mar 1982
TL;DR: The results of these studies indicate that a fuel saving of 15 to 30 percent may be realized by the use of an advanced high-speed turboprop (Prop-Fan) compared to aircraft equipped with high bypass turbofan engines of equivalent technology as discussed by the authors.
Abstract: The increased emphasis of fuel conservation in the world and the rapid increase in the cost of jet fuel has stimulated a series of studies of both conventional and unconventional propulsion systems for commercial aircraft. The results of these studies indicate that a fuel saving of 15 to 30 percent may be realized by the use of an advanced high-speed turboprop (Prop-Fan) compared to aircraft equipped with high bypass turbofan engines of equivalent technology. The Prop-Fan propulsion system is being investigated as part of the NASA Aircraft Energy Efficient Program. This effort includes the wind tunnel testing of a series of 8 and 10-blade Prop-Fan models incorporate swept blades. Test results indicate efficiency levels near the goal of 80 percent at Mach 0.8 cruise and an altitude of 10.67 km (35,000 ft). Each successive swept model has shown improved efficiency relative to the straight blade model. The fourth model, with 45 deg swept blades reported herein, shows a net efficiency of 78.2 at the design point with a power loading of 301 kW/sq meter and a tip speed of 243.8 m/sec (800 ft/sec.).
45 citations
TL;DR: The successful Mach-7 flight test of the Hyper-X/X-43A research vehicle has provided a major, essential demonstration of the capability of the airframe-integrated scramjet engine and hypersonic airbreathing vehicle design tools and vision vehicles as mentioned in this paper.
45 citations