Propulsion

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

Space Propulsion Technology for Small Spacecraft

Abstract: As small satellites become more popular and capable, strategies to provide in-space propulsion increase in importance. Applications range from orbital changes and maintenance, attitude control and desaturation of reaction wheels to drag compensation and de-orbit at spacecraft end-of-life. Space propulsion can be enabled by chemical or electric means, each having different performance and scalability properties. The purpose of this review is to describe the working principles of space propulsion technologies proposed so far for small spacecraft. Given the size, mass, power, and operational constraints of small satellites, not all types of propulsion can be used and very few have seen actual implementation in space. Emphasis is given in those strategies that have the potential of miniaturization to be used in all classes of vehicles, down to the popular 1-L, 1-kg CubeSats and smaller.

Unmanned airborne reconnaissance system

Abstract: An unmanned airborne reconnaissance system, the unmanned airborne reconnaissance system including a lightweight, portable, powered aircraft and a foldable launch rail, the aircraft, in a broken down condition and the launch rail in a broken down condition fitable inside a box, the box capable of being carried by one man. The launch system includes an elongated launch rail with the carriage assembly, and a propulsion means for accelerating the carriage assembly from one end of the launch rail to the other. The carriage assembly releasably engages the aircraft so as to propel the aircraft from one end of the launch rail to the other. The propulsion may be by a cartridge that explodes and releases a gas through a cylinder, or by elastic cords. The aircraft is guided through the air either by a programmed onboard computer which controls the control surfaces of the aircraft and/or by remote control. The aircraft typically contains a camera for recording and transmitting images received from the ground below.

Concepts and status of laser-supported rocket propulsion

Abstract: Laser propulsion, a unique new system in which thrust is produced by the absorption of remote laser energy, has several distinct advantages over existing forms of propulsion. This article is intended as an overview of the status of laser propulsion based on a review of the scientific literature. Included in the discussion is an evaluation of the advantages and limitations of laser propulsion, as well as the types of missions for which it can best be used. The various types of proposed thrusters are also discussed, focusing on operation, current research, and unresolved problems. Also included is a thorough list of references documenting the research in this relatively young field.

Modeling and Near-Space Stationkeeping Control of a Large High-Altitude Airship

Abstract: 3andissolarelectricpowered,with the entire upper surface covered by solar cells. Electric motors and propellers provide propulsion, and batteries are used for power storage. In this paper, the vehicle’s surge and directional dynamics are characterized, the wind environmentismodeled,andsimplecontrolandguidancealgorithmsaredevelopedandevaluated.Inparticular,the maneuvering power required is statistically determined, using a covariance analysis. It is shown that the vehicle is dynamically stable and sluggish, and that significant thrust and control power may be required to stationkeep in turbulence. This additional maneuvering power required may be a significant design driver.

Thrust generation by a heaving flexible foil: Resonance, nonlinearities, and optimality

Abstract: Flexibility of marine animal fins has been thought to enhance swimming performance. However, despite numerous experimental and numerical studies on flapping flexible foils, there is still no clear understanding of the effect of flexibility and flapping amplitude on thrust generation and swimming efficiency. Here, to address this question, we combine experiments on a model system and a weakly nonlinear analysis. Experiments consist in immersing a flexible rectangular plate in a uniform flow and forcing this plate into a heaving motion at its leading edge. A complementary theoretical model is developed assuming a two-dimensional inviscid problem. In this model, nonlinear effects are taken into account by considering a transverse resistive drag. Under these hypotheses, a modal decomposition of the system motion allows us to predict the plate response amplitude and the generated thrust, as a function of the forcing amplitude and frequency. We show that this model can correctly predict the experimental data on plate kinematic response and thrust generation, as well as other data found in the literature. We also discuss the question of efficiency in the context of bio-inspired propulsion. Using the proposed model, we show that the optimal propeller for a given thrust and a given swimming speed is achieved when the actuating frequency is tuned to a resonance of the system, and when the optimal forcing amplitude scales as the square root of the required thrust.