Propulsion systems for space operations - A forward look.
Payload capabilities of launch vehicles, particularly for missions with high velocity requirements, analyzing various propulsion systems
SEARCH · Engineering Papers
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Payload capabilities of launch vehicles, particularly for missions with high velocity requirements, analyzing various propulsion systems
An initial, parametric study was performed to assess the benefits and drawbacks of waste heat recovery on a gas turbine engine. The NASA N+3 technology level reference propulsion system model, an advanced, single-aisle class, gas turbine engine was the baseline cycle. The amount of thermal energy removed from the high-energy core flow and transferred to lower-energy bypass or removed from the cycle was varied. Total pressure losses were included parametrically, as well as the effects of converting some of that thermal energy to work used within the cycle. Propulsion system thrust and thrust specific fuel consumption (TSFC) were minimally affected by total pressure losses or thermal energy removal from the core stream. However, total pressure losses in the bypass stream had significant thrust and TSFC penalties. Those penalties were partially offset if core thermal energy is transferred to the bypass stream. Core thermal energy converted to work for use within the engine cycle via a bottoming cycle showed significant thrust and TSFC benefits. In addition to these results, an engine dataset is also being made available. The dataset contains engine conditions (mass flow rate, total temperature and pressure, flow velocities, etc.) at four flight conditions (maximum climb limit, cruise, rolling takeoff and sea level static) that can be used for specific information to guide heat exchanger design to best realize these benefits with further research. The data set is a .csv (comma-separated values) file and is provided as a supplement to this report (available online from www.sti.nasa.gov).
This paper describes the advanced development and testing of a compact 5 to 15 lbf LOX/LCH4 thruster for a pressure-fed integrated main engine and RCS propulsion system to be used on a spacecraft "vertical" test bed (VTB). The ability of the RCS thruster and the main engine to operate off the same propellant supply in zero-g reduces mass and improves mission flexibility. This compact RCS engine incorporates several features to dramatically reduce mass and parts count, to ease manufacturing, and to maintain acceptable performance given that specific impulse (Isp) is not the driver. For example, radial injection holes placed on the chamber body for easier drilling, and high temperature Haynes 230 were selected for the chamber over other more expensive options. The valve inlets are rotatable before welding allowing different orientations for vehicle integration. In addition, the engine design effort selected a coil-on-plug ignition system which integrates a relay and coil with the plug electrode, and moves some exciter electronics to avionics driver board. The engine injector design has small dribble volumes to target minimum pulse widths of 20 msec. and an efficient minimum impulse bit of less than 0.05 lbf-sec. The propellants, oxygen and methane, were chosen because together they are a non-toxic, Mars-forward, high density, space storable, and high performance propellant combination that is capable of pressure-fed and pump-fed configurations and integration with life support and power subsystems. This paper will present the results of the advanced development testing to date of the RCS thruster and the integration with a vehicle propulsion system.
The development needed for the evolution of selected V/STOL research vehicles into optimized antisubmarine warfare (ASW) aircraft configurations, using numerical procedures and traditional analytical methods, has been examined. Three propulsion systems, which represent state-of-the-art development aimed at solving the thrust-vectoring and attitude-control problems of V/STOL aircraft, are analyzed. The use of NASA computer programs for aircraft synthesis (ACSYNT), and for optimizing configurations (COMMIN), coupled with contractor-supplied propulsion system data provides for accurate performance prediction of the selected ASW configurations. Particular emphasis on the transition phase between the research vehicle and the optimized configuration demonstrates the strengths and weaknesses of using generic research aircraft instead of building prototypes to demonstrate new technology
It is apparent the cost of planetary exploration is rising as mission budgets declining. Currently small scientific beds geared to performing limited tasks are being developed and launched into low earth orbit (LEO) in the form of small-scale satellite units, i.e., CubeSats. These micro- and nano-satellites are gaining popularity among the university and science communities due to their relatively low cost and design flexibility. To date these small units have been limited to performing tasks in LEO utilizing solar-based power. If a reasonable propulsion system could be developed, these CubeSat platforms could perform exploration of various extra-terrestrial bodies within the solar system engaging a broader range of researchers. Additionally, being mindful of mass, smaller cheaper launch vehicles (approximately 1,000 kgs to LEO) can be targeted. Thus, in effect, allows for beneficial exploration to be conducted within limited budgets. Researchers at the Center for Space Nuclear Research (CSNR) are proposing a low mass, radioisotope-based, dual-mode propulsion system capable of extending the exploration realm of these CubeSats out of LEO.
This oral presentation is an update to the Propulsion Systems Lab (PSL) engine ice testing. It provides a summary of the modifications done to the facility and recently completed calibrations and test program.
This paper describes the engineering of several vehicles designed for a crewed mission to the Jovian satellite Callisto. Each subsystem is discussed in detail. Mission and trajectory analysis for each mission concept is described. Crew support components are also described. Vehicles were developed using both fission powered magneto plasma dynamic (MPD) thrusters and magnetized target fusion (MTF) propulsion systems. Conclusions were drawn regarding the usefulness of these propulsion systems for crewed exploration of the outer solar system.
This paper presents an investigation into the potential benefits of a boundary layer ingestion(BLI) aft fuselage propulsion system, or tail-cone thruster (TCT), when applied to two transport category aircraft: a conventional tube-and-wing configuration based on the NASA Common Research Model (CRM) and a transonic truss-braced wing (TTBW) configuration. Through the ingestion of low-momentum flow developed over the airframe of an aircraft, the TCT propulsion system technology can reduce overall power consumption and hence fuel burn and emissions. However, an accurate assessment of this potential requires the application of high-fidelity analysis tools that can capture the relevant propulsion-airframe integration effects, at least to first order. Toward this end, the present study employs aeropropulsive analysis tools based on the Reynolds-averaged Navier-Stokes equations to estimate the power savings coefficient, measured relative to equivalent non-BLI configurations of a given airframe. Results indicate shaft power savings of 4.1% and 5.9% can be obtained for the boundary-layer ingesting TCT configuration of the CRM and TTBW, respectively. The present study also examines the coupling between airframe aerodynamics and the inlet flow distortion experienced by the TCT of a given aircraft configuration through airframe component sensitivity studies.
The major elements of the Space Shuttle Main Propulsion System include two reusable solid rocket motors integrated into recoverable solid rocket boosters, an expendable external fuel and oxidizer tank, and three reusable Space Shuttle Main Engines. Both the solid rocket motors and space shuttle main engines ignite prior to liftoff, with the solid rocket boosters separating about two minutes into flight. The external tank separates after main engine shutdown and is safely expended in the ocean. The SSME's, integrated into the Space Shuttle Orbiter aft structure, are reused after post landing inspections. Both the solid rocket motors and the space shuttle main engine throttle during early ascent flight to limit aerodynamic loads on the structure. The configuration is called a stage and a half as all the propulsion elements are active during the boost phase, and the SSME's continue operation to achieve orbital velocity approximately eight and a half minutes after liftoff. Design and performance challenges were numerous, beginning with development work in the 1970 s. The solid rocket motors were large, and this technology had never been used for human space flight. The SSME s were both reusable and very high performance staged combustion cycle engines, also unique to the Space Shuttle. The multi body side mount configuration was unique and posed numerous integration and interface challenges across the elements. Operation of the system was complex and time consuming. This paper discusses a number of the system level technical challenges including development and operations.
Monopropellant hydrazine-fueled rocket used as post injection propulsion system for Mariner C spacecraft
Prior to the launch of STS-119 NASA had completed a study of an issue in the flow control valve (FCV) in the Main Propulsion System of the Space Shuttle using an adaptive learning method known as Virtual Sensors. Virtual Sensors are a class of algorithms that estimate the value of a time series given other potentially nonlinearly correlated sensor readings. In the case presented here, the Virtual Sensors algorithm is based on an ensemble learning approach and takes sensor readings and control signals as input to estimate the pressure in a subsystem of the Main Propulsion System. Our results indicate that this method can detect faults in the FCV at the time when they occur. We use the standard deviation of the predictions of the ensemble as a measure of uncertainty in the estimate. This uncertainty estimate was crucial to understanding the nature and magnitude of transient characteristics during startup of the engine. This paper overviews the Virtual Sensors algorithm and discusses results on a comprehensive set of Shuttle missions and also discusses the architecture necessary for deploying such algorithms in a real-time, closed-loop system or a human-in-the-loop monitoring system. These results were presented at a Flight Readiness Review of the Space Shuttle in early 2009.
Progress in nuclear electric propulsion (NEP) systems for a multipayload multimission vehicle needed in both deep-space missions and a variety of geocentric missions is reviewed. The space system power level is a function of the initial launch vehicle mass, but developments in out-of-core nuclear thermionic direct conversion have broadened design options. Cost, design, and performance parameters are compared for reusable chemical space tugs and NEP reusable space tugs. Improvements in heat pipes, ion engines, and magnetoplasmadynamic arc jet thrust subsystems are discussed.
This paper provides an overview of the system performance from the first 14,200 hours of ion propulsion system operation in interplanetary space.
A simple family of indirect-transfer trajectories between circular orbits is used to evaluate the mass ratio required to complete round-trip interplanetary missions using low-thrust propulsion systems. These trajectories, although not optimum, yielded very substantial reductions in total round-trip time for Mars missions with moderate increases in initial weight. For a powerplant specific weight a of 10 pounds per kilowatt of jet power, trip times were reduced from 1200 to 600 days, for a typical manned mission, with an initial weight increase of a factor of two. Comparison with a nuclear rocket with 1000-second specific impulse indicated that the electric-propulsion system required less initial weight for trip times as low as 550 days with alpha equal to 10 and as low as 400 days with alpha equal to 5 pounds per kilowatt. Further weight reductions would be expected with more nearly optimum trajectories.
Frequency responses generated from a high-order linear model of the UH-60 Black Hawk have shown that the propulsion system influences significantly the vertical and yaw dynamics of the aircraft at frequencies important to high-bandwidth control law designs. The inclusion of the propulsion system comprises the latest step in the development of a high-order linear model of the UH-60 that models additionally the dynamics of the fuselage, rotor, and inflow. A complete validation study of the linear model is presented in the frequency domain for both on-axis and off-axis coupled responses in the hoverflight condition, and on-axis responses for forward speeds of 80 and 120 knots.
Presented are the results of an analysis of electron bombardment ion propulsion systems for use in the transportation and on-orbit operations of large space systems. Using baseline technology from the ongoing primary propulsion program and other sources, preliminary estimates of the expected characteristics of key system elements such as thrusters and propellant storage systems have been performed. Projections of expected thruster performance on argon are presented based on identified constraints which limit the achievable thrust and/or power density of bombardment thrusters. System characteristics are then evaluated as a function of thruster diameter and specific impulse.
The objectives of the flight test and a description on how those objectives are in support of an overall program goal of attaining user application were described. The approach to accomplishment was presented as it applies to integrating the propulsion system with the host spacecraft. A number of known interface design considerations which affect the propulsion system and the spacecraft were discussed. Analogies were drawn comparing the relationship of the organizations involved with this flight test with those anticipated for future operational missions. The paper also expanded upon objectives, system description, mission operations, and measurement of plume effects.
Application of a differential correction method for the evaluation of rocket propulsion systems by flight simulation techniques