Recent Advancements in Propellant Densification

Next-generation launch vehicles demand several technological improvements to achieve lower cost and more reliable access to space. One technology area whose performance gains may far exceed others is densified propellants. The ideal rocket engine propellant is characterized by high specific impulse, high density, and low vapor pressure. A propellant combination of liquid hydrogen and liquid oxygen (LH2/LOX) is one of the highest performance propellants, but LH2 stored at standard conditions has a relatively low density and high vapor pressure. Propellant densification can significantly improve this propellant's properties relative to vehicle design and engine performance. Vehicle performance calculations based on an average of existing launch vehicles indicate that densified propellants may allow an increase in payload mass of up to 5 percent. Since the NASA Lewis Research Center became involved with the National Aerospace Plane program in the 1980's, it has been leading the way in making densified propellants a viable fuel for next-generation launch vehicles. Lewis researchers have been working to provide a method and critical data for continuous production of densified hydrogen and oxygen

Hot Fire Ignition Test with Densified Liquid Hydrogen using a RL10B-2 Cryogenic H2/O2 Rocket Engine

Enhancements to propellants provide an opportunity to either increase performance of an existing vehicle, or reduce the size of a new vehicle. In the late 1980's the National AeroSpace Plane (NASP) reopened the technology chapter on densified propellants, in particular hydrogen. Since that point in time the NASA Lewis Research Center (LERC) in Cleveland, Ohio has been leading the way to provide critical research on the production and transfer of densified propellants. On October 4, 1996 NASA LeRC provided another key demonstration towards the advancement of densified propellants as a viable fuel. Successful ignition of an RL10B-2 engine was achieved with near triple point liquid hydrogen

Multi-Center Implementation of NPR 7123.1A: A Collaborative Effort

Collaboration efforts between MSFC and GRC Engineering Directorates to implement the NASA Systems Engineering (SE) Engine have expanded over the past year to include other NASA Centers. Sharing information on designing, developing, and deploying SE processes has sparked further interest based on the realization that there is relative consistency in implementing SE processes at the institutional level. This presentation will provide a status on the ongoing multi-center collaboration and provide insight into how these NPR 7123.1A SE-aligned directives are being implemented and managed to better support the needs of NASA programs and projects. NPR 7123.1A, NASA Systems Engineering Processes and Requirements, was released on March 26, 2007 to clearly articulate and establish the requirements on the implementing organization for performing, supporting, and evaluating SE activities. In early 2009, MSFC and GRC Engineering Directorates undertook a collaborative opportunity to share their research and work associated with developing, updating and revising their SE process policy to comply and align with NPR 7123.1A. The goal is to develop instructions, checklists, templates, and procedures for each of the 17 SE process requirements so that systems engineers will be a position to define work that is process-driven. Greater efficiency and more effective technical management will be achieved due to consistency and repeatability of SE process implementation across and throughout each of the NASA centers. An added benefit will be to encourage NASA centers to pursue and collaborate on joint projects as a result of using common or similar processes, methods, tools, and techniques

Simulation and Control Lab Development for Power and Energy Management for NASA Manned Deep Space Missions

The development of distributed hierarchical and agent-based control systems will allow for reliable autonomous energy management and power distribution for on-orbit missions. Power is one of the most critical systems on board a space vehicle, requiring quick response time when a fault or emergency is identified. As NASAs missions with human presence extend beyond low earth orbit autonomous control of vehicle power systems will be necessary and will need to reliably function for long periods of time. In the design of autonomous electrical power control systems there is a need to dynamically simulate and verify the EPS controller functionality prior to use on-orbit. This paper presents the work at NASA Glenn Research Center in Cleveland, Ohio where the development of a controls laboratory is being completed that will be utilized to demonstrate advanced prototype EPS controllers for space, aeronautical and terrestrial applications. The control laboratory hardware, software and application of an autonomous controller for demonstration with the ISS electrical power system is the subject of this paper

Experimental Results of Hydrogen Slosh in a 62 Cubic Foot (1750 Liter) Tank

Extensive slosh testing with liquid and slush hydrogen was conducted in a 62 cubic foot spherical tank to characterize the thermodynamic response of the system under normal gravity conditions. Slosh frequency and amplitude, pressurant type, ramp pressure, and ullage volume were parametrically varied to assess the effect of each of these parameters on the tank pressure and fluid/wall temperatures. A total of 91 liquid hydrogen and 62 slush hydrogen slosh tests were completed. Both closed tank tests and expulsions during sloshing were performed. This report presents and discusses highlights of the liquid hydrogen closed tank results in detail and introduces some general trends for the slush hydrogen tests. Summary comparisons between liquid and slush hydrogen slosh results are also presented

The Need for Intelligent Control of Space Power Systems

As manned spacecraft venture farther from Earth, the need for reliable, autonomous control of vehicle subsystems becomes critical. This is particularly true for the electrical power system which is critical to every other system. Autonomy can not be achieved by simple scripting techniques due to the communication latency times and the difficulty associated with failures (or combinations of failures) that need to be handled in as graceful a manner as possible to ensure system availability. Therefore an intelligent control system must be developed that can respond to disturbances and failures in a robust manner and ensure that critical system loads are served and all system constraints are respected

A Summary of the Slush Hydrogen Technology Program for the National Aero-Space Plane

Slush hydrogen, a mixture of solid and liquid hydrogen, offers advantages of higher density (16 percent) and higher heat capacity (18 percent) than normal boiling point hydrogen. The combination of increased density and heat capacity of slush hydrogen provided a potential to decrease the gross takeoff weight of the National Aero-Space Plane (NASP) and therefore slush hydrogen was selected as the propellant. However, no large-scale data was available on the production, transfer and tank pressure control characteristics required to use slush hydrogen as a fuel. Extensive testing has been performed at the NASA Lewis Research Center K-Site and Small Scale Hydrogen Test Facility between 1990 and the present to provide a database for the use of slush hydrogen. This paper summarizes the results of this testing