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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.

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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1966

Computer program determines performance efficiency of remote measuring systems

Computer programs control and evaluate instrumentation system performance for numerous rocket engine test facilities and prescribe calibration and maintenance techniques to maintain the systems within process specifications. Similar programs can be written for other test equipment in an industry such as the petrochemical industry.

Merewether, E. K.↗
NASA NTRS1967

Negative feedback system reduces pump oscillations

External negative feedback system counteracts low frequency oscillations in rocket engine propellant pumps. The system uses a control piston to sense pump discharge fluid on one side and a gas pocket on the other.

Rosenmann, W.↗
NASA NTRS1978

Concepts and requirements for shuttle/payload orbital operations of the space transportation system

The results of studies and software development activities are summarized. Technical reports and memoranda are presented in a graphical history of contract activities and the expenditure of engineering manhours. Major topics and activities are: (1) flight phase standardization; (2) flight profile standardization; (3) maneuver targeting for solid rocket motors; (4) relative motion and RCS (Reaction Control System) jet flowfield plotting programs; (5) on-orbit aerodynamic models; (6) terminal approach strategy for payload retrieval/docking; (7) proximity navigation; and (8) desk-top flight simulator for proximity operations. A list of recommendations is also presented.

Wilson, S. W.↗
NASA NTRS1986

SRB/SLEEC (Solid Rocket Booster/Shingle Lap Extendible Exit Cone) feasibility study, volume 2. Appendix A: Design study for a SLEEC actuation system

The results are presented of a design feasibility study of a self-contained (powered) actuation system for a Shingle Lap Extendible Exit Cone (SLEEC) for Transportation System (STS). The evolution of the SLEEC actuation system design is reviewed, the final design concept is summarized, and the results of the detailed study of the final concept of the actuation system are treated. A conservative design using proven mechanical components was established as a major program priority. The final mechanical design has a very low development risk since the components, which consist of ballscrews, gearing, flexible shaft drives, and aircraft cables, have extensive aerospace applications and a history of proven reliability. The mathematical model studies have shown that little or no power is required to deploy the SLEEC actuation system because acceleration forces and internal pressure from the rocket plume provide the required energies. A speed control brake is incorporated in the design in order to control the rate of deployment.

Thompson, D. S.↗
NASA NTRS1990

Electron collection enhancement arising from neutral gas jets on a charged vehicle in the ionosphere

Observations of current collection enhancements due to cold nitrogen gas control jet emissions from a highly charged, isolated rocket payload in the ionosphere have been made during the cooperative high altitude rocket gun experiment (CHARGE) 2 using an electrically tethered mother/daughter payload system. The current collection enhancement was observed on a platform (daughter payload) located 100 to 400 m away from the main payload firing an energetic electron beam (mother payload). These results are interpreted in terms of an electrical discharge forming in close proximity to the daughter vehicle during the short periods of gas emission. The results indicate that it is possible to enhance the electron current collection capability of positively charged vehicles by means of deliberate neutral gas releases into an otherwise undisturbed space plasma. The results are also compared with recent laboratory observations of hollow cathode plasma contactors operating in the 'ignited' mode.

Gilchrist, Brian E.↗
NASA NTRS1988

National Space Transportation System Reference. Volume 2: Operations

An overview of the Space Transportation System is presented in which aspects of the program operations are discussed. The various mission preparation and prelaunch operations are described including astronaut selection and training, Space Shuttle processing, Space Shuttle integration and rollout, Complex 39 launch pad facilities, and Space Shuttle cargo processing. Also, launch and flight operations and space tracking and data acquisition are described along with the mission control and payload operations control center. In addition, landing, postlanding, and solid rocket booster retrieval operations are summarized. Space Shuttle program management is described and Space Shuttle mission summaries and chronologies are presented. A glossary of acronyms and abbreviations are provided.

Source record↗
NASA NTRS1992

A neural network-based estimator for the mixture ratio of the Space Shuttle Main Engine

In order to properly utilize the available fuel and oxidizer of a liquid propellant rocket engine, the mixture ratio is closed loop controlled during main stage (65 percent - 109 percent power) operation. However, because of the lack of flight-capable instrumentation for measuring mixture ratio, the value of mixture ratio in the control loop is estimated using available sensor measurements such as the combustion chamber pressure and the volumetric flow, and the temperature and pressure at the exit duct on the low pressure fuel pump. This estimation scheme has two limitations. First, the estimation formula is based on an empirical curve fitting which is accurate only within a narrow operating range. Second, the mixture ratio estimate relies on a few sensor measurements and loss of any of these measurements will make the estimate invalid. In this paper, we propose a neural network-based estimator for the mixture ratio of the Space Shuttle Main Engine. The estimator is an extension of a previously developed neural network based sensor failure detection and recovery algorithm (sensor validation). This neural network uses an auto associative structure which utilizes the redundant information of dissimilar sensors to detect inconsistent measurements. Two approaches have been identified for synthesizing mixture ratio from measurement data using a neural network. The first approach uses an auto associative neural network for sensor validation which is modified to include the mixture ratio as an additional output. The second uses a new network for the mixture ratio estimation in addition to the sensor validation network. Although mixture ratio is not directly measured in flight, it is generally available in simulation and in test bed firing data from facility measurements of fuel and oxidizer volumetric flows. The pros and cons of these two approaches will be discussed in terms of robustness to sensor failures and accuracy of the estimate during typical transients using simulation data.

Guo, T. H.↗
NASA NTRS1998

1998 JANNAF Propulsion Meeting

This volume, the first of four volumes, is a collection of 40 unclassified/unlimited-distribution papers which were presented at the 1998 Joint Army-Navy-NASA-Air Force (JANNAF) Propulsion Meeting (JPM), held 15-17 July 1998 at the Cleveland Marriott Downtown at Key Center and the Celebreeze Federal Building in Cleveland, Ohio. The 1998 JPM was co-located with the 1998 American Institute of Aeronautics and Astronautics Joint Propulsion Conference. Specific subjects discussed include reusable liquid boosters, controllable solid propulsion, advanced propellants for the 2.75' rocket system, air-turbo-rocket propulsion, issues in gun propulsion, electric propulsion, liquid engine turbomachinery, and new liquid propulsion technology.

Eggleston, Debra S.↗
NASA NTRS2010

Verification Tools Secure Online Shopping, Banking

Just like rover or rocket technology sent into space, the software that controls these technologies must be extensively tested to ensure reliability and effectiveness. Ames Research Center invented the open-source Java Pathfinder (JPF) toolset for the deep testing of Java-based programs. Fujitsu Labs of America Inc., based in Sunnyvale, California, improved the capabilities of the JPF Symbolic Pathfinder tool, establishing the tool as a means of thoroughly testing the functionality and security of Web-based Java applications such as those used for Internet shopping and banking.

Source record↗
NASA NTRS2013

CRUQS: A Miniature Fine Sun Sensor for Nanosatellites

A new miniature fine Sun sensor has been developed that uses a quadrant photodiode and housing to determine the Sun vector. Its size, mass, and power make it especially suited to small satellite applications, especially nanosatellites. Its accuracy is on the order of one arcminute, and it will enable new science in the area of nanosatellites. The motivation for this innovation was the need for high-performance Sun sensors in the nanosatellite category. The design idea comes out of the LISS (Lockheed Intermediate Sun Sensor) used by the sounding rocket program on their solar pointing ACS (Attitude Control System). This system uses photodiodes and a wall between them. The shadow cast by the Sun is used to determine the Sun angle. The new sensor takes this concept and miniaturizes it. A cruciform shaped housing and a surface-mount quadrant photodiode package allow for a two-axis fine Sun sensor to be packaged into a space approx.1.25xl x0.25 in. (approx.3.2x2.5x0.6 cm). The circuitry to read the photodiodes is a simple trans-impedance operational amplifier. This is much less complex than current small Sun sensors for nanosatellites that rely on photo-arrays and processing of images to determine the Sun center. The simplicity of the circuit allows for a low power draw as well. The sensor consists of housing with a cruciform machined in it. The cruciform walls are 0.5-mm thick and the center of the cruciform is situated over the center of the quadrant photodiode sensor. This allows for shadows to be cast on each of the four photodiodes based on the angle of the Sun. A simple operational amplifier circuit is used to read the output of the photodiodes as a voltage. The voltage output of each photodiode is summed based on rows and columns, and then the values of both rows or both columns are differenced and divided by the sum of the voltages for all four photodiodes. The value of both difference over sums for the rows and columns is compared to a table or a polynomial fit (depending on processor power and accuracy requirements) to determine the angle of the Sun in the sensor frame.

Heatwole, Scott↗
NASA NTRS1993

Nuclear propulsion control and health monitoring

An integrated control and health monitoring architecture is being developed for the Pratt & Whitney XNR2000 nuclear rocket. Current work includes further development of the dynamic simulation modeling and the identification and configuration of low level controllers to give desirable performance for the various operating modes and faulted conditions. Artificial intelligence and knowledge processing technologies need to be investigated and applied in the development of an intelligent supervisory controller module for this control architecture.

Walter, P. B.↗
NASA NTRS1949

Preliminary Results of a Free-Flight Investigation of the Static Stability and Aileron Control Characteristics of 1/6 Scale Models of the Bell MX-776

An investigation of the static longitudinal stability, static directional stability, and aileron control characteristics at transonic and supersonic speeds is being made of 1/6 scale rocket-propelled model of the Bell MX-776. A stability investigation has been made of two symmetrical models with controls undeflected and centers of gravity one-half and one-body diameter, respectively, ahead of the equivalent design center-of-gravity location of the full-scale version. Both models developed large normal-force coefficients in both the subsonic and supersonic ranges which indicated longitudinal instability at low angles of attack. The side-force coefficients were small for both models and indicated that the models were directionally stable. A possible tendency toward dynamic directional instability in the transonic region was indicated by short-period oscillations of the side forces. The results showed a partial-span inboard aileron to be ineffective or to cause negative control in the the transonic region when deflected approximately 5 deg but not when deflected 10 deg. An investigation of drag showed it to increase with a rearward movement of the center of gravity. This indicates an increase in the trim angle of attack as could be caused by a decrease in static stability.

Michal, David H.↗
NASA NTRS2014

UPSS and G2

The Universal Propellant Servicing System (UPSS) is a dedicated mobile launcher propellant delivery method that will minimize danger and complexity in order to allow vehicles to be serviced and ultimately launched from a variety of locations previously not seen fit for space launch. The UPPS/G2 project is the development of a model, simulation, and ultimately a working application that will control and monitor the cryogenic fluid delivery to the rocket for testing purposes. To accomplish this, the project is using the programming language/environment Gensym G2. The environment is an all-inclusive application that allows development, testing, modeling, and finally operation of the unique application through graphical and programmatic methods. We have learned G2 through classes and trial-and-error, and are now in the process of building the application that will soon be able to be tested on apparatuses here at Kennedy Space Center, and eventually on the actual unit. The UPSS will bring near-autonomous control of launches to those that need it, as well it will be a great addition to NASA and KSC's operational viability and the opportunity to bring space launches to parts of the world, and in time constraints, once not thought possible.

cryogenic fluids↗