Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “lessons learned”

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.

At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Some lessons learned in three years with ADS-33C

Three years of using the U.S. Army's rotorcraft handling qualities specification, Aeronautical Design Standard - 33, has shown it to be surprisingly robust. It appears to provide an excellent basis for design and for assessment, however, as the subtleties become more well understood, several areas needing refinement became apparent. Three responses to these needs have been documented in this paper: (1) The yaw-axis attitude quickness for hover target acquisition and tracking can be relaxed slightly. (2) Understanding and application of criteria for degraded visual environments needed elaboration. This and some guidelines for testing to obtain visual cue ratings have been documented. (3) The flight test maneuvers were an innovation that turned out to be very valuable. Their extensive use has made it necessary to tighten definitions and testing guidance. This was accomplished for a good visual environment and is underway for degraded visual environments.

Key, David L.↗
NASA NTRS1994

Handbook for handling and storage of nickel-cadmium batteries: Lessons learned

The handbook provides guidelines for the handling and storage of conventional NiCd flight batteries. The guidelines are based on many years of experience with ground and in-flight handling of batteries. The overall goal is to minimize the deterioration and irreversible effects of improper handling of NiCd flight batteries on flight performance. A secondary goal is to provide the reader with an understanding, in nonanalytical terms, of the degradation mechanisms of NiCd cells and how these mechanisms are affected by improper ground handling of flight hardware. Section 2 provides the reader with a brief introduction to NiCd cells. The effects of the environment on NiCd batteries are discussed in Section 3, and Section 4 contains 12 guidelines for battery handling and storage with supporting rationale for each guideline. The appendix provides a synopsis of NiCd cell design and evolution over 30 years of space flight on Goddard Space Flight Center (GSFC) satellites, along with a chronological review of key events that influenced the design of NiCd cells being flown today.

Ford, Floyd E.↗
NASA NTRS1994

La Chalupa-30: Lessons learned from a 30-day subsea mission analogue

The Behavior and Performance Laboratory (BPL) utilizes space mission analogs to study issues such as the psychological health and well-being, team characteristics, and task performance of crew members on long-duration missions. The analog used in this investigation was an underwater habitat named La Chalupa, which was selected for its similar features to a space station environment. The primary objectives of the La Chalupa-30 investigation were to evaluate the efficiency of several methods for collecting data in remote environments and to assess aspects of living and working under isolated and confined conditions.

Vanderark, Steve↗
NASA NTRS1993

Benefits gained and lessons learned from NASA's Small Explorer (SMEX) Program

NASA's Small Explorer Program (SMEX) is a sustained program of scientific satellites limited in mass to 200-300 kg (depending on orbital inclination) for a 500-km circular orbit. The SMEX program was undertaken to obtain the benefits of scientific yield, short development time, and high flight rate, with the goal to launch a mission every year. NASA also uses the program to train engineers and managers in designing and developing spacecraft. The phases of a SMEX mission life cycle are described including the competitive selection of missions through announcement of opportunity and evaluation of proposals, the definition of mission and system requirements, design and development of the spacecraft, testing, launch, and operations. Program content of some SMEX missions is then reviewed. The first SMEX mission was the Solar, Anomalous, and Magnetospheric Particle Explorer, which confirmed that anomalous cosmic rays are only partially ionized atoms. The Fast Auroral Snapshot Explorer was intended to measure the electric, magnetic, and time-variable fields and to record particle flow in the auroral acceleration region. A future mission is the Submillimeter Wave Astronomy Satellite to examine low-level molecular transitions.

Gilman, David↗
NASA NTRS1993

Lessons learned - MO&DA at JPL

The issues of how to avoid future surprise growth in Mission Operations and Data Analysis (MO&DA) costs and how to minimize total MO&DA costs for planetary missions are discussed within the context of JPL mission operations support. It is argued that there is no simple, single solution: the entire Project life-cycle must be addressed. It is concluded that cost models that can predict both MO&DA cost as well as Ground System development costs are needed. The first year MO&DA budget plotted against the total of ground and flight systems developments is shown. In order to better recognize changes and control costs in general, a modified funding line item breakdown is recommended to distinguish between development costs (prelaunch and postlaunch) and MO&DA costs.

Handley, Thomas H., Jr.↗
NASA NTRS1992

Formal methods technology transfer: Some lessons learned

IBM has a long history in the application of formal methods to software development and verification. There have been many successes in the development of methods, tools and training to support formal methods. And formal methods have been very successful on several projects. However, the use of formal methods has not been as widespread as hoped. This presentation summarizes several approaches that have been taken to encourage more widespread use of formal methods, and discusses the results so far. The basic problem is one of technology transfer, which is a very difficult problem. It is even more difficult for formal methods. General problems of technology transfer, especially the transfer of formal methods technology, are also discussed. Finally, some prospects for the future are mentioned.

Hamilton, David↗
NASA NTRS1994

F-18 high alpha research vehicle: Lessons learned

The F-18 High Alpha Research Vehicle has proven to be a useful research tool with many unique capabilities. Many of these capabilities are to assist in characterizing flight at high angles of attack, while some provide significant research in their own right. Of these, the thrust vectoring system, the unique ability to rapidly reprogram flight controls, the reprogrammable mission computer, and a reprogrammable onboard excitation system have allowed an increased utility and versatility of the research being conducted. Because of this multifaceted approach to research in the high angle of attack regime, the capabilities of the F-18 High Alpha Research Vehicle were designed to cover as many high alpha technology bases as the program would allow. These areas include aerodynamics, controls, handling qualities, and propulsion.

Bowers, Albion H.↗
NASA NTRS1994

The growth of the UniTree mass storage system at the NASA Center for Computational Sciences: Some lessons learned

In October 1992, the NASA Center for Computational Sciences made its Convex-based UniTree system generally available to users. The ensuing months saw growth in every area. Within 26 months, data under UniTree control grew from nil to over 12 terabytes, nearly all of it stored on robotically mounted tape. HiPPI/UltraNet was added to enhance connectivity, and later HiPPI/TCP was added as well. Disks and robotic tape silos were added to those already under UniTree's control, and 18-track tapes were upgraded to 36-track. The primary data source for UniTree, the facility's Cray Y-MP/4-128, first doubled its processing power and then was replaced altogether by a C98/6-256 with nearly two-and-a-half times the Y-MP's combined peak gigaflops. The Convex/UniTree software was upgraded from version 1.5 to 1.7.5, and then to 1.7.6. Finally, the server itself, a Convex C3240, was upgraded to a C3830 with a second I/O bay, doubling the C3240's memory and capacity for I/O. This paper describes insights gained and reinforced with the burgeoning demands on the UniTree storage system and the significant increases in performance gained from the many upgrades.

Tarshish, Adina↗
NASA NTRS1994

Lessons learned in transitioning to an open systems environment

Software development organizations, both commercial and governmental, are undergoing rapid change spurred by developments in the computing industry. To stay competitive, these organizations must adopt new technologies, skills, and practices quickly. Yet even for an organization with a well-developed set of software engineering models and processes, transitioning to a new technology can be expensive and risky. Current industry trends are leading away from traditional mainframe environments and toward the workstation-based, open systems world. This paper presents the experiences of software engineers on three recent projects that pioneered open systems development for NASA's Flight Dynamics Division of the Goddard Space Flight Center (GSFC).

Boland, Dillard E.↗
NASA NTRS1993

Experience, lessons learned and methodology in the design of space systems to accommodate total dose and SEU effects

We now have considerable experience with successfully designing science systems to function properly, even during and after exposure to ionizing radiation approaching one Megarad, and during large solar particle events with substantial high Z fluxes such as the events that happened in August, 1972 and in the fall of 1989. Nevertheless, with changing device dimensions and properties, newer technologies and new applications, new problems arise. Some recent basic research has shed light on these problems and pointed the way to better diagnostic tests. In the case of single event upsets, clearly one cannot always accurately predict upset probabilities simply by knowing the quiescent Linear Energy Transfer (LET) threshold and the asymptotic cross-section of the device.

Trainor, James H.↗
NASA NTRS1996

The micro conical system: Lessons learned from a successful EVA/robot-compatible mechanism

The Micro Conical System (MCS) is a three-part, multi-purpose mechanical interface system used for acquiring and manipulating masses on-orbit by either extravehicular activity (EVA) or telerobotic means. The three components of the system are the micro conical fitting (MCF), the EVA micro tool (EMCT), and the Robot Micro Conical Tool (RMCT). The MCS was developed and refined over a four-year period. This period culminated with the delivery of 358 Class 1 and Class 2 micro conical fittings for the International Space Station and with its first use in space to handle a 1272 kg (2800 lbm) Spartan satellite (11000 times greater than the MCF mass) during an EVA aboard STS-63 in February, 1995. The micro conical system is the first successful EVA/robot-compatible mechanism to be demonstrated in the external environment aboard the U.S. Space Shuttle.

Gittleman, Mark↗
NASA NTRS1996

Lessons learned: DC-X

The DC-X was conceived and developed specifically to lay the ground work for significantly lowering the cost of space operations. The system design was based on an initial set of program goals and a finite, limited set of resources. The goal in its simplest terms was to demonstrate vertical landing after rotation of the vehicle from a nose-first to an engines-first altitude. Finite resources actually drove the selection of a robust design to reduce fabrication and preflight testing costs. The result was a system with a large amount of flexibility which allowed expansion of the test goals as the system, and test program, evolved. The use of the vehicle flight computer interfacing with the ground control system for flight crew training was also not an initial concept. However, by defining an architecture for the system control modes which allowed additions and modifications as learning progressed, the 6 DOF codes used for flight controls software development were transported to the operating system to be used in a simulated flight mode. Flight data reduction was also greatly improved as the program progressed, and the data needs and presentation were refined. The software, avionics hardware, and the FOCC system development proceeded ahead of the vehicle, primarily because most of the hardware elements were existing at the outset of the program. The Built-in-Test (BIT) for avionics and propulsion systems were adequate. Particularly the flight readiness system which verified the vehicle health after engine start and before throttle-up for flight.

Steinmeyer, D. A.↗
NASA NTRS1996

Cost efficient operations: Challenge from NASA administrator and lessons learned from hunting sacred cows

The conclusions and recommendations that resulted from NASA's Hunting Sacred Cows Workshop are summarized, where a sacred cow is a belief or assumption that is so well established that it appears to be unreasonably immune to criticism. A link was identified between increased complexity and increased costs, especially in relation to automation and autonomy. An identical link was identified for outsourcing and commercialization. The work of NASA's Cost Less team is reviewed. The following conclusions were stated by the Cost Less team and considered at the workshop: the way Nasa conducts business must change; NASA makes its best contributions to the public areas not addressed by other government organizations; the management tool used for the last 30 years is no longer suitable; the most important work on any program or project is carried out before the development or operations stages; automation should only be used to achieve autonomy if the reasons for automation are well understood, and NASA's most critical resources are its personnel.

Hornstein, Rhoda Shaller↗
NASA NTRS1999

A Strategy for Integrating a Large Finite Element Model Using MSC NASTRAN/PATRAN: X-33 Lessons Learned

The X-33 vehicle is an advanced technology demonstrator sponsored by NASA. For the past 3 years the Structural Dynamics and Loads Branch of NASA's Marshall Space Flight Center has had the task of integrating the X-33 vehicle structural finite element model. In that time, five versions of the integrated vehicle model have been produced and a strategy has evolved that would benefit anyone given the task of integrating structural finite element models that have been generated by various modelers and companies. The strategy that has been presented here consists of six decisions that need to be made: purpose of models, units, common materials list, model numbering, interface control, and archive format. This strategy has been proven and expanded from experience on the X-33 vehicle.

McGhee, D. S.↗
NASA NTRS1999

Managing the Moon Program: Lessons Learned from Project Apollo

There have been many detailed historical studies of the process of deciding on and executing the Apollo lunar landing during the 1960s and early 1970s. From the announcement of President John F Kennedy on May 25, 1961, of his decision to land an American on the Moon by the end of the decade, through the first lunar landing on July 20, 1969, on to the last of six successful Moon landings with Apollo 17 in December 1972, NASA carried out Project Apollo with enthusiasm and aplomb. While there have been many studies recounting the history of Apollo, at the time of the 30th anniversary of the first lunar landing by Apollo 11, it seems appropriate to revisit the process of large-scale technological management as it related to the lunar mission. Consequently, the NASA History Office has chosen to publish this monograph containing the recollections of key partcipants in the management process. The collective oral history presented here was recorded in 1989 at the Johnson Space Center's Gilruth Recreation Center in Houston, Texas. It includes the recollections of key participants in Apollo's administration, addressing issues such as communication between field centers, the prioritization of technological goals, and the delegation of responsibility. The following people participated: George E. Muller, Owen W. Morris, Maxime A. Faget, Robert R. Gilruth, Christopher C. Kraft, and Howard W. (Bill) Tindall. The valuable perspectives of these individuals deepen and expand our understanding of this important historical event. This is the 14th in a series of special studies prepared by the NASA History Office. The Monographs in Aerospace History series is designed to provide a wide variety of investigations relative to the history of aeronautics and space. These publications are intended to be tightly focused in terms of subject, relatively short in length, and reproduced in an inexpensive format to allow timely and broad dissemination to researchers in aerospace history.

Source record↗
NASA NTRS1999

Vapor Compression Distillation Urine Processor Lessons Learned from Development and Life Testing

Vapor Compression Distillation (VCD) is the chosen technology for urine processing aboard the International Space Station (155). Development and life testing over the past several years have brought to the forefront problems and solutions for the VCD technology. Testing between 1992 and 1998 has been instrumental in developing estimates of hardware life and reliability. It has also helped improve the hardware design in ways that either correct existing problems or enhance the existing design of the hardware. The testing has increased the confidence in the VCD technology and reduced technical and programmatic risks. This paper summarizes the test results and changes that have been made to the VCD design.

Hutchens, Cindy F.↗
NASA NTRS1999

Propellant Feed System Leak Detection: Lessons Learned From the Linear Aerospike SR-71 Experiment (LASRE)

This paper presents pertinent results and assessment of propellant feed system leak detection as applied to the Linear Aerospike SR-71 Experiment (LASRE) program flown at the NASA Dryden Flight Research Center, Edwards, California. The LASRE was a flight test of an aerospike rocket engine using liquid oxygen and high-pressure gaseous hydrogen as propellants. The flight safety of the crew and the experiment demanded proven technologies and techniques that could detect leaks and assess the integrity of hazardous propellant feed systems. Point source detection and systematic detection were used. Point source detection was adequate for catching gross leakage from components of the propellant feed systems, but insufficient for clearing LASRE to levels of acceptability. Systematic detection, which used high-resolution instrumentation to evaluate the health of the system within a closed volume, provided a better means for assessing leak hazards. Oxygen sensors detected a leak rate of approximately 0.04 cubic inches per second of liquid oxygen. Pressure sensor data revealed speculated cryogenic boiloff through the fittings of the oxygen system, but location of the source(s) was indeterminable. Ultimately, LASRE was cancelled because leak detection techniques were unable to verify that oxygen levels could be maintained below flammability limits.

Hass, Neal↗