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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Practical Aspects of Real-Time Modeling for the Learn-To-Fly Concept

Practical aspects of autonomous onboard real-time modeling for the NASA Learn-to-Fly concept are examined using flight data from two subscale test aircraft. A practical real-time global nonlinear aerodynamic modeling method is developed and explained, along with the multiple-input excitation needed for effective real-time modeling. Critical issues for integrating real-time global nonlinear aerodynamic modeling and local linear modeling with the real-time learning adaptive control and guidance elements of the Learn-to-Fly algorithm are identified and discussed. Real-time modeling results from NASA Learn-to-Fly flight demonstrations are presented and evaluated using model fit metrics and prediction tests.

Morelli, Eugene A.↗
NASA NTRS2019

A Realistic Roadmap to Formation Flying Space Interferometry

The ultimate astronomical observatory would be a formation flying interferometer in space, immune to atmospheric turbulence and absorption, free from atmospheric and telescope thermal emission, and reconfigurable to adjust baselines according to the required angular resolution. Imagine the near/mid-infrared sensitivity of the JWST and the far-IR sensitivity of Herschel but with ALMA-level angular resolution, or imagine having the precision control to null host star light across 250m baselines and to detect molecules from the atmospheres of nearby exo-Earths. With no practical engineering limit to the formation’s size or number of telescopes in the array, formation flying interferometry will revolutionize astronomy and this White Paper makes the case that it is now time to accelerate investments in this technological area. Here we provide a brief overview of the required technologies needed to allow light to be collected and interfered using separate spacecrafts. We emphasize the emerging role of inexpensive smallSat projects and the excitement for the LISA Gravitational Wave Interferometer to push development of the required engineering building-blocks. We urge the Astro2020 Decadal Survey Committee to highlight the need for a small-scale formation flying space interferometer project to demonstrate end-to-end competency with a timeline for first stellar fringes by the end of the decade.

Gioia Rau↗
NASA NTRSDate not supplied

Flying Qualities Analysis and Piloted Simulation Testing of a Lift+Cruise Vehicle with Propulsion Failures in Hover and Low-Speed Conditions

The recent emergence of electric-Vertical Take-Off and Landing (eVTOL) vehicles for Urban Air Mobility (UAM) applications has resulted in a wide variety of configurations with unique stability and control characteristics. NASA is currently conducting research to develop conceptual design tools to accelerate public acceptance of these vehicles which includes requirements for safety during failure scenarios. This paper summarizes progress toward a toolbox for predicting flying qualities of eVTOL vehicles during critical propulsion failures that could impact the allowable design of the vehicle geometry or control system. Key topics include unique vulnerabilities of eVTOL/multirotor vehicles to propulsion failures, relevant flying qualities design metrics, and simulation modeling requirements for assessing flying qualities degradation due to failures. Results of a piloted simulation study conducted in the NASA Ames Vertical Motion Simulator (VMS) are presented. The VMS experiment was designed to assess and validate key handling qualities and safety design metrics for propulsion failures. These results show the correlation between control system design requirements and the degradation in handling qualities for various propulsion failures.

George Altamirano↗
NASA NTRS2002

Autonomous formation flying sensor for the Star Light Mission

The StarLight Mission, an element of NASA's Origins Program, was designed for first-time demonstration of two technologies: formation flying optical interferometry between spacecraft and autonomous precise formation flying of an array of spacecraft to support optical interferometry. The design overview and results of the technology effort are presented in this paper.

AFF sensor AFF formationf flying sensor autonomous↗
NASA NTRS2004

Relative Sensor with 4(pi) Coverage for Formation Flying Missions

The Terrestrial Planet Finder (TPF) pre-project, an element of NASA's Origins program, is currently developing two architectures for a mission to search for earth-like planets around nearby stars. One of the architectures being developed is the Formation Flying Interferometer (FFI). The FFI is envisioned to consist of up to seven spacecraft (as many as six 'collectors' with IR telescopes, and a 'combiner') flying in precise formation within f 1 cm of pre-determined trajectories for synchronized observations. The spacecraft-to-spacecraft separations are variable between 20 m and 100 m or more during observations to support various configurations of the interferometer in the planet-finding mode. The challenges involved with TPF autonomous operations, ranging from formation acquisition and formation maneuvering to high precision formation control during science observations, are unprecedented. In this paper we discuss the development of the formation acquisition sensor, which uses novel modulation and duplexing schemes to enable fast signal acquisition, multiple-spacecraft operation, and mitigation of inherent jamming conditions, while providing precise formation sensing and integrated radar capability. This approach performs delay synthesis and carrier cycle ambiguity resolution to improve range measurement, and uses differential carrier cycle ambiguity resolution to make precise bearing angle measurements without calibration maneuvers.

formation flying sensors↗
NASA NTRS2001

Optimal collision avoidance guidance for formation-flying applications

Several proposed space science missions require deployment of a number of spacecraft to form a single functional unit or a formation flying spacecraft. There are many applications of a formation flying spacecraft; variable baseline optical space interferometry is one of them.

collision avoidance path-planning formation-flying↗
NASA NTRS1999

Design of the ST 3 Formation Flying Interferometer

The interferometer will operate in both a single spacecraft mode and a formation flying mode using two spacecraft. The primary goal is to validate interferometer and formation flying technology for future missions.

ST 3 optical interferometry formation flying↗
NASA NTRS2005

A network architecture for precision formation flying using the IEEE 802.11 MAC Protocol

Precision Formation Flying missions involve the tracking and maintenance of spacecraft in a desired geometric formation. The strong coupling of spacecraft in formation flying control requires inter-spacecraft communication to exchange information. In this paper, we present a network architecture that supports PFF control, from the initial random deployment phase to the final formation. We show that a suitable MAC layer for the application protocol is IEEE's 802.11 MAC protocol. IEEE 802.11 MAC has two modes of operations: DCF and PCF. We show that DCF is suitable for the initial deployment phase while switching to PCF when the spacecraft are in formation improves jitter and throughput. We also consider the effect of routing on protocol performance and suggest when it is profitable to turn off route discovery to achieve better network performance.

precision formation flying↗
NASA NTRS2013

Fruit Fly Lab

The presentation presents the objectives goals, hardware, science, and operations for the Fruit Fly Lab technical demonstration flight. Description: To support multi-generational experiments with Drosophila melanogaster (fruit flies) at various gravity levels (0 to 2 g). The aim is also to include a video monitoring system to measure health and behavior in space.

Fruit Fly Lab↗
NASA NTRS2002

The StarLight mission: a formation-flying stellar interferometer

The StarLight mission is designed to validate the technologies of formation flying and stellar interferometry in space. The mission consists of two spacecraft in an earth-trailing orbit that formation fly over relative ranges of 40 to 600 m to an accuracy of 10 cm.

formation-flying↗
NASA NTRS1970

Rationale for proposed flying-qualities specifications

The NASA Flight Research Center is reviewing the applicability of flying qualities experience to the shuttle mission for the purpose of preparing a shuttle flying qualities specification. This paper is a progress report on this review; the results presented are, of course, preliminary.

Euclid C Holleman↗
NASA NTRS1972

Shuttle free-flying teleoperator system experiment definition. Volume 3: program development requirements

The planning data are presented for subsequent phases of free-flying teleoperator program (FFTO) and includes costs, schedules and supporting research and technology activities required to implement the free-flying teleoperator system and associated flight equipment. The purpose of the data presented is to provide NASA with the information needed to continue development of the FFTO and integrate it into the space shuttle program. The planning data describes three major program phases consisting of activities and events scheduled to effect integrated design, development, fabrication and operation of an FFTO system. Phase A, Concept Generation, represents a study effort directed toward generating and evaluating a number of feasible FFTO experiment system concepts. Phase B, Definition, will include preliminary design and supporting analysis of the FFTO, the shuttle based equipment and ground support equipment. Phase C/D, Design, Development and Operations will include detail design of the operational FFTO, its integration into the space shuttle, hardware fabrication and testing, delivery of flight hardware and support of flight operations. Emphasis is placed on the planning for Phases A and B since these studies will be implemented early in the development cycle. Phase C/D planning is more general and subject to refinement during the definition phase.

Source record↗
NASA NTRS1972

An experimental investigation of STOL longitudinal flying qualities in the landing approach using the variable stability X-22A aircraft.

The first in-flight flying qualities experiment using the variable stability X-22A aircraft investigated longitudinal flying qualities requirements for STOL aircraft in terminal area operations. Emphasis was placed on defining minimum requirements for the short-term response in VFR and IFR landing approaches at representative steep STOL approach conditions of 65 and 80 knots. Evaluation flights were conducted in negligible and moderate turbulence for a wide range of short-term frequencies and dampings. The results were compared with the short-term requirements of MIL-F-83300. The specified Level 1 and 2 VFR boundaries were found to be approximately valid in moderate turbulence for both VFR and IFR flight conditions. In negligible turbulence, the specified VFR Level 2 boundary was also approximately valid but the Level 1 boundary was found to be too stringent. Pilot rating gradients with damping were more apparent than with frequency for the range investigated.

Schuler, J. M.↗
NASA NTRS1973

Development and flight test of a digital fly-by-wire F8.

The objective of the F-8 digital fly-by-wire program is to establish a technology base for the implementation of advanced flight control systems. The central element is the Apollo Lunar Guidance Computer (LGC). This versatile computer ran over 2000 hours in support of fly-by-wire without a failure. Difficulties encountered in the first flights were corrected rapidly and simply by changes in the erasable software memory. Control-configured vehicles offer significant weight-saving possibilities.

Peterson, B. A.↗
NASA NTRS1972

Conference on General Aviation-Business Flying, University of Tennessee, Tullahoma, Tenn., August 17-19, 1972, Proceedings.

The papers deal with safety measures, commuter airlines, charter and lease flying, pleasure flying and private travel, technology for the next decade, avionics, and the airport network. Attention is given to transfer between general and commercial terminals, airport standards, traffic control, increasing training effectiveness through simulation, proposed revision of Part 61 of FAA regulations, and accident prevention. Individual items are announced in this issue.

Source record↗
NASA NTRS1974

Flight investigation of effects of a fan-in-fin yaw control concept on helicopter flying-quality characteristics

Flight-test results which describe flying-quality factors related to the fan-in-fin yaw control concept as utilized on a pre-production version of a European helicopter are presented. Design compromises to be considered with this concept are also presented. The large, fixed vertical fin associated with the fan-in-fin system was helpful in maneuvering flight, but introduced several flying-quality problems when combined with the fan.

Kelley, H. L.↗
NASA NTRS1974

V/STOL flying qualities research using the X-22A

The X-22A has four ducted propellers and four engines. The engines are connected to a common system of rotating shafts which distribute propulsive power to the four propellers. Changes in the direction of the thrust vector are accomplished by rotating the ducts, which are interconnected so that all rotate through the same angle. Thrust magnitude is determined by a collective pitch lever, very similar to a helicopter. There are four variable stability system (VSS) controllers: thrust, pitch, roll, and yaw, and three artificial feel servos for the evaluation pilot cockpit controls, each employing electrohydraulic servos. Longitudinal flying qualities for STOL landing approach, and lateral-directional flying qualities and control power requirements for STOL landing approach are discussed. Attention is given to the data acquisition and processing system.

Smith, R. E.↗