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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 361 records · Page 20
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NASA NTRSDate not supplied

Flightcrew Thrust Control and Engine Display Concepts for the Subsonic Single Aft Engine (SUSAN) Transport Aircraft

NASA is developing a new hybrid-electric aircraft concept called the SUbsonic Single Aft eNgine (SUSAN) Electrofan. The SUSAN airplane is being designed as a 180-passenger commercial regional jet and is expected to fly in the 2040 time frame. The flight deck of the SUSAN airplane is expected to resemble a typical two flightcrew transport. Research issues include pilot control and the display elements needed for the hybrid-electric propulsion system. This paper describes a research study conducted in a high-fidelity simulator where 14 commercial pilots evaluated throttle controls and engine display concepts for a proposed SUSAN flight deck. The results showed that the number of throttle levers did not affect pilot’s situation awareness, workload, or speed control.

hybrid electric aircraft↗
NASA NTRS1974

Fixed-base simulation study of decoupled controls during approach and landing of a STOL transport airplane

A fixed-base visual simulation study has been conducted to evaluate the use of decoupled controls as a means for reducing pilot workload during approach and landing of an externally blown jet-flap short take-off and landing (STOL) transport. All six rigid-body degrees of freedom were employed with the aerodynamic characteristics based on wind-tunnel data. The primary piloting task was to use a flight director to capture and maintain a two-segment glide slope, with a closed-circuit television display of a STOL airport used during simulations of the flare and landing. The decoupled longitudinal controls used constant prefilter and feedback gains to provide steady-state decoupling of flight-path angle, pitch angle, and forward velocity. The pilots were enthusiastic about the decoupled longitudinal controls but believed the decoupled concept offered no significant advantage over conventional controls in the lateral mode.

Miller, G. K., Jr.↗
NASA NTRS1976

STS payloads mission control study (continuation phase)

User oriented space transportation system-payload mission control concepts are developed for optimum contribution of ground flight control support to onboard capability to meet STS payload objectives in a cost effective manner. Flight control ground functions are identified for representative payloads. Present and planned NASA facilities for payload control are investigated. Cost effective system concept options are determined for flight control of the payloads. Implementation guidelines are developed for proposed system concept options. Joint preflight activities are identified. Composite joint resources are identified.

Source record↗
NASA NTRS1986

CID flight/impact

The planned versus the actual results of the controlled impact demonstration of a transport aircraft are discussed. Remote control systems, site selection, manned flight tests, and wreckage distribution are discussed.

Barber, R.↗
NASA NTRS1998

Testing of the Geoscience Laser Altimeter System (GLAS) Prototype Loop Heat Pipe

This paper describes the testing of the prototype loop heat pipe (LHP) for the Geoscience Laser Altimeter System (GLAS). The primary objective of the test program was to verify the loop's heat transport and temperature control capabilities under conditions pertinent to GLAS applications. Specifically, the LHP had to demonstrate a heat transport capability of 100 W, with the operating temperature maintained within +/-2K while the condenser sink was subjected to a temperature change between 273K and 283K. Test results showed that this loop heat pipe was more than capable of transporting the required heat load and that the operating temperature could be maintained within +/-2K. However, this particular integrated evaporator-compensation chamber design resulted in an exchange of energy between the two that affected the overall operation of the system. One effect was the high temperature the LHP was required to reach before nucleation would begin due to inability to control liquid distribution during ground testing. Another effect was that the loop had a low power start-up limitation of approximately 25 W. These Issues may be a concern for other applications, although it is not expected that they will cause problems for GLAS under micro-gravity conditions.

Douglas, Donya↗
NASA NTRS1972

Analysis of Morgantown vehicle steering control

The proposed Morgantown public transportation system will use a fleet of computer-controlled vehicles operating on a separate dedicated network of roadways called a guideway. An automatic steering system on each vehicle will permit the traversal of the proposed route of various guideway sections. A preliminary study was made to analyze the steering control for the Morgantown vehicles. The primary requirement was to design an automatic steering system that would achieve a smooth ride and eliminate the need for excess margin in the guideway width. Front and rear wheel steering and front and rear sensing capabilities were assumed in the analysis. The system finally adopted front and rear wheel steering and front sensing was shown by computer simulation and vehicle steering experiments to be adequate.

Lin, H. S.↗
NASA NTRS1984

Investigation, development and application of optimal output feedback theory. Volume 2: Development of an optimal, limited state feedback outer-loop digital flight control system for 3-D terminal area operation

This report contains the development of a digital outer-loop three dimensional radio navigation (3-D RNAV) flight control system for a small commercial jet transport. The outer-loop control system is designed using optimal stochastic limited state feedback techniques. Options investigated using the optimal limited state feedback approach include integrated versus hierarchical control loop designs, 20 samples per second versus 5 samples per second outer-loop operation and alternative Type 1 integration command errors. Command generator tracking techniques used in the digital control design enable the jet transport to automatically track arbitrary curved flight paths generated by waypoints. The performance of the design is demonstrated using detailed nonlinear aircraft simulations in the terminal area, frequency domain multi-input sigma plots, frequency domain single-input Bode plots and closed-loop poles. The response of the system to a severe wind shear during a landing approach is also presented.

Broussard, J. R.↗
NASA NTRS1977

Study of the application of an implicit model-following flight controller to lift-fan VTOL aircraft

An implicit model-following flight controller is proposed. This controller is relatively simple in concept: it provides an input/output relationship that is approximately that of any selected second order system; it provides good gust alleviation; and it is self-trimming. The flight controller was applied to all axes of a comprehensive mathematical model of a lift-fan V/STOL transport. Power management controls and displays were designed to match the various modes of control provided by the flight controller. A piloted simulation was performed using a six degree of freedom simulator. The fixed-operating-point handling qualities throughout the powered lift flight envelope received pilot ratings of 3-1/2 or better. Approaches and vertical landings in IFR zero-zero conditions received pilot ratings varying from 2-1/2 to 4 depending on the type of approach and weather conditions.

Merrick, V. K.↗
NASA NTRS2012

Optimal Routing and Control of Multiple Agents Moving in a Transportation Network and Subject to an Arrival Schedule and Separation Constraints

We address the problem of navigating a set of moving agents, e.g. automated guided vehicles, through a transportation network so as to bring each agent to its destination at a specified time. Each pair of agents is required to be separated by a minimal distance, generally agent-dependent, at all times. The speed range, initial position, required destination, and required time of arrival at destination for each agent are assumed provided. The movement of each agent is governed by a controlled differential equation (state equation). The problem consists in choosing for each agent a path and a control strategy so as to meet the constraints and reach the destination at the required time. This problem arises in various fields of transportation, including Air Traffic Management and train coordination, and in robotics. The main contribution of the paper is a model that allows to recast this problem as a decoupled collection of problems in classical optimal control and is easily generalized to the case when inertia cannot be neglected. Some qualitative insight into solution behavior is obtained using the Pontryagin Maximum Principle. Sample numerical solutions are computed using a numerical optimal control solver.

Sadovsky, A. V.↗
NASA NTRS2013

ISS Ammonia Leak Detection Through X-Ray Fluorescence

Ammonia leaks are a significant concern for the International Space Station (ISS). The ISS has external transport lines that direct liquid ammonia to radiator panels where the ammonia is cooled and then brought back to thermal control units. These transport lines and radiator panels are subject to stress from micrometeorites and temperature variations, and have developed small leaks. The ISS can accommodate these leaks at their present rate, but if the rate increased by a factor of ten, it could potentially deplete the ammonia supply and impact the proper functioning of the ISS thermal control system, causing a serious safety risk. A proposed ISS astrophysics instrument, the Lobster X-Ray Monitor, can be used to detect and localize ISS ammonia leaks. Based on the optical design of the eye of its namesake crustacean, the Lobster detector gives simultaneously large field of view and good position resolution. The leak detection principle is that the nitrogen in the leaking ammonia will be ionized by X-rays from the Sun, and then emit its own characteristic Xray signal. The Lobster instrument, nominally facing zenith for its astrophysics observations, can be periodically pointed towards the ISS radiator panels and some sections of the transport lines to detect and localize the characteristic X-rays from the ammonia leaks. Another possibility is to use the ISS robot arm to grab the Lobster instrument and scan it across the transport lines and radiator panels. In this case the leak detection can be made more sensitive by including a focused 100-microampere electron beam to stimulate X-ray emission from the leaking nitrogen. Laboratory studies have shown that either approach can be used to locate ammonia leaks at the level of 0.1 kg/day, a threshold rate of concern for the ISS. The Lobster instrument uses two main components: (1) a microchannel plate optic (also known as a Lobster optic) that focuses the X-rays and directs them to the focal plane, and (2) a CCD (charge coupled device) focal plane detector that reads out the position and energy of the X-rays, allowing a determination of the leak location. The effective area of the detection system is approximately 2 cm(exp2) at 1 keV. The Lobster astrophysics instrument, designed for monitoring the sky for Xray transients, gives high sensitivity along with large field of view (30×30deg) and good spatial resolution (1 arc min). This offers a significant benefit for detecting ISS ammonia leaks, since the goal is to localize small leaks as efficiently as possible.

Camp, Jordan↗
NASA NTRS2006

Model Predictive Optimal Control of a Time-Delay Distributed-Parameter Systems

This paper presents an optimal control method for a class of distributed-parameter systems governed by first order, quasilinear hyperbolic partial differential equations that arise in many physical systems. Such systems are characterized by time delays since information is transported from one state to another by wave propagation. A general closed-loop hyperbolic transport model is controlled by a boundary control embedded in a periodic boundary condition. The boundary control is subject to a nonlinear differential equation constraint that models actuator dynamics of the system. The hyperbolic equation is thus coupled with the ordinary differential equation via the boundary condition. Optimality of this coupled system is investigated using variational principles to seek an adjoint formulation of the optimal control problem. The results are then applied to implement a model predictive control design for a wind tunnel to eliminate a transport delay effect that causes a poor Mach number regulation.

Nguyen, Nhan↗
NASA NTRS1990

Thermal control system technology discipline

Viewgraphs on thermal control systems technology discipline for Space Station Freedom are presented. Topics covered include: heat rejection; heat acquisition and transport; monitoring and control; passive thermal control; and analysis and test verification.

Ellis, Wilbert E.↗
NASA NTRS1983

Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Test act system description

The engineering and fabrication of the test ACT system, produced in the third program element of the IAAC Project is documented. The system incorporates pitch-augmented stability and wing-load alleviation, plus full authority fly-by-wire control of the elevators. The pitch-augmented stability is designed to have reliability sufficient to allow flight with neutral or negative inherent longitudinal stability.

Source record↗
NASA NTRS1998

Investigation of Vibrational Control of the Bridgman Crystal Growth Technique

The objectives are: Conduct a parametric theoretical and numerical investigation of vibro-convective buoyancy-driven flow in differentially heated cylindrical containers. Investigate buoyant vibro-convective transport regimes in Bridgman-type systems with a focus on the use of vibration to suppress, or control, convection in order to achieve transport control during crystal growth. Assess the feasibility of vibro-convective control as a means of offsetting "g-jitter" effects under microgravity conditions, Exchange information with the experimental group at the General Physics Institute (GPI) of the Russian Academy of Science who are undertaking a complementary experimental program.

Fedoseyev, Alexandre I.↗
NASA NTRS1979

Transportation and General Traffic Management, Change 2

This Handbook sets forth those transportation and general traffic management responsibilities, guidelines, and procedures governing the use of commercial and Government transportation for NASA. Transportation is an integral function of the logistic process, involving all activities incident to the movement of persons and things. The fundamental and continuous objectives of transportation are to control and diminish the time-distance of lines of communication by the most suitable means. The function of transportation is accomplished through, and encompasses all, the planning, direction, supervision, and execution of the technical, operational, and administrative tasks required to procure or furnish efficient and economical conveyance of cargo and personnel by all modes of commercial and Government transportation. This Handbook is applicable to NASA Headquarters and Field Installations.

Source record↗
NASA NTRS1982

Stability and control flight test results of the space transportation system's orbiter

Flight testing of the Space Shuttle Orbiter is in progress and current results of the post-flight aerodynamic analyses are discussed. The purpose of these analyses is to reduce the pre-flight aerodynamic uncertainties, thereby leading to operational certification of the Orbiter flight envelope relative to the integrated airframe and flight control system. Primary data reduction is accomplished with a well documented maximum likelihood system identification techniques.

Culp, M. A.↗