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At least 109 records · Page 6

Pilot scale testing of an advanced solvent in a 0.7 MWe post-combustion CO 2 capture unit

An advanced Amine Promoted Buffer Solution (APBS), APBS-CDRMax® (CDRMax), developed by Carbon Clean Solutions Limited (CCSL), was tested at the 0.7 MWe CO 2 capture facility at Kentucky Utilities E.W. Brown Generation Station using a heat-integrated two-staged stripping CO 2 capture process. The performance of the solvent was evaluated to determine operating conditions that maximized the cyclic capacity of the solvent and results in energy savings. The regeneration energy ranged from 2.9 to 3.3 GJ/ton CO 2 with 14 vol % (dry) CO 2 inlet and approximately 90 % capture. The difference in the reboiler specific heat duty at stripper pressures of 1.7 and 2.1 bar was minimal as similar amounts of water vapor were observed in the CO 2 product stream at stripper outlet. Recycling of product CO 2 increased the inlet CO 2 concentration to the absorber from 14 to 16 vol% which enhanced mass transfer from the gas to the solvent resulting in about 5 % reduction in the energy of regeneration at the lower stripper pressure. The solvent circulation rate was reduced by about 30 % relative to previous 30 wt% MEA campaign for the CO 2 target capture of 90 %. Finally, the reduced solvent make-up rate of CDRMax shows promise for capital and operating cost savings for post-combustion CO 2 capture.

42 ENGINEERING↗

The application and results of a new flight test technique

The application of a flight test maneuver auto-pilot test technique for collecting aerodynamic and structural flight research data on a highly maneuverable aircraft is described. This newly developed flight test technique was applied at the Dryden Flight Research Facility of the NASA Ames Research Center on the highly maneuverable aircraft technology (HiMAT) vehicle. A primary flight experiment was done to verify the design techniques used to develop the HiMAT aerodynamics and structures. This required the collection of large quantities of high-quality pressure distribution, loads, and deflection data. The effectiveness of the flight test technique is illustrated with a flight test example comparing various pressure distribution measurements.

Duke, E. L.↗

Flight guidance research for recovery from microburst wind shear

Research is in progress to develop flight strategy concepts for avoidance and recovery from microburst wind shears. The objectives of this study are to evaluate the performance of various strategies for recovery from wind shear encountered during the approach-to-landing, examine the associated piloting factors, and evaluate the payoff of forward-look sensing. Both batch and piloted simulations are utilized. The industry-recommended manual recovery technique is used as a baseline strategy. Two advanced strategies were selected for the piloted tests. The first strategy emulates the recovery characteristics shown by prior optimal trajectory analysis, by initially tracking the glideslope, then commanding a shallow climb. The second strategy generates a flight path angle schedule that is a function of airplane energy state and the instantaneous shear strength. All three strategies are tested with reactive sensing only and with forward-look sensing. Piloted simulation tests are in progress. Tentative results indicate that, using only reactive alerts, there appears to be little difference in performance between the various strategies. With forward-look alerts, the advanced guidance strategies appear to have advantages over the baseline strategy. Relatively short forward-look alert times, on the order of 10 or 15 seconds, produce a far greater recovery benefit than optimizing a recovery from a reactive alert.

Hinton, David A.↗

Particle Separator for Improved Flameless Pressurized Oxy-Combustion

The team of Southwest Research Institute® (SwRI®), ITEA, Electric Power Research Institute, Inc. (EPRI), and General Electric Global Research (GE) is advancing Flameless Pressurized Oxy-combustion (FPO), a novel coal technology. This effort seeks to develop a particle separator for the hot-gas stream leaving the FPO loop. In order to maximize the energy extracted from the cycle, the hot gas is put through a turbo-expander before flue-gas treatment. The particle separator designed under this project sought to operate at high temperature and with low-pressure drop, protecting the turbo-expander from erosion damage. The team engaged potential vendors for the test, developed plans for the pilot test loop modification, and refined requirements for the commercial turbo-expander.

01 COAL, LIGNITE, AND PEAT↗

Design, analysis and control of large transports so that control of engine thrust can be used as a back-up of the primary flight controls

A propulsion controlled aircraft (PCA) system has been developed at NASA Dryden Flight Research Center at Edwards Air Force Base, California, to provide safe, emergency landing capability should the primary flight control system of the aircraft fail. As a result of the successful PCA work being done at NASA Dryden, this project investigated the possibility of incorporating the PCA system as a backup flight control system in the design of a large, ultra-high capacity megatransport in such a way that flight path control using only the engines is not only possible, but meets MIL-Spec Level 1 or Level 2 handling quality requirements. An 800 passenger megatransport aircraft was designed and programmed into the NASA Dryden simulator. Many different analysis methods were used to evaluate the flying qualities of the megatransport while using engine thrust for flight path control, including: (1) Bode and root locus plot analysis to evaluate the frequency and damping ratio response of the megatransport; (2) analysis of actual simulator strip chart recordings to evaluate the time history response of the megatransport; and (3) analysis of Cooper-Harper pilot ratings by two NaSA test pilots.

Roskam, Jan↗

Improved Lunar Lander Handling Qualities Through Control Response Type and Display Enhancements

A piloted simulation that studied the handling qualities for a precision lunar landing task from final approach to touchdown is presented. A vehicle model based on NASA's Altair Lunar Lander was used to explore the design space around the nominal vehicle configuration to determine which combination of factors provides satisfactory pilot-vehicle performance and workload; details of the control and propulsion systems not available for that vehicle were derived from Apollo Lunar Module data. The experiment was conducted on a large motion base simulator. Eight Space Shuttle and Apollo pilot astronauts and three NASA test pilots served as evaluation pilots, providing Cooper-Harper ratings, Task Load Index ratings and qualitative comments. Each pilot flew seven combinations of control response types and three sets of displays, including two varieties of guidance and a nonguided approach. The response types included Rate Command with Attitude Hold, which was used in the original Apollo Moon landings, a Velocity Increment Command response type designed for up-and-away flight, three response types designed specifically for the vertical descent portion of the trajectory, and combinations of these. It was found that Velocity Increment Command significantly improved handling qualities when compared with the baseline Apollo design, receiving predominantly Level 1 ratings. This response type could be flown with or without explicit guidance cues, something that was very difficult with the baseline design, and resulted in approximately equivalent touchdown accuracies and propellant burn as the baseline response type. The response types designed to be used exclusively in the vertical descent portion of the trajectory did not improve handling qualities.

Mueller, Eric Richard↗

Astronautics and Aeronautics, 1966

At the opening of the tenth year in the era of man’s mobility in outer space, we can look back on 1966 as offering convincing evidence that the United States had gained great competence. This evidence included: five orbital space flights by ten Gemini astronauts; four lunar missions undertaking the orbiting of and soft landing on the moon; numerous contributions to scientific knowledge by unmanned spacecraft and sounding rockets; and further demonstrations of the practical utility of operational space systems, including weather and communications satellites. During 1966, a record 100 American spacecraft were placed into earth orbit or on escape trajectories. Thousands of revealing and useful pictures of the earth were taken from space and of the moon from lunar orbit and on its surface. The Gemini program ended with rendezvous and docking experiments and extravehicular activity by the Gemini test pilots as the Apollo R&D test flights leading to the manned lunar mission came into the schedule. Thirty-five major scientific, technological, and operational milestones were cited for 1966 by the President in his Report to the Congress on aeronautical and space activities of the United States. This was one measure of the American commitment to share in the peaceful exploration of space for all mankind. Another was our support of the final steps toward a United Nations space treaty, undertaken to ensure that the peaceful exploitation of space had juridical basis in international law. Spectacular as some events in the space venture were in 1966, they nonetheless came to have diminished novelty in the eyes of many laymen. The multitude of both important and unspectacular space activities attained almost an accepted and routine place. This volume, as well as its predecessor chronicles, offers a ready reference on the major as well as the less-well known events. Beyond the welter of documented details on the complex nature of aeronautical and space related events and their impact, this volume helps to provide a better perspective upon today as we contemplate tomorrow. Such intent also serves future historians and analysts who cannot be unmindful of what is herein presented. When the Congress created the National Aeronautics and Space Administration in 1958, it charged NASA with the responsibility to “contribute materially to . . . the expansion of human knowledge of phenomena in the atmosphere and space’’ and to “provide for the widest practical and appropriate dissemination of information concerning its activities and results thereof.” NASA has attempted to do this and to include documentation for the historical record. The relating of NASA history begins with this day-by day chronicle and leads to more specialized studies and histories of the unprecedented task of extending man’s mobility and understanding beyond his planet. While a chronology cannot in itself serve as a full-fledged history, the size of this annual volume alone is illustrative of the scope and complexity of the historical task yet to be completed as memories fade and the records disappear.

SPACE PROBE↗

Pilot-Induced Oscillation Prediction With Three Levels of Simulation Motion Displacement

Simulator motion platform characteristics were examined to determine if the amount of motion affects pilot-induced oscillation (PIO) prediction. Five test pilots evaluated how susceptible 18 different sets of pitch dynamics were to PIOs with three different levels of simulation motion platform displacement: large, small, and none. The pitch dynamics were those of a previous in-flight experiment, some of which elicited PIOs These in-flight results served as truth data for the simulation. As such, the in-flight experiment was replicated as much as possible. Objective and subjective data were collected and analyzed With large motion, PIO and handling qualities ratings matched the flight data more closely than did small motion or no motion. Also, regardless of the aircraft dynamics, large motion increased pilot confidence in assigning handling qualifies ratings, reduced safety pilot trips, and lowered touchdown velocities. While both large and small motion provided a pitch rate cue of high fidelity, only large motion presented the pilot with a high fidelity vertical acceleration cue.

Schroeder, Jeffery A.↗

Design of Experiments for Dynamic Test Runs in Solvent-Based CO 2 Capture Pilot Plants

Test runs in the pilot plants consume significant resources, and therefore, the learning from test runs should be maximized. Test runs conducted in the pilot plants are often steady state. It takes several hours for reaching steady-state in the pilot plants, and thus, the duration of the test runs needs to be long even for collecting few steady-state data points. On the other hand, a large number of measurements can be collected through dynamic test runs in a short span of time. This paper presents a systematic design of dynamic experiments (DoDEs) for identifiability of model parameters, which is achieved by persistently exciting the inputs signals. A pseudorandom binary sequence (PRBS) is designed as the input signal for DoDE due to its efficiency in obtaining sufficient spectral content. However, due to the long sequence size of the PRBS signal, a Schroeder-phase input signal, which is a multisine signal, is also designed. Tests for both types of signals are run in the Pilot Solvent Test Unit (PSTU) at the National Carbon Capture Center in Wilsonville, Alabama. The transient data are used to solve dynamic data reconciliation and parameter estimation problem. The estimated parameters are found to be not only superior to those estimated from using data collected from hundreds of steady-state test runs in a nonreactive (air–water) system, but the parameters could be estimated by using the dynamic data collected for about 24 h from the pilot plant for the MEA-H 2 O–CO 2 system.

CO2 capture↗

Occupant safety in the Space Shuttle

The nature of Space Shuttle missions, i.e., the inclusion of non-pilot payload specialists in addition to military test pilots, necessitates a greater attention to built in safety features than on previous spacecraft. Basic systems such as fire protection, anti-depressurization, toxicity control, and protection from radiation are handled in a manner similar to that of past missions, but some important deviations are noted, most importantly those pertaining to the provisions for on-orbit rescue. A Personnel Rescue System (PRS) is outlined, describing EVA operations whereby the pilots are able to don pressure suits and the crew can be transferred to another vehicle in balloon-like enclosures, which provide one hour's worth of life support and protection from the space environment. Also mentioned are provisions for the quick abort and reentry of the Shuttle Orbiter, as well as passive safety provisions for the Spacelab module.

Schulze, N. R.↗

Entropy, instrument scan and pilot workload

Correlation and information theory which analyze the relationships between mental loading and visual scanpath of aircraft pilots are described. The relationship between skill, performance, mental workload, and visual scanning behavior are investigated. The experimental method required pilots to maintain a general aviation flight simulator on a straight and level, constant sensitivity, Instrument Landing System (ILS) course with a low level of turbulence. An additional periodic verbal task whose difficulty increased with frequency was used to increment the subject's mental workload. The subject's looppoint on the instrument panel during each ten minute run was computed via a TV oculometer and stored. Several pilots ranging in skill from novices to test pilots took part in the experiment. Analysis of the periodicity of the subject's instrument scan was accomplished by means of correlation techniques. For skilled pilots, the autocorrelation of instrument/dwell times sequences showed the same periodicity as the verbal task. The ability to multiplex simultaneous tasks increases with skill. Thus autocorrelation provides a way of evaluating the operator's skill level.

Tole, J. R.↗

Inflight evaluation of pilot workload measures for rotorcraft research

The effectiveness of heart-rate monitoring and the NASA TLX workload rating scale (Hart et al., 1985) in measuring helicopter-pilot workloads is investigated experimentally. Four NASA test pilots flew two 2-h missions each in an SH-3G helicopter, following scenarios with takeoff, hover, cross-country, and landing tasks; pilot performance on the tasks undertaken near the landing area was measured by laser tracking. The results are presented in graphs and discussed in detail, and it is found that the TLX ratings clearly distinguish the flight segments and are well correlated with the performance data. The mean heart rate (measured as interbeat interval) is correlated (r = -0.69) with the TLX workload, but only the standard deviation of the interbeat interval is able to distinguish between flight segments; the correlation between standard deviation and TLX ratings is negative but not significant.

Shively, Robert J.↗

Interaction of feel system and flight control system dynamics on lateral flying qualities

An investigation of feel system and flight control system dynamics on lateral flying qualities was conducted using the variable stability USAF NT-33 aircraft. Experimental variations in feel system natural frequency, force-deflection gradient, control system command architecture type, flight control system filter frequency, and control system delay were made. The experiment data include pilot ratings using the Cooper-Harper (1969) rating scale, pilot comments, and tracking performance statistic. Three test pilots served as evaluators. The data indicate that as the feel system natural frequency is reduced lateral flying qualities degrade. At the slowest feel system frequency, the closed-loop response becomes nonlinear with a 'bobweight' effect apparent in the feel system. Feel system influences were essentially independent of the control system architecture. The flying qualities influence due to the feel system was different than when the identical dynamic systenm was used as a flight control system element.

Bailey, Randall E.↗

Procedure Automation Rating Matrix

The National Aeronautics and Space Administration (NASA) Advanced Air Mobility (AAM) National Campaign (NC) is researching the means by which future Urban Air Mobility (UAM) aircraft will operate safely in an integrated and scalable airspace architecture. Consistent with this objective, the NASA NC Airspace Procedures team designed a matrix to evaluate UAM instrument flight procedure design, flyability and interoperability of candidate departure, enroute, and approach architectures in live flight or simulation. The Procedure Automation Rating Matrix (PARM) is a multi-dimensional rating scale designed to provide direct feedback from test pilots and operators to airspace procedure designers developing airspace constructs for the integration and scalability of AAM operations in the National Airspace System (NAS). The PARM is assessed using a hierarchical decision tree that guides the operator through a ten-point alpha-numeric rating scale initiated either with or without the use of automation.

National Campaign↗

Study of the use of a nonlinear, rate-limited filter on pilot control signals

The use of a nonlinear, rate limited filter for rejecting the remnant (noise) in a pilot's control signal was studied through both an analytical study using pilot models and a simulation study using experienced test pilots. The nonlinear filter was compared with a linear filter and with no filter for both attitude and altitude control tasks. The results show that the nonlinear filter does promote rapid, steady maneuvering better than either the linear filter or the no filter condition. In addition, if the rate limit in the nonlinear filter is set so that it is too restrictive, a pilot induced unstable altitude oscillation can result.

Adams, J. J.↗

Study of the use of a nonlinear, rate limited, filter on pilot control signals

The use of a filter on the pilot's control output could improve the performance of the pilot-aircraft system. What is needed is a filter with a sharp high frequency cut-off, no resonance peak, and a minimum of lag at low frequencies. The present investigation studies the usefulness of a nonlinear, rate limited, filter in performing the needed function. The nonlinear filter is compared with a linear, first order filter, and no filter. An analytical study using pilot models and a simulation study using experienced test pilots was performed. The results showed that the nonlinear filter does promote quick, steady maneuvering. It is shown that the nonlinear filter attenuates the high frequency remnant and adds less phase lag to the low frequency signal than does the linear filter. It is also shown that the rate limit in the nonlinear filter can be set to be too restrictive, causing an unstable pilot-aircraft system response.

Adams, J. J.↗

Distributed Thrust Takeoff for the NASA X-57 Mod IV Flight Demonstrator

The Mod IV configuration of the X-57 flight demonstrator concept featured two forms of distributed electric propulsion—one cruise propulsor at each wingtip for primary propulsion that enabled favorable interaction with the wingtip vortex, and six high-lift propulsors distributed along the leading edge of each wing to enhance low-speed flight characteristics. The power system that fed these propulsors was arranged in two independent power buses. This unique arrangement did not lend itself to traditional “one engine inoperative” methods for determining performance after a critical failure in the propulsion system. Several potential failure scenarios were identified as potential “critical loss of thrust” events, and experiments that included pilot-in-the-loop simulation with the project test pilots were conducted to determine if these events would result in adequate handling and performance. Prior research showed that a total failure of one of the cruise motors during takeoff or initial climb could result in unacceptable performance for a traditional full-power takeoff. A new technique dubbed Distributed Thrust Takeoff (DiTTo) was developed to reduce the impact of the thrust asymmetry and total loss of thrust that could occur in any of the critical loss of thrust scenarios. The results showed that adequate performance and handling qualities could be achieved in each of the critical failure scenarios when using the DiTTo technique.

Distributed Propulsion, Electric Propulsion, Criti↗