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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

NASA aircraft noise reduction research and technology program overview

A brief outline of the chief areas where NASA is making efforts in aircraft noise research is given. This includes studies of the physical basis of aircraft noise and methods for accurately predicting it, the development of practical technologies for noise reduction, and the subjective response of people when exposed to aircraft noise. The JT8D Refan Program was to explore whether the noise reduction design concepts used effectively in modern high-bypass engines could also be applied practically and effectively as retrofittable modifications to existing older, low-bypass JT8D engines. A program has been completed on developing and demonstrating safe and acceptable flight procedures together with necessary airborne electronics to permit two-segment approaches under either VFR or IFR conditions.

Johnson, H. W.↗
NASA NTRS1977

Flight test pilot evaluation of a delayed flap approach procedure

Using NASA's CV-990 aircraft, a delayed flap approach procedure was demonstrated to nine guest pilots from the air transport industry. Four demonstration flights and 37 approaches were conducted under VFR weather conditions. A limited pilot evaluation of the delayed flap procedure was obtained from pilot comments and from questionaires they completed. Pilot acceptability, pilot workload, and ATC compatibility were quantitatively rated. The delayed flap procedure was shown to be feasible, and suggestions for further development work were obtained.

Bull, J. S.↗
NASA NTRS1977

A failure effects simulation of a low authority flight control augmentation system on a UH-1H helicopter

A two-pilot moving base simulator experiment was conducted to assess the effects of servo failures of a flight control system on the transient dynamics of a Bell UH-1H helicopter. The flight control hardware considered was part of the V/STOLAND system built with control authorities of from 20-40%. Servo hardover and oscillatory failures were simulated in each control axis. Measurements were made to determine the adequacy of the failure monitoring system time delay and the servo center and lock time constant, the pilot reaction times, and the altitude and attitude excursions of the helicopter at hover and 60 knots. Safe recoveries were made from all failures under VFR conditions. Pilot reaction times were from 0.5 to 0.75 sec. Reduction of monitor delay times below these values resulted in significantly reduced excursion envelopes. A subsequent flight test was conducted on a UH-1H helicopter with the V/STOLAND system installed. Series servo hardovers were introduced in hover and at 60 knots straight and level. Data from these tests are included for comparison.

Corliss, L. D.↗
NASA NTRS1978

Airline pilot scanning behavior during approaches and landing in a Boeing 737 simulator

A series of approaches using airline-rated Boeing 737 pilots in an FAA qualified simulator was conducted. The test matrices include both manual and coupled approaches for VFR, Category 1 and Category 2 conditions. A nonintrusive oculometer system was used to track the pilot's eye-point-of-regard throughout the approach. The results indicate that, in general, the pilots use a different scan technique for the manual and coupled (auto-pilot with manual throttle) conditions. For the manual approach 73 percent of the time was spent on the Flight Director and 13 percent on airspeed as opposed to 50 percent on Flight Director and 23 percent on airspeed for the coupled approaches. For the visual portion of approach from less than 100m to touchdown or when the touchdown point came into view, the pilots tend to fixate on their aim or touchdown area until the flare initiation, at which time they let their eye-point-of-regard move up the runway to use the centerline lights for rollout guidance.

Spady, A. A., Jr.↗
NASA NTRS1977

Airline pilot scanning behavior during approaches and landing in a Boeing 737 simulator

A series of approaches using airline-rated Boeing 737 pilots in an FAA qualified simulator has been conducted. The test matrices include both manual and coupled approaches for VFR, Category I and Category II conditions. A nonintrusive oculometer system was used to track the pilot's eye-point-of-regard throughout the approach. The results indicate that, in general, the pilots use a different scan technique for the manual and coupled (auto-pilot with manual throttle) conditions. For the manual approach 73 percent of the time was spent on the Flight Director and 13 percent on airspeed as opposed to 50 percent on Flight Director and 23 percent on airspeed for the coupled approaches. For the visual portion of approach from less than 100 m (300 ft) to touchdown or when the touchdown point came into view, the pilots tend to fixate on their aim or touchdown area until the flare initiation, at which time they let their eye-point-of-regard move up the runway to use the centerline lights for rollout guidance.

Spady, A. A., Jr.↗
NASA NTRS1978

Flight management research utilizing an oculometer

This paper presents an overview of the flight management work being conducted using NASA Langley's oculometer system. Tests have been conducted in a Boeing 737 simulator to investigate pilot scan behavior during approach and landing for simulated IFR, VFR, motion versus no motion, standard versus advanced displays, and as a function of various runway patterns and symbology. Results of each of these studies are discussed. For example, results indicate that for the IFR approaches a difference in pilot scan strategy was noted for the manual versus coupled (autopilot) conditions. Also, during the final part of the approach when the pilot looks out-of-the-window he fixates on his aim or impact point on the runway and holds this point until flare initiation.

Spady, A. A., Jr.↗
NASA NTRS1978

Vestibular Function Research aboard Spacelab

NASA is planning to perform a series of Vestibular Function Research (VFR) investigations on the early STS missions to investigate those neurosensory and related physiological processes believed to be associated with the space flight nausea syndrome. The first flight is scheduled for the 1981 Spacelab III Mission in which four frog specimens, mounted on a frog tilting/centrifuge device, will be subjected to periodic acceleration stimuli and periods of artificial gravity. The vestibular nerve firing responses of each frog specimen will be monitored through implanted neutral bouyancy microelectrodes and transmitted to the ground for quick analysis during the flight. The experimentation will be directed at investigating: (1) adaptation to weightlessness; (2) response to acceleration stimuli; (3) response to artificial gravity (in a weightlessness environment) and (4) readaptation to earth's gravity upon return.

Mah, R. W.↗
NASA NTRS1980

Head-up transition behavior of pilots during simulated low-visibility approaches

Each of 13 commercial pilots from four airlines flew a total of 108 manual flight director approaches in a moving base simulation of a medium-sized turbojet (95,000 lb gross weight) which had a day and night Redifon external scene. Three levels of runway visual range (RVR) (1,600; 2,400; and greater than 8,000 ft), three wind-shear profiles, nine ceiling heights, and continuous and intermittent visibility after initial breakout were tested. The results indicated that: (1) mean decision time ranged from 2 to 4.6 sec for ceilings under 380 ft across the three RVR conditions; (2) mean vertical distance traveled during the visual-cue assessment period was a relatively constant proportion below the existing ceiling; (3) a significant three way interaction in mean decision time between wind shear, day-night, and ceiling RVR variables occurred; (4) mean number of head-up transitions to VFR conditions after breakout ranged from 4.6 to 13.4 and increased as a function of ceiling and severity of wind shear; the typical duration of fixation out the window was 1.5 sec; and (5) subjective pilot ratings of controllability and precision of control as well as amount of skill, attention, or effort required to make the landing were influenced significantly by the wind shear, night conditions, and low breakout ceiling conditions.

Haines, R. F.↗
NASA NTRS1980

Analysis of general aviation single-pilot IFR incident data obtained from the NASA aviation safety reporting system

Data obtained from the NASA Aviation Safety Reporting System (ASRS) data base were used to determine problems in general aviation single pilot IFR operations. The data examined consisted of incident reports involving flight safety in the National Aviation System. Only those incidents involving general aviation fixed wing aircraft flying under IFR in instrument meteorological conditions were analyzed. The data were cataloged into one of five major problem areas: (1) controller judgement and response problems; (2) pilot judgement and response problems; (3) air traffic control intrafacility and interfacility conflicts; (4) ATC and pilot communications problems; and (5) IFR-VFR conflicts. The significance of the related problems, and the various underlying elements associated with each are discussed. Previous ASRS reports covering several areas of analysis are reviewed.

Bergeron, H. P.↗
NASA NTRS1979

Flight test evaluation of a digital controller used in a VTOL automatic approach and landing system

As part of the NASA Langley Research Center's effort to develop technology for VTOL operation in the air transportation system in the late 1980's and beyond, research has been conducted aimed at developing digital controller design procedures. This paper describes the verification of one design procedure by the flight evaluation of an advanced digital control algorithm. The control algorithm, operating at 10 iterations per second, follows step guidance commands with zero steady state error and thus provides an autotrim capability for the nonlinear vehicle. Changes in vehicle dynamics are accounted for using a gain scheduling technique. This control algorithm is combined with sensor filters, a trajectory generator, and a closed loop guidance algorithm to form a VTOL autoland system. A CH-47 tandem rotor helicopter which contains a set of sensors, onboard digital flight computers and electro-hydraulic actuators is used in the evaluation. All software, except input-output routines, is coded in FORTRAN using floating point arithmetic and executed in the flight computer. This autoland system is exercised by automatically flying straight-in descending decelerating trajectories typical of VFR manual approaches to a predetermined landing pad.

Downing, D. R.↗
NASA NTRS1981

Analysis and flight evaluation of a small, fixed-wing aircraft equipped with hinged plate spoilers

The results of a four phase effort to evaluate the application of hinged plate spoilers/dive brakes to a small general aviation aircraft are presented. The test vehicle was a single engine light aircraft modified with an experimental set of upper surface spoilers and lower surface dive brakes similar to the type used on sailplanes. The lift, drag, stick free stability, trim, and dynamic response characteristics of four different spoiler/dive brake configurations were determined. Tests also were conducted, under a wide range of flight conditions and with pilots of various experience levels, to determine the most favorable methods of spoiler control and to evaluate how spoilers might best be used during the approach and landing task. The effects of approach path angle, approach airspeed, and pilot technique using throttle/spoiler integrated control were investigated for day, night, VFR, and IFR approaches and landings. The test results indicated that spoilers offered significant improvements in the vehicle's performance and flying qualities for all elements of the approach and landing task, provided a suitable method of control was available.

Olcott, J. W.↗
NASA NTRS1982

Boeing 234 flight control development

The Boeing 234 is the commercially certified derivative of the CH-47 Chinook. The automatic flight control system and flight director with coupler were designed to reduce pilot work-load for missions of approximately six hour duration during VFR, IFR, day and night conditions. The AFCS system for the 234 is essentially the same system as developed for the CH-47D, which has airspeed hold, attitude hold, and maneuver enhancement in all three axes. The system also has the capability to couple to the Sperry Helcis flight director system which provides for enroute navigation and landing approaches. Certification testing was completed, by both the FAA and CAA, to FAR Part 29 for Transport Category Rotorcraft and BCAR Section G: Rotorcraft. The aircraft was certified for civil operation in June 1981.

Morris, J. J.↗
NASA NTRS1983

Analysis of general aviation single-pilot IFR incident data obtained from the NASA Aviation Safety Reporting System

An analysis of incident data obtained from the NASA Aviation Safety Reporting System (ASRS) has been made to determine the problem areas in general aviation single-pilot IFR (SPIFR) operations. The Aviation Safety Reporting System data base is a compilation of voluntary reports of incidents from any person who has observed or been involved in an occurrence which was believed to have posed a threat to flight safety. This paper examines only those reported incidents specifically related to general aviation single-pilot IFR operations. The frequency of occurrence of factors related to the incidents was the criterion used to define significant problem areas and, hence, to suggest where research is needed. The data was cataloged into one of five major problem areas: (1) controller judgment and response problems, (2) pilot judgment and response problems, (3) air traffic control (ATC) intrafacility and interfacility conflicts, (4) ATC and pilot communication problems, and (5) IFR-VFR conflicts. In addition, several points common to all or most of the problems were observed and reported. These included human error, communications, procedures and rules, and work load.

Bergeron, H. P.↗
NASA NTRS1984

NASA Ames-Dryden T-37 demonstration comments

A homemade peripheral vision horizon device (PVHD) made from an eight-ball attitude indicator, with a slit cut at the equator of the eight ball, and a light source at its center that was used on a I-37 for several years is discussed. The instrument produced a sharp white line about one-fourth of an inch that extended completely across the cockpit from about the left to the right quarterpanels. The line remained parallel to the real horizon during all maneuvers. Its brightness and vertical distance from the horizon were adjustable in flight, as was the lateral center-of-rotation in later flights. Flight demonstrations were done on visual flight rules (VFR) moonless nights and over terrain with few lights. Pilot responses were mostly favorable to enthusiastic, with no negative reactions. Problem areas noted were the upright-inverted ambiguity; one pilot recovered inverted following an unusual attitude exercise and a general deterioration in the naturalness of cuing at bank angles greater than 60 deg or pitch attitudes greater than 30 deg.

Source record↗
NASA NTRS1984

Some thoughts on the implementation of pilot night vision devices for helicopters

Night vision enhancement devices greatly expand the range and quality of services by extending night operational capabilities. Evolving military tactical concepts for helicopters survivability and battlefield effectiveness necessitate nap-of-the-earth (NOE) flying under both day and night conditions. From a pilot workload standpoint, flying a helicopter NOE in day VFR conditions with minimum clearance between rotors and obstacles is quite demanding. Doing the same job at night is several times more difficult. There are two general categories of night vision devices in operation in helicopter aviation: the Night Vision Goggles (NVG) and forward looking infrared (FLIR) system. The capabilities and limitations of those two devices are discussed.

Tucker, G. E.↗
NASA NTRS1987

Flight test of a digital controller used in a helicopter autoland system

This paper describes the flight test evaluation of an advanced digital helicopter flight control system. The controller was designed using an optimal control design procedure for a fully coupled lateral and longitudinal vehicle model. Explicit integrals of the guidance error were included to produce a type 1 characteristic. Gain scheduling was used to account for changes in the vehicle dynamics. The digital controller was exercised by combining it with state estimators, a trajectory generator, and a closed-loop guidance algorithm to form a helicopter autoland system. A CH-47 tandem rotor helicopter was equipped with sensors, on-board digital flight computers, and electrohydraulic actuators. The system was exercised by automatically flying straight-in descending decelerating trajectories typcial of VFR manual landing approaches. A description of the test-ground facilities, the flight hardware and software, and the velocity and position tracking performance is included.

Downing, David R.↗
NASA NTRS1989

Human factors in aviation: Terminal control area boundary conflicts

Air-to-air conflicts in the vicinity of Terminal Control Area (TCA) boundaries were studied to obtain a better understanding of the causal dynamics of these events with particular focus on human factor issues. The study dataset consisted of 381 Instrument Flight Rules/Visual Flight Rules (IFR/VFR) traffic conflicts in airspace layers above TCA ceiling and below TCA floors; 213 reports of incursions in TCA terminal airspace by VFR aircraft, of which 123 resulted in conflicts; and an additional set of reports describing problems with Air Traffic Control (ATC) services in and around TCAs. Results and conclusions are detailed.

Monan, William P.↗
NASA NTRS1990

Analysis of general aviation accidents during operations under instrument flight rules

A report is presented to describe some of the errors that pilots make during flight under IFR. The data indicate that there is less risk during the approach and landing phase of IFR flights, as compared to VFR operations. Single-pilot IFR accident rates continue to be higher than two-pilot IFR incident rates, reflecting the high work load of IFR operations.

Bennett, C. T.↗