Aerosol samples obtained from 9-km to 12- km altitude
DC-8 aerosol sampling to determine spatial density of dust, and particle types and size distributions as functions of altitude and time
DUST COLLECTOR↗
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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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A study of turbofan-engine compressor noise suppression techniques
Nacelle design for turbofan engine compressor noise suppression on Douglas DC-8 aircraft
Elias, I.↗
Design concepts
Engineering design studies on noise reduction in turbofan duct of DC-8 aircraft engine
Pendley, R. E.↗
Flight-test nacelles
Design modifications for acoustically absorbing flight test nacelles of DC-8 turbofan engine
Coxon, J. S.↗
Determination of ILS category 2 decision height window requirements
A method for determining the appropriate longitudinal and lateral decision height dispersion limits for any airplane/control system combination during an instrument landing approach is presented. An example is worked out to clarify the steps required. It is shown that the current longitudinal decision height dispersion limits are well suited for a DC-8 with the example control system, but that the lateral limits are too loose to guarantee acceptable touchdowns with the example system subjected to recommended wind and shear disturbances.
Johnson, W. A.↗
Pilot dynamics for instrument approach tasks: Full panel multiloop and flight director operations
Measurements and interpretations of single and mutiloop pilot response properties during simulated instrument approach are presented. Pilot subjects flew Category 2-like ILS approaches in a fixed base DC-8 simulaton. A conventional instrument panel and controls were used, with simulated vertical gust and glide slope beam bend forcing functions. Reduced and interpreted pilot describing functions and remmant are given for pitch attitude, flight director, and multiloop (longitudinal) control tasks. The response data are correlated with simultaneously recorded eye scanning statistics, previously reported in NASA CR-1535. The resulting combined response and scanning data and their interpretations provide a basis for validating and extending the theory of manual control displays.
Weir, D. H.↗
A dynamic response and eye scanning data base useful in the development of theories and methods for the description of control/display relationships
A set of specially prepared digital tapes is reported which contain synchronized measurements of pilot scanning behavior, control response, and vehicle response obtained during instrument landing system approaches made in a fixed-base DC-8 transport simulator. The objective of the master tape is to provide a common data base which can be used by the research community to test theories, models, and methods for describing and analyzing control/display relations and interactions. The experimental conditions and tasks used to obtain the data and the detailed format of the tapes are described. Conventional instrument panel and controls were used, with simulated vertical gust and glide slope beam bend forcing functions. Continuous pilot eye fixations and scan traffic on the panel were measured. Both flight director and standard localizer/glide slope types of approaches were made, with both fixed and variable instrument range sensitivities.
Klein, R.↗
The quiet engine program
Estimates of noise reductions for high bypass ratio engines show that bypass ratio fan noise increases with increasing bypass ratio and dominates above a bypass ratio of about 1.0. Fan noise reduction to the level of jet noise is achieved by elimination of inlet guide vanes, elimination of second fan stage, and increased spacing between rotor and stator. Quiet engine design studies show that, at bypass ratios near 5 or 6 and with low noise fans, noise reductions in the order of 15 to 20 decibels relative to DC-8 and 707 airplanes engines are possible.
Sanders, N. D.↗
Applications to aircraft propulsion systems
Estimates of the prospects for quiet airplanes in the future are summarized. The SST using afterburning turbojets and no sound suppression is estimated to produce 129 EPNdb on the sideline. Suppression devices and operating techniques can reduce this noise markedly. The present fleet of 707's and DC-8's produces noises nearly as high as 120 decibels on approach. Combinations of sound absorbing devices and engine modifications are expected to give a noise near 100 decibels. The new advanced technology transports (ATT) are being studied with two noise goals in mind: one is 10 decibels and the other is 20 decibels below the FAR level of 106 on takeoff. New trijets using new quiet engines are expected to meet 90 EPNdb. Future advances in technology are expected to yield another 5 decibels to give noise levels of 80 EPNdb. The STOL airplane has a noise goal of 95 EPNdb along a sideline 500 feet from the runway.
Sanders, N. D.↗
Effect of shear on aircraft landing
A simulation study was conducted to determine the effect of wind shear on aircraft landings. The landing of various type of commercial and military aircraft was digitally simulated starting from an initial altitude of 300 feet. Assuming no pilot feedback during descent, the deviation in touchdown point due to vertical profiles of wind shear was determined. The vertical profiles of wind shear are defined in terms of surface roughness, Z sub 0, and stability, L, parameters. The effects on touchdown due to Z sub 0 and L have been calculated for the different type aircraft. Comparisons were made between the following types of aircraft: (1) C-130E, (2) C-135A, (3) C-141, (4) DC-8, (5) Boeing 747, and (6) an augmentor-wing STOL. In addition, the wind shear effect on touchdown resulting from different locations of the center of gravity and gross weights was also analyzed.
Luers, J. K.↗
Refan program. Phase 1: Summary report
The Refan Program is aimed at a large reduction in aircraft approach and takeoff noise in the vicinity of airports caused by the JT3D-powered 707's and DC-8's and the JT8D-powered 727's, 737's and DC-9's. These aircraft represent a major part of the existing commercial fleet. The noise reductions can be achieved by engine and nacelle modifications in the form of aircraft retrofit kits. Engine turbomachinery noise is reduced by replacing the current two-stage fan with a larger single-stage fan and by nacelle acoustic treatment. Jet noise is reduced by the reduction on jet velocity caused by additional turbine work extraction to drive the larger bypass fan. The predicted net effect of these modifications on installed performance is large noise reductions on both approach and takeoff, increased takeoff thrust, decreased takeoff field length, and maintained or improved aircraft range depending on the amount of acoustic treatment included. The Refan Program is being conducted in two phases under contracts with one engine and two airframe companies. Results of the Phase I work are summarized in this report which describes the refan nacelle configurations studied, the airplane modifications required to install the nacelles, and the resulting airplane performance and noise reductions predicted for all five aircraft.
Sams, E. W.↗
Resume of the status and benefits of the two-segment approach and its applicability to the jet transport fleet
NASA, in cooperation with the FAA, is evaluating the two-segment approach as a routine procedure for reducing aircraft noise. The program calls for separate flight evaluations using a 727 and a DC-8, and an extrapolation of these results to determine the adaptability of the technique to the rest of the fleet. The total program is reviewed. The profile and procedures developed and the noise reduction achievable are presented. The vortex characteristics behind an aircraft on a two-segment path is covered. Finally, cost estimates for retrofitting aircraft with two-segment avionics are presented.
Denery, D. G.↗
Description and flight performance of two systems for two-segment approach
This paper describes two different avionic systems which were designed and developed to provide guidance and control for two-segment noise abatement approaches. The concept of a low-cost retrofit avionic system evolved into a special-purpose two-segment computer which required a DME collocated with the ILS glide-slope transmitter. This system was evaluated in a Boeing 727-200 aircraft. The second system is an area navigation (RNAV) system modified to include the two-segment approach. This system is more sophisticated than the first system and does not restrict usage to any specific navigation ground aid. The modified RNAV system is a Collins ANS-70A and is currently being evaluated in a DC-8-61 aircraft.
Wehrend, W. R.↗
Engineering flight and guest pilot evaluation report, phase 2
Prior to the flight evaluation, the two-segment profile capabilities of the DC-8-61 were evaluated and flight procedures were developed in a flight simulator at the UA Flight Training Center in Denver, Colorado. The flight evaluation reported was conducted to determine the validity of the simulation results, further develop the procedures and use of the area navigation system in the terminal area, certify the system for line operation, and obtain evaluations of the system and procedures by a number of pilots from the industry. The full area navigation capabilities of the special equipment installed were developed to provide terminal area guidance for two-segment approaches. The objectives of this evaluation were: (1) perform an engineering flight evaluation sufficient to certify the two-segment system for the six-month in-service evaluation; (2) evaluate the suitability of a modified RNAV system for flying two-segment approaches; and (3) provide evaluation of the two-segment approach by management and line pilots.
Morrison, J. A.↗
Comparison of two head-up displays in simulated standard and noise abatement night visual approaches
Situation and command head-up displays were evaluated for both standard and two segment noise abatement night visual approaches in a fixed base simulation of a DC-8 transport aircraft. The situation display provided glide slope and pitch attitude information. The command display provided glide slope information and flight path commands to capture a 3 deg glide slope. Landing approaches were flown in both zero wind and wind shear conditions. For both standard and noise abatement approaches, the situation display provided greater glidepath accuracy in the initial phase of the landing approaches, whereas the command display was more effective in the final approach phase. Glidepath accuracy was greater for the standard approaches than for the noise abatement approaches in all phases of the landing approach. Most of the pilots preferred the command display and the standard approach. Substantial agreement was found between each pilot's judgment of his performance and his actual performance.
Cronn, F.↗
Jet transport noise - A comparison of predicted and measured noise for ILS and two-segment approaches
Centerline noise measured during standard ILS and two-segment approaches in DC-8-61 aircraft were compared with noise predicted for these procedures using an existing noise prediction technique. Measured data is considered to be in good agreement with predicted data. Ninety EPNdB sideline locations were calculated from flight data obtained during two-segment approaches and were compared with predicted 90 EPNdB contours that were computed using three different models for excess ground attenuation and a contour with no correction for ground attenuation. The contour not corrected for ground attenuation was in better agreement with the measured data.
White, K. C.↗
Status report on NASA two-segment approach program
NASA, in cooperation with the FAA, is evaluating the two-segment approach as a routine procedure for reducing aircraft noise. The program calls for separate flight evaluations using a 727 and a DC-8, and an extrapolation of these results to determine the adaptability of the technique to the rest of the fleet. After a review of the total program, this paper presents (1) the profile and procedures developed and the noise reduction achievable, (2) the vortex characteristics behind an aircraft on a two-segment path, and (3) cost estimates for retrofitting aircraft with two-segment avionics.
Denery, D. G.↗
Wind modeling and lateral control for automatic landing
For the purposes of aircraft control system design and analysis, the wind can be characterized by a mean component which varies with height and by turbulent components which are described by the von Karman correlation model. The aircraft aero-dynamic forces and moments depend linearly on uniform and gradient gust components obtained by averaging over the aircraft's length and span. The correlations of the averaged components are then approximated by the outputs of linear shaping filters forced by white noise. The resulting model of the crosswind shear and turbulence effects is used in the design of a lateral control system for the automatic landing of a DC-8 aircraft.
Holley, W. E.↗