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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

The handling qualities and flight characteristics of the Grumman design 698 simulated twin-engine tilt Nacelle V/STOL aircraft

This paper describes three government-conducted, piloted flight simulations of the Grumman Design 698 vertical and short takeoff and landing (V/STOL) aircraft. Emphasis is placed on the aircraft's handling qualities as rated by various NASA, Navy, and Grumman Aerospace Corporating pilots with flight experience ranging from conventional takeoff and landing (CTOL) to V/STOL aircraft. Each successive simulation incorporated modifications to the aircraft in order to resolve the flight problems which were of most concern to the pilots in the previous simulation. The objective of the first simulation was to assess the basic handling qualities of the aircraft with the noncross-shafted propulsion system. The objective of the second simulation was to examine the effects of incorporating the cross-shafted propulsion system. The objective of the third simulation was to examine inoperative single-engine characteristics with and without cross-shafted engines.

Eskey, M. A.↗
NASA NTRS1987

Effect of variable inlet guide vanes on the operating characteristics of a tilt nacelle inlet/powered fan model

The effects of a variable inlet guide vane (VIGV) assembly on the operating characteristics of a V/STOL inlet and on the performance of a 20-in. (0.508-m) diameter fan engine were investigated. The data indicate that the VIGVs are effective thrust modulators over a wide range of free-stream velocities, nacelle angles of attack, and fan speeds. The thrust modulation ranges, including choking limits, fan stall limits, and inlet separation boundaries are presented. The presence of the VIGV assembly causes significant losses in inlet angle-of-attack capability and generally increases the blade stress levels at all limit conditions except at high angle of attack and high free-stream velocity. Reducing the fan nozzle exit area limited the positive VIGV actuation range and consequently decreased the range of thrust modulation at all limit conditions except at both high free-stream velocity and high angle of attack conditions.

Woollett, R. R.↗
NASA NTRS1986

M.I.T./Canadian vestibular experiments on the Spacelab-1 mission. II - Visual vestibular tilt interaction in weightlessness

Adaptation to weightlessness includes the substitution of other sensory signals for the no longer appropriate graviceptor information concerning static spatial orientation. Visual-vestibular interaction producing roll circularvection was studied in weightlessness to assess the influence of otolith cues on spatial orientation. Preliminary results from four subjects tested on Spacelab-1 indicate that visual orientation effects were stronger in weightlessness than pre-flight. The rod and frame test of visual field dependence showed a weak post-flight increase in visual influence. Localized tactile cues applied to the feet in space reduced subjective vection strength.

Young, L. R.↗
NASA NTRS1987

Anisotropic interface kinetics and tilted cells in unidirectional solidification

A nonlinear evolution equation is derived which governs the cellular structure of a binary alloy with a small segregation coefficient, including the effects of anisotropic interface kinetics. This equation, applicable to long-wave instabilities of a planar interface, describes the spatial pattern of the growing disturbances. The presence of anisotropy causes the cells to grow at an angle to the normal of the planar front. This transition to a cellular morphology is shown to be a subcritical instability.

Young, G. W.↗
NASA NTRS1988

Tilted-ring models of the prolate spiral galaxies NGC 5033 and 5055

Observations of the kinematics of H I in the disks of spiral galaxies have shown that isovelocity contours often exhibit a twisted pattern. The shape of a galaxy's gravitational potential well (whether due to luminous matter or dark matter) can be determined from the direction of the twist. If this twist is a manifestation of the precession of a nonsteady-state disk, it is shown that the twists of NGC 5033 and 5055 imply an overall prolate shape, with the major axis of the potential well aligned along the rotation axis of the disk. Therefore, the luminous disks of these galaxies must be embedded in dark halos that are prolate spheroids or prolatelike triaxial figures.

Christodoulou, Dimitris M.↗
NASA NTRS1988

Dynamic perspective displays and the control of tilt-rotor aircraft in simulated flight

Two simulations were conducted to study the effect of dynamic perspective displays on performance measures collected during simulated flight. The first study was a pure altitude regulation task with simple first order plant dynamics. In the second simulation, pilots performed two basic rotary-wing flight tasks with dynamic perspective displays projected out-the-window (panoramic head up display) or on a panel mounted simulation of a sensor display. The data from the two studies, taken together, show that when such displays are used during flight, they will not degrade performance; and, under certain display configurations, they will minimize flight control errors.

Bennett, C. T.↗
NASA NTRS1989

Preliminary design of four aircraft to service the California Corridor in the year 2010: The California Condor, California Sky-Hopper, high capacity short range transport tilt rotor aircraft needed to simplify intercity transportation

The major objective of this project was to design an aircraft for use in the California Corridor in the year 2010. The design process, completed by students in a senior design class at California Polytechnic State University, San Luis Obispo, used a Class 1 airplane design analysis from Jan Roskam's Airplane Design. The California Condor (CC-38), a 38 passenger, 400 mph aircraft, was designed to meet the needs of tomorrow's passengers while conforming to the California Corridor's restrictions. Assumptions were made using today's technology with forecasts into 21st Century technology. Doubling today's commuter aircraft passenger capacity, travelling at Mach .57 with improved cruise efficiencies of over 10 percent, with the ability to land within field lengths of 4000 feet, are the CC-38's strongest points. The California Condor has a very promising future in helping to relieve the air traffic and airport congestion in the 21st Century.

Source record↗
NASA NTRS1990

Parallel flows with Soret effect in tilted cylinders

Henry and Roux (1986, 1987, 1988) have conducted extensive numerical studies on the interaction of Soret separation with convection in cylindrical geometry. Many of their solutions exhibit parallel flow away from end walls. Their parallel flow results can be matched by closed-form solutions. Solutions are nonunique in some parameter regions. Disappearance of one branch of solutions correlates with a sudden transition of Henry and Roux's results from a separated to a well-mixed flow.

Jacqmin, David↗
NASA NTRS1991

Optical design of the Moderate Resolution Imaging Spectrometer - Tilt (MODIS-T) for the Earth Observing System (Eos)

The Moderate Resolution Imaging Spectrometer (MODIS) is an Earth viewing sensor that is planned as a facility instrument for the Earth Observing System (Eos) scheduled to begin functioning in the late 1990's. The MODIS is composed of two mutually supporting sensors one of which is MODIS-T, where 'T' signifies a tiltable along-track field of view. MODIS-T is a 32 channel imaging spectrometer with a required 10 nm to 15 nm spectral resolution (FWHM) in the 400 nm to 880 nm spectral range with less than 2.3 percent instrument induced linear polarization. The instrument provides at nadir a 33 km by 1500 km swath with a 1.1 km spatial resolution and an along-track pointing capability of +/- 50 deg about nadir. The heart of the optical design consists of a f/3 grating-type reflecting Schmidt camera.

Maymon, Peter W.↗
NASA NTRS1991

Development of a large pixel, spectrally optimized, pinned photodiode/interline charge coupled device (CCD) detector for the Earth Observing System (EOS)/Moderate-Resolution Imaging Spectrometer-Tilt (MODIS-T) instrument

A pinned photodiode/interline CCD Detector Array is under development for the EOS/MODIS-T project. Outstanding features of the device include large pixels, spectrally optimized fill factors, and blooming protection. The detector has 30 spatial rows and 32 spectral columns. The device layout is split into two halves; each half has its own detector area, storage area, and output structure.

Ewin, Audrey J.↗
NASA NTRS1992

Design and analysis of a depolarizer for the NASA moderate resolution imaging spectrometer-tilt (MODIS-T)

The design and analysis of a depolarizer for the NASA MODIS-T spectrometer is presented. The theory of spatial pseudodepolarizer operation and its effect on linear polarization sensitivity is described. Details of the HV depolarizer design and issues of depolarizer location and material are discussed. The image doubling and aberrations induced by the depolarizer and the trade-offs between increased polarization performance and decreased image quality are also addressed. The issues considered apply directly to depolarizer design for other remote sensing instruments.

Mcclain, Stephen C.↗
NASA NTRS1956

Transition-flight Tests of a Model of a Low-wing Transport Vertical-take-off Airplane with Tilting Wing and Propellers

An investigation of the stability and control of a low-wing four-engine transport vertical-take-off airplane during the transition from hovering to normal forward flight has been conducted with a remotely controlled free-flight model. The model had four propellers distributed along the wing with the thrust axes in the wing-chord plane. The wing could be rotated to 90 degrees incidence so that the propeller thrust axes were vertical for hovering flight.

CONTROL, LONGITUDINAL↗
NASA NTRS1957

Flight Tests of a Model of a High-wing Transport Vertical-take-off Airplane with Tilting Wing and Propellers and with Jet Controls at the Rear of the Fuselage for Pitch and Yaw Control

An investigation of the stability and control of a high-wing transport vertical-take-off airplane with four engines during constant-altitude transitions from hovering to normal forward flight was conducted with a remotely controlled free-flight model. The model had four propellers distributed along the wing with the thrust axes in the wing chord plane. The wing could be rotated to 90 degrees incidence so that the propeller thrust axes were vertical for hovering flight. An air jet at the rear of the fuselage provided pitch and yaw control for hovering and low-speed flight.

CONTROL, LONGITUDINAL↗