Search NASA⌕ Search

SEARCH · Search NASA

Results for “Flight test measurement”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Sideslip-induced static pressure errors in flight-test measurements

During lateral flight-test maneuvers of a V/STOL research aircraft, large errors in static pressure were observed. An investigation of the data showed a strong correlation of the pressure record with variations in sideslip angle. The sensors for both measurements were located on a standard air-data nose boom. An algorithm based on potential flow over a cylinder that was developed to correct the pressure record for sideslip-induced errors is described. In order to properly apply the correction algorithm, it was necessary to estimate and correct the lag error in the pressure system. The method developed for estimating pressure lag is based on the coupling of sideslip activity into the static ports and can be used as a standard flight-test procedure. The estimation procedure is discussed and the corrected static-pressure record for a typical lateral maneuver is presented. It is shown that application of the correction algorithm effectively attenuates sideslip-induced errors.

Parks, Edwin K.↗
NASA NTRS1990

Sideslip-induced static pressure errors in flight-test measurements

During lateral flight-test maneuvers of a V/STOL research aircraft, large errors in static pressure were observed. An investigation of the data showed a strong correlation of the pressure record with variations in sideslip angle. The sensors for both measurements were located on a standard air-data nose boom. This paper descries an algorithm based on potential flow over a cylinder that was developed to correct the pressure record for sideslip-induced errors. In order to properly apply the correction algorithm, it was necessary to estimate and correct the lag error in the pressure system. The method developed for estimating pressure lag is based on the coupling of sideslip activity into the static ports and can be used as a standard flight-test procedure. The paper discusses the estimation procedure and presents the corrected static-pressure record for a typical lateral maneuver. It is shown that application of the correction algorithm effectifvely attenuates sideslip-induced errors.

Parks, Edwin K.↗
NASA NTRS2000

Flight Test Measurements From The Tu-144LL Structure/Cabin Noise Follow-On Experiment

This follow-on flight experiment on the TU-144LL Supersonic Flying Laboratory, conducted during the period September 1998 to April 1999, was a continuation of previous Structure/Cabin Noise Experiment 2.1. Data was obtained over a wide range of altitudes and Mach numbers. Measured were: turbulent boundary layer pressure fluctuations on the fuselage over its length; structural response on skin panels using accelerometers; and flow direction over three windows using 'flow cones'. The effect of steps in the flow was also measured using two window blank pairs; each pair bridged by a plate which created small sharp forward and aft facing steps. The effect of transducer flushness with the exterior surface was also measured during flight. Height test points were chosen to cover much of the TU-144's flight envelope, as well as to obtain as large a unit Reynolds number range as possible at various Mach numbers: takeoff, subsonic, transonic, and supersonic cruise conditions up to Mach 2. Data on engine runups and background noise were acquired on the ground. The data in the form of time histories of the acoustic signals, together with auxiliary data and basic MATLAB processing modules, are available on CD-R disks.

Rizzi, Stephen A.↗
NASA NTRSDate not supplied

Propeller Source Noise Separation from Flight Test Measurements of the Joby Aviation Aircraft

The Vold-Kalman order-tracking filter is applied to full-scale acoustic flight test measurements of the Joby Aviation eVTOL aircraft. Using synchronized acquisition of the aircraft position, time-varying rotation rates of each propeller, and any given single-channel acoustic signal, harmonic and nonharmonic acoustic content can be separated. Furthermore, this time-domain technique can also separate harmonic content amongst individual propellers, providing additional physical insight into the total acoustic field. A 60 kt level flyover and hover are used to exemplify the effectiveness of the method. Results clearly demonstrate the ability to rank propulsors in terms of their relative importance without the use of phased arrays. Frequency- and order-domain results are provided, as well as noise hemispheres to illustrate directivity and individual propeller contributions. Differences can be associated with interactional or installation effects due to the similarities in propeller states for each condition. Simulated signals that track the measured time-varying shaft rates were used to assess the proper filter pole count and bandwidth.

evtol↗
NASA NTRS1973

Flight test measurements and analysis of sonic boom phenomena near the shock wave extremity

The sonic boom flight test program conducted at Jackass Flats, Nevada, during the summer and fall of 1970 consisted of 121 sonic-boom-generating flights over the 1500 ft instrumented BREN tower. This test program was designed to provide information on several aspects of sonic boom, including caustics produced by longitudinal accelerations, caustics produced by steady flight near the threshold Mach number, sonic boom characteristics near lateral cutoff, and the vertical extent of shock waves attached to near-sonic airplanes. The measured test data, except for the near-sonic flight data, were analyzed in detail to determine sonic boom characteristics for these flight conditions and to determine the accuracy and the range of validity of linear sonic boom theory. The caustic phenomena observed during the threshold Mach number flights and during the transonic acceleration flights are documented and analyzed in detail. The theory of geometric acoustics is shown to be capable of predicting shock wave-ground intersections, and current methods for calculating sonic boom pressure signature away from caustics are shown to be reasonably accurate.

Haglund, G. T.↗
NASA NTRS1976

Flight-test measurement of the noise reduction of a jet transport delayed flap approach procedure

A delayed flap approach procedure was flight tested using the NASA CV-990 airplane to measure and analyze the noise produced beneath the flight path. Three other types of landing approaches were also flight tested to provide a comparison of the noise reduction benefits to the delayed flap approach. The conventional type of approach was used as a baseline to compare the effectiveness of the other approaches. The decelerating approach is a variation of the delayed flap approach. A detailed comparison of the ground perceived noise generated during the approaches is presented. For this comparison, the measured noise data were normalized to compensate for variations in aircraft weight and winds that occurred during the flight tests. The data show that the reduced flap approach offers some noise reduction, while the delayed flap and decelerating approaches offer significant noise reductions over the conventional approach.

Foster, J. D.↗
NASA NTRS2024

UAM Source Noise Hemisphere Flight Test Measurement Protocol

The overall goal of the NASA Urban Air Mobility Noise Working Group (UNWG) Ground and Flight Test Subgroup (SG2) is to develop a research measurement protocol, or set of guidelines, which can be used to adequately quantify the Urban Air Mobility (UAM) community noise impact via the creation of acoustic profiles that describe the vehicle source emission characteristics. This document lays out a measurement protocol for acquiring data suitable for the development of compact noise hemispheres that characterize the source acoustic emissions from full-scale UAM or Advanced Air Mobility (AAM) vehicles in outdoor flight. It also provides a narrative describing the numerous aspects of outdoor flight test design and execution that will hopefully prove useful to flight test engineers and practitioners.

Acoustics↗
NASA NTRS1974

Flight test measurements and analysis of sonic boom phenomena near the shock wave extremity

A NASA flight test program conducted during the summer and fall of 1970 was devoted to investigating sonic boom phenomena near caustics formed by steady flight near the threshold Mach number, during accelerations, and at the lateral extremes of the ground carpet. The vertical extent of the shock waves attached to near-sonic airplanes was also studied. The flights were conducted over the 1500 ft instrumented BREN tower so that vertical surveys through the shock waves were measured. These data on caustic phenomena near the shock wave extremity were analyzed in detail and compared with theoretical results. Amplifications of shock wave strength varied from 2 to 5 during longitudinal accelerations, from 1 to 1.8 during steady threshold Mach number flight, and up to 3 for small inadvertent accelerations during flight near the threshold Mach number.

Haglund, G. T.↗
NASA NTRS2011

Navigation Doppler Lidar Sensor for Precision Altitude and Vector Velocity Measurements Flight Test Results

An all fiber Navigation Doppler Lidar (NDL) system is under development at NASA Langley Research Center (LaRC) for precision descent and landing applications on planetary bodies. The sensor produces high resolution line of sight range, altitude above ground, ground relative attitude, and high precision velocity vector measurements. Previous helicopter flight test results demonstrated the NDL measurement concepts, including measurement precision, accuracies, and operational range. This paper discusses the results obtained from a recent campaign to test the improved sensor hardware, and various signal processing algorithms applicable to real-time processing. The NDL was mounted in an instrumentation pod aboard an Erickson Air-Crane helicopter and flown over vegetation free terrain. The sensor was one of several sensors tested in this field test by NASA?s Autonomous Landing and Hazard Avoidance Technology (ALHAT) project.

Pierrottet, Diego F.↗
NASA NTRS1977

Flight-test measurements of ground effect - STOL airplanes

Powered-lift STOL aircraft exhibit special aerodynamic characteristics that necessitate changes in established procedures of flight testing. Methods used in ground-effect flight testing of STOL-configured aircraft are described, with special emphasis on results obtained from tests of the YC-15 AMST prototype aircraft. Ground effect on lift and on drag is theoretically analyzed in terms of trailing vortices, bound vortex, and flight-path angle. Airspeed static source position errors are induced by ground constraint and must be considered in the data reduction. Flight-test results show a positive lift increment due to ground proximity.

Parks, E. K.↗
NASA NTRS2000

Flight Test Measurements From The Tu- 144LL Structure/Cabin Noise Experiment

During the period September 1997 to February 1998, the Tupolev 144 Supersonic Flyine Laboratory was used to obtain data for the purpose of enlarging the data base used by models for the prediction of cabin noise in supersonic passenger airplanes. Measured were: turbulent boundary layer pressure fluctuations on the fuselage in seven instrumented window blanks distributed over the length of the fuselage; structural response with accelerometers on skin panels close to those window blanks-, interior noise with microphones at the same fuselage bay stations as those window blanks. Flight test points were chosen to cover much of the TU- 144's flight envelope, as well as to obtain as large a unit Reynolds number range as possible at various Mach numbers: takeoff, landing, six subsonic cruise conditions, and eleven supersonic conditions up to Mach 2. Engine runups and reverberation times were measured with a stationary aircraft. The data in the form of time histories of the acoustic signals, together with auxiliary data and basic MATLAB processing modules, are available on CD-R disks.

Rizzi, Stephen A.↗
NASA NTRS1959

An Analysis of Flight-Test Measurements of the Wing Structural Deformations in Rough Air of a Large Flexible Swept-Wing Airplane

An analysis is made of wing deflection and streamwise twist measurements in rough-air flight of a large flexible swept-wing bomber. Random-process techniques are employed in analyzing the data in order to describe the magnitude and characteristics of the wing deflection and twist responses to rough air. Power spectra and frequency-response functions for the wing deflection and twist responses at several spanwise stations are presented. The frequency-response functions describe direct and absolute response characteristics to turbulence and provide a convenient basis for assessing analytic calculation techniques. The wing deformations in rough air are compared with the expected deformations for quasi-static loadings of the same magnitude, and the amplifications are determined. The results obtained indicate that generally the deflections are amplified by a small amount, while the streamwise twists are amplified by factors of the order of 2.0. The magnitudes of both the deflection velocities and the twist angles are shown to have significant effects on the local angles of attack at the various stations and provide the main source of aerodynamic loading, particularly at frequencies in the vicinity of the first wing-vibration mode.

Murrow, Harold N.↗
NASA NTRS1980

Analysis of flight test measurements in ground effect

Three sources of errors, introduced into the air-data measurements of altitude and airspeed as a result of ground proximity, are evaluated. It is shown that the primary error results from ground constraint of the wing lifting pattern. Smaller errors result from constraint of the flow over the fuselage and of the engine exhaust. Equations are derived to provide corrections for the three error contributions. The equations are general and can be applied to airplanes of different geometries operating in different conditions. Applications illustrating different types of flight operations (takeoff and landing) are presented using CV-990 data. Applications illustrating the effect of different static orifice locations (fuselage and nose-boom) are presented with YC-15 data. Finally, an application to trajectory reconstruction is illustrated using DC-10 data.

Parks, E. K.↗
NASA NTRS2005

Optical Air Flow Measurements for Flight Tests and Flight Testing Optical Air Flow Meters

Optical air flow measurements can support the testing of aircraft and can be instrumental to in-flight investigations of the atmosphere or atmospheric phenomena. Furthermore, optical air flow meters potentially contribute as avionics systems to flight safety and as air data systems. The qualification of these instruments for the flight environment is where we encounter the systems in flight testing. An overview is presented of different optical air flow measurement techniques applied in flight and what can be achieved with the techniques for flight test purposes is reviewed. All in-flight optical airflow velocity measurements use light scattering. Light is scattered on both air molecules and aerosols entrained in the air. Basic principles of making optical measurements in flight, some basic optical concepts, electronic concepts, optoelectronic interfaces, and some atmospheric processes associated with natural aerosols are reviewed. Safety aspects in applying the technique are shortly addressed. The different applications of the technique are listed and some typical examples are presented. Recently NASA acquired new data on mountain rotors, mountain induced turbulence, with the ACLAIM system. Rotor position was identified using the lidar system and the potentially hazardous air flow profile was monitored by the ACLAIM system.

Jentink, Henk W.↗
NASA NTRS2000

Airborne Coherent Lidar for Advanced In-Flight Measurements (ACLAIM) Flight Testing of the Lidar Sensor

The purpose of the ACLAIM program is ultimately to establish the viability of light detection and ranging (lidar) as a forward-looking sensor for turbulence. The goals of this flight test are to: 1) demonstrate that the ACLAIM lidar system operates reliably in a flight test environment, 2) measure the performance of the lidar as a function of the aerosol backscatter coefficient (beta), 3) use the lidar system to measure atmospheric turbulence and compare these measurements to onboard gust measurements, and 4) make measurements of the aerosol backscatter coefficient, its probability distribution and spatial distribution. The scope of this paper is to briefly describe the ACLAIM system and present examples of ACLAIM operation in flight, including comparisons with independent measurements of wind gusts, gust-induced normal acceleration, and the derived eddy dissipation rate.

Soreide, David C.↗