Analysis of an Air Motion System on a Light Aircraft for Boundary Layer Research

Wood, Roy C.; Stromberg, I. M.; Jonas, P. R.; Mill, C. S.

doi:10.1175/1520-0426(1997)014<0960:aoaams>2.0.co;2

Cited by 15 publications

(8 citation statements)

References 14 publications

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“…Here, we are concerned solely with a mean horizontal wind measurement observed during steady, level flight, which greatly relaxes some of the difficulties of the measurement (variations of angle of attack, pitch, etc.) We point out that there have been other airborne systems developed to also measure turbulence, but these systems required significant modifications to the basic airframe, such as the installation of booms (Crawford and Dobosy 1992) or wing pods (Wood et al 1997), or the installation of pressure ports on the aircraft nose (Brown et al 1983). While turbulence would be a desirable additional measurement, what we describe here is a system that requires no modification to the basic airframe and measures accurate mean horizontal winds.…”

Section: Introductionmentioning

confidence: 99%

A Low-Cost System for Measuring Horizontal Winds from Single-Engine Aircraft

Conley

Faloona

Lenschow

et al. 2014

Journal of Atmospheric and Oceanic Technology

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The implementation and accuracy of a low-rate (;1 Hz) horizontal wind measurement system is described for a fixed-wing aircraft without modification to the airframe. The system is based on a global positioning system (GPS) compass that provides aircraft heading and a ground-referenced velocity, which, when subtracted from the standard true airspeed, provides estimates of the horizontal wind velocity. A series of tests was performed flying ''L''-shaped patterns above the boundary layer, where the winds were assumed to be horizontally homogeneous over the area bounded by the flight (approximately 25 km 2 ). Four headings were flown at each altitude at a constant airspeed. Scaling corrections for both heading and airspeed were found by minimizing the variance in the 1-s wind measurements; an upper limit to the error was then computed by calculating the variance of the corrected wind measurements on each of the four headings. A typical uncertainty found in this manner tends to be less than 0.2 m s 21 . The measurement system described herein is inexpensive and relatively easy to implement on single-engine aircraft.

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Section: Introductionmentioning

confidence: 99%

A Low-Cost System for Measuring Horizontal Winds from Single-Engine Aircraft

Conley

Faloona

Lenschow

et al. 2014

Journal of Atmospheric and Oceanic Technology

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“…9. Wind speed and direction estimates obtained from other aircraft-based systems have given standard deviations of 0.5-1.0 m s 21 and 108 for AAVs (van den Kroonenberg et al 2008) and 2 m s 21 for light aircraft (Wood et al 1997). 9.…”

Section: Resultsmentioning

confidence: 99%

Estimating Wind Velocities in Mountain Lee Waves Using Sailplane Flight Data*

Millane

Stirling

Brown

et al. 2010

Journal of Atmospheric and Oceanic Technology

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Mountain lee waves are a form of atmospheric gravity wave that is generated by flow over mountain topography. Mountain lee waves are of considerable interest, because they can produce drag that affects the general circulation, windstorms, and clear-air turbulence that can be an aviation hazard, and they can affect ozone abundance through mixing and inducing polar stratospheric clouds. There are difficulties, however, in measuring the three-dimensional wind velocities in high-altitude mountain waves. Mountain waves are routinely used by sailplane pilots to gain altitude. Methods are described for estimating three-dimensional wind velocities in mountain waves using data collected during sailplane flights. The data used are the logged sailplane position and airspeed (sailplane speed relative to the local air mass). An algorithm is described to postprocess this data to estimate the three-dimensional wind velocity along the flight path, based on an assumption of a slowly varying horizontal wind velocity. The method can be applied to data from dedicated flights or potentially to existing flight records used as sensors of opportunity. The methods described are applied to data from a sailplane flight in lee waves of the Sierra Nevada in California. * This work is dedicated to Steve Fossett, a true adventurer.

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“…Although fixed and rotating vanes 16,17 have been used to measure airflow relative to the aircraft; it is now more common to use a differential pressure method [18][19][20] to avoid the vibration and frequency response problems of long airdata booms. Further refinement of the hemispherical pressure sensing head used to sense flow angles is described by Wyngaard 21 and Wood 22 . A more advanced instrument is the BAT Probe 23-25 which uses a nine hole pressure port formation in conjunction with differential GPS and fast-response accelerometers to give wind vector measurements at up to 50 Hz.…”

Section: A Backgroundmentioning

confidence: 99%

Using Indirect Turbulence Measurements for Real-Time Parameter Estimation in Turbulent Air

Martos

Morelli

2012

AIAA Atmospheric Flight Mechanics Conference

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The use of indirect turbulence measurements for real-time estimation of parameters in a linear longitudinal dynamics model in atmospheric turbulence was studied. It is shown that measuring the atmospheric turbulence makes it possible to treat the turbulence as a measured explanatory variable in the parameter estimation problem. Commercial off-theshelf sensors were researched and evaluated, then compared to air data booms. Sources of colored noise in the explanatory variables resulting from typical turbulence measurement techniques were identified and studied. A major source of colored noise in the explanatory variables was identified as frequency dependent upwash and time delay. The resulting upwash and time delay corrections were analyzed and compared to previous time shift dynamic modeling research. Simulation data as well as flight test data in atmospheric turbulence were used to verify the time delay behavior. Recommendations are given for follow on flight research and instrumentation.

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Analysis of an Air Motion System on a Light Aircraft for Boundary Layer Research

Cited by 15 publications

References 14 publications

A Low-Cost System for Measuring Horizontal Winds from Single-Engine Aircraft

A Low-Cost System for Measuring Horizontal Winds from Single-Engine Aircraft

Estimating Wind Velocities in Mountain Lee Waves Using Sailplane Flight Data*

Using Indirect Turbulence Measurements for Real-Time Parameter Estimation in Turbulent Air

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