Aerodynamic Properties of Spherical Balloon Wind Sensors

Fichtl, G. H.; DeMandel, R.E.; Krivo, S. J.

doi:10.1175/1520-0450(1972)011<0472:aposbw>2.0.co;2

Cited by 7 publications

(5 citation statements)

References 3 publications

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“…The drag coefficient (Cd) is that of a homogeneous sphere whose movement is not impeded unlike the situation when wind tunnel experiments are used to measure the parameter. In our case, the balloon or sphere can experience significant horizontal movements due to the aerodynamic forces at play as it rises (Fichtl et al, 1972). These movements remove energy from the vertical motion which explains why the Cd for free ascent pilot balloons are higher than those calculated in wind tunnels for the same Reynolds number value (Scoggins et al, 1964).…”

Section: Drag Coefficient CD How It Varies As a Function Of Altitude And Its Impact On The Evolution Of The Ascent Ratementioning

confidence: 72%

Thermodynamic model for a pilot balloon

Favà

Curto

Gilabert

2021

Preprint

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Abstract. In the early part of the 20th century, tracking a pilot balloon from the ground with an optical theodolite was one of the few methods that was able to provide information from the upper air. One of the most significant sources of error with this method, however, was involved in calculating the balloon height as a function of time, a calculation dependent on the ascent rate which was traditionally taken to be constant. This study presents a new thermodynamic model which allows us to compute the thermal jump between the surrounding environment and the lifting gas as a function of different parameters such as the atmospheric temperature lapse rate or the physical characteristics of the balloon. The size of the thermal jump and its effect on the ascent rate is discussed for a 30 g pilot balloon, which was the type used at the Ebro Observatory (EO) between 1952 and 1963. The meridional and zonal components of the wind profile from ground level up to 10 km altitude were computed by applying the model using EO digitized data for a sample of this period. The obtained results correlate very well with those obtained from the ERA5 reanalysis. A very small thermal jump with a weak effect on the computed ascent rate was found. This ascent rate is consistent with the values assigned in that period to the balloons filled with hydrogen used at the Ebro Observatory and to the 30 g balloons filled with helium used by the US National Weather Service.

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Section: Drag Coefficient CD How It Varies As a Function Of Altitude And Its Impact On The Evolution Of The Ascent Ratementioning

confidence: 72%

Thermodynamic model for a pilot balloon

Favà

Curto

Gilabert

2021

Preprint

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“…By contrast, modeled and experimental results for supercritical fiow (e.g., for weather balloons) show that the lift forces are cumulative over many periods (Fichtl et al 1972). Given this description of the lift force f¿, we may approximate lift perturbations along a single horizontal axis for a rising sphere as a sinusoidal acceleration of the effective balloon mass at a dominant frequency.…”

Section: Analysis Of Balloon Advection Fidelitymentioning

confidence: 88%

“…As described by Fichtl et al (1972), secondorder vector perturbations neglected in the formulation of Eq. (A2) give rise to unsteady lift forces acting normal to the drift velocity V. Similar but smaller drag perturbations act in the vertical direction.…”

Section: Analysis Of Balloon Advection Fidelitymentioning

confidence: 95%

Wind Field Characterization from the Trajectories of Small Balloons

Wilkerson

Marchant

Apedaile

2012

Journal of Atmospheric and Oceanic Technology

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This paper reports the development and application of a new wind sensing system, ValidWind. ValidWind consists of small, helium-filled tracer balloons and an instrument that tracks them with high spatial resolution by means of an eye-safe lidar rangefinder and records 3D balloon position as a function of time. Lightweight retroreflectors attached to the balloons enhance the optical range. Balloon tracking is automatic. The data products include horizontal wind speed, wind direction, and vertical shear as functions of time and geolocation. Vertical wind speeds can be inferred from variations of the balloons' rate of rise given the balance between buoyancy and aerodynamic drag. Applications of ValidWind include characterization of katabatic and ridge-top wind fields and monitoring of windborne aerosol transport. The capability of ValidWind balloons to provide useful profiles of the wind from the ground up to an altitude of 2 km AGL is presented and analyzed.

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“…Elle culmine vers 19 kilomètres sous l'équateur. Les mouvements propres de la Jimsphere consistent principalement en un mouvement ondulatoire régulier, à haute fréquence -typiquement 0,15 Hz, soit une quarantaine de mètres de longueur d'onde verticale -et d'amplitude généralement inférieure à 1 m/s (Armendariz et Rachele, 1967 ;Fichtl et al, 1972), ce qui fait d'elle un traceur remarquable des mouvements de l'air.…”

Section: Illustration Visuelle Des Mouvements Propres Des Ballonsunclassified

La détermination du profil du vent pour les activités spatiales - Quelques approches expérimentales et théoriques

Jacquemin¹,

Voiron²

2001

Météorologie

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Les vents rencontrés par un lanceur spatial durant la phase atmosphérique de son vol constituent une contrainte très importante, tout spécialement les cisaillements de vent sur des épaisseurs proches des dimensions caractéris-tiques du lanceur (typiquement la centaine de mètres). La mesure du profil du vent par ballon ascensionnel est analysée : nous situons les principaux facteurs limitant la précision et la résolution de la mesure et présentons deux types de ballons, la Jimsphere et la Méduse. La structure verticale des profils de vent provient notamment de la superposition de mouvements ondulatoires. Elle est couramment analysée par la méthode spectrale ; nous montrons les caractéristiques du « spectre universel » atmosphérique, puis les propriétés spectrales des profils de vent et de température mesurés en Guyane durant la campagne expérimentale VEHRT en 1996-1997. Nous présentons ensuite la nouvelle méthode de caractérisation statistique des cisaillements verticaux de vent sur des épaisseurs de l'ordre de la centaine de mètres, méthode développée par le Centre national d'études spatiales et s'appuyant sur les résultats de la campagne. Divers travaux complémen-taires, en cours ou prévus, sont enfin brièvement présentés. Determining the wind profile for space activities; some experimental and theoretical approachesThe winds to be encountered are a major constraint on the launch of a space vehicle, especially shear over lengths roughly corresponding to the size of the launcher -about one hundred metres. The main factors which limit the accuracy and resolution of pilot balloon measurements are outlined, then we describe two specific balloons, the Jimsphere and the Meduse (Jellyfish). Vertical wind structure is largely due to gravity waves and is conveniently described in spectral terms. We show the characteristics of the "universal" saturated wave spectrum and then the profiles of wind and temperature measured during the VEHRT campaign, held at Kourou, Guyana, in 1996-1997. We then present a new statistical characterization of vertical wind shears for thin layers, developed by CNES, and based on the results of the campaign. Finally we outline various related studies presently in progress or planned at CNES. Résumé AbstractLa détermination du profil du vent pour les activités spatiales Quelques approches expérimentales et théoriques Bruno Jacquemin(1) et Thierry Voiron

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Aerodynamic Properties of Spherical Balloon Wind Sensors

Cited by 7 publications

References 3 publications

Thermodynamic model for a pilot balloon

Thermodynamic model for a pilot balloon

Wind Field Characterization from the Trajectories of Small Balloons

La détermination du profil du vent pour les activités spatiales - Quelques approches expérimentales et théoriques

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