A Universal Procedure for Deploying Constant-Volume Balloons and for Deriving Vertical Air Speeds from Them

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  • 1 Air Resources Laboratories, NOAA, Silver Spring, Md., 20910
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Abstract

A graphical method for flying any type constant-volume balloon at specified heights up to 500 m above mean terrain is described. The flight parameters, surface free-lift, and surface superpressure are determined from graphs whose only argument is the air temperature difference between balloon flight level and inflation shelter. Another graph corrects the flight parameters for any balloon other than the 150 cm tetroon by using the balloon's volume and volume ratio. Flight-level error is about 30 m per degree Celsius of flight-level temperature error in a normal lapse rate. The balloon will fly too low if the air temperature is warmer than estimated.

Instructions for constructing flight-parameter graphs for any particular constant-volume balloon are included along with an outline of the inflation theory. The mechanical details of correctly ballasting constant-volume balloons are given. Air ballast is used inside the balloon, thereby virtually eliminating impact dangers.

Vertical air speeds are estimated directly from a graph whose arguments are observed tetroon (150 cm) vertical speed and the tetroon's vertical distance from its equilibrium level. A correction graph allows the use of any other constant-volume balloon whose frontal area to volume ratio and drag coefficient are known.

Because of the tetroon's large drag coefficient (0.74), the tetroon's vertical speed itself may be used as first-order estimates of vertical air speed.

Abstract

A graphical method for flying any type constant-volume balloon at specified heights up to 500 m above mean terrain is described. The flight parameters, surface free-lift, and surface superpressure are determined from graphs whose only argument is the air temperature difference between balloon flight level and inflation shelter. Another graph corrects the flight parameters for any balloon other than the 150 cm tetroon by using the balloon's volume and volume ratio. Flight-level error is about 30 m per degree Celsius of flight-level temperature error in a normal lapse rate. The balloon will fly too low if the air temperature is warmer than estimated.

Instructions for constructing flight-parameter graphs for any particular constant-volume balloon are included along with an outline of the inflation theory. The mechanical details of correctly ballasting constant-volume balloons are given. Air ballast is used inside the balloon, thereby virtually eliminating impact dangers.

Vertical air speeds are estimated directly from a graph whose arguments are observed tetroon (150 cm) vertical speed and the tetroon's vertical distance from its equilibrium level. A correction graph allows the use of any other constant-volume balloon whose frontal area to volume ratio and drag coefficient are known.

Because of the tetroon's large drag coefficient (0.74), the tetroon's vertical speed itself may be used as first-order estimates of vertical air speed.

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