Superpressure balloon

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A super pressure balloon in flight NASA-NSF super pressure balloon.jpg
A super pressure balloon in flight
Flight profile of Super-Pressure Balloons versus Zero-Pressure Balloons Super v zero pressure balloon.jpg
Flight profile of Super-Pressure Balloons versus Zero-Pressure Balloons

A superpressure balloon (SPB) is a style of aerostatic balloon where the volume of the balloon is kept relatively constant in the face of changes in ambient pressure outside the balloon, and the temperature of the contained lifting gas. This allows the balloon to keep a stable altitude for long periods. This is in contrast with much more common variable-volume balloons, which are either only partially filled with lifting gas, or made with more elastic materials. Also referred to as pumpkin or Ultra Long Distance Balloons (ULDB) balloons, the sealed balloon envelopes have a pumpkin shape at flight altitude. [1]   In a variable-volume balloon, the volume of the lifting gas changes due to heating and cooling in the diurnal cycle. The cycle is magnified by a greenhouse effect inside the balloon, while the surrounding atmospheric gas is subject to a much more limited cyclical temperature change. As the lift gas heats and expands, the displacement of atmospheric gas increases, while the balloon weight remains constant. Its buoyancy increases, and this leads to a rise in altitude unless it is compensated by venting gas. Conversely, if the balloon cools and drops, it becomes necessary to release ballast. Since both ballast and gas are finite, there is a limit to how long a variable-volume balloon can compensate in order to stabilize its altitude. In contrast, a superpressure balloon will change altitude much less without compensation maneuvers. [2]

Contents

Since the volume of the balloon is more constrained, so is the volume of air displaced by it. In accordance with the Principle of Archimedes, the upwards force on the balloon is equal to the weight of the displaced ambient gas. But the weight of the atmospheric gas is reduced as the balloon rises, because its density diminishes with increasing altitude. [3] So the force pushing the balloon upwards diminishes with altitude and at some particular altitude, the upwards force will equal the weight of the balloon. As a result, the balloon will be stable in a finite equilibrium altitude range for long periods.

The disadvantage is that such balloons require much stronger materials than non-pressurized types.

Applications

Superpressure balloons (SPB) are typically used for extremely long duration flights of unmanned scientific experiments in the upper atmosphere, [2] where atmospheric gas temperature is quite stable through the diurnal cycle. [4] In 1985, such balloons were used for aerobots flying at an altitude of approximately 50 kilometres (160,000 ft) in the atmosphere of Venus, in the international, Soviet-led Vega program.

In February 1974, Colonel Thomas L. Gatch Jr, USAR attempted to make the first crossing of the Atlantic by balloon in a superpressure balloon named Light Heart . Following the loss of at least two of the ten balloons which provided lift, and after deviating substantially from the course that Colonel Gatch had plotted to take advantage of the jet stream, the last reported sighting of the Light Heart was 1,610 kilometres (1,000 mi) west of the Canary Islands; no further trace of the aircraft was ever found. [5]

NASA Super Pressure Balloon Wanaka Airport, New Zealand NASA Super Pressure Balloon Begins Globetrotting Journey (27072743125).jpg
NASA Super Pressure Balloon Wanaka Airport, New Zealand

In March 2015, NASA launched a SPB to an altitude of 110,000 feet (34,000 m) for 32 days from New Zealand and landed in Australia after a leak was detected. [6] This was the first time a SPB was flown for a long duration through the day and night cycle. When fully inflated, it was the size of a football stadium.

Google's Project Loon uses controllable altitude superpressure balloons to achieve flights of over 300 days. [7]

The SPB TRAVALB-2 surpassed previous Antarctic balloon flights by staying aloft for 149 Days, 3 hours, and 58 minutes after launch from the NASA Long Duration Balloon (LDB) site at LDB Camp, McMurdo Station, Antarctica. The operation was supported by  National Science Foundation and United States Antarctic Program.   [8] After the Travalb-1 launch abort, the Travalb-2 lifted off on 29 December 2019 to test NASA balloon trajectory predictions in Antarctica and to study electron loses from Earth's radiation belts. [9]

See also

Related Research Articles

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Aerobot

An aerobot is an aerial robot, usually used in the context of an unmanned space probe or unmanned aerial vehicle.

Weather balloon High-altitude balloon to which meteorological instruments are attached

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Radiosonde Meteorological instrumentation

A radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calculate the following variables: altitude, pressure, temperature, relative humidity, wind, cosmic ray readings at high altitude and geographical position (latitude/longitude). Radiosondes measuring ozone concentration are known as ozonesondes.

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Aerostat Lighter than air aircraft

An aerostat is a lighter than air aircraft that gains its lift through the use of a buoyant gas. Aerostats include unpowered balloons and powered airships. A balloon may be free-flying or tethered. The average density of the craft is lower than the density of atmospheric air, because its main component is one or more gasbags, a lightweight skin containing a lifting gas to provide buoyancy, to which other components such as a gondola containing equipment or people are attached. Especially with airships, the gasbags are often protected by an outer envelope.

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High-altitude balloon Balloon released into the stratosphere, most commonly weather balloons

High-altitude balloons are crewed or uncrewed balloons, usually filled with helium or hydrogen, that are released into the stratosphere, generally attaining between 18 and 37 km above sea level. In 2002, a balloon named BU60-1 reached a record altitude of 53.0 km.

Gas balloon

A gas balloon is a balloon that rises and floats in the air because it is filled with a gas lighter than air. When not in flight, it is tethered to prevent it from flying away and is sealed at the bottom to prevent the escape of gas. A gas balloon may also be called a Charlière for its inventor, the Frenchman Jacques Charles. Today, familiar gas balloons include large blimps and small latex party balloons. For nearly 200 years, well into the 20th century, manned balloon flight utilized gas balloons before hot-air balloons became dominant. Without power, heat or fuel, untethered flights of gas balloons depended on the skill of the pilot. Gas balloons have greater lift for a given volume, so they do not need to be so large, and they can stay up for much longer than hot air balloons.

Columbia Scientific Balloon Facility

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The Global horizontal sounding technique (GHOST) program was an atmospheric field research project in the late 1960s for investigating the technical ability to gather weather data using hundreds of simultaneous long-duration balloons for very long-range global scale numerical weather prediction in preparation for the Global Atmospheric Research Program (GARP).

A sky anchor is a system of two balloons in tandem, with a "zero-pressure" lifting gas balloon tethered to a superpressure balloon "anchor". The gas balloon is filled with a lifting gas and provides the buoyancy, while the superpressure balloon is filled with air, and pressurized to provide the desired ballast weight. In a passive sky anchor, the superpressure balloon is sealed, while in an active system, its pressure can be varied. Both versions have been tested in flight, but have had frequent failures with only occasional successful outcomes. The tandem arrangement makes launching difficult, and this complexity can lead to mission failure.

A lifting gas or lighter than air gas is a gas that has a lower density than normal atmospheric gases and rises above them as a result. It is required for aerostats to create buoyancy, particularly in lighter-than-air aircraft, which include free balloons, moored balloons, and airships. Only certain lighter than air gases are suitable as lifting gases. Dry air has a density of about 1.29 g/L at standard conditions for temperature and pressure (STP) and an average molecular mass of 28.97 g/mol, and so lighter than air gases have a density lower than this.

Light Heart was a balloon constructed by Colonel Thomas Leigh Gatch Jr., USAR for an unsuccessful attempt at the first crossing of the Atlantic Ocean by balloon.

The Two Eagles Balloon is a custom balloon designed to break world records. A January 2015 launch from Japan toward North America has officially broken two world records as validated by the Fédération Aéronautique Internationale.

GUSTO (telescope)

The GUSTO mission is a planned high-altitude balloon mission that will carry an infrared telescope to measure emissions from the interstellar medium. The mission is being developed by NASA's Explorers Program for launch in December 2021 from Antarctica.

References

  1. "Scientific Balloons". NASA.gov. NASA. Retrieved 14 July 2020.
  2. 1 2 "Successful Flight Of NASA Prototype Super-Pressure Balloon In Antarctica". space-travel.com. January 27, 2009.
  3. Shelquist, Richard (2010). "An Introduction to Air Density and Density Altitude Calculations". Shelquist Engineering.
  4. Seidel, Dian J.; Free, Melissa; Wang, Junhong (2005). "Diurnal cycle of upper-air temperature estimated from radiosondes" (PDF). Journal of Geophysical Research . American Geophysical Union. 110 (D9). doi:10.1029/2004JD005526.
  5. "Private flight: transatlantic balloon attempt". Flight International . IPC Transport Press Ltd. 105 (3390): 263. 1974. Retrieved 2011-06-30.
  6. Chirgwin, Richard (28 April 2015). "NASA 'UFO' pops a leak, lands in outback Australia: Super Pressure Balloon flight terminated, 32 days into planned 100-day flight". The Register .
  7. "Medium: "312 Days in the Stratosphere"". www.medium.com. Retrieved 2020-12-28.
  8. "NASA Long Duration Balloon (LDB) site at LDB Camp, McMurdo Station". csbf.nasa.gov. NASA. Retrieved 14 July 2020.
  9. "NASA campaign in Antarctica (IV)". stratocat.com. Stratocat.com. Retrieved 14 July 2020.