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At least 19 records

Overpressurized zero pressure balloon system

Typical zero pressure scientific balloon systems experiencing diurnal cycles require on board expendable ballast to maintain design float altitude. In the past, pressurized balloon systems have been employed to overcome the need for ballast while maintaining small diurnal altitude excursions. However, requirements on material characteristics and manufacturing methods have enforced limitations on balloon size and therefore payload and altitude capabilities. This effort was aimed at considering the use of current (or slightly modified) zero pressure balloon systems (design, manufacturing and materials) as candidates for pressurized vehicles. Data gathered through performance analysis, structural analysis and flight testing has shown that the use of current zero pressure designs can be expanded to enhance balloon performance.

Simpson, Joel M.↗

Midstratospheric circulations in the southern hemisphere from super pressure balloon trajectories

Three instrumented super pressure balloons were flown throughout the southern hemisphere at 18 mbar, over a period of five months. The balloon trajectories, reconstructed from NIMBUS 6 satellite location data, have proved to be valuable indicators of midstratospheric structure and dynamics in the Lagrangian frame of reference. Several examples of high zonal and meridional winds are reported. Also shown in the analysis is a feature encountered between 30 S-40 S during a two-week period. The feature appears to be a breakdown of large-scale zonal flow and its replacement by weak cyclonic eddies. During the observational period the balloon motions document the spring reversal. Mean zonal wind speed analysis from balloon positions were obtained covering the area 15 S-65 S. The results presented here are in substantial agreement with those of Hartmann (1977).

Olivero, J. J.↗

Meshed-Pumpkin Super-Pressure Balloon Design

An improved, lightweight design has been proposed for super-pressure balloons used to carry scientific instruments at high altitudes in the atmosphere of Earth for times as long as 100 days. [A super-pressure balloon is one in which the pressure of the buoyant gas (typically, helium) is kept somewhat above ambient pressure in order to maintain approximately constant density and thereby regulate the altitude.] The proposed design, called "meshed pumpkin," incorporates the basic concept of the pumpkin design, which is so named because of its appearance. The pumpkin design entails less weight than does a spherical design, and the meshed-pumpkin design would reduce weight further. The basic idea of the meshed-pumpkin design is to reinforce the membrane of a pumpkin balloon by attaching a strong, lightweight fabric mesh to its outer surface. The reinforcement would make it possible to reduce the membrane mass to one-third or less of that of the basic pumpkin design while retaining sufficient strength to enable the balloon to remain at approximately constant altitude for months.

Jones, Jack↗

NASA Super Pressure Balloon

NASA is in the process of qualifying the mid-size Super Pressure Balloon (SPB) to provide constant density altitude flight for science investigations at polar and mid-latitudes. The status of the development of the 18.8 million cubic foot SPB capable of carrying one-tone of science to 110,000 feet, will be given. In addition, the operating considerations such as launch sites, flight safety considerations, and recovery will be discussed.

Super Pressure Balloon↗

NASA Super Pressure Balloon

NASA is in the process of qualifying the mid-size Super Pressure Balloon (SPB) to provide constant density altitude flight for science investigations at polar and mid-latitudes. The status of the development of the 18.8 million cubic foot SPB capable of carrying one-tonne of science to 110,000 feet, will be given. In addition, the operating considerations such as launch sites, flight safety considerations, and recovery will be discussed.

Balloon↗

Non-Linear Analysis of the NASA Super Pressure Balloons: Whole Flight Simulations

Tensys have a long-established background in the shape generation and load analysis of architectural stressed membrane structures. Founded upon their inTENS finite element analysis suite, these activities have broadened to encompass 'lighter than air' structures such as aerostats, airships, hybrid air vehicles and stratospheric balloons. Tensys have acted as consultants to the NASA Super Pressure Balloon (SPB) Program since 2004. Previous papers have focussed upon the application of inTENS to the overall structural and stability analysis of pumpkin type balloons as used in the SPB Program. Particular emphasis has been placed upon the ability to study both stress and stability at all stages of a flight. As the program has developed, increasing modelling fidelity has been introduced as design refinement has moved emphasis from the overall shape to the performance of individual details. Examples include the introduction of a contact capability into inTENS to better represent the separate cap layer of film. Localised investigations have considered the consequence of local geometric anomalies introduced during fabrication and the effects of debonding of the PBO tendon within its sleeve. Analysis to date has used a material model for the polyethylene shell film developed by Dr Rand of Winzen Engineering, supported by a program of fine resolution material tests at the Balloon Research and Development Laboratory (BRDL) at the GSFC Wallops Island Facility. Based upon work first reported by Schapery, this model has been incorporated into so-called 'snapshot' analyses within inTENS. For a given elapsed time point and temperature distribution, non-linear material properties are iteratively updated for the current stress state in each individual element until changes in those material properties are insignificant. This process has to be iterative as the film stresses and material properties are interdependent. Attempts to derive a time-stepping incremental viscoelastic capability using the Schapery Rand model encountered problems when dealing with the varying temperatures associated with balloon deployment, pressurisation and diurnal behaviour. An alternative approach has been developed by Pellegrino et al at Caltech, again with support from the NASA Balloon Program Office. This is a large strain non-linear viscoelastic model that includes film out-of-plane mechanical and thermal effects. Working from a unified base, this model can be utilised for time-stepping analyses in both a modulus or compliance mode, or a combination of both. This new capability is intended to enhance the current NASA balloon design process. This paper presents the implementation of the Caltech model into a specialist finite element suite, inTENS and its application to whole flight simulations.

Wakefield, David↗

THERMTRAJ: A FORTRAN program to compute the trajectory and gas film temperatures of zero pressure balloons

A FORTRAN computer program called THERMTRAJ is presented which can be used to compute the trajectory of high altitude scientific zero pressure balloons from launch through all subsequent phases of the balloon flight. In addition, balloon gas and film temperatures can be computed at every point of the flight. The program has the ability to account for ballasting, changes in cloud cover, variable atmospheric temperature profiles, and both unconditional valving and scheduled valving of the balloon gas. The program was verified for an extensive range of balloon sizes (from 0.5 to 41.47 million cubic feet). Instructions on program usage, listing of the program source deck, input data and printed and plotted output for a verification case are included.

Horn, W. J.↗

Helium Balloon Valve Improvement

The NASA Balloon Program Office (BPO), located at Wallops Flight Facility asked the Mechanical Systems Branch (Code 548) to improve the design of their balloon valve. BPO uses two main types of balloons, Zero Pressure Balloon (ZPB) and Super Pressure Balloon (SPB), which both use the valve. It is used for termination of the ZPB, and inflation and termination of the SPB. During launch campaigns the valve showed signs of helium leakage which lead the BPO to ask for an improvement. As part of a Professional Readiness Engineering Program (PREP), research and review of the current valve was conducted and a new design was prepared. The current custom designed valve consists of a "pie" plate that is actuated up and down via a gear rack that is driven by a globe motor. When closed the knife edge of the pie plate bites into a silicone gasket to seal the structure. Unfortunately, the gasket material permanently deforms after being compressed and the plate itself bends under the force induced by the motor, introducing two possible helium leak paths. The new custom designed valve utilizes o-rings instead of one gasket to reduce the possibility of leakage from permanent deformation. One o-ring seals the valve structure to its mating surface and a spring energized o-ring is used in a piston design to seal the valve once it's closed. The design also utilizes different materials to increase stiffness and strength so that it is less likely to bend under the force from the motor. Currently the new valve has finished the design and analysis phases and is proceeding towards manufacturing and testing.

Seo, Lindsey↗

Balloon-borne pressure sensor performance evaluation utilizing tracking radars

The pressure sensors on balloon-borne sondes relate the sonde measurements to height above the Earth's surface through the hypsometric equation. It is crucial that sondes used to explore the vertical structure of the atmosphere do not contribute significant height errors to their measurements of atmospheric constituent concentrations and properties. A series of radiosonde flights was conducted. In most cases, each flight consisted of two sondes attached to a single balloon and each flight was tracked by a highly accurate C-band radar. For the first 19 radiosonde flights, the standard aneroid cell baroswitch assembly used was the pressure sensor. The last 26 radiosondes were equipped with a premium grade aneroid cell baroswitch assembly sensor and with a hypsometer. It is shown that both aneroid cell baroswitch sensors become increasingly inaccurate with altitude. The hypsometer radar differences are not strongly dependent upon altitude and it is found that the standard deviation of the differences at 35 km is 0.179 km.

Norcross, G. A.↗

The NASA Balloon Program: Implementing a New Flight Program for the Future

The U.S. National Aeronautics and Space Administration (NASA) Balloon Program continues to support the scientific community providing enhanced capabilities across a spectrum of balloon related disciplines. Long Duration Ballooning (LDB) continues to be a prominent element of the program with a mission model of a two flight campaign in each the Northern and Southern Hemispheres per year. A new LDB endurance record was achieved in Antarctica with the LDB/CREAM mission. Both polar and mid-latitude LDB capabilities continue to be on-going operational elements of the flight program. The Swedish Space Corporation/Esrange and the National Aeronautics and Space Administration (NASA) inaugurated a joint European/U.S. capability for LDB balloon flights from Sweden to Canada in June 2005. This will complement the NASA/U.S. National Science Foundation Office of Polar Programs achievement of more than a decade of successful long-duration flights around Antarctica. Most of Antarctic flights have flown one time around the South Pole in 8-20 days using conventional (zero differential pressure) balloons. One flight went twice around in 31 days and another went three times around in 42 days using conventional balloons. Balloon technology efforts have continued to broaden in scope and new plans for activities to provide advancements have been initiated. A new balloon volume record was established with the successful flight of a 1,700,000 m3 volume zero-pressure balloon. The capability to fly a 700 kg payload (200 kg science instrument) to 160,000 ft has also been demonstrated. A new super-pressure (constant volume) balloon is currently under development for future flights of 60 - 100 day at any latitude. The Ultra-Long Duration Balloon (ULDB) project for the development of a 100-day duration balloon capability has been progressing with additional ground and flight tests having been conducted. The Program has also continued to introduce new technology and improvements into flight systems, ground systems and operational techniques. An overview of the various aspects of the NASA Balloon Program will be presented as well as the outlook for the future.

Pierce, David L.↗

An aneroid pressure sensor for constant-level balloons

The pressure sensor for the Tropical Wind Energy conversion and Reference Level Experiment (TWERLE) is described. Key design features of the sensor are: capacitive coupling, reference at midrange, up-down counting, passive oven, storage at flight pressure and prelaunch calibration. Sensor specifications are given which are based on the production results of 440 units. Drift, as estimated from simulated life tests, is 1 mb per 6 months. The overall weight of the sensor, including thermal package, is 180 g.

Levanon, N.↗

Development Overview of the Revised NASA Ultra Long Duration Balloon

The development of the National Aeronautics and Space Administration s (NASA) Ultra Long Duration Balloon (ULDB) has made significant strides in addressing the deployment issues experienced in the scaling up of the balloon structure. This paper concentrates on the super-pressure balloon developments that have been, and are currently being planned by the NASA Balloon Program Office at Goddard Space Flight Center s Wallops Flight Facility. The goal of the NASA ULDB development project is to attempt to extend the potential flight durations for large scientific balloon payloads. A summary of the February 2005 test flight from Ft. Sumner, New Mexico will be presented. This test flight spurred a number of investigations and advancements for this project. The development path has pursued some new approaches in the design, analysis, and testing of the balloons. New issues have been ideEti6ed throu& both analysis md testing. These have been addressed in the design stage before the next balloon construction was begun. This paper will give an overview of the recent history for this effort and the development approach pursued for ULDB. A description of the balloon design, including the modifications made as a result of the lessons learned, will be presented. Areas to be presented include the design approach, deployment issues that have been encountered and the proposed solutions, ground testing, photogrammetry, and an analysis overview. Test flight planning and considerations will be presented including test flight safety. An extended duration test flight of the National Aeronautics and Space Administration s Ultra Long Duration Balloon is planned for the May/June 2006 time frame. This flight is expected to fly from Sweden to either Canada or Alaska. Preliminary results of this flight will be presented as available. Future plans for both ground testing and additional test flights will also be presented. Goals of the future test flights, which are staged in increments of increasing suspended load and altitude, will be presented. This will include the projected balloon volumes, payload capabilities, test flight locations, and proposed flight schedule.

Cathey, H. M.↗

Exploration of Mars Using Aerial Platforms

The exploration of the atmosphere of Mars can be conducted using aerial platforms such as balloons and airships. Current research and development efforts at NASA include a lobed pressurized balloon system for the Ultra Long Duration Balloon Program. The capabilities of this system, in regards to pressure, load carrying capability, and duration, are far greater than anything previously flown. This technology can be adapted for use in the atmosphere of Mars.

Fairbrother, D. A.↗

Balloon Design Software

PlanetaryBalloon Version 5.0 is a software package for the design of meridionally lobed planetary balloons. It operates in a Windows environment, and programming was done in Visual Basic 6. By including the effects of circular lobes with load tapes, skin mass, hoop and meridional stress, and elasticity in the structural elements, a more accurate balloon shape of practical construction can be determined as well as the room-temperature cut pattern for the gore shapes. The computer algorithm is formulated for sizing meridionally lobed balloons for any generalized atmosphere or planet. This also covers zero-pressure, over-pressure, and super-pressure balloons. Low circumferential loads with meridionally reinforced load tapes will produce shapes close to what are known as the "natural shape." The software allows for the design of constant angle, constant radius, or constant hoop stress balloons. It uses the desired payload capacity for given atmospheric conditions and determines the required volume, allowing users to design exactly to their requirements. The formulations are generalized to use any lift gas (or mixture of gases), any atmosphere, or any planet as described by the local acceleration of gravity. PlanetaryBalloon software has a comprehensive user manual that covers features ranging from, but not limited to, buoyancy and super-pressure, convenient design equations, shape formulation, and orthotropic stress/strain.

Farley, Rodger↗

Middle atmospheric electric fields over thunderstorms

This grant has supported a variety of investigations all having to do with the external electrodynamics of thunderstorms. The grant was a continuation of work begun while the PI was at the Aerospace Corporation (under NASA Grant NAS6-3109) and the general line of investigation continues today under NASA Grants NAG5-685 and NAG6-111. This report will briefly identify the subject areas of the research and associated results. The period actually covered by the grant NAG5-604 included the following analysis and flights: (1) analysis of five successful balloon flights in 1980 and 1981 (under the predecessor NASA grant) in the stratosphere over thunderstorms; (2) development and flight of the Hy-wire tethered balloon system for direct measurement of the atmospheric potential to 250 kV (this involved multiple tethered balloon flight periods from 1981 through 1986 from several locations including Wallops Island, VA, Poker Flat and Ft. Greely, AK and Holloman AFB, NM.); (3) balloon flights in the stratosphere over thunderstorms to measure vector electric fields and associated parameters in 1986 (2 flights), 1987 (4 flights), and 1988 (2 flights); and (4) rocket-borne optical lightning flash detectors on two rocket flights (1987 and 1988) (the same detector design that was used for the balloon flights listed under #3). In summary this grant supported 8 stratospheric zero-pressure balloon flights, tethered aerostat flights every year between 1982-1985, instruments on 2 rockets, and analysis of data from 6 stratospheric flights in 1980/81.

Holzworth, Robert H.↗