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National Aeronautics and Space Administration

Goddard Space Flight Center

Scientific Ballooning

Balloon Program Office

Test Flight 540NT - Ft. Sumner Deployment Test Flight, 6.2 MCF Balloon
   And
Test Flight 555NT Sweden Deployment Test Flight, 6.2 MCF Balloon

Test Flight 540NT
  • The goal of this flight was balloon deployment
  • Ft. Sumner Test Flight, February 4, 2005
  • Balloon volume 176,000 m3 (~6,200,000 ft3)
  • Successful launch, ascent, reached float altitude, and started to pressurize
  • Full deployment in upper section of the balloon
  • Seal opened up in lower section of balloon after the start of pressurization
  • Satisfied the flight goal of balloon deployment
  • Seal issue resolved and minor design modifications for next balloon
  • No evidence of the "S" shaped clefts that had been seen on the previous flights prompted the program to move forward with another test flight of an almost identical balloon.
  • 540NT Internal camera - Upper section of balloon fully deployed
    540NT Internal camera - Upper section of balloon fully deployed
Test Flight 555NT
  • The goals of this flight were balloon deployment and ~4 day flight
  • June 12, 2006 from Kiruna, Sweden
  • Balloon volume 176,000 m3 (~6,200,000 ft3)
  • Very similar design to the 540NT balloon with minor changes to address flight issues seen during Ft. Sumner test flight
  • Very minor change in lobe angle of the balloon
  • Successful launch, ascent, reached float altitude, and pressurized to target level
  • The balloon did not fully deploy, with one area of ~11 gores forming an “S” cleft
  • All of the ballast was incrementally dropped in 12 separate drops to pressurize the balloon to the fullest extent possible
  • The balloon’s final maximum differential pressure was ~265 Pa, 10% above the maximum design pressure
  • The “S” cleft did not come out even with the extra pressurization, but the balloon operated perfectly in this undesired shape
  • Flight rules prohibited allowing the balloon to go off of the coast in this undesired shape
  • The total flight time was approximately 8 hours and 50 minutes.
  • 555NT cleft feature of un-deployed balloon
    555NT “S” cleft feature of un-deployed balloon

Nearly identical balloons ended up with one balloon fully deploying and the other not deploying with ~11 gores of trapped material. The results of these two flights provided clear direction to the project for the next steps in the development. These included the expanded knowledge and characterization of the materials used, analytical studies of the balloons, and ground testing (Ground Model Testing) to further explore the deployment continuum. A number of areas were also explored including the impact/influence of the launch process, “path dependence” of balloon deployment, and any minor differences between “as built” balloons and the resulting deployment.


NASA Code 820

Scientific Balloon Update

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