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System and method for altitude control

  • US 7,469,857 B2
  • Filed: 09/09/2004
  • Issued: 12/30/2008
  • Est. Priority Date: 09/09/2003
  • Status: Expired due to Fees
First Claim
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1. A differential expansion system for balloon altitude control, said system comprising:

  • a volume flexible, zero pressure envelope substantially absent fluid communication with ambient conditions, and a single substantially volume constant envelope, and a lift gas in said envelopes; and

    a gas transfer device in fluid communication with said envelopes, for change of sum envelope volume to control balloon ascent and descent.

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