Autonomous Altitude Control Device for Latex HAB

The advent of latex High Altitude Balloons has dramatically reduced the costs associated with conducting research at altitudes reaching the stratosphere. Latex balloons are less expansive than zero-pressure and super-pressure alternatives, but they have an important disadvantage: while zero-pressure and super-pressure balloons can float at a desired altitude for long periods of time, latex balloons ascend continuously, flying only around two hours before reaching a bursting altitude (usually around 100,000 ft) and falling back to earth. Enabling latex High Altitude Balloons to float at a constant altitude for extended (and specifically defined) periods of time could make them significantly more useful and cost-effective. An autonomous altitude control vent for latex high altitude balloons was designed and fabricated. The vent releases helium during the balloon’s ascent, first to cause the balloon to reach neutral buoyancy at a specified altitude, and again later in the flight to cause the balloon and payload to descend for a soft landing. The vent is completely autonomous; it makes decisions using altitude and ascent rate feedback, which is measured using an external pressure sensor. Two preliminary test flights were conducted. It was found that the vent allows gas flow rates sufficient to achieve a soft landing. At an altitude of roughly 30,000 ft, the balloon achieved negative lift in under two minutes. A faulty altimeter, which was used only on the second flight, prevented the vent from operating on altitude and ascent rate feedback. Several additional test flights are planned in the coming months