Altitude Control with Vented Solar High Altitude Balloons (SHAB-Vs)

Vented Solar High Altitude Balloons (SHAB-Vs) utilize a lightweight balloon envelope with ideal thermal properties for absorbing direct solar radiation and heating the envelope and internal ambient air through conduction and convection. These balloons therefore do not require a lifting gas to generate lift, and are a simple, inexpensive, passive form of high altitude balloon flight. Until recently, SHABs have not had venting capabilities and been strictly free floating for high altitude science missions. In this work we present vent technology development and flight experiments for vented solar high altitude balloons (SHAB-Vs), Early vent experiments proved that changing altitude with a mechanically vented SHAB was possible. These early flights were on timed missions with precisely timed vent openings; after venting the balloon descended to a new altitude and settled at the new equilibrium. On more recent flights we introduced altitude control to guide the balloons to specific altitudes. During these flights we demonstrated precise altitude control down to 16 km with ± 75 m altitude oscillations and changed the horizontal trajectory of the SHAB-Vs several times by entering different wind flows. The ability to change the altitude of the SHABs can lead to more sophisticated maneuvers in the future such as station-keeping or waypoint trajectory following by leveraging opposing winds at various layers of the atmosphere.