Performance Characterization of Heliotrope Solar Hot-Air Balloons during Multihour Stratospheric Flights

TL;DR

This study systematically characterizes the performance of heliotrope solar hot-air balloons during multi-hour stratospheric flights, highlighting their potential for high-cadence stratospheric sensing due to low cost and passive design.

Contribution

It provides the first comprehensive analysis of heliotrope flight behavior and performance during a large-scale campaign, including flight stages and parameter dependencies.

Findings

Heliotropes achieve stable near-level flight in the lower stratosphere for hours.

Flight behavior is consistent across nearly identical envelopes with minor variations.

Data enables understanding of nominal and anomalous flight conditions.

Abstract

Heliotropes are passive solar hot air balloons that are capable of achieving nearly level flight within the lower stratosphere for several hours. These inexpensive flight platforms enable stratospheric sensing with high-cadence enabled by the low cost to manufacture, but their performance has not yet been assessed systematically. During July to September of 2021, 29 heliotropes were successfully launched from Oklahoma and achieved float altitude as part of the Balloon-based Acoustic Seismology Study (BASS). All of the heliotrope envelopes were nearly identical with only minor variations to the flight line throughout the campaign. Flight data collected during this campaign comprise a large sample to characterize the typical heliotrope flight behavior during launch, ascent, float, and descent. Each flight stage is characterized, dependence on various parameters is quantified, and a discussion of nominal and anomalous flights is provided.