Near-Space Station-Keeping Performance of a Large High-Altitude Notional Airship

TLDR

High‑altitude near‑space airships must maintain station in the presence of winds, requiring propulsive power despite operating above weather. The study analyzes station‑keeping performance of a notional solar‑powered airship at ~65,000 ft by estimating aerodynamic drag, characterizing wind environments, and evaluating solar power for various locations and seasons. The airship is a 450‑ft, 6.1‑million‑ft³ solar‑electric vehicle with full‑surface solar cells, electric motors, propellers, and batteries, and its available power is compared to the power needed for station keeping. The analysis shows that diurnal solar variations and seasonal winds can prevent a large airship from meeting station‑keeping requirements in some months because of power limits.

Abstract

A key technical challenge for high-altitude (near-space) concepts is autonomous station keeping, or the ability to remain fixed over a geo-location in the presence of winds. Although operational altitudes of 65,000 ft. altitude and above are above weather (i.e., storms, rain), winds still exist. And to station keep in the presence of these winds requires propulsive power. This paper focuses on the analysis of the station keeping performance of a notional solar-powered airship operating at an altitude around 65,000. The vehicle has a lifting-gas volume of 6.1 million ft 3 , is 450 ft in length, and is solar-electric powered with the entire upper surface covered by solar cells. Electric motors and propellers provide propulsion, additional on-board power is required for the payload and auxiliary equipment, and batteries are used for power storage. In this paper, the aerodynamic drag of the vehicle is estimated, the wind environment is characterized, and the solar-power available is determined for several geo-locations and time of year. This power available is then compared to the power required for station keeping in the presence of winds. It is shown that due to diurnal solar variations and season winds a large airship may be unable to meet station-keeping performance requirements in certain months of the year due to power limitations