SZ-155 STRATOSPHERIC AIRSHIP

The SZ-155 STRATOSPHERIC AIRSHIP is a high-altitude, solar-powered platform designed for persistent stratospheric operations with applications to fields like communications, Earth observation, and wildfire detection. It was developed by Stratoship, an Australian aerospace startup founded in 2020 by Daniel Field. The design is based on the experience gained in the development of a high-altitude balloon called "The Pebble" flown in 2021.

In the image at left we can see the only known image of the fully-inflated airship during an indoor test.

Although Stratoship does not disclose full technical specifications such as length, volume, or material specifics in its public updates, what we know is that the SZ-155 is the first fully sovereign-designed and built HAPS prototype, sized to carry multiple payload types to ~20�km altitude. The platform features a solar-powered envelope (likely multi-layered composite) with an internal structure optimized for high-altitude pressure stability and gas-tight integrity to minimize helium leakage.

Propulsion is achieved via electric motors and propellers.

Balloon launched on: 5/5/2025 at 7:55 AEST
Launch site: Queensland, Australia  
Balloon launched by: Stratoship
Balloon manufacturer/size/composition: Stratospheric Airship  
End of flight (L for landing time, W for last contact, otherwise termination time): 5/5/2025 at 19:07 AEST
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 11 h 12 m

The airship was launched from outside the Corfield Racecourse, in the Shire of Winton in north-western Queensland, Australia on Monday, 5 May 2025 at 07:55 am AEST and landed at 19:07 pm after a total flight time of 11 hours and 12 minutes. It reached a maximum altitude of 65,780 feet and remained in the stratosphere for over 8 hours. This marked Australia's first sovereign-designed and manufactured high-altitude platform station (HAPS) to reach the stratosphere. The flight tested the endurance and performance of the airship and carried research payloads, including a bushfire detection system.

The mission demonstrated the capability of the airship to maintain position in the stratosphere, enabling real-time disaster detection and persistent communication and Earth observation services. Some issues occurred during the flight, and further analysis and improvements are needed

• Stratoship Website