SoftBank and TOPPAN Pioneer Ultra-Durable Wing Material for Stratospheric Solar Aircraft
Tokyo, Monday, 27 April 2026.
SoftBank and TOPPAN have developed an innovative wing skin capable of withstanding near -100°C temperatures, paving the way for long-endurance stratospheric aircraft to bridge global telecommunication gaps by 2029.
Engineering for the Stratosphere
High-Altitude Platform Stations (HAPS), frequently described as “base stations in the sky,” are engineered to operate in the stratosphere at an altitude of approximately 20 kilometers [1][3]. At this elevation, aircraft are subjected to a brutal environment that rapidly degrades conventional all-purpose materials [2][3]. The atmospheric challenges include exposure to short-wave ultraviolet (UV-C) radiation, high-concentration ozone levels ranging from 10 to 20 parts per million (ppm), and staggering temperature fluctuations [2][3]. During operations, the aircraft skin must withstand extreme cold dropping to between -50°C and -95°C—approaching -100°C—while also enduring direct solar heating that can push temperatures to roughly 100°C [3][5].
Replicating the Edge of Space
Developing a material capable of surviving the stratosphere required equally innovative testing protocols. TOPPAN constructed a specialized testing environment designed to simulate the simultaneous stresses of the upper atmosphere [1][2]. This facility accelerates weather-resistance testing by exposing materials to ultralow temperatures, UV-C rays, and high ozone concentrations concurrently [2][3]. To ensure the simulation’s accuracy, SoftBank supplied real-world flight data from its previous HAPS operations, providing precise environmental metrics on temperature variations and deep-UV exposure [1][3].
Timeline to Commercialization
The development announced today, April 27, 2026, marks the beginning of a structured timeline toward commercial viability [1][2]. By the end of fiscal year 2027, which concludes on March 31, 2028, SoftBank and TOPPAN aim to refine the material further, making the skin even lighter and stronger based on upcoming performance tests [1][2][3]. Following this optimization phase, the partnership plans to establish full mass-production technology by fiscal year 2028 [1][3].