PHASA-35, the solar-powered stratospheric aircraft developed by BAE Systems’ Prismatic, has been selected as the flight demonstration platform for a power beaming technology intended to keep high-altitude aircraft flying through the night and the winter, under a £15.7 million contract linked to the Advanced Research and Invention Agency, the company stated.
The work forms part of ARIA’s Enduring Atmospheric Platforms programme, which aims to develop low-cost, long-endurance platforms for high-altitude communications. It runs in three stages over three and a half years and concludes with an integrated flight demonstration aboard PHASA-35.
The problem it addresses is the one every solar-powered high-altitude aircraft faces. Flight depends on the sun, and the company describes that as a significant challenge in places like Britain, where winter daylight is limited and the nights are long. According to BAE Systems, power beaming removes that dependency by supplying constant power regardless of season, making it easier to fly continuously for up to several months at a time.
The system uses what the company describes as a highly controlled ground-based energy beam directed at a dedicated receiver built into the aircraft’s wing, which converts it back into electricity to power the aircraft and charge its batteries. The release notes that similar microwave frequencies are already widely used in aviation, satellite communications and radar.
Bob Davidson, chief executive of Prismatic, said: “PHASA-35 has already proven its worth in the stratosphere as a low-cost alternative to satellites and now this exciting project will explore whether we can make it even more capable. This is a strong example of British organisations working together to advance an emerging technology.”
Rico Chandra, programme director for Enduring Atmospheric Platforms at ARIA, said: “This research expands the UK’s leadership in high-altitude platforms to become the place where this industry is designed, built and scaled. Getting there means backing bold ideas, from fixed-wing solar aircraft to designs nobody predicted, including aircraft that fly on spinning wings instead of propellers.”
PHASA-35 has a 35-metre wingspan and weighs 150kg, and according to the company has the potential to operate above 66,000ft for months at a time, delivering persistent communications, Earth observation and surveillance at a fraction of the cost of traditional satellites and with greater flexibility to deploy and upgrade.
According to the company the benefit may extend beyond endurance, since reducing the weight of onboard battery arrays could free capacity on an aircraft that already carries a payload of up to 15kg, which the company says can be used for sensors across intelligence, surveillance and reconnaissance, communications, Earth observation and defence applications.
Batteries are a large share of the weight on any solar aircraft of this kind, since they have to carry the aircraft through every hour of darkness, and the longer the night the more of them are needed. An aircraft able to draw power from the ground overnight could, in principle, carry fewer batteries and more equipment.
ARIA was established in 2023 as an independent body funding high-risk research, modelled in part on the American Defense Advanced Research Projects Agency, with the freedom to back programmes that conventional funding routes would not.
Prismatic became part of BAE Systems in 2019, and PHASA-35 has flown a series of stratospheric trials in recent years.
