Problem

Radical addresses the gap between expensive, inflexible satellites and short-endurance aircraft, drones, and terrestrial infrastructure. Satellite launches can cost $10 million–$100 million and provide either broad coverage or high resolution, while orbital platforms move quickly over targets and can suffer from latency, cloud cover, and coverage gaps. Ground towers and backhaul can take years to build and may not reach the locations where coverage is needed, while conventional aircraft can cost $1,000 or more per operating hour and drones typically fly for only minutes.

The strongest use case is persistent coverage over a defined area where customers need continuous, high-resolution information or connectivity: defense intelligence, surveillance and reconnaissance; maritime and border monitoring; wildfire detection; and direct-to-device 5G. Radical’s thesis is that a stratospheric platform can remain over an area of interest, deliver better resolution and bandwidth than satellites, and do so at substantially lower cost than orbital or traditional airborne systems.

Product / Service

Radical is developing Evenstar, a configurable autonomous solar-electric aircraft that it calls a StratoSat, operating at roughly 65,000 feet. The full-scale design has a 120-foot wingspan, weighs about 240 pounds, carries up to 33 pounds of payload, and is intended to fly continuously for months. Payloads can include ultra-high-resolution imaging systems, sensing equipment, and direct-to-device telecommunications hardware; Radical says Evenstar can capture sub-10-centimeter-resolution video and provide 5G connectivity.

The aircraft uses a highly efficient wing covered in solar cells to power electric propellers during the day and recharge batteries for overnight flight. Because it operates in the atmosphere rather than orbit, it can reposition in real time, remain over a target, land to change or upgrade payloads, and avoid rocket launches. Radical’s model appears to be a platform developed in close collaboration with government and commercial users rather than a single standardized application: customers can use the aircraft’s persistent, targeted infrastructure for observation, connectivity, weather, and other mission payloads.

Market

Radical competes in the high-altitude platform station, or HAPS, and stratospheric unmanned-aircraft market. Its StratoSat is positioned as a middle layer between satellites and terrestrial or low-altitude systems. Direct competitors include Airbus/AALTO’s solar-powered Zephyr and AeroVironment’s solar-powered stratospheric aircraft. Radical differentiates itself primarily through claimed lower cost, faster iteration, payload flexibility, and the ability to combine useful payload capacity with long endurance; the company has said its system could be roughly ten times cheaper than existing alternatives, while its prototype cost less than $500,000 to develop.

Radical was founded in 2022 by former Amazon Prime Air engineers and entered the market through Y Combinator’s Winter 2023 batch. It raised a reported $4.5 million seed round led by Scout Ventures, with participation from Inflection and Y Combinator. Its technical traction includes a 24-plus-hour flight by a subscale autonomous prototype in 2023 and a first flight of the full-size Evenstar prototype in 2025, although that test was low-altitude and not yet solar-powered; the company was preparing for a stratospheric flight campaign in 2026. Radical has reported interest from government and commercial groups, but customer details were undisclosed, and contemporaneous reporting described the company as pre-revenue.