A low-observable loyal wingman, built at Warton.

Brontanax was designed and built by BAE Systems' FalconWorks advanced projects division at Warton, Lancashire. BAE describes the aircraft as a "pre-series, pre-production prototype" and an Operational Concept Demonstrator for CCA — self-funded from the company's internal R&D budget. Over 500 BAE engineers and more than 75 UK suppliers have contributed. The name is drawn from Ancient Greek for "thunder" and "king".

The full-scale model displayed at Farnborough shows a low-observable delta planform with canted twin tails, a single engine, and a belly-mounted air inlet below the nose — a layout consistent with reduced radar signature from the forward hemisphere.

BAE has deliberately not released dimensions, empty weight, payload, range or speed. The company describes Brontanax as similar in size to a BAE Systems Hawk trainer, and FalconWorks director Dave Holmes has said the design targets 70–80% of Typhoon's capability at 20–25% of the cost.

Development began in 2022 and grew out of BAE's earlier "Concept 2" autonomous-combat-aircraft demonstrator, shown publicly at DSEI 2023. The company frames Brontanax as building on more than 25 years of BAE work on uncrewed and autonomous systems, and as a "stepping stone" toward the crewed sixth-generation GCAP / Tempest fighter.

The prototype is assembled at Warton; a Naval News report also flagged BAE promotional imagery showing a Brontanax launching from a Queen Elizabeth-class carrier — a nod to the Royal Navy's Project Vanquish requirement, though carrier operation is not part of the RAF-facing StormFighter brief.