FalconWorks' headline number for Brontanax — 70 to 80 per cent of a Typhoon's combat effect at 20 to 25 per cent of its cost — is the single most important figure BAE Systems has attached to the aircraft. Every export pitch, every Treasury argument for buying meaningful fleet numbers, and every RAF slide about mass in a contested European air battle ultimately trace back to whether that ratio survives contact with real integration work over 2026 and 2027.
The ratio is credible on paper. A single-engine, unmanned, subsonic-optimised airframe with a modest low-observable signature, no ejection seat, no life-support system and a stripped human-machine interface can plausibly be built and sustained for a fraction of a twin-engine, supersonic, pilot-rated fighter. The unknowns are software and integration: autonomy validation, weapons certification, secure data-links and the ground segment that actually flies the thing all sit outside the airframe unit cost, and all have a habit of eating budgets.
Watch three data points over the next eighteen months. First, whether the Rolls-Royce propulsion choice draws on an existing certified core or demands a bespoke development — the latter would push unit cost up quickly. Second, whether the autonomy stack reuses mature building blocks from Taranis, Mantis and the Tempest teaming work, or whether BAE quietly has to start again. Third, whether the MoD commits to a production tranche beyond the initial £300 million StormFighter envelope; without that signal, industrial suppliers will price in risk and the cost curve slips.
If the ratio holds, Brontanax becomes the anchor for a several-hundred-airframe fleet strategy across the 2030s and a serious export contender in the Gulf and Indo-Pacific. If it slips to, say, 40 per cent of Typhoon cost, the aircraft still works — but the political case for buying it in genuine combat mass collapses into the familiar British pattern of a small, exquisite, under-bought fleet. That is the risk BAE and the RAF are quietly managing behind the Farnborough optics.