Tally-ho, chocks away, and jolly good show: The UK’s new Tempest fighter jet will be a decidedly British affair. In July, the UK’s Ministry of Defence announced its new jet will be developed almost exclusively on British soil. The Brits hope the airplane will exhibit the country's military prowess even as it exits the European Union, and as its traditional defence partners and longtime allies in the United States back into isolationism.

The Royal Air Force’s current key aircraft, the Eurofighter Typhoon and the Lockheed Martin F-35, are both the result of distinctly multinational efforts. The Tempest will learn from these foreign cousins—and try to improve on them. The full-scale mock-up of the sleek aircraft, unveiled at the Farnborough Airshow, is Lockheed F-22 Raptor-esque, with twin engines and two vertical stabilisers. The military called the jet a sixth-generation fighter, which would put the Brits ahead of today’s fifth-gen crop: the US’s F-35 and F-22, Russia’s Sukhoi Su-57, and China’s Chengdu J-20. (All of these countries, plus France and Germany, are also working on sixth-generation aircraft.)

"We are entering a dangerous new era of warfare, so our main focus has to be the future,” noted UK defense secretary Gavin Williamson during the unveiling. “Today, we offer you a glimpse of tomorrow." The ministry has devoted $2.6 billion to developing the Tempest concept through 2025, and it will decide then whether to roll out a final aircraft by 2035.

Analysts say it’s no surprise that the UK would look to tend its own garden right now. Brexit has isolated the country from its typical European defense partners, like Airbus. Meanwhile, the US has turned inwards. “The fighter is almost more significant politically than technologically or aeronautically,” says Richard Aboulafia, an aviation analyst with the aerospace and defense consultancy Teal Group. This gives the team in charge of engineering the Tempest a particular challenge: learning to reproduce the specialities, and dodge the pitfalls, of other international programs.

Learning From The Cousins

One big hurdle for the Brit-led effort: building highly complex stealth technology, on which the US usually leads. An effective stealth program needs deliberately chosen materials and manufacturing processes, and impeccable design. A slight miss in any of these can become a literal dead giveaway. The Tempest team will also want to take a close look at the American-born F-35’s combat and sensor systems.

But the British will want to improve upon the F-35’s airworthiness. The fifth-gen fighter is sloth-like and weighty—well, for a fighter jet. The concept should get a boost from a new Rolls-Royce engine, which will come equipped with an adaptive cycle engine. This relatively new technology is supposed to optimize the engine for both speed and range, rather than one or the other. The key difference is in the amount of air pushed by front fan blades into the engine core, where it’s mixed with fuel and detonated. (In your conventional commercial jet engine, wider fans push most of the air around the core. These engines are larger, but also quieter.) The adaptive cycle engine should allow the best of both worlds, with components that alter the airflow mid-flight.

The Brits will also want to ensure their fighter jet doesn’t become a money pit. Unlike, ahem, the Lockheed F-22 and F-35, both notoriously over budget and behind schedule. The Royal Air Force knows this too well. It has ordered 135 F-35s over the next decade, for around $12 billion. “The cost of the F-35s the UK has purchased will weigh heavily on how much it can do with the Tempest,” says Aboulafia.

Still, there’s plenty to spend on. Other technologies for the Tempest are in similarly early stages of development. A virtual cockpit could dispense with conventional instruments and switches, but it will need to come a long way in 10 to 15 years if pilots are to feel comfortable without physical instruments in their craft. (If your augmented-reality helmet blinks off mid-combat, you need a backup.) An artificial-intelligence-driven autonomous flight system would allow the aircraft to fly without a pilot on board, coordinating instead with other fighter jets, but will need to be perfected before anyone feels free to liberate their fighter jets of humans.

Of course, the country’s long-standing relationships won’t simply vanish. The UK says it’s seeking additional international partners for the “Team Tempest” program, led today by BAE Systems, Rolls-Royce, the RAF’s Rapid Capabilities Office, multinational European weapons supplier MBDA, and Italian defense contractor Leonardo.

But then, if the British can learn enough from other fighter programs, and their protracted development timelines and cost overruns, it might come out a victor. Aboulafia notes that the outstanding Lockheed F-35 order isn’t necessarily binding, and while the UK has said officially that the new jet won’t affect the F-35 investment, the British can cancel its airplanes at any point and divert funds to the Tempest. Who’s declaring independence now?