LONDON-Boeing is developing a hypersonic military aircraft that could ‘circle the globe in three hours’ to strike targets at five times the speed of sound.

The secretive concept vehicle, which has been billed as a potential successor to the legendary Blackbird SR-71 spy plane, is thought to be codenamed ‘Valkyrie II’.

Boeing first unveiled a concept model for the high-speed strike and reconnaissance vehicle last month, but a senior researcher at the company has now revealed new details. Kevin Bowcutt, Senior Technical Fellow of hypersonics at Boeing Research & Technology, claimed the uncrewed aircraft - nicknamed by aviation fans as the ‘Son of Blackbird’ - will travel more than twice the speed of a bullet. In a Facebook live video, Mr Bowcutt said: ‘It’s two-and-a-half times the speed of a speeding bullet. It’s more than twice as fast as the Concorde.

‘So basically you can get anywhere in the world in one hour across the Atlantic, two hours across the Pacific – pretty much anywhere between two points in one-to-three hours.’ A concept model for the military craft was first unveiled by Boeing at the American Institute of Aeronautics and Astronautics SciTech forum in Orlando, Florida in January.

Although the company has not yet greenlit the project, it said at the conference that a proof-of-concept vehicle could be built in the next 10-20 years.

In Friday’s video, Mr Bowcutt, who is based at Boeing’s research centre in Long Beach, California, said: ‘This is one of several concepts and technologies we’re studying for a hypersonic aircraft.

‘This particular concept is for a military application that would be targeted for an intelligence, surveillance and reconnaissance, or ISR, and strike capabilities.’

By definition, hypersonic vehicles can travel five times the speed of sound, and Boeing’s craft could help US officials ensure their nuclear weapons can breach almost any missile defence system.

Hypersonic vehicles would travel so rapidly and unpredictably they could provide an almost-immediate threat to nations across the globe.

The craft would travel at such speeds that the gap between identifying a threat and launching an attack on it would drop from hours to minutes, even at long distances. The Valkyrie II is designed to carry out undetectable spy missions in a similar fashion to Lockheed and Martin’s Blackbird SR-71, which is no longer in operations. The spy plane was the world’s fastest and highest-flying operational manned aircraft during its operational run from 1966-1998, and in 1976 set an absolute speed record of 2,193.2mph (3,529kmh) - a record it still holds today. If developed by Boeing, the Valkyrie II will smash this record, with the hypersonic craft capable of reaching Mach 5 or higher.

Mach 1 is around 767 mph (1,235 kmh), meaning a Mach 5 aircraft would travel at an astonishing 3,836 mph (6,174 kmh).

Boeing is planning a two-step development process.

First, it plans to begin test flights with an F-16, single-engine design and then test flights with a twin-engine, full-scale operational vehicle that measures 107 ft long (33 metres).

The design unveiled in Florida last month has not yet been approved for full-scale development but it shows a twin-tail, highly swept delta wing configuration.

Speaking to Aviation Week last month, Mr Bowwcutt said: ‘It’s a really hard problem to develop an aircraft that takes off and accelerates through Mach 1 all the way to Mach 5 and beyond.

‘The specific impulse of an air breathing engine goes down with increasing velocity, so you have to make the engine bigger to get to Mach 5.

‘But doing that means a bigger inlet and a bigger nozzle, and trying to get that through Mach 1 is harder.’

In September last year it was announced Lockheed Martin was already testing a radical hypersonic update of its Mach 3 SR-71 Blackbird.

The SR-72 hypersonic plane will be a strike and reconnaissance aircraft that tops Mach 6, and the firm has been working on the project since the early 2000s.

‘Although I can’t go into specifics, let us just say the Skunk Works team in Palmdale, California, is doubling down on our commitment to speed,’ Orlando Carvalho, executive vice president of aeronautics at Lockheed Martin, told the SAE International Aerotech Congress and Exhibition last year.

‘Simply put, I believe the United States is on the verge of a hypersonics revolution.’