Boeing has finally unveiled a successor to the legendary Blackbird SR-71 spy plane, capable of travelling at five times the speed of sound.

The new 'Son of Blackbird' was revealed at an event in Orlando, Florida, but it's only a concept design for now.

The new aircraft will be a direct competitor to Lockheed martin's upcoming SR-72.

These rival firms are racing to create a hypersonic aircraft that's capable of stealthy recon assignments – and strike missions, too.

Speaking to Aviation Week Aerospace Daily, Boeing's hypersonics chief described how Boeing was planning a two-step development process for the new war plane.

The first stage would involve flight tests of an "F16-sized, single-engine" precursor vehicle that acts as a "proof of concept".

The second stage is the creation of a "twin-engine, full-scale operational vehicle" that has roughly similar dimensions to the 107-foot-long SR-71.

Boeing's end goal is an aircraft that can travel at speeds beyond Mach 5 – that's five times the speed of sound.

The speed of sound – or Mach 1 – is around 1235km/h. So hitting Mach 5 would mean the Son of Blackbird would have to travel at an incredible 6,174km/h.

For comparison, a Boeing 747 passenger jet typically reaches cruising speeds of just 885km/h.

The tricky part is that the SR-71 replacement needs to to be able to take off, accelerate, slow down and land all on its own – just like the original 1964 model.

Boeing is looking at using a conventional turbojet to hit Mach 3, then switching to a different configuration to boost beyond Mach 5.

Sadly, there's no guarantee when Boeing will have a sky-ready model, so we'll just have to drool over concept renders for now.

This story originally appeared in The Sun.