The United States Air Force has set its sights on developing a new unmanned flying weapon whose speed is five times the speed of sound.

US Air Force chief scientist Mica Endsley said the military is developing an aircraft it launched in May 2013, the X-51A Waverider, to create a better, more comprehensive vehicle that can reach a speed of up to Mach 5 by 2023.

A Mach 5 speed is equivalent to about 3,800 mph or five times the speed of sound. An aircraft of this speed can travel across the United States in around 30 minutes, but will be unsafe for human passengers.

"X-51 was really a proof of concept test. It showed that you could get a scramjet engine, launch it off an aircraft and it could go hypersonic," Endsley explained.

"It was able to go more than Mach 5 until it ran out of fuel. It was a very successful test of an airborne hypersonic weapons system," the scientist added.

The X-51A was able to accelerate up to Mach 4.8 in 26 seconds when it was launched two years ago. It hit Mach 5.1 as it climbed to 60,000 feet but crashed into the ocean after running out of fuel.

To be able to develop a better hypersonic aircraft, engineers will have to develop new materials and guidance systems.

"What they are trying to do now is build the whole system so that it is not just about the engine," Endsley said.

"You have to have materials that can operate at the kind of temperatures you have when you are going at hypersonic speeds. You have to have guidance systems that will function when you are going at those types of speeds," the US Air Force official added.

The new aircraft being developed is seen to be a game-changer in the arena of warfare, since it can be launched from long distances and can travel undetected.

China and Russia are also said to be developing their own hypersonic vehicles.