You might remember that back in 2013 the US military unveiled a tiny rocket called the X-51 Waverider. Unassuming at first glance, it was in fact the first major step towards building hypersonic aircraft.
The tests were problematic at first but eventually in 2013, the X-51 had a successful test run and reached the eye-watering speed of Mach 5.1 or to be more specific 3,882mph.
That's right, it reached over 3,000 miles per hour. Well on the back of that successful test, the US Military has now announced that it's building a new one, and this time it has its eyes firmly set on the prize.
X-51 was actually pretty crude - it was nothing more than the engine components and a pack of sensors to send information back to the teams on the ground.
This new aircraft will be a significant step forward. Speaking to Military.com Air Force Chief Scientist Mica Endsley said:
"What they are trying to do now is build the whole system so that it is not just about the engine. 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. There are a bunch of technological challenges that have to be addressed to make a functioning system that will work,"
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Why is hypersonic so important?
Well aside from the obvious speed benefits, an aircraft or missile that can travel at hypersonic speeds is actually cheaper to produce and maintain because it has fewer parts.
Using the same 'scramjet' or pulse jet engines that were first truly developed during the Second World War, the scram jet uses supersonic compressed air which is then passed through the combustion chamber.
With a theoretical top speed of Mach 24, scramjets are having a resurgence among national militaries.
When can I fly in one?
Well at the moment you can't and you probably won't be able to for some time. Endsley reports that there is a major hurdle for humans and hypersonic travel which is that the sheer acceleration needed to reach those speeds makes it impossible for humans to survive the trip without getting a serious -- and potentially permanent -- nose bleed.