Hypersonic Plane Aims to Fly One Mile Per Second

A “hypersonic” aircraft tested this week could cross the Atlantic in an hour. However, the military plane is more likely to carry missiles than passengers.

The X-514A WaveRider is intended to be a hypersonic plane. Exactly what that means (other than being a very fast form of a supersonic plane – one that breaks the speed of sound) is slightly debatable. One definition is that the vehicle flies at a speed of Mach 5, which is equivalent to five times the speed of sound through air. While the precise figure would vary depending on the particular airspace and conditions, it’s roughly one mile a second.

The details of the project are understandably confidential, though it is known to use a supersonic combustion ramjet (or scramjet) engine. This uses the plane’s forward motion to compress incoming air, which is then burned alongside a gaseous fuel.

The craft was tested last year and reached Mach 5, though its engine didn’t reach full power and the plane fell short of the target speed of Mach 6. A separate project last year aimed to get a plane to Mach 20, but staff lost contact with the craft before recording its speed.

At the moment the experiments are little more than proof of concept. The craft used in this week’s test was only expected to fly for around five minutes before disintegrating.

In the long-term there are two main possibilities for the research. One would be for commercial flight. Although this would probably be restricted to Mach 4, it would effectively mean any two cities in the world could be connected by a short haul flight, something that would be particularly attractive to businesses that dealt in both North America and Asia.

The economics of such flight are still highly questionable of course, and in any case the US military appears to be more interested in the defense (or rather attack) possibilities. There’s a long term goal of being able to land a missile anywhere on the planet within one hour.

(Update: Since this piece was first written, the US Air Force confirmed this week’s test flight failed, with the craft breaking up after just 31 seconds. A spokesman said the problem was with a fin on the rocket booster designed to get the craft moving in the first place.)