An artist's rendering of a High Speed Strike Weapon hypersonic missile under development (Picture: Lockheed Martin).
By David Hambling, technology expert
Hypersonics, missiles and aircraft that can travel faster than Mach 5, or about 4,000 mph – about twice the speed of a rifle bullet – are the subject of a new arms race.
Ballistic missiles like Trident are faster, but most of their trajectory is in an atmosphere where they cannot steer.
This predictable path makes them relatively easy to intercept. The new hypersonics, which travel through the atmosphere at high speed, will be far more agile.
In March, Russia released video of the test-firing of a new missile, the Kh-47M2 Kinzhal or “Dagger”, which President Putin described as ‘invincible’.
The missile, launched from an aircraft, weighs around four tonnes has a range of 1,800 miles and can carry a nuclear or conventional warhead.
Such missiles are a key part of Russia’s new nuclear strategy, which aims to bypass defensive systems being built by the US.
A Kinzhal with a conventional warhead might make an effective anti-ship weapon, able to strike aircraft carriers from outside the range of their defensive fighter screen.
Analysts are somewhat sceptical of Russian claims that Kinzhal is already in service. While the video certainly shows a test-firing, it does not show a target being hit, and there are doubts over how well the missile can steer.
But it does show that there is some substance to Putin’s claims that Russia is pushing ahead in this area.
America has been researching the field of hypersonics for some years, with a series of tests of the unmanned X-43 hypersonic vehicle in the early 2000s.
These succeeded in setting a new speed record of Mach 9.6 or over 7,000 mph, but the technology was not judged to be mature enough to merit taking beyond the test stage. Now that the Russians are in the game, things are changing.
“We’re going to see their hand and raise them one, in both offensive and defensive capabilities,” Michael Griffin, formerly of NASA and now the Undersecretary of Defence for research and engineering, told reporters in July.
In July, the US Air Force awarded a $928 million contract to Lockheed Martin for a missile called the Hypersonic Conventional Strike Weapon or HCSW – pronounced ‘Hacksaw’.
Virtually no details have been released and even the type of propulsion has not been officially announced. The aim is to have a prototype weapon within three years, able to hit mobile, ‘time critical’ targets, such as missile launchers.
Getting a missile to work in that timeframe is a big ask. Previous US hypersonic projects have run into difficulty with heat: at high speed, atmospheric friction produces temperatures too high for existing materials to handle.
The US Defence Advanced Research Projects Agency (DARPA) has also kicked off ‘Glide Breaker’, a new interceptor to tackle agile hypersonic targets like those new Russian missiles.
This program is also shrouded in secrecy and unanswered technical questions.
Identifying, locating, and plotting a course to intercept a ballistic missile has been compared to hitting a bullet with another bullet.
When the target is also manoeuvring, the challenge becomes even greater. At present, Glide Breaker seems to be more of an idea than an actual defence system.
Meanwhile, the UK is quietly working on its own hypersonic technology.
This operates in two modes. At low altitudes, it sucks in and compresses air, burning liquid hydrogen fuel with atmospheric oxygen. At higher altitudes, it shuts the intakes and uses liquid oxygen instead.
The unique feature of SABRE is a precooler which reduced the temperature of the incoming compressed air. Operating at low temperatures allows a lightweight construction; less mass means higher speed.
Reaction Engines has been going since 1989, and their ideas have gradually been gaining support. The company now benefits from investment from both Boeing and Rolls Royce, as well as the UK government, and plans to test an engine core in 2020.
They are focused on developing SABRE for space launches, but there is certainly military potential. And if the design works as planned, it may end up superior to anything the US or Russia can produce.