On Monday, the United States announced yet another successful test of its scramjet-powered hypersonic cruise missile known as the Hypersonic Air-breathing Weapon Concept, or HAWC. This news comes directly on the heels of last week’s announcement of successful tests of two different kinds of hypersonic boost-glide missiles; Lockheed Martin’s AGM-183A ARRW and DARPA’s OpFires missile.

It would seem America’s hypersonic efforts are beginning to hit their stride.

“The test demonstrated how we’ve rapidly matured affordable scramjet technology, which is the basis for air-breathing weapons,” said Colin Whelan, president of Advanced Technology for Raytheon Missiles & Defense in a press release.

“Our second HAWC flight test success is an important milestone for our nation as we advance hypersonic systems.”

There has been a lot of discussion about a hypersonic arms race between ʀussιᴀ, cнιɴᴀ, and the United States in recent years, with each nation devoting a great deal of money and effort toward fielding these high-speed weapons. While weapons that achieve hypersonic velocities (speeds above Mach 5) are nothing new, these modern hypersonic missiles couple extreme speeds with maneuverability, making them exceedingly difficult to intercept with existing technology.

These modern maneuverable hypersonic weapons fall within one of two categories: hypersonic boost-glide systems and scramjet-powered hypersonic cruise missiles.

America’s successful tests included both kinds of modern hypersonic missiles

The successful tests of Lockheed Martin’s AGM-183A Air-launched Rapid Response Weapon (ARRW) and DARPA’s OpFires missile last week both fall under hypersonic boost-glide weapons. This week, another successful test of DARPA’s HAWC missile marks even further progress in scramjet-powered hypersonic missiles as well.

In total, the U.S. now has more than 70 different hypersonic programs drawing funds from Pentagon coffers, including at least one that may aim to field a reusable hypersonic reconnaissance and strike drone.

Boost-glide systems are the only hypersonic weapons currently in service for any nation, with cнιɴᴀ’s hypersonic anti-ship DF-ZF system carried aloft by their DF-17 ballistic missile, and ʀussιᴀ’s nuclear Avangard carried aboard the nation’s new RS-28 Sarmat ICBM. These weapons function somewhat similarly to existing ballistic missile technology, being launched via conventional rocket booster before separating (often at a lower altitude than ballistic missile warheads) and gliding unpowered towards a target at extremely high speeds—sometimes as high as Mach 20 or more.

Scramjet-powered hypersonic cruise missiles represent completely different technology, though they’re lumped in with boost-glide systems due to their high speed and maneuverability. These weapons leverage experimental air-breathing propulsion systems called Supersonic Combustion Ramjets, or scramjets, to achieve and sustain hypersonic speeds. Scramjets are air-breathing jet engines that allow air to flow through them at supersonic speeds, unlike other forms of jet engines, which slow the airflow to more manageable subsonic speeds.

In effect, these weapons function just like any other cruise missile… just faster. They fly along a largely horizontal flight path under the power of its onboard propulsion system much like an aircraft. This is the class of weapon Raytheon and Northrop Grumman’s recent HAWC missile success falls under, though the HAWC program has also seen success when powered by a Lockheed Martin scramjet as well.

The HAWC missile has now had three successful tests with two different scramjets

Monday’s announcement marks the second consecutive success of the scramjet-powered Hypersonic Air-breathing Weapon Concept, or HAWC, missile using a Northrop Grumman-designed scramjet propulsion system, but it’s actually the program’s third overall success in less than a year.

The last test of the Northrop Grumman-powered HAWC missile took place in September. Then, the Raytheon-designed weapon was tested again in April of this year using a Lockheed Martin-sourced scramjet system for propulsion instead, which resulted in another success. That Lockheed Martin-powered missile sustained hypersonic flight for a record-crushing 327 seconds, breaking the decade-spanning record set by Boeing’s X-51 Waverider of 210 seconds.

Now, a third success (the second with the Northrop scramjet) makes it evident that the previous wins weren’t a fluke. The United States now appears to have at least two functional scramjet propulsion systems for missile applications, potentially making it the frontrunner in the development of these types of modern hypersonic weapons.

ʀussιᴀ has claimed successes of their 3M22 Zircon missile, which some have postulated is powered by a scramjet — but to date, there’s no evidence to suggest the weapon actually has a functional scramjet, or that it will enter service any time soon. As the world has grown increasingly privy to throughout ʀussιᴀ’s ongoing invasion of uκʀᴀιɴᴇ, Moscow has a habit of overstating its military capabilities.

However, cнιɴᴀ may be a real competitor in scramjet technology, with their recently announced test of a rocket-based combined cycle system said to incorporate a rocket, a ramjet, and a scramjet for propulsion. However, like ʀussιᴀ, news of these tests emerges via state-owned news outlets barred from independent reporting, making it difficult to divine just how far along this program truly is.