For an unpowered hypersonic boost glide vehicle, such as ARRW, to work properly, a booster rocket must accelerate it to an appropriate speed and altitude.
/https%3A%2F%2Fthe-drive-2.imgix.net%2Fhttps%253A%252F%252Fapi.thedrive.com%252Fwp-content%252Fuploads%252F2019%252F06%252Fb-52-top.jpg%253Fquality%253D85%3Fw%3D1440%26auto%3Dcompress%252Cformat%26ixlib%3Djs-1.2.1%26s%3D8ff8fb4418cacec81e14a83f9009dd8c)
Once there, it then glides toward its target at extreme speeds. DARPA has said that it expected TBG to hit Mach 20 as it screamed back to earth. It very possible that the final AGM-183A design will have the outward apperance of an air-launched ballistic missile, though it will function a completely different manner.
In general, the sheer speed, as well as the level atmospheric flight profile and ability to maneuverable in unpredictable ways, makes hypersonic weapons ideally suited to penetrating past enemy defenses to perform short- or no-notice strikes against time-critical and other strategic targets. Especially compared to traditional ballistic missiles, which follow more predictable flight paths, hypersonic weapons are extremely difficult to spot, let alone intercept, making it very hard, if not impossible, for defenders to either shield themselves or relocate important assets.
This speed and extreme stand-off range also makes hypersonic weapons very applicable to non-stealthy platforms, such as the B-52, which might otherwise have an increasingly hard time penetrating enemy air defense networks. Depending on the exact size of the ARRW, the venerable BUFF may be the only realistic platform to carry it, too. These bombers have a long history carrying over-sized weapons and other payloads on various specialized heavy underwing pylons.
/https%3A%2F%2Fthe-drive.imgix.net%2Fhttps%253A%252F%252Fs3-us-west-2.amazonaws.com%252Fthe-drive-cms-content-staging%252Fmessage-editor%25252F1560451681463-x-43.jpg%3Fauto%3Dcompress%252Cformat%26ixlib%3Djs-1.2.1%26s%3Dea2644cc0a54fd5ce81ecd1f3b2d49c1)
A NASA B-52 carries the X-43A hypersonic research vehicle during a test in 2001.
In June 2018, the Air Force announced it was looking to purchase new pylons for the B-52 to carry multiple, unspecified 20,000-pound class weapons. Lockheed Martin won the contract to begin ARRW development nearly a year before and had told the Air Force that it had a plan to meet desired production targets within three years. Testing of the AGM-183A is set to continue into 2021, according to a separate Air Force briefing.
“We set out an aggressive schedule with ARRW," Will Roper, the Assistant Secretary of the Air Force for Acquisition, Technology and Logistics, said in a statement about the flight test. "Getting to this flight test on time highlights the amazing work of our acquisition workforce and our partnership with Lockheed Martin and other industry partners."
The U.S. military as a whole is aggressively pursuing hypersonic weapons for various platforms. In addition to ARRW, the Air Force is moving forward with the Hypersonic Conventional Strike Weapon, or HCSW, which is pronounced "hacksaw." The B-52 is also set to be the launch platform for HCSW. This air-launched hypersonic boost-glide vehicle will share a number of common components with submarine- and ground-launched weapons for the U.S. Navy and U.S. Army respectively.
Lastly, the Air Force is pushing ahead with an air-breathing hypersonic missile design, the Hypersonic Air-breathing Weapon Concept (HAWC), which will also go into the B-52's hypersonic arsenal. Lockheed Martin, which is also the prime contractor on HAWC, has shown concept art of a potential follow-on design that could work with the F-35 Joint Strike Fighter or other smaller aircraft.
/https%3A%2F%2Fthe-drive-2.imgix.net%2Fhttps%253A%252F%252Fs3-us-west-2.amazonaws.com%252Fthe-drive-cms-content-staging%252Fmessage-editor%25252F1560452039335-hawc.jpg%3Fauto%3Dcompress%252Cformat%26ixlib%3Djs-1.2.1%26s%3Da1eccfae1e2fc5f32c4d1e9e549f00ac)
An artist's conception of a U.S. Navy F-35C employing a variant of the HAWC hypersonic missile.
"We’re using the rapid prototyping authorities provided by Congress to quickly bring hypersonic weapon capabilities to the warfighter," Assistant Secretary of the Air Force Roper said. "This type of speed in our acquisition system is essential – it allows us to field capabilities rapidly to compete against the threats we face."
This first successful captive-carry flight test of the AGM-183A does follow a number of hypersonic weapons developments, especially in Russia, which has fielded its own air-launched hypersonic missile and says it is getting close to deploying a ground-based hypersonic boost-glide vehicle. China is actively pursuing various hypersonic weapons, as well.
The hypersonic weapons space as a whole appears to be rapidly expanding. On June 12, 2019, India claimed to have successfully test-fired an air-breathing hypersonic vehicle, which could serve as the basis for a weapon, using a modified Agni-I short-range ballistic missile as the booster. There are conflicting reportsabout whether or not this launch met all of the required test points.
With the ARRW test, the Air Force has moved one step closer to fielding its own air-launched hypersonic weapon on the B-52.