Stratolaunch To Build Aerial Target For U.S. Hypersonic Defense Testing

The company, which operates the Roc, the world’s largest airplane, said it would shift focus to providing high-speed flight test services two years.

byJoseph Trevithick|
U.S. Homeland photo


Stratolaunch, the owner and operator of the massive Roc, the largest plane ever flown, has received a contract from the U.S. Missile Defense Agency to supply a target that mimics certain hypersonic threats to support the development of new defensive capabilities. Hypersonic weapons present significant challenges for defenders in terms of detecting and tracking incoming threats, as well as attempting to intercept them. Being able to test new sensors and interceptors against real representative targets will be essential going forward. 

Stratolaunch announced its deal with Missile Defense Agency (MDA) yesterday, but provided only limited details about the expected work. 

An artist's conception of the Talon-A, a resuable, air-launched hypersonic vehicle that Stratolaunch is developing., Stratolaunch

"We're excited to provide MDA with a threat-representative and threat-replicating target that allows them to understand how to engage and intercept hypersonic threats," Dr. Daniel Millman, Chief Technology Officer of Stratolaunch, said in a statement contained in a company press release.

"The company plans to augment existing Department of Defense flight test resources through affordable, commercially contracted, rapid-turnaround hypersonic flight testing for the Department of Defense and its prime contractor partners," that same release added.

This MDA contract is exactly the kind of work that Stratolaunch had said publicly back in December 2019 that it would start to seek out. That had represented a change in direction away from the firm's original focus on space launch services, with the Roc serving as a mothership for air-launching various expendable and reusable vehicles to put payloads into space. The shift to high-speed flight testing services had come after the company was sold to Cerberus Capital Management following the death of the company's founder, Microsoft co-founder Paul Allen, in 2018. 

It's not clear from Stratolaunch's press release whether the target it will provide to MDA will be an entirely new development or one based on an existing design the company has been working on. The firm did announce the completion of a Critical Design Review of its Talon-A hypersonic test vehicle design in September and said that the goal was to conduct the first flight test of one of those vehicles next year. Separate testing is also ongoing to prepare the Roc, which was developed and built for Stratolaunch by Scaled Composites, a Northrop Grumman company, for its role as the launch platform.

Talon-A is a resuable, unmanned vehicle with various modular payload spaces to support various flight test activities. It is expected to be able to reach speeds of at least Mach 6, with hypersonic speed being defined as anything above Mach 5. 

The Talon-A, which is 28 feet long and has a wingspan of just over 11 feet, is a powered glider-type vehicle that uses a liquid fuel rocket motor to help propel it to the desired speed after launch. After completing its mission, it is designed to land on a conventional runway using its tricycle landing gear.

A rendering of Talon-A with its landing gear down., Stratolaunch
A graphic depicting, in very broad strokes, the basic profile of launches of Talon-A vehicles from the Roc., Stratolaunch

Stratolaunch is also working on a similar, but larger vehicle called Talon-Z, as well as a spaceplane called Black Ice that could be configured to carry cargo, and even possibly passengers.

The Talon-A design, or a derivative thereof, could be viable for use as a surrogate for hypersonic weapons that use unpowered boost-glide vehicles, such as Russia's Avangard or China's DF-17. North Korea also claimed to have tested a weapon of this type earlier this year. The mysterious fractional orbital bombardment system-like weapon that China has been testing recently appears to use some kind of hypersonic glider, as well. 

These are, of course, only some of the hypersonic weapons currently known to be in development in Russia, China, and other countries around the world, including the United States, reflecting a growing arms race in this regard. This has, in turn, prompted the U.S. military, among others, to initial work on systems to defend against these threats.

Hypersonic boost-glide vehicles present particular obstacles for defenders due to their combination of high speed and maneuverability while traveling along an atmospheric flight trajectory. This is a general flight pattern that is dramatically different from the ones that most missile defense systems, which have been focused for years primarily on detecting, tracking, and intercepting more conventional ballistic missiles, are optimized to protect against.

A graphic offering a very rudimentary depiction of a notional hypersonic boost-glide vehicle flight profile as compared to that of a typical ballistic missile. The flight path of a low-flying air-breathing hypersonic cruise missile is also shown., GAO

In response, the U.S. military has been looking to expand and improve its missile defense sensor networks. This includes plans for new space-based systems, as well as terrestrial ones. Just this week, the Pentagon announced that the construction of its first new Long-Range Discrimination Radar (LRDR) array, at Clear Space Force Station in Alaska, had been completed. Another LRDR array is eventually set to be built in Hawaii.

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LRDR has "the ability to search, track and discriminate multiple, small objects in space, including all classes of ballistic missiles," according to the Pentagon. "Future iterations of the radar's software will allow it to also track hypersonic missiles."

There is separate work being done on the development of new interceptors to actually try to shoot down incoming hypersonic weapons. MDA, together with the U.S. Navy, has previously announced plans to test a missile defense-specific version of the highly capable SM-6 missile against a surrogate for an "advanced maneuvering threat," a term that has been used to refer to hypersonic boost-glide vehicles.

In November, MDA had announced that it had hired Raytheon, Lockheed Martin, and Northrop Grumman to provide competing designs for an all-new Glide Phase Interceptor (GPI). The goal of the GPI program is to acquire an interceptor capable of knocking down a hypersonic boost-glide vehicle in the midcourse portion of its flight. 

Artwork Raytheon released in relation to its Glide Phase Interceptor (GPI) proposal., Raytheon

Any new sensors or interceptors will need to be tested against representative threats and the U.S. military's need to expand testing capacity to support its growing work on hypersonic defense, as well as actual hypersonic weapons, has been increasingly clear. MDA has leveraged previous U.S. military hypersonic weapon tests as one way to help gather relevant data for hypersonic defense work. 

However, having its own surrogate targets to test against, which could be built to be more representative of potential threats, would be a valuable addition to MDA's overall testing architecture. If the vehicle that Stratolaunch will now provide is designed to be reusable, it could introduce new economies to future testing regimens. 

Stratolaunch's goal is for the Roc, which only flew for the second time ever in April, to be eventually able to carry up to three Talon-A-sized vehicles at once. "This unique capability enables multiple hypersonic flight opportunities on a single day or the near-simultaneous launch of three Talon vehicles, which may support specific operational scenarios," according to the company's website. This might point, potentially, to Roc's future ability to support testing representing multiple incoming hypersonic threats at once depending on the size of the target design.

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In addition, a reusable vehicle combined with the Roc mothership would offer a very flexible system to support a high testing tempo at multiple locations. This could all be especially valuable given that the vast majority of U.S. hypersonic and missile defense-related flight and live-fire testing takes place at various locations across the Pacific.

For Stratolaunch itself, the new deal with MDA points to a more secure future for the company and for the Roc. After Paul Allen died, there were concerns that the entire enterprise might fold.  

As it stands now, the world's largest airplane looks set to become an important addition to the test assets supporting future U.S. military hypersonic defense developments.

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