Northrop Grumman and Raytheon have revealed that they have been working together on a scramjet-powered hypersonic cruise missile, which uses an engine that is entirely 3D-printed. Their design is competing against one from Lockheed Martin under the Defense Advanced Research Project’s Hypersonic Air-breathing Weapon Concept program, or HAWC.
The two companies publicly announced their partnership at the 2019 Paris Air Show on June 18, 2019, but they have been working together secretly for years on HAWC, according to Aviation Week. DARPA began the HAWC program in 2014, in cooperation with the U.S. Air Force Research Laboratory (AFRL).
“We have a flight test planned for the near future where we will begin flying this particular class of weapon system,” Tom Bussing, the Vice President of Raytheon’s advanced missile system division, told reporters in Paris. “This weapon is fundamentally game-changing. There’s nothing like it.”
Raytheon had revealed concept art of the missile ahead of the Paris Air Show. From what we can see so far, the design has a relatively typical layout for this weapon concept, with a rocket booster attached to the rear of the main scramjet-powered weapon. The booster motor will accelerate the missile to near hypersonic speed in order for the scramjet to work properly, before falling away.
Concept art of Northrop Grumman and Raytheon’s HAWC design, at right, along with an unpowered hypersonic boost-glide vehicle design. Raytheon had submitted a bid to build this kind of hypersonic vehicle for DARPA’s Tactical Boost Glide (TBG) program, as well as one for the US Air Force’s Air-launched Rapid Response Weapon (ARRW) program, but lost out to Lockheed Martin in both cases.
The two partners offered few details about the scramjet itself, but said that it leveraged their decades of combined experience in hypersonics. This includes the development of the scramjet-powered X-43A hypersonic test vehicle for NASA. General Applied Science Laboratory (GASL), then part of Allied Aerospace, built the engine for this craft in the 1990s.
In 2003, Alliant Techsystems (ATK) bought GASL. In 2015, ATK merged with Orbital Sciences Corporation, which had also worked on the X-43A program, to form Orbital ATK. In 2018, Northrop Grumman purchased Orbital ATK, renaming it Northrop Grumman Innovation Systems, the division of the company that is now working with Raytheon on HAWC.
The X-43A remains the fastest jet-powered air vehicle to date after it hit a top speed of Mach 9.6 – approximately 7,000 miles per hour – during a flight test in 2004. But John Wilcox, Northrop Grumman’s Vice President of Advanced Weapons and Technology, said that the new engine was multiple generations ahead of the one developed for the X-43A.
He also said that the company had built the scramjet entirely using advanced additive manufacturing processes, commonly known as 3D printing, which helped reduce the design’s total weight. It is reportedly half the weight of the scramjet Boeing developed for its experimental X-51A Waverider more than a decade ago. Finding ways to keep the overall size and weight down is important for HAWC, which is meant to be a relatively small hypersonic weapon that even a fighter jet-sized aircraft might be able to carry. The X-43A weighed 3,000 pounds and required a modified B-52 bomber to lift it.
As for the overall design of Northrop Grumman and Raytheon’s missile, like the X-51A, it is also a “waverider” design, which “skips” on top of the shockwaves produced during high-speed flight to produce additional lift. The main missile has a contoured nose that hides its inlet, the design of which is classified, according to Aviation Week. Ensuring proper airflow into the scramjet engine at extremely high speed, while also keep drag to a minimum is a complex task.
Boeing’s X-51A Waverider.
The shrouded inlet could also offer stealthy characteristics, making the missile even more difficult to spot. The extreme speed and atmospheric flight profiles of hypersonic weapons, together with their maneuverability, already make hypersonic weapons, in general, difficult, if not impossible to spot, track, and intercept. This makes them ideal for penetrating through heavy air defenses to execute short- or no-notice strikes against time-sensitive targets or otherwise critical targets.
A powered design, such as the one that Northrop Grumman and Raytheon are working on now, would potentially have unique performance over the unpowered boost-glide vehicles, another common type of hypersonic weapon, as well. You can read more about the game-changing capabilities of both powered and unpowered designs in a past War Zone feature here.
It’s also important to note that DARPA and the Air Force have described HAWC as some of a technology demonstration that would lead into the development of a more refined hypersonic cruise missile. So, it is unclear when the missile, or a follow-on design, might actually become operational.
An overview of the HAWC program.
A first flight would certainly be an important step in that direction. While Raytheon’s Bussing did not say specifically when the first flight of their design would occur, in its most recent budget request, DARPA said HAWC flight testing was set to begin in the 2020 Fiscal Year, which starts on Oct. 1, 2019. It is possible that the program, or Northrop Grumman and Raytheon’s particular design, is moving ahead of schedule.
HAWC program schedule details from DARPA’s Fiscal Year 2020 budget request.
“We’re on track for both to have flights … before the calendar year ends,” Dr. Steven Walker, head of DARPA, told reporters on May 1, 2019, referring to HAWC and a second hypersonic weapons program known as Tactical Boost Glide (TBG). But when “you actually get into the building of these things and qualifying the hardware, … things tend to slip,” he added.
There is a real push throughout the U.S. military to move quickly to both develop and actually field hypersonic weapons for air-launched, as well as sea- and ground-based applications. Just last week, the Air Force revealed that it had conducted the first captive-carry flight test of the AGM-183A Air-launched Rapid Response Weapon, or ARRW, which is an air-launched unpowered boost-glide vehicle design.
Hypersonic developments among potential opponents, especially Russia, have been driving the United States to speed up its own work in this space. China is also actively pursuing hypersonic weapons.
Work on advanced scramjets could also support the development of hypersonic manned or unmanned aircraft down the road. DARPA is separately working on a hybrid engine that combines the features of a traditional jet turbine with that of a ramjet or scramjet under the Advanced Full Range Engine (AFRE) program. This configuration, also known as a turbine-based combined-cycle propulsion (TBCC) arrangement, would allow an aircraft to accelerate from a standing start to hypersonic speeds and then slow back down, making it more practical for regular use using conventional runways.
Orbital ATK, and now Northrop Grumman, is working on the AFRE effort. There are other similar developments publicly the works elsewhere, as well, including Lockheed Martin’s Skunk Works advanced design division’s SR-72 hypersonic plane concept, and that’s to say nothing of other projects that might be in progress in the classified realm.
All told, the exciting and potentially revolutionary work within the U.S. military on hypersonic weapons seems to be moving ahead at its own increasingly feverish clip. Northrop Grumman and Raytheon’s flight test of their HAWC design, likely to come within the next six months, will be another important step forward in these developments.
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