The Offensive Anti-Surface Warfare Increment 2.0 (OASuW 2.0) program is underway once again, a Northrop Grumman executive confirmed to Naval News this month at the Surface Navy Association’s National Symposium. The effort brings back a program that originally planned to field the once-cancelled Hypersonic Air Launched Offensive (HALO) missile.
The program was not shuttered entirely in April 2024 when the U.S. Navy first confirmed HALO’s cancellation to Naval News. The missile in development was cancelled and the program was restructured and re-evaluated to scope in lower cost, more available weapons as the time to fielding requirements became more urgent.
Gordon LoPresti, Northrop Grumman’s Senior Director of Propulsion Systems and Controls, spoke to Naval News about the future of Northrop Grumman’s 21-inch motor and how additional motor development programs in Northrop Grumman could contribute to the OASuW 2.0 program.
“The baseline SM-6 uses a 14-inch second stage rocket motor, and [the 21-inch motor] can significantly extend range, increase velocity, and increase the altitude in which engagements can occur,” LoPresti explained to Naval News in an interview. “That’s where it started. The Navy has continued to develop their vision for a workhorse motor that can be used across a number of different [types] of ordnance.”
The 21-inch motor has potential applications across air, sea, surface, and land engagements beyond the new SM-6 Block IB. Successful testing wrapped in late 2024 and the competition, with Northrop Grumman and Anduril, ended in November with the former now being qualified to deliver the new motors.
Northrop Grumman’s recently certified 21-inch solid rocket motor, originally designed for the hypersonic SM-6 Block IB, won’t be directly applied to the OASuW 2.0 program, but the company does expect solid rocket motors to be part of the mix of propulsion systems pitched to fulfill the program’s requirements. Navy officials have emphasized a focus on affordability and scalable production for the new HALO missile above all else, avoiding some exquisite propulsion systems.
“The [21-inch motor] is probably a little too big to be able to serve the purposes of HALO,” LoPresti said. “Are they potentially considering solid rocket motors? Absolutely. I certainly believe they are considering it.”
Naval News understands that in a surface or air-launch capability, Northrop Grumman’s 21-inch motor delivers roughly twice the range and twice the height of legacy 14-inch motors. with a much higher burnout speed included.
With the SM-6 Block IB program under review in a ‘strategic pause’, LoPresti could not comment on the U.S. Navy’s intentions or plans for the program’s future. Questions were deferred to the service regarding program intentions and current progress.
The Department of the Navy has worked to re-evaluate its hypersonic weapons portfolio with lower cost systems that can be fielded in larger numbers. HALO’s exquisite design resulted in extremely high costs for development, including additional research into hydrocarbons that can detonate in the short length of the missile’s scramjet or ramjet motor. Since then, the U.S. Navy has pivoted toward systems that use solid rocket motors.
Candidates for OASuW Increment 2 are now weapons like the Advanced Capacity Maritime Effector (ACME), which explicitly mentions investment into new propulsion methods for time sensitive strike, aiming for rapid development. ACME FNC lists goals for an engineering and manufacturing development phase in FY2030 and early operational capability in FY2031.
China Lake’s internally developed Capacity High-Altitude Integrated Naval Strike Weapon (CHAINSAW), a testbed missile used to test ramjet propulsion, is another option for a future OASuW 2.0 missile. The U.S. Navy tested CHAINSAW on a BQM-34 target drone last year.
Lockheed Martin has its internally developed Mako as a potential OASuW 2.0 weapon candidate, which it unveiled at Sea Air Space 2024 after seven years of internal research and development.
The U.S. Navy is evaluating multiple options all capable of being rapidly fielded in the coming years.
