Two recent remarkable hypersonic test flights used a groundbreaking capability developed by US-based defence and aerospace giant Northrop Grumman, designed to allow high-speed systems to safely navigate and maintain manoeuvrability even when GPS signals are not available.
The company announced this week in an exclusive statement to Defense News that the inertial measurement unit (IMU) they developed successfully served on the first two major hypersonic flights of Stratolaunch’s Talon-A hypersonic glide vehicle in December 2024 and March 2025.
The successful integration of IMU technology on a hypersonic aircraft capable of cruising at Mach 5 (five times the speed of sound) or faster and performing complex maneuvers is an industry first, said Jonathan Green, chief technology officer of Northrop Grumman’s new capabilities development division. “It has met all of our objectives to the fullest extent … and the fact that it has successfully completed this first flight test is an incredibly positive reflection of how successfully we have matured this technology,” Green said in an interview.
The Pentagon also announced the Talon-A tests this week. These tests represent the first successful flights of a reusable hypersonic vehicle since the end of the legendary X-15 program in 1968. The U.S. has significantly increased its investment in high-speed weapons and aircraft technologies in recent years, and the test platform offered by Stratolaunch reflects a growing urgency to create critical opportunities for real-world flight testing of components and subsystems that are vital to supporting large-scale hypersonic development efforts.
Precise Navigation Possibility Without GPS
Northrop Grumman’s Advanced Hypersonic Technology IMU was specifically designed to enable high-speed systems to navigate with precision without the need for GPS signals. This critical capability provides a vital advantage in situations where GPS signals are rendered unreliable or eliminated due to adverse weather conditions, difficult terrain, or hostile jamming and spoofing attempts.
Using highly sophisticated sensors to understand how a platform moves in its environment, the IMU constantly calculates the system’s current location, speed, and orientation. It processes this data to determine with high accuracy where the system is moving and what path it should follow to stay on its designated orbit. According to Josei Chang, senior director of advanced technologies at Northrop Grumman Mission Systems, the system performed flawlessly during flight tests, calculating the vehicle’s path with astonishing accuracy.
Northrop Grumman has been developing IMUs for spacecraft for many years. However, this new version is a smaller and much more robust system that has been redesigned to fit into the limited space of an aircraft. It is also specifically designed to successfully withstand the harsh physical conditions (high temperatures, vibrations, accelerations, etc.) of hypersonic flights at Mach 5 and above.
“What we did at Northrop Grumman was develop an inertial navigation technology that came out of our deep background in space-based inertial navigation,” said Jonathan Green. “We took that capability, that portfolio of technologies, and developed it further for this particular application.”
Future Tests and Collaborations
Hypersonic flight represents a significant milestone for the innovative system, which is still in the midst of intensive research and development. An abstract prepared for an upcoming navigation conference states that Northrop Grumman is developing the IMU technology in collaboration with the U.S. Army Combat Capabilities Development Command’s Aviation and Missile Systems Center. However, company officials declined to confirm any formal development partners or contracts.
Northrop Grumman also has ambitious test plans for the coming period. The company plans to test the IMU on a sounding rocket this quarter and is focused on another major test event at Holloman Air Force Base in Utah later this year. The primary goal of this test will be to analyze in detail how the system will perform in a high-gravity environment.
Company officials are also closely monitoring the Talon-A’s test schedule, but Jonathan Green would not say for sure whether the IMU will be included in Stratolaunch’s next hypersonic flight, scheduled for this spring or summer.
“This strategic partnership with Stratolaunch to bring the system to market and test it in real-world flight conditions was absolutely critical,” Green said. “It really shows how important it is to be able to test these types of advanced technologies and have the resources to do that.” Northrop Grumman’s success is a promising development for future hypersonic technologies, paving the way for safe and precise navigation of high-speed systems even in the absence of GPS.
