RDAS: Next Generation Protection for F-35 and Beyond

Asian Military Review interviews Michelle Moholt, Raytheon technical director and chief architect for RDAS and Common Open Secure Mission Computing (COSMC).

Raytheon is using the technology it has developed for its Electro-optical Distributed Aperture System (EO-DAS) system for the F-35 to develop a versatile and modular derivative to bring similar capabilities to a wider range of platforms.

When the Lockheed Martin F-35 Lightning II Joint Strike Fighter first emerged, some of its technology was unique, and seemed almost impossibly futuristic. A Northrop-Grumman AN/AAQ-37 Distributed Aperture System provided missile detection and tracking (including launch point detection) and a high definition Infra-Red Search and Track (IRST) capability all around the aircraft, using six sensors to provide complete spherical coverage. The resulting picture was projected in the pilot’s helmet visor, allowing him to ‘look’ through the cockpit floor, or in any direction, even if it might be ‘obscured’ by the airframe.

Former F-16 pilot and Wing Commander John P. ‘Bama’ Montgomery, 5th Generation Improvements Derivatives manager at Northrop Grumman memorably compared it to “sitting in Wonder Woman’s invisible jet, and being able to see in all directions.” But behind the ‘gee whizzery’ implicit in that statement, DAS had the crucial responsibility of providing an F-35 pilot with spherical 360° missile warning and situational awareness.

But while impressive and vital, the Northrop Grumman system is now becoming obsolescent, and the replacement EO-DAS being supplied by Raytheon promises to deliver a ‘next generation capability’, and one that will be five times more reliable and twice as capable as the older AN/AAQ-37. This will leverage a more than 50 percent reduction in operations and sustainment costs, a 45 percent reduction in unit recurring costs, and savings of more than $3 billion in life cycle costs.

Furthermore progress has been rapid, and service entry is coming close according to Michelle Moholt: “We’ve completed qualification testing and we have delivered several test and evaluation centres to Lockheed Martin and we are ahead of our first deliveries in the first quarter of 2023.”

But EO-DAS is more than a simple modernised one-for-one replacement of AN/AAQ-37 on the F-35, and promises to bring this once ‘unique-to-F-35’ capability to a whole range of platforms, while also adding laser warning and an inertial measurement unit inside the system.

The Raytheon Distributed Aperture System or RDAS is an airframe agnostic sensor suite that is tailorable to multiple platforms. RDAS uses the same next-generation technology as the EO-DAS used on the F-35, according to Michelle Moholt. “We’ve leveraged a lot of the hardware and the technology from EO-DAS, and we’ve advanced it to the air cooled configuration,” Moholt says.

Being air-cooled means that the aircraft does not have to provide additional cooling and has allowed Raytheon to reduce size, weight and power (SWaP) requirements, to reduce cost and to broaden the range of platforms that the system can be fitted to.

This versatility is further facilitated by the open architecture, platform-agnostic COSMC (Common Open Secure Mission Computer) processing element that hosts the RDAS software and firmware.

“This mission computer serves as the connective tissue across all of the different sensors that are hosted on a given platform,” Moholt explained. “It was developed using model-based systems engineering and gives us the ability to adapt the design. It has a Sensor Open Systems Architecture, or SOSA, aligned so we can upgrade obsolescence issues quickly and rapidly deploy different configurations with different platform. It’s all about getting capability out to aircrews and operators.”

The RDAS gives multiple resolutions and the number of sensors can be scaled up and down based on the platform to give 360° imaging around the aircraft, ranging from four to eight sensors. “We’ve spent a lot of investment dollars in developing the next generation of these sensors so that we can see in those cluttered environments and in detection range.”

The RDAS employs a large, best-in-class focal plane array that boasts best-in-class detection range and resolution, even in cluttered environments and uses multiple high-resolution infrared sensors mounted around a platform to produce a continuous 360-degree spherical image that allows pilots and crew members to effectively “look through” those parts of the airframe that would otherwise obstruct their view.

RDAS effectively turns night into day and provides unmatched 360-degree situational awareness, significantly reducing and relieving crew workload. It can provide passive missile detection capability, autonomously detecting, locating, tracking, and warning of any incoming threats that has an infrared signature. The system’s high visual acuity can aid pilots by providing obstacle avoidance even in the most contested environments, enhancing platform survivability.

After winning a contract from Lockheed Martin to develop a next-generation electro-optical Distributed Aperture System (DAS) for the F-35 in June 2018, Raytheon said that it was hoping to install the technology on helicopters, and there were reports in February 2019 that a system, then known as the Advanced Distributed Aperture System, had undergone 200 hours of flight testing on US Army Sikorsky UH-60 Black Hawks.

Moholt told Asian Military Review that rotary and future vertical lift were potential applications for RDAS, and that the system would provide these kind of platforms with a “technology advantage”.

“We’re working to get our size, weight and power down so that we can fit on rotary platforms, as well as on unmanned aerial systems,” she said. “We’ve actually worked this past year and invested some money into getting into a lower configuration, leveraging our COSMC secure mission computer platform, and we’ve been able to reduce size, weight and power significantly, so it looks like we’ll actually be very viable for those markets.”

Another perhaps particularly strong potential market for RDAS is the fast jet combat air sector, with the platform agnostic RDAS requiring no cooling from the platform and less electrical power and thereby offering the potential to simply upgrade fourth generation fighter aircraft types with F-35 like capabilities.

Raytheon is looking to have a capability that it can offer to the customer by 2024, but is also looking at integrating RDAS with the company’s electronic warfare system, radars and situational awareness tools to provide an increased battlespace advantage for aircrews and operators.

by Jon Lake