Communication is key, during war or peace. In this day and age, both require the ability to conduct airborne intelligence, surveillance, and reconnaissance (ISR), at will and upon demand. But there continue to be challenges in obtaining real-time airborne ISR. For example, helicopters are relatively limited by distance capabilities and flight times, while fixed-wing manned and unmanned aircraft can fly farther and longer but require either aircraft carriers or large, fixed land bases with long runways often longer than a mile.
It was with those challenges in mind that DARPA launched the Tactically Exploited Reconnaissance Node (Tern) program in May 2014 with the Office of Naval Research (ONR), in the hopes of combining the strengths of both land- and sea-based approaches to supporting airborne assets. It was envisioned that Tern would enable on-demand, ship-based unmanned aircraft systems (UAS) operations without extensive ship modifications, providing ships with a “mission truck” that could transport ISR and strike payloads far from the host vessel.
Recently, DARPA awarded Phase 3 of Tern to a team led by the Northrop Grumman Corp. The first two phases focused on preliminary design and risk reduction. In Phase 3, DARPA intends to build a full-scale demonstrator system of a medium-altitude, long-endurance (MALE) UAS designed to use forward-deployed small ships as mobile launch and recovery sites.
"We intend to highly leverage our Unmanned Systems Center of Excellence to develop and demonstrate this type of demanding unmanned systems capability," said Chris Hernandez, Vice President—Research, Technology, and Advanced Design, Northrop Grumman Aerospace Systems.
Initial ground-based testing, if successful, would lead to an at-sea demonstration of takeoff, transition to and from horizontal flight, and landing—all from a test platform with a deck size similar to that of a destroyer or other small surface-combat vessel.
“The design we have in mind for the Tern demonstrator could greatly increase the effectiveness of any host ship by augmenting awareness, reach, and connectivity,” said Dan Patt, DARPA Program Manager.
Progress continues to be made on Tern toward creating a new class of unmanned air system combining shipboard takeoff and landing capabilities, enhanced speed and endurance, and sophisticated supervised autonomy. Tern could open up future capabilities for Navy small-deck surface combatants and U.S. Marine Corps air expeditionary operations.
“Through Tern, we seek to develop and demonstrate key capabilities for enabling distributed, disaggregated U.S. naval architectures in the future,” said Bradford Tousley, Director of DARPA’s Tactical Technology Office (TTO), which oversees Tern.
The Tern Phase 3 design envisions a tailsitting, flying-wing aircraft with twin counter-rotating, nose-mounted propellers. The propellers would lift the aircraft from a ship deck, orient it for horizontal flight, and provide propulsion to complete a mission. They would then reorient the craft upon its return and lower it to the ship deck. The system would fit securely inside the ship when not in use.
"We believe our unique ship-based unmanned systems experience, expertise, and lessons learned from programs including our MQ-8B/C Fire Scout, MQ-4C Triton, X-47A Pegasus and X-47B UCAS, is critical to the success of the Tern," said Hernandez.
The potential capabilities inherent in Tern are said to have been on the Navy’s wish list in one form or another since World War II. The production of the first practical helicopters in 1942 helped the U.S. military realize the potential value of embedded vertical takeoff and landing (VTOL) aircraft to protect fleets and reduce the reliance on aircraft carriers and land bases.
The Tern demonstrator is expected to resemble the Convair XFY-1 Pogo, an experimental ship-based VTOL fighter designed by the Navy in the 1950s to provide air support for fleets. Despite numerous successful demonstrations, the XFY-1 never advanced beyond the prototype stage, in part because the Navy at the time was focusing on faster jet aircraft and determined that pilots would have needed too much training to land on moving ships in rough seas.
“Moving to an unmanned platform, refocusing the mission, and incorporating modern precision relative navigation and other technologies removes many of the challenges the XFY-1 and other prior efforts faced in developing aircraft based from small ships,” Patt said. “Tern is a great example of how new technologies and innovative thinking can bring long-sought capabilities within reach.” Once airborne, the VTOL Tern will transition an efficient flying wing configuration.
DARPA and the Navy have a Memorandum of Agreement to share responsibility for the development and testing of the Tern demonstrator system. The Marine Corps Warfighting Laboratory has also expressed interest in Tern’s potential capabilities and is providing support to the program.
The Northrop Grumman Tern team includes its wholly owned subsidiary Scaled Composites, as well as GE Aviation, AVX Aircraft Co., and Moog.