The SHEPARD program, managed by Steve Komadina, aims to mature a specific propulsion architecture and power class, leveraging the series hybrid electric architecture and component technologies from the earlier AFRL/IARPA Great Horned Owl (GHO) project. This “X-prime” program seeks to rapidly integrate emerging technologies, reducing system-level risks and paving the way for the quick fielding of a new missionized long-endurance aircraft design.
According to Komadina as cited in a DARPA essay, The DARPA X-prime is engineered to be a missionized long-endurance aircraft.
The XRQ-73 aircraft, weighing approximately 1,250 pounds, is classified as a Group 3 UAS. Its first flight is expected by the end of 2024. With its hybrid-electric propulsion system, the XRQ-73 promises to offer enhanced endurance, reduced emissions, and lower operating costs compared to traditional fossil-fuel-powered aircraft. Komadina emphasizes that “The SHEPARD program is maturing a specific propulsion architecture and power class, which will be of great benefits to the Department of Defense.”
The XRQ-73’s hybrid-electric propulsion system combines a traditional gas turbine engine with an electric motor and battery pack. This architecture enables the aircraft to optimize fuel efficiency and reduce noise levels. The series hybrid electric architecture allows for the efficient transfer of power between the gas turbine, electric motor, and battery pack, ensuring optimal performance and endurance.
When compared to existing UAS platforms, the XRQ-73’s hybrid-electric propulsion system offers distinct advantages. Traditional UAS platforms like the MQ-9 Reaper rely on internal combustion engines, which, while powerful, are noisy and have limited endurance due to fuel constraints. Purely electric UAS, on the other hand, are often hampered by the current limitations of battery technology, which restricts their range and payload capacity.
The XRQ-73, with its hybrid-electric system, bridges the gap between these two extremes. It offers the extended range and endurance of a combustion engine with the efficiency and stealth of electric propulsion. This hybrid approach not only improves operational flexibility but also reduces the logistical footprint, as the aircraft can refuel more efficiently and require less maintenance compared to traditional combustion engines.
