DARPA and Northrop Grumman Complete First Flight of XRQ-73 Hybrid UAV

This article is based on an official press release from Northrop Grumman.

In a significant milestone for military aviation, the Defense Advanced Research Projects Agency (DARPA) has successfully conducted the first flight of the XRQ-73, an experimental hybrid-electric uncrewed aerial vehicle (UAV). According to an official press release from Northrop Grumman and supplementary industry research, the inaugural flight took place at Edwards Air Force Base in California in April 2026, with the official announcement following on May 6, 2026.

Developed under DARPA’s Series Hybrid Electric Propulsion AiRcraft Demonstration (SHEPARD) program, the XRQ-73 was built in collaboration with the Air Force Research Laboratory (AFRL), Northrop Grumman, and its rapid-prototyping subsidiary, Scaled Composites. The aircraft is designed to test and validate the military utility of series hybrid-electric propulsion systems in a fieldable design.

By decoupling the combustion engine from the direct propulsion of the aircraft, the XRQ-73 aims to provide future military fleets with enhanced fuel efficiency, reduced emissions, and ultra-quiet operation. These characteristics are highly sought after for stealthy intelligence, surveillance, and reconnaissance (ISR) missions in contested environments.

The SHEPARD Program and XRQ-73 Development

The SHEPARD program is classified by DARPA as an “X-prime” initiative. As noted by former SHEPARD Program Manager Steve Komadina in 2024, the primary objective of an X-prime program is to leverage emerging technologies and rapidly “burn down system-level integration risks” to mature new, mission-ready aircraft designs quickly.

The XRQ-73 builds directly upon the technological foundation laid by the earlier Great Horned Owl (GHO) project. That initiative produced the XRQ-72 drone for the Intelligence Advanced Research Projects Activity (IARPA) and the AFRL. However, the XRQ-73 represents a significant scale-up in size and capability. Industry research indicates that the new aircraft weighs approximately 1,250 pounds (567 kilograms), making it substantially larger than the XRQ-72, which weighed between 300 and 400 pounds.

Aircraft Classification and Design

The U.S. Department of Defense classifies the XRQ-73 as a Group 3 Uncrewed Aircraft System (UAS). Based on standard U.S. military definitions, Group 3 drones typically operate at altitudes ranging from 3,500 to 18,000 feet and achieve top speeds between 100 and 250 knots (up to 288 mph). To maximize aerodynamic efficiency and stealth, the XRQ-73 utilizes a tailless flying-wing configuration.

Technological Innovations: Series Hybrid-Electric Propulsion

The core innovation driving the XRQ-73 is its series hybrid-electric propulsion system. Unlike parallel hybrid systems, where both a gas engine and an electric motor physically drive the aircraft’s propellers or fans, a series hybrid system operates differently. According to technical overviews of the program, the XRQ-73 uses a conventional fuel-burning gas turbine engine solely to generate electricity. This electrical power is then routed to electric motors that drive the aircraft’s propulsion.

This architecture allows the combustion engine to run continuously at its most efficient operating point, regardless of the aircraft’s airspeed or maneuvering requirements. The result is a highly efficient power generation cycle that extends the aircraft’s endurance.

Stealth and Advanced Payload Capabilities

Beyond fuel efficiency, the series hybrid-electric system offers profound tactical advantages. The electric propulsion motors are ultra-quiet, significantly reducing the aircraft’s acoustic signature. Furthermore, the system lowers the thermal (infrared) signature of the drone, making it much harder for adversary air defense systems to detect.

Additionally, because the gas turbine acts as a high-capacity flying generator, the XRQ-73 can produce substantial amounts of electrical power. This opens up new possibilities for integrating high-energy payloads directly into the aircraft’s systems. Future iterations could easily support power-hungry advanced sensors, electronic warfare (EW) jamming suites, or even directed energy weapons.

Flight Testing and Official Statements

While DARPA officially stated the first flight occurred in April 2026, metadata from released photographs suggests the exact date may have been April 14, 2026. The successful test at Edwards Air Force Base marks the beginning of a comprehensive flight-test campaign expected to run throughout the year.

In a statement regarding the successful flight, DARPA highlighted the broader implications of the technology:

“This milestone is not just about a single flight. The architecture proven by the XRQ-73 paves the way for new types of mission systems and delivered effects. We look forward to advancing this technology through the flight test program and delivering new capabilities for our warfighters.” — Lt. Col. Clark McGehee, DARPA SHEPARD Program Manager

Northrop Grumman also emphasized the operational flexibility the new propulsion system provides to the military:

“The XRQ-73’s innovative hybrid-electric propulsion system combines fuel efficiency, reduced emissions and enhanced operational flexibility, enabling new mission possibilities and supporting the evolution of new aircraft designs.” — Northrop Grumman Official Statement

AirPro News analysis

The successful first flight of the XRQ-73 highlights a critical pivot in the U.S. military’s approach to uncrewed aerial reconnaissance. As traditional, combustion-engine drones like the MQ-9 Reaper face increasing vulnerability to modern, sophisticated air defense networks, the Pentagon is actively seeking quieter, low-observable alternatives that can persist in semi-contested or denied airspaces.

We view the XRQ-73 not as a final production model, but as a vital technology demonstrator. Because it carries an “X” designation, its primary mission is to generate actionable flight data. The success of this series hybrid-electric architecture will likely dictate the design parameters for the next generation of stealthy, long-endurance ISR platforms fielded by the U.S. Air Force and allied branches in the 2030s.

Frequently Asked Questions

What is a Group 3 UAS?
According to U.S. Department of Defense classifications, a Group 3 Uncrewed Aircraft System (UAS) is a drone that typically weighs between 51 and 1,320 pounds, operates at altitudes between 3,500 and 18,000 feet, and flies at speeds ranging from 100 to 250 knots.

What is the difference between a series and parallel hybrid aircraft?
In a parallel hybrid system, both the combustion engine and the electric motor are mechanically connected to the propulsion system (e.g., the propeller) and can drive it simultaneously. In a series hybrid system, like the one used on the XRQ-73, the combustion engine only turns a generator to produce electricity. That electricity then powers separate electric motors that drive the aircraft.

Will the XRQ-73 be used in combat?
No. The XRQ-73 carries an “X-plane” designation, meaning it is an experimental technology demonstrator. It is designed to test and prove the viability of series hybrid-electric propulsion so that the technology can be integrated into future operational combat and reconnaissance aircraft.

Sources

• Northrop Grumman