Researchers at the U.S. Army Combat Capabilities Development Command Army Research Laboratory have successfully flown the VICTOR, a vertical take-off and landing drone powered by a heavy-fuel rotary engine that was rapidly developed using metal 3D printing, according to a report by Tom's Hardware. The engine runs on JP8, a denser kerosene-based fuel the military wants to use across as much of its gas equipment as possible.
JP8 is denser than regular jet fuel, which makes it attractive for cutting fuel load or extending range. It is also less volatile and harder to atomize, and its flash point of 140F, against minus 40F for gasoline, means an engine needs far higher compression to ignite it, making pressure leaks a common problem.
The Army Research Laboratory team used computational fluid dynamics and a clean-sheet design to optimize the heavy-fuel rotary engine and extract more performance from it. According to Tom's Hardware, rapid iteration allowed the researchers to improve fuel atomization and reduce compression leaks.
"The use of advanced manufacturing, including 3D metal printing, allowed us to rapidly redesign engine components based on lessons learned through experimentation," Dr. Kweon, one of the ARL researchers, said to Army.mil.
Kweon further explained that 3D printing allowed the team to design an air-cooled engine and ditch a bulky liquid cooling system, reducing the size of the propulsion system. Air cooling adds another layer of robustness by avoiding maintenance on a liquid cooling system, according to the report.
The engine does not drive the drone's propellers directly. It spins a 400-volt motor-generator that produces electricity for the propeller motors, letting the engine run independently at its most efficient revolutions per minute. Tom's Hardware compares the layout to hybrid electric cars on the road, with the difference that the engine has no mechanical link to the propellers.
That arrangement may include a battery so the drone can fly with the engine off, though the report says the military has not disclosed much about the VICTOR's battery configuration. With a battery system, the drone could cover large distances on a single fuel-up.
The VICTOR is a vertical take-off and landing aircraft, so it needs no runway. The Army has shared a video of its first flight, and the drone can take off and land on terrain that would be impossible for other, non-VTOL two-winged aircraft.
Analysis
Why This Matters
- The first flight shows a route to running small military drones on the same dense fuel as ground vehicles and aircraft, which could simplify how units store and move fuel.
- Using 3D printing to redesign engine parts quickly points to shorter development cycles for propulsion hardware that has to cope with difficult fuels.
- An air-cooled, hybrid layout could reduce maintenance demands, though the publicly released detail so far stops at a first-flight video.
Background
Heavy-fuel engines have long been of interest to the US military because JP8 is already the standard fuel for much of its ground equipment and aircraft, and using one fuel across a force simplifies logistics. Rotary engines are compact and light for their power output, which suits small aircraft, but they must be adapted to burn fuels that resist ignition. Hybrid electric propulsion, in which an engine generates electricity rather than driving a propeller through a shaft, is being explored across aviation because it lets the power source run at a steady, efficient speed. DEVCOM Army Research Laboratory is the Army's corporate research laboratory, and its work typically sits at the early, experimental end of development.
What to Watch
- Whether the Army Research Laboratory releases flight endurance, payload or battery details for the VICTOR beyond the first-flight video.
- Further flight testing of the 3D-printed, air-cooled engine design, and whether the approach moves out of the laboratory.
- Whether the single-fuel approach is extended to other unmanned systems, which the report identifies as the military's goal.
Checked
12 claims in this story checked against 1 source: 12 supported.
Show each claim
- SupportedDr. Kweon said, “The use of advanced manufacturing, including 3D metal printing, allowed us to rapidly redesign engine components based on lessons learned through experimentation.”Latest from Tom's Hardware: “"The use of advanced manufacturing, including 3D metal printing, allowed us to rapidly redesign engine components based on lessons learned through experimentation,” Dr. Kweon, one of the ARL researchers, said to Army.mil.”
- SupportedThe Army researchers successfully flew the VICTOR, a hybrid-electric drone with a 3D-printed heavy-fuel rotary engine.Latest from Tom's Hardware: “Researchers at U.S. Army Combat Capabilities Development Command (DEVCOM) Army Research Laboratory (ARL) recently successfully flew the VICTOR hybrid electric drone with a heavy-fuel rotary engine, rapidly developed thanks to metal 3D printing”
- SupportedThe engine spins a 400-volt motor-generator rather than driving the propellers directly.Latest from Tom's Hardware: “The heavy-fuel rotary engine doesn’t actually drive the drone’s propellers directly; it uses the engine to spin a 400-volt motor-generator to generate electricity to drive the propeller motors”
- SupportedMetal 3D printing enabled the team to design an air-cooled engine and remove a bulky liquid cooling system, reducing the propulsion system’s size.Latest from Tom's Hardware: “Dr. Kweon further explained that 3D printing allowed them to design an air-cooled engine and ditch a bulky liquid cooling system, reducing the size of the propulsion system.”
- SupportedThe VICTOR is a vertical-take-off-and-landing aircraft that can fly without a runway.Latest from Tom's Hardware: “The VICTOR drone is a vertical take-off and landing (VTOL) unmanned aircraft, able to fly without a runway.”
- SupportedThe engine runs on JP8, a denser kerosene-based fuel than regular jet fuel.Latest from Tom's Hardware: “The heavy fuel (JP8) used in the drone is a denser kerosene-based fuel source compared to regular jet fuel”
- SupportedThe military initiative is to power as much of its gas equipment as possible with a single fuel source.Latest from Tom's Hardware: “The JP8 fuel is part of the military’s initiative to power as much of its gas equipment on a single fuel source.”
- SupportedJP8 has a flash point of 140°F, compared with −40°F for gasoline.Latest from Tom's Hardware: “the fuel’s flash point is 140℉, compared to gasoline’s -40℉”
- SupportedThe researchers used computational fluid dynamics and a clean-sheet design to optimize the engine.Latest from Tom's Hardware: “The researchers used computational fluid dynamics (CFD) and a clean-sheet design (designing from scratch, essentially), allowing the engineers to come up with more innovative solutions to get more out of the engine with less.”
- SupportedRapid iteration improved fuel atomization and reduced compression leaks.Latest from Tom's Hardware: “The rapid iteration eventually allowed the researchers to improve fuel atomization and decrease compression leaks.”
- SupportedThe engine can spin independently at its most efficient RPM, with no mechanical link to the propellers.Latest from Tom's Hardware: “allowing the engine to spin independently at its most optimal RPM — similar to some hybrid EVs on the road today, except that the engine doesn’t have a mechanical link to the propellers.”
- SupportedThe report says the system may include a battery, but the military has not disclosed much about the VICTOR’s battery configuration.Latest from Tom's Hardware: “This system may include a battery for the drone to fly without the engine running; however, the US military has not disclosed much about the VICTOR drone’s battery configuration.”
