The US Air Force Research Laboratory (AFRL) Advanced Power Technology Office (APTO) has conducted ground-based testing on a diesel engine for unmanned aircraft.

The testing was carried out in collaboration with Engineered Propulsion Systems and the Arnold Engineering and Development Center.

Designed by Engineered Propulsion Systems, the Graflight V-8, 4.3l engine is intended to replace current manned and unmanned aircraft internal combustion engines.

The ground testing of the Graflight engine was conducted at Arnold Engineering and Development Center’s T-11 Test Cell, under operational flight conditions ranging from sea level to 30,000ft and back to validate performance factors such as fuel consumption, calibration, vibration, and power output.

Data collected from the test will be used to prepare for future flight testing, confirm the engine’s efficiency and validate the engine’s performance characteristics for future airforce users.

The advanced diesel engine has the ability to increase the utility and ease the logistics burden of military aircraft missions, the US Air Force stated.

“It is claimed to use up to 40% less fuel than typical aircraft engines, with less vibration.”

It is claimed to use up to 40% less fuel than typical aircraft engines, with less vibration. The increased efficiency extends the engine’s operational range and loiter time by up to 50%.

APTO Aviation Working Group lead captain Randall Hodkin said: “Since this engine requires less fuel to fly the same distance, an aircraft or unmanned air vehicle could either carry more payload or fly a longer mission.

“Overall, if implemented, this technology has the potential to provide the airforce a significant improvement in mission flexibility.”

The engine uses Jet-A or JP-8 fuels that are readily available in-theatre, reducing or eliminating the need to transport specialised fuels.

Image: The AFRL APTO’s high-efficiency innovative aviation diesel engine is shown here in the Arnold Engineering Development Center T-11 Test Cell. Photo: courtesy of AEDC.