Unmanned

Air Force Looks to Hybrid Electric Solution for eVTOL and UAS Energy Concerns

By Kelsey Reichmann | March 4, 2021
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The X-Engine technology would use fuel to power a generator and charge the aircraft’s batteries extending its flight time and range. (LiquidPiston)

The Air Force is investing in LiquidPiston’s X-Engine technology to create a hybrid-electric propulsion system to power emerging technologies like unmanned aircraft systems (UAS) and orbs, the company announced on March 4. 

The Small Business Technology Transfer (STTR) contract worth $150,000 was awarded through AFWERX to support Agility Prime, a program developing electric vertical take-off and landing (eVTOL) aircraft for commercial and military use. 

UAS and eVTOLs are being developed with battery-powered propulsion systems which have limited their range of flight. The X-Engine technology would use fuel to power a generator and charge the aircraft’s batteries extending its flight time and range, according to the company. 

“Today’s solutions for power and energy are held back by a lack of technological innovation; gasoline engines are inefficient, diesel engines are big and heavy, and while the world wants to go electric, batteries lack significantly compared to the energy density of fuel,” Alec Shkolnik, CEO and co-founder of LiquidPiston, said in a statement. “The X-Engine solves these challenges, and with this contract, we look forward to showcasing the value a hybrid-electric configuration can bring to unmanned flight.”

The X-Engine runs on JP-8, diesel, and other heavy fuels but is 30 percent more fuel-efficient than a diesel engine, according to LiquidPiston. It is also five to 10 times smaller and lighter than a diesel engine and is two to four times more fuel-efficient than a small turbine. 

The Army also awarded LiquidPiston a Small Business Innovation Research (SBIR) contract in December 2020 to develop the X-Engine platform for small tactical generators. 

“Our work with the Air Force demonstrates the versatility and utility of our X-Engine across the Department of Defense including our ongoing work with the US Army,” Shkolnik said. 

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  • Been watching the eVTOL project for a while. Very interesting hybrid addition and look forward to seeing how it develops.