The US Army has awarded a Phase II contract to technology start-up LiquidPiston to develop its Hybrid Electric X-Engine (HEXE) propulsion system.    

The $1.7m contract is part of the Army’s plan to achieve Future Tactical Unmanned Aircraft System (FTUAS) vertical take-off and landing (VTOL).

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This requires the propulsion system to deliver fuel-efficient power and enhanced take-off and inflight capabilities, ensuring compatibility with military-grade heavy fuels.

The latest deal follows a successful conclusion of Phase I xTechSearch Small Business Innovation Research (SBIR).

LiquidPiston’s HEXE system was prototyped and tested towards the end of Phase I. 

The new system offers electric-assist sprint and climb modes and ensures a quiet, electric-only cruise.

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US Army Combat Capabilities Development Command Army Research Laboratory Strategic Partnerships Office Zeke Topolosky said: “One of the army’s major areas of focus for modernisation is Future Vertical Lift (FVL).

“Over the past few years, Army xTech judging panels have repeatedly recognised LiquidPiston’s technological developments in holding great promise for supporting critical Army requirements for FVL modernisation. We are pleased to see their efforts advance with this Army Phase II SBIR programme.”

Leveraging LiquidPiston High-Efficiency Hybrid Cycle’s (HEHC) thermodynamic concepts, the X-Engine features compact rotary engine architecture.

The hybrid system overcomes range and payload concerns by offering portability, low maintenance, and jet fuel compatibility. 

The X-Engine can also recharge batteries in flight, enabling power VTOL, along with over 30 minutes of quiet electric cruise.

The HEXE VTOL system will help the troops launch and land in small areas.

LiquidPiston founder and CEO Alec Shkolnik said: “Reliable and efficient sources of power and energy for intelligence, surveillance and reconnaissance (ISR), weapons systems, forward operating bases, and other solutions are critical to protecting the warfighter, enhancing warfighting capability, improving fuel efficiency, and reducing the logistical burden and operational costs.”

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