By Daniel Smoot and Dana Hatchett, Army Innovation Programs

WASHINGTON – LiquidPiston, supported by Army innovation programs, is poised to transform the U.S. Army’s capabilities as the company delivers compact, heavy-fuel-capable rotary engines and hybrid electric power systems to Soldiers, setting new standards for power density and performance in military applications.

In 2020, the U.S. Army xTech Program named LiquidPiston a finalist in the xTechSearch 3 competition and awarded the firm $145,000 in cash prizes for its Hybrid-Electric X-Engine (HEXE) technology solution. The X-Engine used in the HEXE configuration, up to 90% smaller than an equivalently rated piston diesel engine, enables direct and hybrid electric propulsion systems for unmanned aerial and other autonomous vehicles.

Shortly after, the Army Small Business Innovation Research and Small Business Technology Transfer Program awarded the company an Army SBIR Phase I contract to develop and demonstrate a prototype HEXE UAS propulsion system. During the Phase I contract period, LiquidPiston demonstrated its HEXE system’s ability to stop and restart while in the air. The technology also allows for a quiet, electric-only cruise in addition to electric-assist sprint and climb modes, enhancing Soldier lethality and securing critical supply logistics in contested environments.

“The xTech and the Army SBIR|STTR Programs have helped LiquidPiston do what we’re set up to do, and to fund that effort,” said Per Suneby, member of the board of directors and senior vice president of corporate development at LiquidPiston. “We are excited and gratified that military agencies are interested in the possibilities of using our technology.”

Suneby also noted that prominent industrial players use LiquidPiston’s technology on other government contracts, providing the company with a pathway to product revenue. For example, in 2021, LiquidPiston received a subcontract worth nearly $8.3 million from Parsons to integrate the X-Engine into a lightweight 10-kilowatt generator for the U.S. Army Combat Capabilities Development Command’s Command, Control, Computers, Communications, Cyber, Intelligence, Surveillance, and Reconnaissance Center. The system underwent lab testing in 2024, with a prototype expected for mid-2025

LiquidPiston also received about $9 million from the DEVCOM Army Research Laboratory in 2022 to design, build and demonstrate an advanced, heavy-fueled 25 hp rotary combustion engine that produces the same power output as piston diesel engines up to 10 times larger.

Following its subcontract with Parsons, LiquidPiston received an Army SBIR Phase II contract in 2022 valued at around $1.7 million to continue HEXE-based unmanned aircraft system propulsion development, aiming to demonstrate a hybrid electronic vertical take-off and landing aircraft powered by the 25-horsepower rotary heavy-fuel engine.

“The Army xTech and SBIR|STTR programs really enabled us to gain visibility in the Army market. These programs help our business because it’s difficult for small companies to penetrate the military market and figure out who to talk to about what,” said Suneby. “LiquidPiston has been able to connect with different agencies and commands; building those connections and relationships in a win-win way is good for us and the customer.”

LiquidPiston’s work with the Army positioned the company for two genset-related SBIR Phase II contracts under the Air Force’s AFWERX Program. In 2023, LiquidPiston received a nearly $35 million strategic funding increase contract to develop a new, larger heavy-fuel-capable rotary engine and a hybrid electric power system using the new larger engine. LiquidPiston is developing a new class of hybrid power solutions, and a new engine program based on its HEXE platform. The firm collaborates with Air Force end-users to develop and field ground and airborne power systems based on its compact, heavy-fuel-capable engine and hybrid power system platforms.

Building on the small business’s success with the Army and other organizations, the Army selected LiquidPiston for the Army SBIR CATALYST Program in 2024. The Army SBIR CATALYST Program speeds up the transition of innovative technologies into practical military applications by providing up to $15 million in funding and fostering collaboration between small businesses, Army partners, and technology integrators. Under the Army SBIR CATALYST Program, LiquidPiston will deliver a 10 kW Ultra-Compact Mobile Command Post Auxiliary Power Unit prototype. The technology addresses a critical component in the operation of easily deployed, practical mobile command posts.

LiquidPiston’s xTechSearch 3 concept white paper evolved into a six-year trajectory of breakthrough innovation. With support from the Army xTech and SBIR|STTR programs, LiquidPiston turned vision into reality, developing next-generation engine and hybrid power technologies, securing major contracts and forging essential partnerships across the DoD and military ecosystem.

Programs such as xTech and SBIR|STTR don’t just support funding innovation, they open doors to lasting impact, enabling companies like LiquidPiston to deliver cutting-edge solutions that strengthen the Army’s capabilities and drive forward the future of national defense.

About the Army xTech Program

Since its inception in 2018, the Army xTech Program has become a catalyst for innovation, bridging the gap between emerging technology developers with Army stakeholders. More than just competitions, xTech provides participants with essential feedback, training, and meaningful opportunities to network. By hosting multiple competitions annually, the program accelerates the development of dual-use technologies that directly addresses Army needs, enabling innovators to refine their solutions, navigate the defense ecosystem and transition towards partnerships that deliver meaningful capabilities to Soldiers.

About the Army SBIR|STTR Program

Army SBIR continuously releases funding opportunities, including Phase I funding for commercially viable, feasible, and technically sound solutions. Firms with mature technologies meeting Phase I requirements can advance to Phase II or go directly to Direct to Phase II contracts. Throughout the process, technical, acquisition, and operational Army experts guide businesses to align their innovations with the Army’s critical needs.

Army STTR integrates small businesses in the Army innovation ecosystem by coordinating with universities, federally funded research and development centers, or qualified non-profit research institutions, with small businesses as the prime contractors. Small businesses must function as prime contractors, performing at least 40 percent of the work while research partners perform at least 30 percent.

ASA(ALT) leverages innovative technologies to give Soldiers a decisive advantage in any environment by developing, acquiring, fielding, and sustaining the world’s finest equipment and services. For more information, visit the ASA(ALT) web page and follow @ArmyASAALT.