LiquidPiston, a Connecticut-based engineering firm, claims to have solved the efficiency, lubrication, and fuel type issues that have long plagued the Wankel rotary engine with its new XTS-210. The supercharged, liquid-cooled two-stroke engine, which is about the size of a basketball and weighs only 19 kg (42 lb), can run on multiple fuels, including diesel and kerosene/jet fuel, and is said to deliver five times the power of an equivalent size or weight diesel engine, with three times the torque.
The XTS-210 is targeted at military, commercial, and aerospace applications, with a prototype expected for delivery in 2024 under a $9 million US Army contract. LiquidPiston has been working on these engines for nearly 20 years, with numerous prototypes already tested in small planes and go-karts. Other prototypes have included naturally aspirated versions making up to 40 hp and forced-induction engines up to 70 hp, running on diesel, gasoline, hydrogen, and propane.
The XTS-210’s design uses just two primary moving parts: a rotor and a shaft, compared to the long, skinny, moving combustion chamber of the Wankel. According to Alec Shkolnik, LiquidPiston’s co-founder and CEO, the company’s design uses a stationary combustion chamber that’s nice and round, which enables it to drive the compression to a high level, just by making the chamber smaller. Additionally, because it’s stationary, the company can directly inject fuel where the Wankel could not, providing two key advantages of the diesel: high compression ratio and direct injection.
Moreover, the XTS-210 has solved the durability issues and emissions problems caused by the oiling challenges that the Wankel rotary engine faced. LiquidPiston’s solution is to make the components stationary, which solves the challenges of the old rotary, and to upgrade its cycle to give it much higher efficiency. The company is developing the XTS-210 at the moment on JP-8/Jet-A fuel due to its ubiquity in defense and aerospace.
Overall, LiquidPiston’s XTS-210 engine appears to have significant potential in a wide range of military, commercial, and aerospace applications. Its compact size, lightweight, and ability to run on multiple fuels, combined with its high power and torque outputs, make it an attractive alternative to traditional diesel engines. With the US Army backing its development, it seems that the XTS-210 may soon become a game-changer in the world of portable generators and UAVs.