Most piston-driven helicopters use aviation-grade gasoline or avgas, but as part of the European Clean Sky initiative, Airbus Helicopters has begun flight testing of a new high-compression engine that burns widely-available kerosene aviation fuel. Installed in an H120 demonstrator aircraft, the advanced lightweight V8 piston engine promises to be a more efficient, cleaner alternative to turbine powerplants in high-performance rotorcraft.

According to Airbus Helicopters, the new 4.6-liter, V8 high-compression piston engine demonstrates a wide variety of advanced features and technologies. With one turbocharger per cylinder bank, the engine achieves pressures of 1800 bar and has common-rail direct injection. It has fully-machined aluminum blocks, titanium connecting rods, steel pistons and liners, and for the motor oil it uses liquid-cooling and a dry sump management system similar to that used on aerobatic aircraft and race cars.

The engine has been under development since 2011 and ground tests of the H120-equipped helicopter were conducted in February and March 2015. Its maiden flight took place on November 6 at about 3 pm at Marignane Airport, France. Airbus Helicopters says that future tests will work on determining the optimum power-to-weight ratios, confirming the engine's emission standards, and making it competitive with turbine power plants.

"The first result of the 30 minutes flight confirms the advantages of new-technology high-compression piston engines for rotorcraft in offering reduced emissions; up to 50 percent lower fuel consumption depending on duty cycle, nearly doubled range and enhanced operations in hot and high conditions," says Tomasz Krysinski, Head of Research and Innovation at Airbus Helicopters.

The kerosene-burning engine is being developed by Airbus Helicopter as part of the European Clean Sky initiative's Green Rotorcraft Integrated Technology Demonstrator (ITD) program which aims to produce greener, quieter, more efficient aircraft engines. The goal is to eventually cut down fuel consumption by 30 percent, CO2 emissions by 40 percent, and NOx by 53 percent.