Challenge

Modern diesel engines for automobiles and trucks feature very low fuel consumption and gas emissions. High compression ratio with turbocharging and intercooling, high pressure direct injection with common rail, pilot injection with digital control unit are essential enabling technologies implemented in order to obtain such excellent performance improvements. Moreover, the power-toweight ratio of diesel engines is steadily increasing with the
development of those news technologies.
This triggered successful research and development efforts that lead to substituting modern diesel engines to obsolescent gasoline fueled engines on some general aviation aircraft. However, the current performance and power-to-weight ratio of current EASA certified diesel engines still fall short of what is needed for efficient
helicopter flight.
In this context, the GRC4 project is pursuing a two fold objective: firstly to modify, assemble and test a flightworthy helicopter with a light diesel engine in order to explore the technical difficulties and validate the foreseen benefits in terms of gas emissions; secondly to define further breakthroughs and innovations for the next helicopter generation which would feature very advanced diesel engine along with a vehicle fully optimised for that type of powerplant. The figure shows the maturity path of such complementary streams. 

Expected benefits

With the demonstrator engine implementing mature technologies installed on an existing helicopter, the fuel consumption will be reduced by at least 30% over complete missions.
With helicopters of the next generation specifically optimised for advanced diesel engine technologies incorporating exhaust depolluting systems, the gain in fuel consumption and CO2 emission is foreseen to exceed 40% whilst reducing NOx emissions by 50%.