The diesel engine research and development project that Airbus Helicopters (formerly Eurocopter) is conducting with racing car engine specialist Teos Powertrain Engineering and engine manufacturer Austro Engine, under Europe’s Clean Sky joint technology initiative, has cleared significant milestones. The demonstration engine is now being tested on an iron bird, before the first flight planned for this year on a modified EC120. The stakeholders in the Green Rotorcraft “integrated technology demonstrator” program hope diesel engines will eventually offer reduced fuel burn on light singles.
The modified EC120 iron bird (which includes an airframe) is located at the Airbus Helicopters factory in Marignane, France. Testing began last November, after extensive engine trials took place on a dedicated test bench earlier last year. No particular difficulty has been encountered since the beginning of the test phase, project officer Sébastien Dubois told AIN.
With the iron bird, engineers are assessing the way the diesel engine interacts, in terms of vibration, with the airframe. The engine has been powered up very gradually to avoid any problem, Dubois explained. The process may appear slow but the idea is to avoid surprises such as an unexpected major failure, which could cause several weeks of delay and a serious cost increase, he pointed out. But so far the installation, tests and performance have met expectations. Iron bird testing will continue this quarter.
The engine will then be installed on the flight-test aircraft. Modifications for the installation began late last year. Ground trials are planned to begin in the third quarter and the first flight is expected to take place later in 2014. The first flight was previously scheduled for April 2014.
The 440-shp demonstrator is a tradeoff between car racing performance and aviation’s safety and durability requirements. Compared to a turboshaft engine, the main benefit of a diesel is its fuel efficiency; Dubois and his partners hope for a 30-percent reduction in fuel burn. But the engine’s main shortcoming is its lower power-to-weight ratio. The HIPE AE 440 engine has a total weight (including oil, accessories, etc.) of 528 pounds. For an equivalent level of performance, a turboshaft would weigh between 265 and 285 pounds. However, on a light helicopter, part of the weight penalty is hoped to be recouped thanks to an airframe adapted for that engine and the smaller amount of fuel needed for a given range.
The V8 engine that is being tested is the result of a collaboration between France’s Teos and Austria’s Austro Engine. The former company designed the core engine. The latter manufacturer focused on components like the Fadec and, above all, airworthiness.