Airbus Flies Diesel-powered H120 Light Single
Airbus Helicopters is flying an H120 powered by a diesel engine in place of
its usual Turbomeca Arrius 2F turboshaft. The main benefit of the effort, part
of Europe's Clean Sky joint technology initiative, is expected to be
significantly lower fuel consumption.
The 30-minute first flight on November 6 started with a hover and various
low-speed maneuvers, before the helicopter transitioned to 60 knots. The engine
is a 4.6-liter V8, featuring high-pressure (1,800 bar) common-rail direct
injection and one turbocharger per cylinder bank. The cylinders have a 90-degree
V. To reduce weight, designers looked to racecar design for inspiration, evident
in the construction of the cylinder heads (aluminum) and connecting rods
(titanium). The high-compression engine, as Airbus Helicopters prefers to call
it, runs on kerosene/jet-A.
The Fadec's performance has been particularly satisfactory, according to
Tomasz Krysinski, Airbus Helicopters' head of research and innovation. When the
pilot increases the collective pitch, the Fadec injects more fuel into the
combustor for more power. "As a result, the rotor's speed changes by a maximum
of three rpm, less than one percent of the nominal 406 rpm," Krysinski told
AIN.
Fuel burn has already proved to be much lower than with the Arrius 2F, 143
pph versus 220 pph in hover, a reduction of 35 percent. The companies involved
in the project expect specific fuel consumption to be cut by half at economy
cruise speed. "It is interesting for those cycles that include a long portion of
relatively slow forward flight, like the police do," Krysinski
suggested.
Aerial work operations could also benefit from the piston engine. Unlike a
turboshaft, a turbocharged piston engine retains its power at altitude and in
hot temperature. In the mountains, this can be felt from around 3,500 feet,
according to project manager Alexandre Gierczynski.
The engine produces 442 hp compared with the Arrius 2F's 504 shp. However,
"we use the same power for takeoff and the high-compression piston engine will
be better in hot-and-high conditions," Gierczynski said.
Other objectives include a 30-percent improvement in direct operating cost
and a 2,000-hour TBO. Asked about emissions other than CO2, Krysinski said there
is no standard for comparing turboshafts and piston engines. "Burning less fuel
cuts pollutant emissions," Krysinski noted. There is no plan on the diesel
engine for a NOx-reduction device or a particulate filter, like those now
mandatory on cars. One reason is weight: after further development, the
flight-tested piston engine will tip the scales at 530 pounds-twice the weight
of a turboshaft of equivalent power.
In addition to Airbus Helicopters, the project involves Teos Powertrain
Engineering and Austro Engine. The former company, which has experience in car
racing, designed and manufactured the prototype engine. The latter firm, a
specialist in diesel engines for fixed-wing aircraft, has been in charge of the
Fadec, the fuel system and obtaining a permit to fly.
Iron-bird tests started in February 2014 and the first ground runs took
place one year later. The project dates back to 2009, when a first attempt
failed for lack of funding. The companies aim to bring the engine to technology
readiness level six, suitable for program launch.
Ingen kommentarer:
Legg inn en kommentar
Merk: Bare medlemmer av denne bloggen kan legge inn en kommentar.