In The Works: Honda Aircraft HondaJet

 - December 7, 2006, 10:23 AM

Honda Aircraft and Spectrum Aeronautical both announced at the NBAA Convention that they will use the GE-Honda HF120 engine in their new business jets.

The GE-Honda HF120 engine produces more power than the HF118 that is installed in the prototype yet it weighs less. This is a result of the collaboration between Honda and General Electric. “Honda did a great job for 18 years moving that engine along,” said Gary Leonard, president of GE-Honda Aero Engines. “The last two years we’ve been getting the GE and Honda engineering organizations working closely together.”

The HF120’s titanium one-piece blisk-style fan is 18.5 inches in diameter, about an inch larger than the HF118’s fan. The engine uses GE’s NX fan technology to deliver greater efficiency and a broader band of efficient operation, according to Leonard. The axial compressor has grown to two stages from the HF118’s single stage, which increases the pressure ratio while reducing the diameter of the engine’s core. Honda engineers refined the centrifugal titanium compressor so it now has a higher specific flow, thanks to advanced 3-D aerodynamic design.

The engine’s combustor is reverse flow, a key characteristic of small turbines, Leonard said. The high-pressure turbine also uses GE’s NX technology in the form of single-crystal alloy blades, which are uncooled. In small turbines, he said, “Cooling technology doesn’t pay off and introduces as many losses as gains.” The low-pressure turbine is now two-stage. “We did that to get more efficient expansion of the gases and better fuel efficiency,” said Leonard.

With the larger fan and additional stages, the HF120 weighs less than the HF118 but delivers about 25 percent more thrust–up to 2,050 pounds versus 1,670. The HF120’s thrust-to-weight ratio is more than five (the HF118’s was less than 4.5) and the maximum engine pressure ratio is 24. A goal of the GE-Honda program is to deliver an engine with a 5,000-hour TBO, with no requirement for major component removal between overhauls, just visual inspections.

GE-Honda will run the HF120 core by the end of this month or early next year, followed by the first prototype engine by the end of next year’s first quarter. While GE-Honda has not yet applied for the HF120’s FAA type certificate, it will soon, Leonard said. GE-Honda will hold the type certificate, and the engine will be built under GE’s production and quality system, with fabrication of many parts outsourced to a variety of international companies.