New engine programs
The design of new airframes always depends heavily on availability of new engine types. The very light jet segment, for example, had to wait until engine manufacturers Pratt & Whitney Canada and Williams International designed smaller engines to power a new class of light jet, and the same is true on the upper end of the market, with new large jets spurring development of ever more powerful and efficient turbofans. In some cases, engine development precedes new airframe designs, and there are some engines like Snecma’s Silvercrest still looking for a home. But engine manufacturers are always looking for opportunity and remain at the ready to fill the needs of airframe manufacturers.
Williams International (Booth No. 4140) is developing several new engine versions. Its FJ44-4 will provide 3,600 pounds of takeoff thrust for the Citation CJ4. According to company spokesman Matt Huff, the -4 is an upscale version of the FJ44-3. The twin-spool Fadec-controlled engine has a single-stage fan, three axial low-pressure (LP) compressor stages, one centrifugal high-pressure (HP) compressor stage, one HP turbine stage and two LP turbine stages. Certification is expected in the fourth quarter of this year.
The company’s FJ44-3AP is under development for Piper’s single-engine PiperJet, the Nextant 400NXT (a Beechjet 400 retrofit), the Stratos 714 single turbofan and the Hawker Beechcraft Premier II. Compared to earlier FJ44-3 versions, the -3AP features aerodynamic improvements in most stages. It also benefits from some component and overall weight reductions, and the result is an 8-percent increase in thrust. Depending on the number of engines on the aircraft, the Fadec’s software differs. Certification is expected this year.
The smaller FJ33-5 (1,700 to 1,900 pounds of thrust) has features similar to those of the FJ44-3AP, but is scaled down. It is being developed for the Diamond D-Jet and the Cirrus Vision, and for those applications, it is designated as the FJ33-5A and FJ33-5C, respectively. Certification of both is expected next year but Williams would not give precise thrust numbers. “The basic engines are identical but fuel control schedules and the interface with the airframe differs slightly,” Huff explained.
GE-Honda Aero Engines
GE-Honda Aero Engines (Booth No. 5176), a 50/50 joint venture between General Electric and Honda, started HF120 ground tests late last month. The engine is expected to fly on GE’s Cessna Citation CJ1 flying testbed in December, replacing the aircraft’s right FJ44-1A. The HF120 is to power the HondaJet and the Spectrum S.40 Freedom.
Eleven HF120 engines will be used for certification, which is scheduled at the end of next year. The base engines for the Spectrum S.40 and the HondaJet are identical and their uninstalled thrust will be 2,095 pounds, but that could change due to installation; on the S.40, the engines are mounted on the aft fuselage, while on the HondaJet, they are in an over-the-wing configuration. The HF120’s initial TBO will be 5,000 hours.
France-based engine manufacturer Snecma (Booth No. 5152) is still looking for a business jet application for its Silvercrest, a turbofan engine in the 9,500- to 12,000-pound-thrust range. Parent Safran Group claims it is using its experience with commercial CFM56 engines to bring new standards–notably in maintenance–to business aviation. “We are starting from a clean sheet and thus can introduce commercial engine technology and experience in the design,” program manager Laurence Finet said. He added that from the early stages of the design they have taken maintainability into account.
Snecma is hoping the engine will be able to fly 9,000 hours before the first shop visit, a number that is much higher than the current average in business aviation. “Compared to other business jet engines, we will offer true on-condition maintenance, as opposed to hard-time visits,” Finet told NBAA Convention News. He also explained that parameters recorded via Fadec will assist with health monitoring.
Since the core engine test campaign concluded early last year, the company has carried out exhaustive analysis. The core engine ran 80 hours, including 60 hours with combustion on. The takeoff setting was tested at more than 20,000 rpm and the results confirmed the core’s “excellent thermomechanical performance.” Not only did the engine perform as expected, but the analysis showed results that exceeded expectations, Snecma said after the work was completed. From full program launch–when an aircraft maker selects the engine–three years will be needed to get it certified.
The manufacturer claims fuel burn will be 15 percent lower than that of current engines. NOx emissions are expected to be 50 percent better than CAEP 6 standards. Noise is expected 20 dB below Stage 4.
Honeywell (Booth No. 2600) is developing the 7,445-pound HTF7250G for the Gulfstream G250. The airframer has received test engines and the aircraft’s official rollout took place early this month in Tel Aviv, Israel. The engine has already flown on Honeywell’s Boeing 757 testbed. Certification is expected to occur by mid-2011.
Compared to the HTF7000, the HTF7250G has higher thrust and lower emissions. “We achieve this performance with improved compressor aerodynamics and an advanced mixer nozzle design,” said Mike Bevans, senior technical sales manager. “Our new combustor design offers both lower emissions and improved durability.” As a result, emissions are expected to be 40 percent better than ICAO requirements. In addition, Honeywell made minor changes to incorporate improved maintenance features.
Also in development is the 7,000-pound-class HTF7500E for the Embraer Legacy 450 and 500. The engine is a derivative of the HTF7000 that powers Bombardier’s Challenger 300. “We have completed the preliminary design stage and we are now working toward our critical design review,” Bevans said. The first ground run should take place in the middle of next year.
Pratt & Whitney Canada
Pratt & Whitney Canada (Booth No. 5711) is developing the 6,100-pound PW307B for the Learjet 85. The engine features PWC’s Talon advanced combustor technology, which is claimed to outperform ICAO standards by more than 30 percent for NOx emissions. The engine will also meet Zurich 5 requirements for zero noise surcharge fees.
P&WC is also working on a new member of the PW535 family–the 3,360-pound-thrust Fadec-controlled PW535E for the Embraer Phenom 300. The PW535 is also slated for the Cessna Citation Encore+ and Hawker Beechcraft 450XP. The PW535E was to be certified in 2008 but is now expected this month.
Finally, NBAA Convention News has learned that the PW810 has been shelved after Cessna canceled its Citation Columbus program. “Nevertheless,” said a Pratt & Whitney Canada spokesperson, “we will continue to work with Cessna to ensure we resume the program as soon as the market recovers. P&WC is committed to this market and believes there are other opportunities in this segment, which we are actively pursuing. Our intention is to continue the design and development of the PW800 engine program.”
France-based Price Induction is still searching for a firm application for its DGEN 380 geared turbofan. The engine has an unusually high-bypass ratio for a small jet engine: 7.6, and a thrust of 570 pounds. The company claims to have gathered enough money to complete the certification program. The full engine has run 50 hours on a testbed and trials are under way with the core engine. Price Induction is pursuing so-called personal jets, smaller than today’s very light jets, for the application.
A derivative version, the DGEN 390, will target 740 pounds of thrust. These engines are designed to power aircraft flying at 240 to 280 knots at 25,000 feet. The first aircraft the DGEN 390 might power the GP-210, a twinjet proposed by Brazilian startup GP Aerospace, which is headed by former Embraer technical director Guido Pessotti.
Rolls-Royce's (Booth No. 2266) 10,000-pound-class RB282 turbofan had been in development for Dassault’s still-under-wraps SMS, a supermidsize business jet. The airframer recently acknowledged it is rethinking the design and has reopened the engine choice.
Rolls-Royce’s BR725, chosen for Gulfstream’s G650, received EASA certification in June for a 16,100-pound rating. In tests, the engine has logged some 1,100 running hours and 3,500 engine cycles. The G650 is expected to fly by year-end.
The BR725 is derived from the BR710, which powers Bombardier’s Global and Gulfstream’s GV/G500 families of ultra-long-range jets. The BR725 is more powerful and offers 4.6 percent more takeoff thrust, up to a maximum of 17,000 pounds. The BR725 is also more than 4 dB quieter, has 4-percent better specific fuel consumption and yields a 21-percent improvement in NOx emissions than the BR710.
The engine has a 50-inch swept fan with 24 titanium blades. Driven by a three-stage LP turbine, it provides improved flow, increased efficiency, reduced noise and lower emissions, according to Rolls-Royce. The 10-stage HP compressor has been aerodynamically improved and some of its stages are bladed integrated disks (blisks), resulting in “improved performance and optimized weight.” The new combustor design helps cut the engine’s emissions. The two-stage HP turbine uses advanced design and the latest materials for higher efficiency, enhanced performance retention and longer life, according to Rolls-Royce.
The BR725’s entirely new nacelle is made of composites and features a higher flow capability. It also has a new thrust reverser system which increases reverse thrust and lowers drag.