Startup to offer 560-lb-thrust turbofan

 - May 27, 2008, 10:41 AM

Price Induction, a startup company based in Anglet, France, is studying a 560-lb-thrust high-bypass-ratio turbofan that would establish a new thrust class. Applications of the DGEN380 would be four-seaters, allowing pilots to upgrade from piston singles to twinjets. Another market could be airline-pilot training. The company told AIN talks are under way with an unnamed airframer, and the development schedule calls for the first engine to run early next year, and a proof-of-concept aircraft may fly late next year.

“We have now found the right cycle for the engine and aerodynamic studies are almost completed,” said Bernard Etcheparre, Price Induction’s chairman and CEO. The company should have three employees (all engineers) by March. At the Paris Air Show in June, Etcheparre’s project received much interest from an airframer as the powerplant for a 3,300-lb mtow airplane that would seat four or five people. He would not name the company but revealed, “this led us to focus on 560 pounds instead of the 450 pounds we intended previously.”

According to Etcheparre, “A DGEN380-powered twinjet would cruise at 220 knots at 18,000 or 20,000 feet.” Range would be around 700 nm, the aircraft would be able to climb at 2,000 fpm and takeoff distance would be close to that of current aircraft of similar performance. “The twinjet would be able to take off over a 50-foot obstacle in about 1,600 feet–comparable with a Socata TB21 GT piston single,” Etcheparre said.

Price for two engines should be about $157,500. They should suit an aircraft priced “between $480,000 and $550,000,” Etcheparre told AIN. An aircraft designed around the DGEN engine would also provide better comfort and crashworthiness than current four-seat piston singles,” he added. “Such an aircraft would be a high-end four-seater more than an entry-level business jet.”

Engine Design

The engine is a twin-spool, two-shaft, Fadec-controlled turbofan. The single-stage high-pressure turbine is linked to a centrifugal, single-stage compressor. The single-stage low-pressure turbine runs the fan through a gear. The combustor is a conventional one, with a reverse-flow design. “We went to great lengths to get an easy relight even under difficult conditions,” Etcheparre noted.

Price Induction’s first design was a single-spool engine with variable fan blades. “But this was too complex and certification would have been too difficult,” Etcheparre told AIN. Engineers also dropped a lateral hot gas exhaust, which was making the design simpler but would have compromised efficiency.

Length of the DGEN engine is 3 ft 11 in. and maximum diameter is 1 ft 7 in., including the nacelle, according to Etcheparre. Bypass ratio is 8:1 and total dry weight should be around 90 lb. “Our target total weight for two engines and accessories is 220 lb,” Etcheparre added. The engine weight appears to be close to that of the Williams EJ22 engine, which has a thrust of 770 lb. “This relatively higher weight is due to the higher bypass ratio, which increases the size of the engine,” Etcheparre answered. The Eclipse 500 engine’s bypass ratio is 4.6:1.

Specific fuel consumption for the DGEN engine would be 0.49 lb of fuel per pound of thrust per hour, whereas it would be about 0.75 lb of fuel per pound of thrust per hour at Mach 0.30 and 10,000 ft, according to Etcheparre. This puts fuel burn at around 180 pph for a twinjet aircraft. Etcheparre would not assign numbers to noise levels, but he stressed that the high-bypass ratio should keep them low.

The engine has no accessory gearbox but features an integrated alternator-starter. “It starts the engine and then becomes a current generator that charges a battery,” Etcheparre explained. He said that it was easier to design such a small engine this way than with a conventional gearbox. On the maintenance side, Etcheparre said the designers have only defined that the engine will be able to fly 3,500 cycles before a major overhaul.