Textron Aviation announced on 24 July that the first full airframe test article for the Cessna Denali – a single-engined, seven- to nine-seat turboprop – is set to make its debut flight next year.
Separately, GE Aviation revealed the internal architecture of the Denali’s Advanced Turboprop (ATP) engine in a marketing brochure distributed for the first time at the Experimental Aircraft Association’s AirVenture fly-in in Oshkosh, Wisconsin.
After launching the Denali at AirVenture two years ago, the first clean-sheet aircraft launched since the acquisition of Hawker Beechcraft by Cessna remains on track for certification in 2019.
“We’re making excellent progress in the aircraft’s development programme,” says Brad Thress, senior vice-president of engineering for Textron Aviation.
In addition to fabricating fuselage structures, Textron Aviation has done fit checks for an optional aft cargo door that measures 51in (129cm) wide by 53in tall.
The Denali features a 63in-wide fuselage cross section, which is 3in wider than the nearest competitor in a class that includes the Daher TBM 930, Pilatus PC-12NG and Piper Meridian M600.
Textron Aviation also has started tests on the aircraft's McCauley five-bladed, composite propeller, Thress says.
Instead of selecting a new version or successor to the Pratt & Whitney Canada PT6, Textron Aviation chose to power the Denali with the ATP, a new engine in development by GE to challenge P&WC’s near-hegemony in the turbine-powered general aviation market.
According to the marketing brochure, the ATP will feature a reverse-flow architecture, with four axial stages of compression and one centrifugal stage of high-pressure compression. The air will then be mixed with fuel and ignited inside a reverse-flow combustor, before diffusing through a two-stage core turbine and a three-stage power turbine.
The latter feature offers the most significant break with the architecture of the PT6, which is designed with a single-stage power turbine. By using three stages, the GE design is intended to be more efficient at transferring rotational energy from the gas generator into shaft horsepower that drives the propeller, explains Brad Mottier, the company's vice-president and general manager of business, general aviation and integrated systems.
The ATP architecture is designed to support a 16:1 overall pressure ratio, which, while less intense than the 18:1 ratio in T700 engines that GE supplies to military helicopters, sets a new standard in the general aviation market. The engine also features cooled turbine blades, variable stator vanes and a digital control system for the engine and the propeller.
Source: FlightGlobal.com
