Pratt & Whitney Canada JT15D
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|JT15D at Canada Aviation Museum|
|Manufacturer||Pratt & Whitney Canada|
|Major applications||Cessna Citation I
Cessna Citation V
SIAI Marchetti S.211
The Pratt & Whitney Canada JT15D is a small turbofan engine built by Pratt & Whitney Canada. It was introduced in 1971 at 2,200 lbf (9,800 N) thrust, and has since undergone a series of upgrades to just over 3,000 lbf (13 kN) thrust in the latest versions. It is the primary powerplant for a wide variety of smaller jet aircraft, notably business jets. Over 6,000 JT15D's have been delivered since the 1970s, with over 30 million hours of operation.
Design and development
The JT15D is rare among modern turbofans in that it uses a centrifugal compressor as its main high-pressure system. This was a common feature of early jet engines, but was quickly replaced by axial compressors in most roles due to its large frontal size. In the turbofan role most of the jet thrust is generated by the cold air blown past the engine, and the internal "jet" portion is quite small. In this role the high single-stage compression of the centrifugal design has advantages, and the main reason most small turbofans don't use them is that they are often developments of previous turbojet designs.
In the JT15D the fan blows about 70% of the air into the bypass duct, producing most of the overall thrust. On JT15D-4 models and above there is a small "booster" axial stage just behind the fan which is running at the same speed as the fan and directing the remaining 30% of the airflow into the engine core. This air is further compressed by the centrifugal stage, and burned in a reverse-flow annular combustor. The hot gases flow through a "high-pressure" turbine that drives the centrifugal stage, and then two more turbines driving the fan and booster.
The first model, the JT15D-1, was introduced to power the Cessna Citation I, then known as the Fanjet 500. Deliveries started in 1972, and eventually on 1,417 -1s were delivered. The JT15D-4 was introduced the next year, improving thrust to 2,500 lbf (11,000 N). The -4 was the primary engine for the Cessna Citation II, and went on to find use on the Mitsubishi Diamond 1A, Aerospatiale Corvette and SIAI Marchetti S.211. Eventually 2,195 engines of the -4 series were delivered.
The next major model was the JT15D-5, certified in 1983. The first versions delivered 2,900 lbf (13,000 N) and were used on the Beechjet 400A and Cessna T-47A. Several minor versions were introduced, the -5A for the Cessna Citation V, while the -5B powered the Beechcraft T-1A Jayhawk, the -5C the DASA Ranger 2000 and S-211A.
- Aérospatiale Corvette
- Alenia Aermacchi M-311
- Beechcraft Beechjet 400
- Cessna Citation I
- Cessna Citation II
- Cessna Citation V/Ultra
- Hawker 400
- Mitsubishi MU-300 Diamond
- Raytheon T-1 Jayhawk
- Rockwell Ranger 2000
- SIAI Marchetti S.211/Aermacchi S-211
- Sport Jet II
- Boeing Bird of Prey
- Type: Turbofan
- Length: 60.5 inches
- Diameter: 27 inches
- Dry weight: 630 pounds
- Compressor: Axial flow LP, centrifugal flow HP
- Maximum thrust: 3,050 pounds
- Specific fuel consumption: 0.562 lb/(lbf·h) at max, 0.552 lb/(lbf·h) at cruise (typ)
- Thrust-to-weight ratio: 4.58/1 (approximation)
- Gunston 1989, p.131.
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