Piaggio P180 Avanti

The Piaggio P180 Avanti is an Italian twin-engine turboprop aircraft produced by Piaggio Aero. It seats up to nine passengers in a pressurized cabin, and may be flown by one or two pilots. The design uses a small forward wing and a main wing combination that places the wing spars outside of the passenger cabin area. Although the front wing resembles a canard configuration, a conventional horizontal stabilizer on the tail provides longitudinal stability and pitch trim. It features a lifting laminar flow fuselage and has engines in pusher configuration

The Avanti's turboprop engines are placed on a mid-fuselage, high aspect ratio wing, located behind the cabin. The design utilizes both a T-tail and a pair of small, fixed anhedral forward wings that have flaps. The arrangement of the wing surfaces allows the horizontal stabilizer to maintain nearly neutral lift, as opposed to a conventional configuration, where the horizontal stabilizer creates a downward force to counteract the nose-down moment generated by the center of gravity being forward of the aircraft neutral point. This was patented in 1982 as "Three-Lifting-Surface Configuration" (3LSC). The Avanti II's forward wing flaps automatically descend in concert with main wing flaps. This reduces the force the horizontal stabilizer has to produce to compensate for the pitch-down effect of the wing flap deflection. This allowed both the stabilizer and the main wing size to be reduced for efficiency.Scaled Composites Triumph was also built with this approach and for this market, but did not go to production.

The forward wing angle of incidence relative to the fuselage is set so it stalls before the main wing, producing an automatic nose-down effect; its five-degree negative dihedral keeps the stream wash interference clear of the engine inlets, the main wing and the horizontal stabilizer.

Cabin cross-section varies continuously along the length of the aircraft; the shape approximates a NACA airfoil section, and the slowly changing curve helps prolong laminar flow on the front of the fuselage. Piaggio claims the fuselage contributes up to 20% of the Avanti's total lift with the front and rear wing providing the remaining 80%. Due to the unusual fuselage shape, the mid cabin is considerably wider than the cockpit. The front and rear airfoils are custom sections designed by Dr. Jerry Gregorek of Ohio State University's Aeronautical and Astronautical Research Laboratory to achieve a drag-reducing 50% laminar flow at cruise. The company claims the overall design of the P180 Avanti II enables the wing to be 34% smaller than on conventional aircraft.

The P180 is known for its fuel efficiency relative to small turbojets that fly in the same speed and altitude range. Flight International stated: "The Avanti has no direct turboprop competitors, its closest jet rivals are the Raytheon Premier I and the Cessna Citation CJ2+... Piaggio says low-drag laminar flow is maintained to around 50% of wing chord, compared with around 20-25% for conventional tractor turboprops where propeller wash disturbs the airflow over the wing... specific air range at high altitude is 3.4km/kg (0.84nm/lb) compared with around 2km/kg (0.49nm/lb) for current jets or 2.7km/kg (0.67nm/lb) for other turboprops." By this estimate, mileage is 70% better per-fuel-unit than comparable jet aircraft, however this extreme efficiency is achieved only at a relatively slow 315 KTAS and FL410. P180 Avanti II Specifications now show slightly lower numbers for specific range of 3.1 km/kg (0.76 nm/lb).

As the propeller disks and engine exhausts are located behind the cabin, the interior noise is lower than conventional turboprop aircraft. Piaggio quotes 68 dBA. However, due to the strongly disturbed flow in which the pusher propellers operate, the exterior noise is higher than desirable. The exterior noise level and its higher pitched sound has been shown to be the result primarily of the interaction of the turbine engine exhaust flows and the 5 bladed pusher props (est. +9 dB). The reduction of external noise is an active research topic at Piaggio.On take off, the Avanti has been measured at 81.9 dBA, slightly lower than the Beechcraft King Air at 82.8 dBA.

General characteristics

• Crew: one or two pilots
• Capacity: up to nine passengers
• Cabin dimensions: 1.75 m (5 ft 9 in) high, 1.85 m (6 ft 1 in) wide, 4.45 m (14 ft 7 in) long
• Payload: 907 kg (2,000 lb)
• Length: 14.41 m (47 ft 3½ in)
• Wingspan: 14.03 m (46 ft 0½ in)
• Height: 3.97 m (13 ft 0¾ in)
• Wing area: 16 m² (172.2 ft²)
• Foreplane area: 2.19 m²  (23.59 ft²)
• Horizontal stabilizer area: 3.83 m²  (41.27 ft²)
• Empty weight: 3,400 kg (7,500 lb)
• Useful load: 1,860 kg (4,100 lb)
• Max. takeoff weight: 5,239 kg (11,550 lb)
• Powerplant: 2 × Pratt & Whitney Canada PT6A-66 turboprop, 634 kW (850 shp) each

Performance

• Maximum speed: 737 km/h (398 kn, 458 mph)
• Cruise speed: 732 km/h (395 kn, 455 mph) cruise at 30,000 ft, 660 km/h (356 kn, 410 mph) economy cruise at 39,000 ft
• Stall speed: 172 km/h (93 kn, 107 mph)
• Range: 2,795 km (1,509 NM, 1,737 mi) at 11,900 m (39,000 ft) IFR
• Service ceiling: 12,500 m (41,000 ft)
• Rate of climb: 15 m/s (2,950 ft/min)
• Wing loading: 327 kg/m² (67.1 lb/ft²)
• Power/mass: 0.24 kW/kg (6.79 lb/hp
• Fuel economy: 0.84 NM/Lbs @FL410 and 316 KTAS