The Avanti’s forward wing flaps deploy automatically with the main wing flaps to maintain neutral pitch trim.
The forward wing's angle of incidence is slightly greater than that of the main wing, so that it stalls before the main wing, producing an automatic nose-down effect prior to the onset of main wing stall; its five-degree anhedral (negative dihedral) keeps the stream wash interference clear of the engine inlets, the main wing and the tailplane.[36]
Showing the continuously-varying curve of the fuselage cross-section and forward wing
The cabin cross-section varies continuously along the length of the aircraft; the shape approximates an NACA airfoil section, and the slowly changing curve helps prolong laminar flow on the front of the fuselage. Piaggio claims that 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 Jerry Gregorek[39] 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.[40]
Cabin
The P180 is said to have good fuel efficiency relative to small turbojets flying 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 the 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."[41] By this estimate, mileage is 70% better per fuel unit than comparable jet aircraft, although this greater efficiency is achieved only at a relatively slow 315 KTAS and FL410.[42] P180 Avanti II Specifications now show slightly lower numbers for specific range of 3.1 km/kg (0.76 nm/lb).
Interior noise is lower than conventional turboprop aircraft, because the propellers and engine exhausts are behind the cabin. Piaggio quotes 68 dBA. However, due to the strongly disturbed flow in which the pusher propellers operate, the exterior noise is higher. 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 five-bladed pusher propellers (est. +9 dB).[43] On takeoff, the Avanti has been measured at 81.9 dBA sideline noise level, slightly lower than the Beechcraft King Air at 82.8 dBA. This is below FAA stage 3 noise limits, which set a maximum of 89 EPNdB for takeoff.[44][45] However, the P180 has been the subject of noise complaints at airports, such as Aspen–Pitkin County Airport in Colorado[46] as well as Naples Municipal Airport, Florida, where that airport authority determined it was the noisiest aircraft using the facility.[47] Alan Parker, chairman of the Naples Municipal Airport Authority's technical committee, described the Avanti as "irritating loud" and compared the high pitched sound "to fingernails on a chalkboard".[48]
The Piaggio P.180 Avanti has a sea level, standard day, maximum gross weight takeoff distance of 869 m (2,851 ft) and a landing roll of 872 m (2,861 ft).[49]
Deliveries were at a high of 30 in 2008, but only two in 2013.
