a Piaggio P.166T,maybe a Project ?.
Yes, the P.166T remained an unbuilt project.
According to Tony Chong (
Flying Wings & Radical Things: Northrop's Secret Aerospace Projects - 1939-1994, Specialty Press, 2021, page 166), The P.166T project was connected with the Northrop-Piaggio P.166M submitted to the US Army at Fort Rucker in 1963 as a light tactical transport. [1] A piston-engined P.166 was provided for evaluation by the US Army but no order was placed. According to Chong:
"There were also plan to make a turboprop version of the aircraft called the P.166T. The [Northrop 'Long-Range Planning Committee] recommended the final decision on the P.166T be deferred pending the outcome of the initial P.166M sales. Although the civil market was part of the equation, the major portion of business would come from US and MAP military purchases. The committee also provided an escape clause to the [Northrop-Piaggio] agreement. If no military sales occurred, the aircraft used for the Army proposal would be returned to Italy and the agreement ended."
BTW, your clipping's caption reads something like ...
"A 3-view plan of the Piaggio P-166T project, a variant of the well-known P-166. The aircraft is powered by two turbopropeller engines, likely the 870 ehp Turboméca «Astazou» XIVs. The fuselage is lengthened 1.80 m to carry fourteen passengers. Take-off distance: 470 m (FAR 23). Landing distance: 500 m. Maximum cruising speed: 460 km/h. Practical ceiling: 8,700 m. Range with ten passengers: 2,200 kilometers."
Had the Northrop-Piaggio P.166T proceeded, the US-assembled models would presumably have been powered by Continental CAE Model 217-5 engines (DoD designation XT72) - the US licensed version of the
Astazou.
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[1] This P.166-based Northrop-Piaggio Aircraft Project scheme had been bandied about since 1961 (when Northrop took on three P.166s for demonstration) but was not pursued seriously until September 1963.