In 1931 the US Navy used three PA-34, with 45’0″ rotor, designated XOP-1, for testing stability in carrier use.
Of the three, A8850, A8976, and A8977, the first was modified as the wingless XOP-2, and the last two were flown by the USMC.
Engine: Wright R-975/E2, 420 hp
Gross wt: 3300 lb
Empty wt: 2300 lb
Rotor dia: 46 ft 2 in
No of blades: 3
Seats: 2
All Aero 