Partenavia developed a “lightweight” Oscar, the P.66B Oscar 100, by the simple expedient cutting out a slice of the cockpit and only fitting it with two seats, reducing length by 14 centimeters (5.5 inches) and empty weight by 110 kilograms (242 pounds). It was powered by an O-235 engine with only 75 kW (100 HP); 80 were built. The “P.66B Oscar 150” had the same spliced-out fuselage as the P.66B Oscar 100, but with a third seat crammed in, and a 112 kW (150 HP) Lycoming engine; 50 were built.
The “P.66C Charlie” was an update of the original full-length P.64 Oscar series, with four seats. It was fully aerobatic, though it was powered by a 120 kW (160 HP) Lycoming engine, giving it less pep than the Oscar 180. However, its empty weight was 70 kilograms less than that of the Oscar 180, meaning it could get by with a less powerful engine. 96 were built.
P.66 Oscar
Engine: Lycomimg O-235-C1B, 115 hp
Seats: 2
P.66B Oscar-100
P.66B Oscar-150
Engine: Lycomimg O-320-E2A, 150 hp
Seats: 3
All Aero 