This coaxial, contra-rotating helicopter was built by the Marquis Raúl Pateras Pescara de Castelluccio and is the only survivor to illustrate the work of this giant pioneer of rotary flight. The Pescara Model 2R was the first helicoopter capable of hovering for 1 minute at a height of 1 m. This exhibit is one of the oldest in the museum and one of the last machines built by Pescara, probably from elements taken from its previous helicopters. The museum do not attribute it as a 4S but it contains the Salmson 9 radial engine with a small cooling propeller, so possibly a pre-4S test frame.