Experimental Autogiro on display in the Vertical Flight exhibition at the Steven F. Udvar-Hazy Center, National Air and Space Museum. These series of Autogiros were difficult to handle, leading to several accidents. The USAAF abandoned the Autogiro in favor of the more reliable Sikorsky helicopter.

Kellett Model KD-1 autogiro procured by the USAAF in 1942 and designated XO-60 in the O for Observation aircraft sequence.

Based on Cierva technology, the Kellett Autogiro Corporation's KD-1 first flew in 1934. Small numbers were built but the military O-60 did not make it as an army observation aircraft. A KD-1 went to Japan in 1939 and a Japanese variant, the Kayaba Ka-1/Ka-2, was deployed on anti-submarine patrols from 1944.

The XO-60 represents the final evolution of the Autogiro before the type became obsolete. The slow loitering speeds and almost vertical takeoff and landing abilities of the XO-60 made it ideal for military observation duties. However, the inability to hover sealed the fate of the Autogiro after the development of helicopters. This XO-60 was fully restored by the NASM in 1975 and is now on display at the Udvar-Hazy Center.