Hiller X-18 experimental VTOL transport
The Hiller X-18, begun in February 1957, used various components from existing aircraft. The fuselage was that of a Chase YC-122C transport.
The two wing-mounted 7,100 eshp Allison T40-A-14 turboshafts came from the XFY-1/XFV-1. It had three engines, the two turboprops drove
the 16 ft diameter counter-rotating three-bladed propellers and a 3,400 lb thrust Westinghouse J34 turbojet.
The 33,000 lb loaded X-18 underwent extensive ground tests beginning in December 1958, and made its first conventional flight
on 24 November 1959. It made partial conversions with wing angles of up to 33°.
On the 20th flight it had a propeller pitch control problem at 10,000 ft and went into a spin. It was recovered before impact, but was grounded.
It continued to test ground effects before it was damaged by a test stand failure.