CarterCopter CCTD becomes first rotorcraft to exceed μ=1

Description

Rotorcraft flight with a rotor advance ratio (μ) >= 1 (retreating blade completely in reverse flow) has always been considered  a significant technology 'barrier' to break. This 'barrier' was broken by the CarterCopter Technology Demonstrator (CCTD) using it's slowed rotor autogyro in high speed forward flight. The test pilot was Larry Neal.

Source: Carter's Slowed-Rotor Compound: Putting a New Spin on an Old Concept, Raymond L. Robb, VERTIFLITE March/April 2013, Page 20.