Stratolaunch's TA-1 hypersonic prototype vehicle launched on its first powered test flight on March 9., reaching high supersonic speeds.

Stratolaunch launches 1st rocket-powered flight of hypersonic prototype from world's largest airplane

Source: space
Source Link: https://www.space.com/stratolaunch-first-rocket-powered-hypsersonic-talon-a1-test-flight