The North American X-15 N°3 56-6672 flew for the 1st time 20ieth Dec 1961 with Neil A Armstrong as pilot. 

- "On 15 November 1967, U.S. Air Force test pilot Major Michael J. Adams was killed during X-15 Flight 191 when the X-15-3, AF Ser. No. 56-6672, entered a hypersonic spin while descending, then oscillated violently as aerodynamic forces increased after re-entry. As his aircraft's flight control system operated the control surfaces to their limits, acceleration built to 15 g vertical and 8.0 g lateral. The airframe broke apart at 60,000 feet (18 km) altitude, scattering the X-15's wreckage for 50 square miles (130 km²). On 8 May 2004, a monument was erected at the cockpit's locale, near Randsburg, California. Major Adams was posthumously awarded Air Force astronaut wings for his final flight in X-15-3, which had reached an altitude of 50.4 miles (81.1 km). In 1991, his name was added to the Astronaut Memorial." (Wikipedia)

- Extra details:

https://en.wikipedia.org/wiki/North_American_X-15

http://www.thisdayinaviation.com/tag/56-6672/