UPDATE: From The Collection of Steve Durst
Group of 15 commemorative covers honoring flights of experimental aircraft including the X-15 and X-24B, each signed in ink by a legendary test pilot. Signers are: Chuck Yeager, Scott Crossfield, Milt Thompson, Joe Engle (2), Pete Knight (2), Forrest S. Petersen, Bill Dana, Robert M. White, John Manke (2), and Robert A. Rushworth (3). In overall fine condition.
