"Today was a great day for the Stratolaunch team. I am extremely proud of their perseverance to reach this point. The successful outcome of the test is a direct result of the team’s technical prowess and professionalism... While I can’t share the specific altitude and speed TA-1 reached due to proprietary agreements with our customers, we are pleased to share that in addition to meeting all primary and customer objectives of the flight, we reached high supersonic speeds approaching Mach 5 and collected a great amount of data at an incredible value to our customers...
Source: Dr. Zachary Krevor, President and CEO of Stratolaunch, following the first powered test flight of their TA-1 hypersonic test vehicle.