The saucer was supposed to reach a top speed of “between Mach 3 and Mach 4, a ceiling of over 100,000 ft. and a maximum range with allowances of about 1,000 nautical miles,” according to the document.
If the plans had followed through to completion they would have created a saucer, which could spin through the Earth’s stratosphere at an average top speed of about 2,600 miles per hour. Wow. It was also designed to take off and land vertically (VTOL), using propulsion jets to control and stabilize the aircraft. Admittedly the range of 1,000 nautical miles seems limited in comparison to the other specifications – but if you’d hopped on the disk in New York it could’ve had you in Miami within about 24 minutes.
Declassified at Last: Air Force's Supersonic Flying Saucer Schematics | Danger Room | Wired.com