Ranges of Speed

Subsonic Usually less than Mach 0.8. Air is flowing slower than sound over every part of the airplane. DC-3, Air Transportation gallery.

Transonic About Mach 0.8 to Mach 1.2. Air is flowing faster than sound over some parts of the airplane. Bell X-1, Milestones of Flight gallery.

Supersonic Greater than about Mach 1.2. Air is flowing faster than sound over the entire airplane. F-104, near the Einstein Planetarium.

Hypersonic Greater than about Mach 5. Heat becomes a critical factor. X-15, Milestones of Flight gallery.

(Rev. 09/17/96)