To Mach 7 and beyond

Research into high speed flight has always been fraught with technical difficulties, but the promise of hypersonic travel continues to fuel the imagination. The ultimate goal is the fully reusable, single-stage space plane, which could take off horizontally from an ordinary airport runway, deliver its payload to orbit, and land. A sibling concept is the long-haul, hypersonic passenger aircraft, which would take a sub-orbital trajectory from one side of the Earth to another. Flight times could be anywhere between two hours and 45 minutes. Either version would be as important for business and tourism in the 21st century as the early jetliners were in the 20th century.