WALL STREET JOURNAL: Supersonic Flight Prepares For Takeoff Again.

The first commercial supersonic era, from 1969 to 2003, had some well-documented issues. There was the tragic crash of Air France Flight 4590, a Concorde jet that went down in flames just after takeoff in July 2000. There was the window-rattling sonic boom produced by successful flights, which precluded airlines from scheduling overland routes. And there was the cost of fueling four gas-guzzling turbojet engines, which required 6,770 gallons of fuel an hour to reach and maintain a cruising speed of Mach 2—just under 1,500 miles per hour. The new breed of supersonic aircraft brings a reduction in both noise and environmental pollution. Aviation startups are developing planes with two engines (compared with the Concorde’s four) and lower cruising speeds of Mach 1.1 to Mach 1.6. Along with thinner noses, this will minimize sonic boom and possibly allow for overland flights. Here’s how the three leading startups are preparing for takeoff.

I wrote something about this last summer.