Sixty years ago this week Chuck Yeager in a Bell X-1 dropped from the belly of a Boeing B-29 and rocketed through the sound barrier in level flight over the California desert. Since then, military projects have gone through many a Mach, approaching 10 for the most envelope-pushing scramjets. It's fair to say that, apart from the Airbus A380 and Boeing 747 programmes, speed has made most of the really big aviation news since Yeager's breakthrough flight.
That's no surprise. People have always valued speed, right back to ancient Olympic laurels for the fastest runners. In military aviation, speed meant survival until the advent of stealth - and now the Lockheed Martin F-22 is supersonic and stealthy, so the need for speed remains.
On the civil side, we have a more complicated relationship with speed. Our heads tell us supersonic flight is uneconomical and not at all green. No-one will tolerate sonic booms, and subsonic airliners get us around the world quite fast enough, thank you. Instead of the (slightly subsonic) Sonic Cruiser we're getting the 787, which will be very nice when it's finished.
Except, the enduring allure of Concorde and its awesome speed doesn't go away. Supersonic business jet projects persist, as do Japanese flirtations with 300-seat supersonic jetliners.
All the improvements being made to normal aircraft are worthy, but it's speed that's exciting. Let's hope aviators keep pushing the envelope.