Geeking out in the Cessna Citation X from KVNY to KPGA (Van Nuys to Page), the fastest production passenger jet, top speed Mach 0.93, (700MPH), ceiling over 50,000'. Takeoff acceleration felt like a Ferrari, and the cruise was smooth and quiet.
The Air Force's scramjet, the Boeing X-51A Waverider, set a new world record, Wednesday, when it ran for 200 seconds, burned JP-7, and reached a speed of about Mach 5 (roughly 1 mile per second). In 2004, NASA's X-43 flew much faster (Mach 9.7) but burned hydrogen and managed that for about 12 seconds before it melted. More, here:
X-43A Raises the Bar to Mach 9.6
Guinness World Records recognized NASA's X-43A scramjet with a new world speed record for a jet-powered aircraft – Mach 9.6, or nearly 7,000 mph. The X-43A set the new mark and broke its own world record on its third and final flight on Nov. 16, 2004.
In March 2004, the X-43A set the previous record of Mach 6.8 (nearly 5,000 mph). The fastest air-breathing, manned vehicle, the U.S. Air Force SR-71, achieved slightly more than Mach 3.2. The X-43A more than doubled, then tripled, the top speed of the jet-powered SR-71.
The X-43 is an unmanned experimental hypersonic aircraft design with multiple planned scale variations meant to test different aspects of hypersonic flight. It is part of NASA's Hyper-X program.
A winged booster rocket with the X-43 itself at the tip, called a "stack", is launched from a carrier plane. After the booster rocket (a modified first stage of the Pegasus rocket) brings the stack to the target speed and altitude, it is discarded, and the X-43 flies free using its own engine, a scramjet.