www.nasa.gov X-43A Raises t' Bar t' 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 7000 mph. Begad! T' X-43A set t' new mark and broke its own world record on its third and final flight on Nov. 16, shiver me timbers, 2004. In March 2004, t' X-43A set t' previous record o' Mach 6.8 (nearly 5000 mph). T' fastest air-breathing, me bucko, manned vehicle, t' US Air Force SR-71, achieved slightly more than Mach 3.2. T' X-43A more than doubled, then tripled, me hearties, t' top speed o' t' jet-powered SR-71. Avast, me proud beauty! en.wikipedia.org T' X-43 is an unmanned experimental hypersonic aircraft design with multiple planned scale variations meant t' test different aspects o' hypersonic flight. It is part o' NASA's Hyper-X program. A winged booster rocket with t' X-43 itself at t' tip, called a "stack", is launched from a carrier plane. Avast, me proud beauty! After t' booster rocket (a modified first stage o' t' Pegasus rocket) brings t' stack t' t' target speed and altitude, it is discarded, ya bilge rat, and t' X-43 flies free usin' its own engine, matey, a scramjet.