On October 14, 1947 pilot Chuck Yeager _Officially_ broke Mach 1 in level flight. This aircraft was launched in mid-air by a modified B-29 from the bomb bay and Yeager was not really the first man to exceed Mach 1. At least two XP-86 Sabre pilots also claim to unofficially have broken Mach 1 in 1947 before October. Before that both Me-262 and Me-163 pilots claimed to have broken Mach 1- chiefly Hans Mutke in Weiss 9 (Me-262) and Dittmar in the Me-163 (one tough climb in the roket Me-163 reached 702 mph, but broke the tail; however, many engineers claim to have heard the sonic booms on several other test flights. And to top it off, the US Govt. is hiding information on the Lippisch Lp.13b ramjet assembled in 1945 for Mach 1 flight. The Intel reports only go as far as initial construction and then abruptly stop- no information. Photos have surfaced of the aircraft under assembly and parts of the ramjet engine... but disappeared from the Internet mysteriously after a short time. And then there is the captured Zippermayr Pfeil that was taken to the US and claimed completed and flown- another German supersonic aircraft! Refer to my reports at the bottom from my old site and Wiki ref on the sound barrier with Wright's official 1946 report on the Me-262. There is also a pic of the X-1 "Glamorous Glennis" (GG) named after Chuck's wife below...

http://aviationblog.dallasnews.com/Chuck%20Yeager%20and%20X-1.jpg http://en.wikipedia.org/wiki/Sound_barrier http://discaircraft.greyfalcon.us/LIPPISCH%20P.htm http://discaircraft.greyfalcon.us/Zippermayr%20Pfeil.htm