Jetrader - March/April 2008 - (Page 27)

aviation history Mach 1 – Chuck Yeager standing in front of the X-1 Who’s On First? By Bill Bath Photo courtesy of the United States Air Force O n October 14, 1947, the Bell XS-1 rocket plane was dropped from a B-29 over the Mohave Desert, and with Captain Charles “Chuck” E. Yeager at the controls it exceeded Mach 1. The Air Force Museum Web site said that on the ninth ﬂight of the Air Force test series, he was the ﬁrst pilot to have exceeded the speed of sound. Around 1998 they revised the statement to read “ exceeded the speed of sound in level ﬂight.” Why the change? It’s a fairly long story; however, it can be summarized to say that in Washington, DC, politics usually trump the facts. Toward the end of WWII, piston-engine-powered combat aircraft were drilling large holes in the ground when pilots executed a terminal-speed dive and the controls froze solid or reversed themselves. The airﬂow over the wing’s top surface was going trans-sonic and the center of pressure jumped forward to exert tuck-under from the resulting longitudinal instability—pulling back hard on the stick would cause the air ﬂow force on the up commanded elevators to twist the horizontal tail plane in the opposite direc- tion followed frequently by structural failure. When jet aircraft came on the scene, there were a number of accidents, such as the DeHavilland DH108 Swallow th ﬂying wing, and journalists termed the cause “the journ sound barrier.” The ﬁrst of the three DH108s built was designed thre to test low-speed charac characteristics. After the fatal crash at Mach .9 of the secon DH108, killing Geoffrey de second Havilland, Jr.—the son of the ﬁrm’s owner—the third aircraft (VW120) exceed Mach 1 in September 1948. exceeded Piloted by John Cunningham, a WWII night ﬁghter Cunnin ace, it was the ﬁrst British plane to exceed Mach 1 Bri after the ﬁrst two Amer Americans on the ofﬁcial record. The Race October 1, 1947, two weeks before the Yeager-piloted w Bell X-1 was dropped from the belly of a B29 at 20,000 fro feet and accelerated to Mach 1.07, the North American M Aviation XP-86 took off from Muroc Air Force Base on its ﬁrst ﬂight; at 35,000 feet George Welch, the NAA test pilot rolled over into a 40 degree dive and headed int west. He had a plan, and in spite of having to re-cycle several the landing gear sever times before the warning lights were out and the chase plane’s pilot conﬁrmed full retraction and closed gear doors, he pushed the clos throttles to full power. At 405 mph indicated, the airA speed indicator (ASI) stuck, although Welch could feel stu the aircraft accelerating; he increased the dive angle accelerating indicator ﬂicked to 470 mph and when suddenly the indi continued to climb to 520 mph at 25,000 feet (uncor5 rected, that translates to 720 mph true at that altiJetrader 27

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Jetrader - March/April 2008 Contents Calendar A Message from the President ISTAT’s 25th Annual Conference Q and A: R. Stephen Hannahs History on Display Aircraft Appraisals From the ISTAT Foundation Aviation History Index to Advertisers

Jetrader - March/April 2008

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