Editing Bell X-1 (section)

===X-1A===
('''Bell Model 58A''')
[[File:Bell X-1A.jpg|thumb|right|X-1A]]
Ordered by the Air Force on 2 April 1948, the '''X-1A''' (serial number 48-1384) was intended to investigate aerodynamic phenomena at speeds greater than Mach&nbsp;2 (681&nbsp;m/s, 2,451&nbsp;km/h) and altitudes greater than 90,000&nbsp;ft (27&nbsp;km), specifically emphasizing dynamic stability and air loads. Longer and heavier than the original X-1, with a stepped canopy for better vision, the X-1A was powered by the same Reaction Motors XLR-11 rocket engine. The aircraft first flew, unpowered, on 14&nbsp;February 1953 at Edwards AFB, with the first powered flight on 21&nbsp;February. Both flights were piloted by Bell test pilot [[Jean "Skip" Ziegler]].

After [[NACA]] started its high-speed testing with the [[Douglas Skyrocket]], culminating in [[Scott Crossfield]] achieving Mach&nbsp;2.005 on 20&nbsp;November 1953, the Air Force started a series of tests with the X-1A, which the test pilot of the series, [[Chuck Yeager]], named "Operation NACA Weep". These culminated on 12&nbsp;December 1953, when Yeager achieved an altitude of {{convert|74700|ft}} and a new airspeed record of Mach&nbsp;2.44 (equal to 1620&nbsp;mph, 724.5&nbsp;m/s, 2608&nbsp;km/h at that altitude). Unlike Crossfield in the Skyrocket, Yeager achieved that in level flight. Soon afterwards, the aircraft spun out of control, due to the then not yet understood phenomenon of [[inertia coupling]]. The X-1A dropped from maximum altitude to {{convert|25000|ft}}, exposing the pilot to accelerations of as much as 8g, during which Yeager broke the canopy with his helmet before regaining control.<ref>Young, Dr. Jim. [https://web.archive.org/web/20080215062652/http://www.af.mil/shared/media/document/AFD-080107-018.pdf "Major Chuck Yeager's Flight to Mach 2.44 In the X-1A"].   ''AFFTC History Office'', Edwards AFB. Retrieved 14 October 2009.</ref>

On 28 May 1954, Maj. [[Arthur W. Murray]] piloted the X-1A to a new record of {{convert|90440|ft}}.<ref name=Martin>Martin, Douglas |title=Arthur Murray. [https://www.nytimes.com/2011/08/05/us/05murray.html?src=recg "Test Pilot, Is Dead at 92"]. ''[[The New York Times]]'', 4 August 2011. Retrieved 6 August 2011.</ref>

The aircraft was transferred to NACA during September 1954, and subsequently modified. The X-1A was lost on 8 August 1955, when, while being prepared for launch from the [[Boeing B-50 Superfortress|RB-50]] mothership, an explosion ruptured the plane's liquid oxygen tank. With the help of crewmembers on the RB-50, test pilot [[Joseph A. Walker]] successfully extricated himself from the plane, which was then jettisoned. Exploding on impact with the desert floor, the X-1A became the first of many early X-planes that would be lost to explosions.<ref>Miller 2001, p. 21.</ref><ref>Thompson, Lance. [http://www.ufomind.com/area51/org/afftc/articles/airspace_9502.html "The X-Hunters"]. ''[[Air & Space]]'', February/March 1995, ISSN 0886-2257. Retrieved 12 March 2008.</ref>