The Bell X-1C was a stillborn second generation X-1.
Although similar in general construction to the other X-1 airframes, the X-1C differed by being fitted with large vertical yaw damping surfaces to the upper and lower skins of each wing, combined with a retractable ventral fin under the rear fuselage. In addition, the nose compartment was designed to accommodate many different types of armament fit, as opposed to the test instrumentation used on the other X-1s.
Originally intended to serve as a high speed armament and fire control testbed, the X-1C was included in contract W33-038-ac-20692, issued on 2 April 1948 for a quartet of second generation X-1 aircraft. However, the arrival of transonic aircraft, such as the F-86 and F-100, led to the X-1C being cancelled before the start of construction, with it's intended serial number of 48-1386 passing to the X-1D.