The X-4's design allowed it to be separated into two parts, aft of the engines, for servicing and instrumentation work.
E-1000A
The X-4’s design allowed it to be separated into two parts, aft of the engines, for servicing and instrumentation work. The X-4 Bantam, a single-place, low swept-wing, semi-tailless aircraft was designed and built by Northrop Aircraft, Inc. It had no horizontal tail surfaces and its mission was to obtain in-flight data on the stability and control of semi-tailless aircraft at high subsonic speeds.1953NACA/NASA Photo› X-4 Project Description