The XAH-1X experimental attack helicopter was more a testing platform for advanced concept helicopter systems than an actual pre-prototype aircraft. Consisting of several modified, surplus Supercobra AH-1J dual-engine attack helos, the program began at Groom Lake Air Force Base.
Initially, the helos were fitted with an experimental, sustained EMP system designed to blind or damage enemy electronics to prevent detection of non-Stealth aircraft. The system was dubbed the Eclipse--a name given to the test platform helicopters to distinguish them from standard Supercobras. While the jamming systems proved effective it was decded that a Stealth aircraft like the F-117 or RAH-66 would be better suited, allowing for surgical strikes of hostile installations, rather than the unfocused, electronics-damaging XAH-1X.
Chosen for its dual engines--required for the heavy generators required for EMP bursts, the Eclipse helos saw new life in the late 1980s as test plarforms for experimental plasma-shell anti-armor guns.
By 1995, the Eclipse program had been discontinued and the remaining aircraft were consigned to storage at Groom Lake. However, when the costumed parahuman Sentinel began a series of terrorist attacks an emergency refit of one Eclipse gunship was ordered, the plasma-filled projectiles its vulcan cannon could fire believed to be capable of injuring the Sentinel. The helicopter was successful in injuring Sentinel and driving him out of U.S. airspace. (SS04: Shades of War).
It is presumed any Eclipse helicopters have been returned to storage at Groom Lake.