The Lockheed XV-4 Hummingbird (originally designated VZ-10) was a U.S. Army project to demonstrate the feasibility of using VTOL for a surveillance aircraft carrying target-acquisition and sensory equipment.[1] It was designed and built by the Lockheed Corporation in the 1960s, one of many attempts to produce a V/STOL vertical take off/landing jet. Both prototype aircraft were destroyed in accidents.