testing at Wright Field was all-weather testing. It represented the first major attempt to solve the many problems encountered in flying under all weather conditions, both day and night. WADC developed two "workhorse" aircraft during the 1950s; the Boeing B-52 Stratofortress and Lockheed C-130 Hercules. WADC also developed experimental systems, known as the X-series aircraft, in an effort to advance aviation technology and the flight envelope, including the first flight of a vertical takeoff and landing (VTOL). WADC programs have also contributed to the space program through the X-20 and Zero-G training. The XQ-6 and XQ-9 target drones were conceived by the Wright Aeronautical Development Center but never reached the hardware phase. WADC was inactivated and replaced by the Wright Air Development Division in 1959 then by the Aeronautical Systems Division (ASD) in 1961. That year, the Air Force merged the Air Research and Development Command with the procurement functions of Air Material Command to form the Air Force Systems Command. In 1963, the Materials, Avionics, Aero Propulsion, and Flight Dynamics Laboratories were established and placed under one organization, the Research and Technology Division. Research during this time included examining different materials for aircraft structure, phased-array radar, and improved power plants. During the Vietnam War, ASD set up a special division called Limited War/Special Air Warfare to respond to the special requirements dictated by the conflict. Part of this concept was "Project 1559" which provided a means for rapidly evaluating new hardware ideas to determine their usefulness for conducting limited war. Support systems included a highly mobile tactical air control system, disposable parachutes, intrusion alarms for air base defense, and a grenade launcher for the AR-15 rifle. In response to the unique climate found in Southeast Asia ASD an evaluation of chemical rain repellents for fighter aircraft and discovered that varieties of repellant applied to cockpit windshields on the ground prior to the flight had a long life and could last several hours, even days. During the early 1970s the Department of Defense became concerned with the rising costs of military procurement and consequently abandoned the concept of buying a weapon system as a complete, finished package, and reorganized the acquisition cycle into five phases: conceptual, validation, development, production, and deployment. The Air Force viewed this as a more flexible approach; providing oversight, review, and evaluation during each phase. Under this new process the ASD continued enhancing airframes, and developing