was canceled in 1969 and withdrawn from service 1968–1973. DASHes proved unreliable in shipboard service, with over half of the US Navy's 746 drones lost at sea. This was possibly due to inadequate maintenance support, as other services had few difficulties with their DASHes. Although low reliability was the official reason, the manufacturer pointed to the expenses of the Vietnam War, and the lack of need for antisubmarine capability in that war. Modified DASH vehicles continued to operate for several more years in the Vietnam War. With attached television cameras, they were used as remote artillery spotters and organic reconnaissance by their ships. Until May 2006, a small number of QH-50D DASH drones were operated by the United States Army at White Sands Missile Range, where they were used to tow targets and calibrate radars and electronic systems. The Japanese Maritime Self-Defense Force (JMSDF) operated a fleet of 20 QH-50 drones, for use on its Takatsuki-class and Minegumo-class destroyers. Because the JMSDF regarded the DASH operation as highly prestigious and the aircraft were flown and serviced regularly, they suffered a much lower loss rate than the US Navy. However, with the difficulty of maintaining DASH operations after the termination of the U.S. program, the drones and associated equipment were removed from JMSDF service in 1977. Variants DSN-1U.S. Navy designation for nine pre-production aircraft, redesignated QH-50A in 1962. DSN-2U.S. Navy designation for three pre-production aircraft, redesignated QH-50B in 1962. DSN-3U.S. Navy designation for 373 production aircraft, redesignated QH-50C in 1962. QH-50ADSN-1 redesignated in 1962, nine pre-production aircraft for evaluation, with a 72 hp (54 kW) Porsche flat-four piston engine. QH-50BDSN-2 redesignated in 1962, three pre-production aircraft powered by two 86 hp (64.5 kW) Porsche flat-four piston engines. QH-50CDSN-3 redesignated in 1962, production aircraft powered by a 300 shp (225 kW) Boeing T50-8A turboshaft engine, 373 built. QH-50D Production aircraft with a larger Boeing T50-12 turboshaft engine, fibreglass rotor blades, increased fuel capacity, and no tail assembly. 377 built. QH-50DM There were 10 modified QH-50Ds manufactured (Serial number 150AO- 160AO). The "DM" 550shp was supplied by a modified version of the Boeing T50-12. These were used for military reconnaissance for the United States Army during the Vietnam War. YQH-50E Three QH-50D aircraft modified with Allison T63-A-5A engines. QH-50F Proposed production version of YQH-50E, not built. QH-50H Proposed twin-engine version of QH-50F with larger fuselage and rotors, not built. Operators Japan Maritime Self-Defense