US Battlefield UAVs - The DASH Helicopter Drones / SEAMOS

The DASH Helicopter Drones / SEAMOS

The first operational battlefield UAV developed by the US military was for antisubmarine warfare (ASW). In the early 1960s, the US Navy obtained a small "Drone Anti-Submarine Helicopter" (DASH) Gyrodyne QH-50 that could fly off a frigate or destroyer to carry homing torpedoes or nuclear depth charges for attacks on enemy submarines that were out of range of the ship's other weapons. This was a relatively simple requirement, involving a neatly defined mission in a combat environment where presumably nobody would usually be shooting back at the drone, and it seemed achievable with the technology of the time.

Gyrodyne Company of Long Island, New York, was awarded the contract to build DASH, and based the design on a one-man helicopter the company had already developed, the "YRON-1". The initial DASH demonstration prototype, designated the "DSN-1", used a Porsche flat-four piston engine with 54 kW (72 hp), with nine such prototypes built. Initial flights were in the summer of 1961, at first with a pilot on board, leading up to an unpiloted helicopter flight in August 1961.

A second-generation prototype, the "DSN-2", was powered by two Porsche engines, each with 64.5 kW (86 hp). Three such drones were built, and then led to the production DASH, the "DSN-3", which was powered by a Boeing T50-BO-8A turboshaft engine with 225 kW (300 shp). First flight of the DSN-3 was also in the summer of 1961.

The US military services adopted a common aircraft designation scheme in 1962, and the DASH variants were given new designations. The DSN-1 became the "QH-50A", the DSN-2 became the "QH-50B", and the DSN-3 became the "QH-50C". The general configuration of all three of the DASH prototype variants was similar, though the QH-50C was scaled up, with an empty weight almost twice that of the QH-50A. The QH-50C was an ugly little machine that was reminiscent of an insect. It had a frame made of steel tubing, with all machinery directly accessible, and stood on twin skids, with one or two homing torpedoes or nuclear depth charges carried between the skids. It had a coaxial rotor system and a dropdown inverted vee tail.

The QH-50C had a height of 2.96 meters (9 feet 8 inches), a rotor diameter of 6.1 meters (20 feet), and an empty weight of 500 kilograms (1,100 pounds). It was guided solely by radio control, and had neither sensors nor autonomous navigation capability. Combat radius was a modest 54 kilometers (34 mi), which was adequate for its mission. Greater range would not have been very useful, as the DASH flew at low altitude and used a line-of-sight communications link, limiting its range in any case.

The US Navy originally ordered 900 QH-50Cs, but the type suffered from reliability problems, with a quarter of the first batch of 100 lost in crashes. The order was cut to a little over 500, with final production being the "QH-50D" variant, with an uprated engine providing 274 kW (365 shp), fiberglass rotors, and increased fuel capacity. The Japanese Maritime Self-Defense Force also bought a small batch of 16 DASHes in 1968.

The career of the DASH was undistinguished, but it was one of the first drones ever used in a strictly tactical environment, and pointed the way to the future. A small number of DASHes were apparently given reconnaissance gear and used for naval surveillance over the Gulf of Tonkin in 1966 in a project codenamed SNOOPY.

In the early 1970s the Air Force evaluated the QH-50D for a battlefield drone test program codenamed NITE GAZELLE. NITE GAZELLE apparently experimented with using drones to drop bomblets and carry machine guns, but details are unclear, as are reports that the DASH was used in other evaluations as a countermeasures platform.

In the 1980s, Aerodyne corporation attempted to sell an updated version of the DASH, designated the "CH-84 Pegasus", with an Allison 250-C20F turboshaft engine and updated electronics. While it appears the Pegasus was not a success, the DASH was resurrected a second time in the 1990s by the German Dornier company, now part of Daimler Chrysler, for the "SEAMOS" naval UAV.