The usefulness of UAVs for aerial reconnaissance was demonstrated to the United States in the Vietnam War. At the same time, early steps were being taken to use them in active combat at sea and on land, but unmanned combat aerial vehicles would not come into their own until the 1980s.

History

UAVs, such as the Northrop Falconer, had been developed for battlefield reconnaissance beginning in the 1950s, but these machines saw little or no combat service. Israelis pioneered the operational use of battlefield UAVs in the early 1980s, during their operations in southern Lebanon. Very few of the technologies they used were all that new, but the Israelis finally achieved the proper formula for operational success, using their battlefield UAVs to help destroy Syrian surface-to-air missile sites and assist in other combat operations.

With the successes in southern Lebanon, international interest in battlefield UAVs picked up significantly. During the 1980s, all the major military powers and many of the minor ones acquired a battlefield UAV capability, and continue to expand that capability. These battlefield UAVs fall into two broad categories, which can be designated for convenience as "combat surveillance" and "tactical reconnaissance" UAVs.

Combat surveillance UAV The function of a combat surveillance UAV is to observe events on a battlefield in real-time, orbiting over the battle area and relaying intelligence to a ground control station. They are generally powered by small rotary or two-stroke piston "chain saw" engines.

They are directed by an autopilot system with RC backup. The autopilot directs the aircraft from sets of waypoints programmed in before takeoff. The flight-plan is set up by displaying a map on a workstation, clicking on the desired map coordinates with a mouse or directly on to a touch-screen, and then uploading the flight-plan into the UAV. Navigation is often verified by a GPS-INS navigation system. However, combat surveillance UAVs usually use the autopilot to get to the operating area, with the aircraft then operating by radio control to find targets of opportunity. The need to stay within radio range restricts combat surveillance UAVs to ranges within a line-of-sight of the transmitter. This is usually the determining factor in "range" specifications for such UAVs. For this reason, "endurance" is a more useful specification than "range".

The UAV sensors are generally housed in a turret underneath the aircraft, and almost always feature day-night imagers. The turret may also include a laser designator to allow the UAV to mark targets for smart weapons. Other specialized payloads, such as SIGINT packages, or new lightweight synthetic aperture radar (SAR)sensors with all-weather imaging capability, are now being fielded as well.

The larger combat surveillance UAVs have landing gear, usually fixed, and can take off and land on an unimproved airstrip, with an arresting hook to snag a cable for short landings. Such UAVs may also be launched by a RATO booster, and recovered by parachute, parasail, or by flying into a net. Smaller combat surveillance UAVs may be launched with a pneumatic, hydraulic, or electric catapult, with the very smallest launched by an elastic-bungee catapult.

Tactical reconnaissance UAV The tactical reconnaissance UAV is usually larger, jet powered, with longer range and higher speed. Like a combat surveillance UAV, it has an autopilot with radio control backup, but it relies more on the autopilot than on radio control, since its primary mission is to fly over predesignated targets out of line of sight, take pictures, and then come home. The tactical reconnaissance UAV will usually not loiter over the battle area, and real-time intelligence is less essential.

A tactical reconnaissance UAV usually carries day-night reconnaissance cameras, rather than a sensor turret, though SAR can be carried as well. They are generally launched by RATO booster and recovered by parachute, though they can be launched from aircraft as well.

The dividing line between combat surveillance and tactical reconnaissance UAVs, as well as between them and other classes of UAVs, is fuzzy. Some types of UAV may be usable for both missions. The distinction between a combat surveillance UAV and some kinds of "endurance" UAVs, discussed later, and between a tactical reconnaissance and a strategic reconnaissance UAV, as discussed earlier, is also very thin.

There are also many variations on themes. The smaller combat surveillance UAVs, in the size range of a large hobbyist RC model plane and used to support military forces at the brigade or battalion level, are sometimes called "mini-UAVs", and their low cost makes them particularly suitable for "expendable" missions. Such expendable missions might involve carrying a jammer payload into an enemy's operational area to disrupt radar and communications, or even being fitted with a radar seeker and a warhead to attack enemy radars. Such an "attack drone" or "harassment UAV" now becomes difficult to logically distinguish from a cruise missile.

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 , 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 . 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 , a rotor diameter of , 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 , 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.

SEAMOS SEAMOS owed much to DASH, and in fact a modified QH-50D was used as the SEAMOS demonstrator prototype. Like the original DASH, SEAMOS was a coaxial-rotor drone helicopter with twin landing skids, though it was unsurprisingly a more refined system, and in particular even had a real fuselage. SEAMOS was powered by an Allison 250-C20W turboshaft engine with 315 kW (420 shp).

SEAMOS flight tests were performed with the technology demonstrator in 1991, leading to a production contract in 1996 and flight tests of a true prototype in 1999. Service introduction was expected in 2005, but the program was cancelled in early 2003, SEAMOS having been judged "overdesigned and too expensive". The German government put out a request for an off-the-shelf solution, sensibly stating specifications in line with a machine that they could afford. The EADS Orka-1200, discussed later, is the prime candidate.

EXDRONE During the Gulf War, the US Marines also used about 60 cheap battlefield mini-UAVs, the "BQM-147 Exdrone (Expendable Drone)", that were fitted with simple TV camera payloads for battlefield reconnaissance.

The Exdrone was built by BAI Aerosystems of Maryland. It was mostly made of styrofoam, balsa wood, and plastics, and was powered by a chainsaw engine. It was a "symmetrical delta", meaning it didn't matter if it flew upside-down, allowing it to offer some protection to its payload when necessary. A later version was the BQM-147 Dragon.

BRAVE 200

While the Army was floundering with the Aquila, the Air Force was going through its own struggles with the tactical UAV concept. Beginning in the mid-1970s, the USAF Flight Dynamics Laboratory, working with Teledyne Ryan, developed a piston-powered tactical UAV designated the "XBQM-26 Teleplane". A total of 23 were built, in 13 different configurations. It is unclear if there was ever any intent to adopt the XBQM-26 for operational service, since the program had a strongly experimental flavor, with the different configurations used to evaluate a wide range of possibilities for tactical UAV operations. The program ended in the mid-1980s.

However, the Air Force did conduct a program to obtain an operational tactical UAV, the "Boeing Robotic Air Vehicle (BRAVE) 200". The BRAVE 200 was intended to be used as an antiradar attack drone, a jamming platform, or for other expendable battlefield missions. The BRAVE 200 was a neat little canard machine, with a span of , a length of , and a launch weight of . It was powered by a two-stroke, two-cylinder engine, driving a pusher propeller. The BRAVE 200 had an interesting launch scheme, with 15 of the UAVs stowed in a transport "box". A drone was shoved out of its cell in the box on an arm, and then launched by a RATO booster. It was recovered by parachute if the mission allowed it be recovered.