Flying fodder for guns and missiles: the ideal defence product is one which offers a good profit margin, a support element and is frequently consumed and thus requires replacement. The target drone must be regarded as one of the leading candidates for this enviable label, although strictly it applies to the upper end of the market. (Unmanned Flight).

Drones have existed since before the Second World War, Royal Navy systems having a dial `spin' function to ensure they fell from the sky after being bracketed by anti-aircraft fire even when the shells inflicted no damage. A target drone is an unmanned aircraft usually under remote control which is designed to replicate the performance of manned combat aircraft, and the modern drone market is an extraordinary versatile one which encompasses everything from models to real aircraft.

They are used by more than 50 countries for both training and testing. At the lowest end of the training regime are the simple, low fidelity systems designed to give infantry and base defence forces target practice using automatic, rifle-calibre weapons and light cannon against air targets, although some forces use them for man-portable missile operator training. The drones are often extremely sophisticated versions of home-built model aircraft with handheld radio control. They tend to be lightweight systems (under 10 kg) and while miss distance indicators are occasionally carried, the usual payload consists of smoke and/or infrared flares.

Typical examples, such as the Aaruustekniika AT 85/97, Dragon Merlin, the Stephansen Delta Mats-E and the Meggitt Imp, have glass-fibre reinforced resin fuselages with lightweight wood skin and tail planes and may be launched either by hand or by using a simple bungee- operated launch ramp. They are powered by one or two cylinder piston engines including the Limbach L275/L550, Meggitt WAE 342, the Northrop Grumman RD^E 4318 and the Quadra Aerrow Q 50t82/100 series in both `pusher' (propeller to the rear) and `tractor' (propeller at the front) configuration. After a flight of about 30 minutes, recovery is by means of a belly, skid or undercarriage landing keeping a parachute drop as an option.

These drones are quite inexpensive; the Belgian Army's Ultima 14/255 is reported to have a unit price equivalent to $ 3300. The Spanish Army, for example, having used more sophisticated drones in the 1980s, issued a requirement for a low-cost system leading to the Inta Alba (Avion Ligero Blanco Aero) whose first successful test with a missile was in 1996. To exploit this market, Eads/Aerospatiale Matra has been developing since the early 1990s the Boucaniere hand-launched low-cost basic aerial target with a target unit price of FF 50,000 (equivalent now to about $ 8500).

The most common target drones are used to support medium calibre anti-aircraft guns (30 to 40 mm) and man-portable surface-to-air missile teams supplementing the work, which is performed in dome trainers against images. These drones are not only used to provide live-firing experience: since they have high speeds and can manoeuvre, they provide experience in tracking low-flying, high-velocity combat aircraft.

Those powered by two cylinder piston engines are generally larger, with launch-weights ranging from 15 to 180 kg. These require launching systems, most often bungee catapults, and usually have an endurance of between 60 and 90 minutes. Because they are being used against weapon systems with more sophisticated target acquisition and tracking systems they tend to have larger and more sophisticated payloads.

The granddaddy of them all, and one still in service after nearly 60 years, is the Northrop Basic Training Target (BTT). This is a 181-kilogram launch weight aircraft that uses a radio command guidance system with an automatic altitude hold supported by a radar tracking system. Brazil uses a derivative as the Aeromot K1 AM, launched with a solid propellant booster rocket, while the Chilean derivative is the Industrias Electricas RMS Trauco III with the guidance system augmented by Global Positioning System (GPS) equipment.

The BTT used traditional airframe construction techniques based on aluminium alloys supplemented by steel, but the latest generation feature composite construction through glass fibre and epoxy materials. In the Swiss Farner Topaz, the airframe is built with aluminium to reinforce its composite structure.

One of the smallest target drones is the rail-launched Nefer TM-105 EDO with a maximum launching weight of 18 kg. It can simulate various aircraft attack modes and manoeuvres and whose payload relays data from the miss distance indicator to the ground and whose profile can receive infrared augmentation for missile training.

A more common system is the bungee-catapult-launched Greek STN Atlas-3 Sigma Iris. The payload options for which include a smoke generator, an infrared enhancement pod radar augmentation system and a laser enhancement system. The drone can also carry towed targets. Although remote control remains an option, this system has a programmable microprocessor-based guidance system with a GPS element. The Universal Target Systems' Missile Subsonic Aerial Target (Msat) has a similar payload package.

Radio control is often augmented by a more sophisticated control. The widely used (42 countries) Meggitt Defence Systems Banshee, whose payload includes corner reflectors sets to augment the radar cross section and a reusable infrared thermal source (on the Banshee 400), has both radar and optical tracking systems so that it may be operated at distances of more than 30 kilometres. For distances in excess of 40 km, a GPS tracking system may be brought into use. France has recently awarded Meggitt an order for 52 Banshees per year for the next five years, and the series 500 Banshee is already in service with Egypt, Germany, the Netherlands and Turkey. A similar system will be used with the catapult-launched Voodoo, whose first deliveries of ten air vehicles and one each launcher and ground station are anticipated this year to Bahrain. The Voodoo flies at a 300 kt airspeed, which is sustainable at altitudes from 15 to 16,000 feet throughout an operational range in excess of 120 km. Mission payloads include radar, visual and infrared augmentation while a variety of towed sleeve, banner and rigid body targets are supported.

The Eads Cac Fox TS1 and TS3 also feature sophisticated control stations with a digital flight control computer and GPS receiver which allows two or three TS 1 or four TS 3 targets to be controlled simultaneously. The Fox TS 1 has a radio altimeter allowing the aircraft to simulate a sea-skimming missile, the TS 3 differs in having a hydraulic or pneumatic launcher and pre-programmed flight management system.

Canada's pneumatically launched Schreiner Vindicator II is controlled from a Schreiner Universal Target Control Station. A fully programmable digital autopilot allows the aircraft to fly waypoints using GPS inputs with the aircraft position shown on a moving map to permit night-time operation. This was the first target drone to be fitted with the Boeing Helicopter Radar Signature Simulator (HRSS) with blade/hub Doppler and blade `flash' effects. Reportedly, the HRSS is incorporated in the Vindicator III, which is now under development.

Meteor has completed development of its Mirach 10, originally developed as a reconnaissance unmanned aerial vehicle, which uses a mechanical or a pneumatic catapult. This has alternative control stations; a line-of-sight unit and the GPS-based control unit for operations beyond line-of-sight.

An unusual feature of the Vindicator II is the UELAR 731 26.1 kW ram-air-cooled rotary engine. A similar engine but with longer life, the 28.3 kW UEL AR 741 is used by the Turkish TAI Turna S38. A jet-powered version of the Iris, the PVK, with an unidentified variable-speed turbojet, is reported to be in production while the company also produces the turbojet-powered Sigma Perseas of which more than 100 have been built.

To familiarise air defence forces with potential targets a number of companies produce scale replicas of potential enemy aircraft. Nefer produced a MiG-27 scale target while Taiwan's Thunder Tiger Model Company produces T-10 and T-20 in MiG-27 and MiG-29 configuration. Taiwan has also purchased the BAE Systems' Flight Systems' (formerly Tracor) QMiG-21. The US forces are supplied by Continental RPVs with a wide selection of target drones, many used in the Close Air Support System, which can interact with the Multiple Integrated Laser Engagement System (Miles), which allows them to have a `shoot-back' capability.

Up Market

At the top of the target drone range are the sophisticated, jet-powered aircraft that are operated for surface-to-air and air-to-air weapon training. They were originally used to simulate manned, high-speed fixed-wing combat aircraft but now may simulate sea-skimming anti-ship missiles, surface-to-surface and air-to-surface cruise missiles, `smart' bombs or even Unmanned Aerial Vehicles (UAV). They are also used in both aircraft and missile development programmes, indeed in April the Eurofighter DA 4 development aircraft destroyed a Meteor Mirach drone with an Advanced Medium Range Air-to-Air Missile (Amraam) on the Qinetiq range at Benbecula, Scotland. These targets are also used in missile development providing realistic targets for the later stages of development and, on occasion, can carry a far more sophisticated payload than most target drones, for they are often required to make sophisticated manoeuvres and report flight progress to a ground station.

These larger drones are more often sub-sonic with a launch-weight of between 200 and 700 kg, frequently using solid-propellant rocket take-off boosters. Most are of composite construction around a metal frame and are frequently powered by the Microturbo single-shaft turbojets; either the TRI 60, with thrust ratings of 3.40 to 4.22 kN, or the TRS 18 rated at 1.13 to 1.47 kN, which provide endurances of between 60 and 150 minutes.

One of the most widely used systems is the US Navy's Northrop Grumman MQM-74 Chukar, which is powered by a Williams WR24 single-shaft turbojet rated at 0.54 to 1.07 kN. Designed as a successor to the company's very successful BQM-34 Firebee, more than 7300 have been produced with the latest US Navy contract in April 2001 for the BQM-74E. Customers include the Nato Missile Firing Installation (Namfi) in Crete, where it is used to train crews of radar and non-radar air defence guns, active and semi-active radar-guided missiles as well as visual and infrared guided missiles.

The Chukar uses radio-command guidance and, for operations beyond line-of-sight, automatic stabilisation and command with radar tracking, with the BQM-74Es being upgraded with a new integrated avionics unit with some ship-launched Chukars being capable of operating only three metres above the waves as anti-ship missile targets. The BQM-74E version of the Chukar has the Luneberg lens for passive augmentation of the radar signature as in earlier versions, a seeker simulator to duplicate the emissions of a cruise missile, radar transponder for Identification Friend or Foe (IFF), active D-band (one to two GHz) and J-band (10 to 20 GHz) radar augmentation elements for operating with search and fire-control radars.

The US Defense Department is in the early stages of a competition to replace both the Chukar and the Firebee. Target 21 began in March 1999 with the concept design study contract awards to Northrop Grumman and Lockheed Martin, each worth $1.8 million.

The US Army uses the Raytheon MQM-107 Streaker powered by the Teledyne Continental J402-CA-702 single-shaft turbojet rated at 4.27 kN. More than 1500 of these aircraft have been purchased for use by the US forces and foreign customers, including Australia where it is known as the Kalkara as a replacement for the Asta Jindivik. The Streaker is unusual in its being used largely to tow infrared or visually augmented targets, but passive and active radar augmentation is available together with both flare and chaff dispensers.

In Europe, the most widely used competitors are the Meteor Mirach 100 and Mirach 100/5, which incorporate active and passive radar as well as infrared augmentation. Both active radar and infrared targets may also be towed. The Mirach 100/4 versions for the German Navy were modified by Dornier with a new flight guidance system and electronics specifically for use with the Rolling Airframe Missile (Ram) surface-to-air missile system.

The Mirach 100 is supported by the Alamak command, control, tracking, telemetry and display system, but the fifth generation version, the Mirach 100/5, has a BAE Systems inertial navigation and GPS guidance unit. Up to eight aircraft in formation can be controlled from the ground station. Payloads include a Thales Optronics (formerly Vinten) infrared countermeasures pod, radar simulators and plume generators as well as passive radar signature augmentors.

France's MBDA developed the C22 and Britain's Flight Refuelling the Falconet II to meet similar domestic requirements and with a similar range of payloads as the Chukar and Meteor 100. The C22L was modified to be capable of making up to nine passes for ground-based missile batteries and the use of a version with six wing-tip-mounted infrared flares allows the aircraft to make up to six passes. The Falconet may be configured specifically to operate with a wide range of surfaceto-air missiles including the Crotale, Hawk, Roland and the Stinger.

The ultimate in target drones is the converted manned combat aircraft. A number of air forces provide their own drones from obsolete machines, but since the early 1970s BAE Systems Flight Systems (formerly Tracor Flight Systems) has been converting F-4 Phantom II combat aircraft into preprogrammed QF-4E/G or QRF-4C drones and the US Navy Air Depot at Cherry Point has converted aircraft into remotely controlled QF-4N/S. The drone Phantoms, which can also support manned training missions, are used to provide full-scale representative threats to test and to evaluate weapon systems, and they can carry the usual augmentation devices as well as the old AN/ALE-29 chaff/infrared decoy dispenser and the AN/ALE-50 towed radar decoy for enhanced realism.

Although BAE Systems received an additional $ 8.95 million order for a dozen QF-4 drones last year, the US Air Force feels that the QF-4 is no longer a representative threat. It has already approached industry seeking alternatives from about 2010 with solutions including drone versions of the F-16A/B Fighting Falcon II, any new designs or the provision to size up sub-scale targets. The requirement was actually envisaged in the 1990s, and as a potential cheaper alternative to full-scale aircraft Boeing's Phantom Works produced a version of the MQM-107 Streaker as the Drone RF Electronic Enhancement Mechanism (Dreem). The aircraft had two under-wing pods, one with radar augmentation system and the other with electronic countermeasures, for which test flights began in 1998. The programme appears to have been grounded, but there is little doubt that the aims of the Dreem programme could be achieved by the next decade.

Demand for target drone aircraft remains high but the most comprehensive need is in Britain where the Combined Aerial Target Service (Cats) requirement, due for implementation from 2004, is likely to be worth $1.2 billion over 20 years. Four consortia, including most of the major players in the target drone market, are competing to provide a service representing a wide range of threats rather than specific aircraft. If this programme proves a success, it might well see the target drone business migrating from pure system provision to full out-sourcing.