Oerlikon GDF


The Oerlikon GDF or Oerlikon 35 mm twin cannon is a towed anti-aircraft gun made by Oerlikon Contraves. The system was originally designated 2 ZLA/353 ML but this was later changed to GDF-001. It was developed in the late 1950s and is used by around 30 countries.

Design and development

The system uses twin autocannons, firing 35×228mm NATO-standard ammunition. It was originally designated 353 MK and is now designated as the KD series. The same KD series 35mm cannons are used in the Leopard 1 based Gepard and Type 74 tank based Type 87 SPAAG and Marksman self-propelled anti-aircraft guns. The system could be paired with the off-gun Super Fledermaus fire control radar, which in the late 1970s was upgraded to the Skyguard system. The weapons were aimed either directly, by way of an advanced sighting system, or automatically, by locking onto the target with radar. Early models carried 112 rounds ready to fire, and an additional 126 stored on the chassis as reloads. Later versions with automated reloading carry 280 rounds total. A typical engagement burst is 28 rounds.
In 1980 an upgraded model, the GDF-002 was produced, which featured an improved sight, and the ability to be directed by an off-gun digital control system. A few years later a third version of the system was being produced, the GDF-003, which was broadly similar to the GDF-002, but included some enhancements like self-lubricating weapons and integrated protective covers.
A self-propelled concept, the GDF-001 Escorter 35 existed.
In 1985 a further upgraded model was produced, the GDF-005, which was introduced, featuring the Gunking 3D computer-controlled sight with an integrated laser range-finder and digital control system. The GDF-005 also introduced an automated ammunition-handling system, which eliminated the need for the two reloaders, reducing the crew from 3 to 1.
The guns are usually transported by a 5-tonne 6×6 truck.

KD series cannons

Development of the KD series cannon began around 1952 soon after Oerlikon calculated that 35 mm was the optimum calibre for an anti-aircraft gun. The KD series cannons were a design adapted from the post-war 20 mm KAA 204 Gk cannon. Several designs were developed, including a water-cooled design, designated Mk 352, which was tested by the U.S. Navy.
The final design was the Mk 323, which was developed in two variants, a belt-fed version the KDA, and a linkless version the KDC, fed by seven-round clips. Both designs are gas-operated, with a propped-lock locking system.

Super Fledermaus

The Super Fledermaus fire control system was designed and built by the then separate Contraves company. It consists of a four-wheeled towed trailer with an E/F band pulse doppler search radar with a range of around 15 km and a pulse doppler tracking radar operating in the J band, also with a range of 15 km. It was also used as the fire control system on the Gepard SPAAG.

Skyguard

The Skyguard is a fire control system developed by Contraves and introduced in the 1977 to replace the Contraves Super Fledermaus system in the Swiss Air Force. It is produced by Oerlikon-Buehrle. Updated versions were fielded in 1975, 1995 and 2010. It's an all weather low to medium altitude air defence system with the maximum effective distance of 4,000 m.
The Skyguard fire control system performs air surveillance, target acquisition, calculation of the derivative-action values and control of the twin 35 mm guns or missiles. Pulse doppler search radar, pulse doppler tracking radar and co-axial television camera are mounted on the roof of the towed trailer. Skyguard is operated by four people. The radar is deployed quickly through the use of hydraulic systems for antenna erection. The trailer houses the crew of two and a small power generator.
A typical fire unit consists of two twin 35 mm gun platforms with a single Skyguard fire control radar. Skyguard systems can also incorporate an optional SAM module based on the GDF's mount and radar system but with the guns replaced by four missile canisters. It can be armed with either AIM-7 Sparrow, RIM-7 Sea Sparrow or Aspide missiles.
The Skyguard radar system was used in the German Air Force for surveillance of low-altitude flight zones. In Taiwanese service, the system includes the Sky Sentinel radar, two 35 mm Oerlikon twin gun and an AIM-7 Sparrow Missile Launcher. Greek service the Skyguard system with RIM-7M is known as the VELOS. In Spanish service, Toledo is a Skyguard system with Aspide launchers where the fire control unit has been replaced with Skydor from Navantia.
A total of 468 systems were built through 1994 and major users were Italy, Spain and Pakistan.

Ammunition

Norwegian Nammo, in addition to Oerlikon, supplies at least some variants of this ammunition. Norwegian ammunition was supplied to Ukraine in 2022 for use in the GDF guns in its Flakpanzer Gepard anti-aircraft systems, but it was found not to be compatible, requiring modification.

Versions

  • GDF-001 / 2 ZLA/353 MK: XABA sight
  • GDF-002: Introduced in 1980. Improved Ferranti sight and digital data bus. The gun has 112 rounds ready and 126 in reserve
  • GDF-003: Minor enhancements including protective covers and automatic weapon lubrication.
  • GDF-005: Introduced in 1985. Fitted with Gunking 3D computer-controlled sight with a laser range finder and digital fire control system. Integrated power supply and diagnostics. 280 rounds on the gun and an automatic re-loading system.
  • GDF-006: GDF-001/002/003 upgraded with AHEAD system.
  • GDF-007: GDF-005 upgraded with AHEAD system.
  • GDF-009: Unveiled at IDEF 2015, held in May 2015 in Istanbul. To date, its exterior significantly changed, although the installation has retained the design of the original serial versions of the systems. Unlike other variants, this one relies on an internal power source. The GDF-009 model is based on a four-wheeled carriage, and is raised off the ground by three stabilisers when deployed in the firing position. It also features an automatic levelling system that can compensate for a maximum tilt angle of up to 7°. Mounted on the forward part of the carriage is the integrated battery, which functions as the gun's power supply unit and can be recharged from an external source if required.
  • AHEAD: An upgrade for the GDF series guns built around a special projectile which explodes at a pre-calculated point in front of the target, sending a cone of 152 tungsten sub-projectiles at the target. Used by Canada, Pakistan, Greece, Oman, Spain, Taiwan, and Chile.
  • MKE GDF-003B: Turkish version of 35 mm GDF series. The gun of the system manufactured under licence by Turkish company Mechanical and Chemical Industry Corporation.
  • MKE/Aselsan GDF-003B Modernized: MKE GDF-003B system modernized by another Turkish company Aselsan. MKE made 35mm guns linked with an Aselsan made Fire and Command Control System. The system has similarities with Skyguard system. The Fire and Command Control System consists of Aselsan made 3D search radar, fire control radar, electro-optical sensors and other electronics. Each weapons system can fire up to 1100 rpm to an effective range of 4 km. The upgradation enables the system to fire Aselsan ATOM 35mm airburst round which explodes at a pre-calculated point in front of the target, sending a cone of tungsten pellets at the target. The gun can also fire HEI and TP-T ammunitions. The concept of ATOM 35mm air burst ammunition came up in order to increase the efficiency of the gun systems against modern targets including fixed/rotary wing aircraft, cruise missiles, air-to-ground missiles and unmanned aerial vehicles and other precision guided weapons. Aselsan Fire and Command Control system can also incorporate a low altitude air defense SAM along with 35 mm gun platform. Like the GDF-009 each gun platform equipped with the integrated battery, which functions as the gun's power supply unit and can be recharged from an external source if required.
  • KORKUT: Turkish Self-propelled variant designed by Aselsan. The system developed from modernized GDF-003B and based around the amphibious capable FNSS ACV-30. KDC-02 cannon of the system manufactured under licence by MKE. Each Korkut system comprises a command-and-control vehicle and three weapons platform vehicles. The command-and-control vehicle has the 3D search radar with an effective radar range of 70 km. Each weapon platform vehicle carries enclosed twin 35 mm cannons, fire control radar and electro-optical sensors.
  • Aselsan GOKDENIZ: CIWS version of KORKUT. The system's primary purpose is to defend against sea skimming anti-ship missiles, unmanned aerial vehicles and other precision guided weapons.
  • Gepard: Self-propelled version of the system based around the Leopard 1.
  • Marksman: Self-propelled version of the system based around the Marksman turret, which could be fitted on numerous tank chassis. The only model that went into production was a version based on the T-55AM chassis for Finland, seven systems of the ITPSV 90 Marksman were produced. After having been moved to reserve storage since 2010, the Marksman turrets had their electronics modernized and were transferred over to Leopard 2 chassis in 2015, creating the ITPSV Leopard 2 Marksman.
  • Type 87: Japanese SPAAG using the system.
  • PZA Loara: Polish SPAAG based on the PT-91 tank.
  • Type 90 : Chinese licensed copy of GDF-002. The PG99 is a towed anti-aircraft gun suitable for point and coastal air defence. It is usually deployed near military bases, airfields, tunnels, islands, and along the coast to defend Sea Land of Communication, ports, bridges and other important assets.
  • MAA-01: Myanmar's locally made variant using Chinese GDF guns.Similar to Type-90.
  • CS/SA1: Chinese upgrade of GDF-002. Mounted on the 6×6 SX2190 truck, the PG99 is a self-propelled variant of the Type 90 35 mm AA system, previously available only as a towed AA piece.
  • Type 09 SPAAA: Self-propelled version of the system based around the Type 90. First appeared in 2015 China Victory Day Parade.
  • Samavat: Iranian version of these guns with night vision sight and used with Skyguard & Super Fledermaus FC radars.
  • Amoun: Egyptian version of Skyguard & Sparrow SAM.