Developed in the 1960s by Oerlikon Contraves, the Oerlikon GDF or Oerlikon 35 mm twin cannon is one of the most popular anti-aircraft guns in the world, with more than 30 countries in use.
Having undergone many upgrades, modern variants of this air defense system can not only fire conventional 35mm anti-aircraft ammunition, but also programmable munitions.
The Oerlikon 35 mm is classified as a towed anti-aircraft gun. The guns are usually transported by a 5-tonne 6×6 truck. Many variants have been developed, the most common being versions from GDF-001 to GDF-009. The system uses twin autocannons, firing 35×228mm NATO-standard ammunition. The system could be paired with the off-gun (remote) Super Fledermaus fire control radar, which in the late 1970s was upgraded to the Skyguard system.
The weapons was 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.
On later upgrades many improvements were applied, improved visibility and the ability to be directed by an off-gun digital control system. On the GDF-005, an automatic ammunition handling system was introduced, which eliminated the need for two reloaders, reducing the crew from 3 to 1.
The Skyguard is a fire control system introduced in the 1960s to replace the Contraves Super Fledermaus system in the Swiss Air Force. Updated version were fielded in 1975, 1995 and 2010. It’s an all weather low to medium altitude (up to 3,000 m) 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. A typical fire unit consists of two twin 35 mm gun platforms with a single Skyguard fire control radar.
The Oerlikon twin-gun uses 35 mm autocannons, which were originally designated 353 MK and are now designated as the KD series. The cannon is mounted to a cradle, with the upper mount determining the traverse of the guns, which is in the pivot bearing of the lower mount. The upper mount platform supports the auxiliary aiming equipment, the seats for the crew, and both 63-round reloading containers. The guns have a maximum elevation speed of 56º/s and a maximum traverse speed of 112º/s. The Oerlikon 35mm gun is able to fire 1,100 rds/min.
The latest version, the GDF-009, is capable of firing AHEAD programmable projectiles, although this “requires some modification of a ballistic computer.” Such ammunition is detonated at a given point on the trajectory – closest to the target and sends the maximum possible number of striking elements to it. In recent decades, new requirements for guns have appeared, and the Swiss company has responded to them by developing promising projects.