The Bofors Missiles RBS56 Bill 1 is a man-portable, medium-range, tube-launched, wire-guided Anti-Tank Guided Weapon (ATGW), which is capable of being fired from either ground or vehicle mounts.

Bill 1 integrates fully the Over-fly Top Attack (OTA) technology with an elevated flight, a 30° canted warhead and an interactive dual-purpose sensor system. In addition to this the weapon is also fitted with an impact fuze.

The solid propellant sustainer rocket motor burns for approximately 2 seconds (or 400 m downrange) following ejection of the missile by the gas generator from the launch tube. The missile then continues in free flight and the warhead is kept pointing downwards by gyrostabilisation in roll.

The missile flies 0.75 m above the gunner's line of sight in order to keep it free from ground interference or obstacles close to the gunner's line of sight. The advantage of this flight profile is the high target accessibility for the gunner when engaging targets that expose only a small vertical section to his firing position.

The highly sophisticated Semi-Automatic Command to Line Of Sight (SACLOS) guidance system is based on the linear quadratic method. All the gunner has to do is to keep the cross-hairs of his sight 0.75 m below the turret roof of the MBT. For targets with flat turrets or no turrets, the aiming point is adjusted downwards accordingly.

Slow-moving, crossing or head-on helicopters hovering behind a tree line can also be engaged. Likewise, moving targets at very close ranges can be engaged.

The laser beacon at the rear of the missile emits individually coded laser signals back to the sight, thereby making the system unjammable. All electronics are resistant to electromagnetic radiation and pulses.

Late in 1996, the FMV (Swedish Defence Materiel Administration) decided that remaining deliveries of the Bofors Missiles RBS 56 Bill Anti-Tank Guided Weapon (ATGW) to the Swedish Army will be in the latest Bill 2 configuration (see separate entry).

The Bill Night Sight (BNS) has been designed as an add-on thermal imaging night sight for use with the Bofors Missiles RBS56 Bill 1 and Bill 2 anti-tank missile systems.

The BNS is mounted on top of the day sight with the thermal image mirrored into the front lens of the day sight. It can be mounted rapidly while maintaining sightline accuracy, without the need for harmonisation.

The front lens is coated with a diamond hard anti-reflection carbon coating which has increased resistance against mechanical abrasion.

The thermal image is displayed in red (hot) and black (cold) but can be reversed by inverting the polarity of the image to improve target recognition and false target revelation.

The Bill Night Sight now exists in two versions. The Bill NS which has two fields of view, wide for surveillance and narrow for more detailed observation and aiming. It is powered by a battery pack and high pressure air bottle for cooling. BNS is equipped with low battery and gas pressure indicators.

The second is the Bill Tl (BTI) with the Tl standing for thermal imager which is a better name since the Tl can also be used in daytime. It has also been provided with a special filter giving an optimised mix of visual and infra-red image during daylight.

This version uses a closed cycle Stirling cooling engine, has a single field of view and a power consumption of 10W. It can be powered either by a standard Ni/Cd lithium battery or via a built-in vehicle power converter and has an automatic change over between the different power sources.

Prime contractor for the Bill Night Sight is Celsius Tech Electronics and production commenced in 1990. It is now in service with Austria and Sweden.

Details of this turret, which is fitted with three Bofors Missiles RBS56 Bill ATGW in the ready to launch position, are given in the ATGW turrets section later in this volume.

A prototype of this turret, which is Bill Under Armour (BUA), has been tested on an MT-LB full tracked vehicle of the Swedish Army.

Production complete. In service with Austria (as PAL2000), Brazil (first deliveries late 1996) and Sweden.

• Tracked armour vehicles Pbv 3023 (single-tube launcher - Swedish Army)

• Tracked all-terrain vehicle Pvbv 2062 (single-tube launcher - Swedish Army).