What were a bunch of gun designers doing in a brewery, a few years ago?
What's probably the biggest improvement in medium-caliber ammunition since the first Bofors gun is ready for full-scale development, according to BAE Systems. Talking at Farnborough, BAE program manager Charles Hookey excused the company's land weapons brief by saying that the new case-telescoped ammunition (CTA) gun - developed by CTA International, a joint venture betweeen BAE and Nexter - "shoots down aeroplanes pretty well."
The CTA concept has been around in theory since the early 1900s. The USAF briefly considered it as an option for the F-22, in the 1980s, but US armourers could not make it work. The Royal Ordnance Factory - now part of BAE - picked up the baton in the 1990s.
In the CTA gun, the projectile is completely enclosed in the cartridge case and surrounded by propellant. It's designed so that the charge first kicks the projectile down the barrel and then completes ignition. Meanwhile, the pressure of the blast keeps the gun sealed.
The big advantage is the shape of the round: a pure cylinder. The gun has a rotating breech; its axis of rotation is right angles to the bore and on the same line as the trunnion. To load a round, the breech rotates so that the round is pushed into it through the trunnion. It rotates in line with the bore and fires, then rotates into the loading position. The next round is loaded, simultaneously ejecting the spent cartridge on the other side of the gun.
It is not only compact, fast and simple, but the loading point is fixed: the round loads through the trunnion,, the only part of the gun which doesn't move relative to the turret. The cylindrical rounds also pack more efficiently and are easier to handle, which is where the brewery comes in: BAE Systems designers visited a local brewery to gather ideas for automated storage systems and conveyors that would be used in the turret's autoloader.
Overall, the gun is smaller and more compact than conventional weapons, with a sliding breech. Also, it has a higher muzzle velocity, making its anti-armor round more effective, and the general-purpose airburst/high explosive round packs a larger charge than a conventional 40 mm round. In all, the weapon's lethality is more like that of a 50 mm cannon, but it is smaller than a 30 mm Bushmaster.
A BAE Systems manned turret (MTIP 2, Manned Turret Integration Program 2) was cleared for manned testing in December 2007. The gun has been selected by the UK MoD for the Warrior Fightability Lethality Improvement Program and for the Future Rapid Effects System (FRES) Scout platform.
pic credits CTA International