THE RED QUEEN AND THE VIGILANTE
© Anthony G Williams
With thanks to various contributors for additional information
This may sound like an exotic romance, but in fact it's the tale of two attempts to develop advanced Army AA guns in the 1950s; one British, one American.
The Second World War clearly demonstrated the importance of air power over the battlefield and the havoc which could be wreaked by ground attack planes, whether fighter-bombers like the P-47 and Typhoon, or specialised armoured attack planes such as the Hs 129 and Il-2 Sturmovik. Clearly, it would be important for armies to have their own close-range defence against such threats and much effort was put into developing appropriate systems.
Guided AA missiles were still in their infancy in the 1950s so the obvious solution was a fast-firing automatic cannon. The UK (with help from Switzerland) and the USA developed gun systems to prototype stage, both of considerable technical interest, but neither proceeded further. The British weapon was code-named Red Queen, the American one Vigilante.
Oerlikon RK 421
The genesis of Red Queen is rather convoluted. It started with the Mauser MG 213C revolver cannon, which had reached prototype stage at the end of World War 2. In order to achieve a higher rate of fire, this broke down the loading cycle (the main constraint on RoF) into stages by providing a revolving cylinder with several chambers, into which the ammunition was chambered and from which the fired case was subsequently extracted. This enabled much higher rates of fire than with other single-barrel guns so was of much interest to armament firms. Members of the Mauser design team therefore went to work in France (leading to the 30mm DEFA cannon), the UK (30mm Aden), the USA (20mm M39) and Switzerland (a range of different Oerlikon cannon, of which only the 30mm KCA achieved sales success).
In the early 1950s the British Army decided it wanted to replace its 40mm Bofors L/56 guns with a system with a much better ballistic performance and a higher rate of fire, plus a large magazine capacity. It is unclear whether they issued a specification internationally, or approached Oerlikon, or Oerlikon heard about it and approached them. Whatever, Oerlikon was soon designing a gun to meet this requirement.
The RK 421 (Revolver Kanone, 42mm, 1st model) which emerged was fascinating. The unusual calibre of 42mm was selected, and a 42 x 348 rimless cartridge designed (shown HERE). Note that this particular drawing is labelled RK 422, which suggests that some development changes had been made. This fired a 1.09 kg shell at 1,070 m/s to develop a muzzle energy of 624,000 joules, an increase of 80% over the 40 x 311R Bofors. The gun design chosen was a revolver, but with a seven-chamber cylinder and two barrels. It is not clear whether the barrels fired simultaneously or alternately. Ammunition feed was by means of a 75-round pan magazine (with the rounds pointing inwards) to the left side of the gun, and a rate of fire of 450 rpm was claimed. The picture of the gun HERE is from Oerlikon's 'The History of the Revolver Cannon' by Doug Richardson.
Red Queen
For some reason no longer known, the UK decided to take over the development of this weapon under the 'Red Queen' designation (British projects of the time were all given colour code names at random to ensure that they didn't indicate the purpose of the system). The gun which emerged differed in various respects from the Oerlikon. First, the ammunition was changed quite significantly; the 42mm calibre was retained but the cartridge case was made shorter and fatter (81-82mm diameter instead of 70mm). Different case lengths were tried; a drawing of one version with a 251mm long case is shown HERE, but it seems that a longer 270mm case was selected. A 42 x 270 cartridge is illustrated HERE (with thanks to Tim Gurney). It is assumed that the ballistics remained the same as the RK 421's, but no firm data survives. The reason for the change in the shape of the cartridge case from the RK 421 is not recorded, but it may have been to reduce the action length and thus speed up its operation. It appears that different calibres were considered at some point since a drawing of a 45mm version of the case exists (shown HERE), although this is associated with the otherwise unknown code Red King.
Very little information has survived about the gun; it appears that records were destroyed at some point. The mechanism remained a twin-barrel revolver fed by a large , upright, pan magazine. Some very small photos of a mock-up survive on a contact print, and these are reproduced HERE (with thanks to Geoff Tillotson). Additional information from Alec Beanse: the MoD Pattern Room originally contained a Red Queen and it took up quite a lot of room there; it was removed some years before Enfield closed to an unknown destination. Also some Proof Rounds for it were still in existence as late as the 70's. The projectile was a typical Proof Shot, short and flat ended and unpainted. The rounds had long Flash Tubes that screwed into the base of the Cases.
It appears that the weapon experienced significant development problems. Once Bofors had introduced the much-improved 40mm L/70 in the early 1950s, Red Queen was cancelled and the Bofors was adopted by the British Army for close-range air defence until it was replaced by the Rapier missile system in 1979.
Vigilante
The US Army also wanted a 40mm Bofors replacement and towards the end of the 1950s a new gun and cartridge were developed to meet this need. They chose a calibre which they had traditionally used, 37mm, but a new 37 x 219SR T68 cartridge was developed, featuring a shell with a long, tapered ballistic cap or windshield. The cartridge case is based on the 40 mm Bofors case, shortened, necked and with the rim turned down. Early Vigilante cases even retained the 40mm Bofors' clip groove in the base. The mouth, neck and shoulder of the case were the same as the 37mm M16 and 37mm M17 cases for the U.S. anti tank and anti aircraft weapons, respectively, except the neck was shortened so the cartridge could have a similar overall length while employing a projectile with the rotating band farther to the rear. Standing next to each other, the Vigilante ammo and the anti-tank round have similar overall length, and nearly identical placement of the shoulder and the same shoulder angle, the only real difference is the shorter neck and wider base of the vigilante round. (with thanks to Greg - GKielbasa for additional information). Muzzle velocity of the T68m was 915 m/s, but the shell weight is not given. This PHOTO shows the Vigilante cartridge (right) next to the 35x228 Oerlikon round.
The gun was also different; the biggest of the rotary cannon. In general principle rotary guns are similar to revolvers in that they have multiple chambers to speed up reloading, except that each chamber has its own barrel and the whole lot spin round under external power. The gun was designated T250, had six barrels and was fired at 3,000 rpm (reduced to 120 rpm for engaging ground targets). The gun was fitted to a tracked carrier, the T249, based on lengthened version of the chassis of the M113 APC. The gun is shown HERE and HERE; it had a 192-round drum or pan magazine shown HERE (with thanks to Neil Baumgardner for the photos and additional information). Additional photos of the remaining prototype HERE and HERE are from Thomas Tencza.
Vigilante had reached the evaluation stage in 1960 but was cancelled shortly thereafter. Its development was overtaken by a precocious new American missile system called Mauler, which was intended to operate automatically once switched on. It was supposed to detect threats, fire a missile and guided it to its target without human intervention, leaving the operators (in Ian Hogg's words) to chalk up the score. Like many ambitious early missile projects, this promised far more than it was able to deliver and was eventually cancelled in 1965, but not before it had terminated the Vigilante. The US Army was left with the M163, a 20mm Vulcan rotary mounted on a M113 tracked vehicle.
One last postscript to the Vigilante story--Sperry brought the gun back out for one last try during the US Army's DIVAD competition. Their unsuccessful entry used the Vigilante rechambered for 35 x 228 Oerlikon, mounted on an M-60 chassis.
Any other information about the gun and ammunition for Red Queen or Vigilante will be gratefully received.
