V-3 Cannon - Development

Development

The origin of the multi-chamber gun dates back from the 19th century. In 1857 U.S. arms expert Azel Storrs Lyman (1815–1885) was granted a patent on "Improvement in accelerating fire-arms" and built in 1860 a prototype which proved to be unsuccessful. The idea was perfected in collaboration with James Richard Haskell that had been working for years on the same principle Haskell and Lyman reasoned that subsidiary propellant charges, spaced at intervals up the barrel of a gun in side chambers and ignited an instant after a shell had passed them, could increase the muzzle velocity of a projectile. The "Lyman-Haskell multi-charge gun", constructed on the instructions of the US Army's Chief of Ordnance, did not resemble a conventional artillery piece. The barrel was so long that it had to be laid on an inclined ramp, and it had pairs of chambers angled back at 45 degrees let into it. It was test fired at the Frankfort Arsenal at Philadelphia in 1880 and was proven unsuccessful. Due to faulty obturation, the flash from the original propellant charge bypassed the projectile and prematurely ignited the subsidiary charges before the shell passed them, slowing the shell down. The best velocity that could be obtained from it was 335 metres per second (1,100 ft/s), inferior to the performance of a conventional RBL 7 inch Armstrong gun of the same period. Although new prototypes of multi-charge guns were built and tested, Lyman and Haskell abandoned the idea.

During the same period, a French engineer Louis-Guillaume Perreaux, one of the pioneers of motorcycle, had been working on a similar project since before 1860. Perreaux was granted a patent in 1864 for a multi-chamber gun. In 1878 Perreaux presented his invention at the World Exhibition of Paris. In 1918 the French Army made plans for very long range multi-chamber gun in response to the German Paris Gun. This Krupp gun could bombard Paris from German lines over a distance of no less than 125 kilometres (78 mi). However, the French initiative did not reach the prototype stage because the retreat of the German armies and the armistice put an end to the bombardment. The plans for the multi-chamber gun envisaged to counter the German fire were archived.

Twenty years later, when France collapsed in June 1940 at the beginning of World War II, the German troops got their hands on the plans of this long-range gun. In 1942, this patent attracted the attention of August Coenders, developer of the Röchling shell and chief engineer of the plants "Röchling Stahlwerk AG" in Wetzlar, Germany. Coenders thought that the gradual acceleration of the shell by a series of small charges spread over the length of the barrel may be the solution to the problem of designing very long range guns. The very strong explosive charge needed to project the shells at high speed were causing very rapid degradation of the gun tube. Coenders proposed the use of electrically activated charges to eliminate the problem of the premature ignition of the subsidiary charges experienced by the Lyman-Haskell gun. Coenders built a prototype of a 20 mm multi-chamber gun using the machinery readily available at the Wetzlar plant that was producing tubes of this caliber for the Flak 38 anti-aircraft guns of 20 mm. The first tests were encouraging but to get the support of the Ministry of arms Hermann Röchling had to present to Albert Speer Coenders' project of a cannon capable of firing on London from the coast of the Pas-de-Calais. Two batteries could crush London under a barrage of hundreds of shells per hour, shells of 140 kilograms (310 lb) with an explosive charge of 25 kilograms (55 lb).

Cönders constructed a full-calibre gun at the Hillersleben proving ground near Magdeburg, but by the end of 1943 he had encountered severe problems both in putting the gun's basic principle into operation and in producing a feasible design for the shells it was to fire. Even when everything worked, the muzzle velocity was just over 1,000 metres per second (3,300 ft/s), which was nowhere near what had been promised. Nonetheless, plans were proposed to build a single full-size gun with a 150-metre (490 ft) barrel at Misdroy on the Baltic island of Wolin, near Peenemünde, while construction at the Mimoyecques site in France (which had already been attacked by the USAAF and the RAF) went ahead. By March 1944, with no good news from Misdroy, the Heereswaffenamt (Weapon Procurement Office) took control of the project, and Cönders became one of the engineers working on the three chief problems: projectile design, obturation, and ignition of the secondary charges.

Six different companies, including Krupp and Skoda, produced satisfactory designs for projectiles. Obturation problems were solved by placing a sealing piston between the projectile and the initial propellant charge, which in turn prevented the flash from the charge from getting ahead of the projectile and solved the problem of controlling the initiation of the secondary charges. By the end of May 1944, there were four designs for the 150-mm finned projectile, one manufactured by Fasterstoff (designed by Füstenberg), and three others by Röchling (Cönders), Bochumer (Verein-Haack), and Witkowitz (Athem).

Trials were held at Misdroy from May 20–24, 1944 with ranges of up to 88 km (55 mi) being attained. On July 4, 1944, the Misdroy gun was test-fired with 8 rounds (one of the 1.8 m (5.9 ft) long shells travelled 93 km (58 mi)). The gun burst during the testing, putting an end to the tests.