The V3 - The "England-Canon"

The V stands for "Vergeltungswaffe" engl. something like "Repayment-weapon"

After Conquering France Hitler don't want to invade Britain, because he wants to fullfill his plans for conquering the east.
He also knew that the Russian army grew from day to day and that it will come to a conflict between Russia and Germany in the near future.
So he wanted to demoralize the Britons by bombing the shit out of them to force them to a peace-treaty.
But after loosing the "Airbattle for England" he needs a new weapon which is able to target London.The search for an alternative reminds Hitler of the old railguns from the first World War, with which the Germans bombed Paris. But the range of the best railgung of that time was about ~70 kilometers. But London was something like 160 kilometers away from Calais. So, he needs a new sort of gun.

Picture of the profile

In 1943, German engineer August Cönders, of Röchling Stahlwerk AG, proposed an electrically initiated multiple-charge weapon. Thanks to the success of Cönders's other projects, including the "Röchling shell", major figures in the Nazi establishment took notice of him, most importantly Albert Speer, the Minister of Munitions.
Cönders was ordered to produce a prototype of the Hochdruckpumpe and duly constructed one in 20 mm calibre, which proved satisfactory. At this point, Adolf Hitler, who had been following the project with interest, took a hand and decided that a battery of 50 full-size guns would be sited in northern France for bombarding London.
Cönders had 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 metres (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 being attained. On July 4, 1944, the Misdroy gun was test-fired with 8 rounds (one of the 1.8 meter long shells travelled 93 km). The gun burst during the testing, putting an end to the tests.

photo of remains of V-3 in Zalesie

(Testing Area)

The gun used multiple propellant charges placed along the barrel's length and timed to fire as soon as the projectile passed them, to provide an additional boost. Because of their greater suitability and ease of use, solid-fuel rocket boosters were used instead of explosive charges. These were arranged in symmetrical pairs along the length of the barrel, angled to project their thrust against the base of the projectile as it passed. This layout spawned the German codename Tausendfüßler ("millipede"). Unlike conventional rifled weapons of the day, the smooth-bore gun fired a fin-stabilized shell, dependent upon aerodynamic rather than gyroscopic forces to prevent tumbling, which resulted in a lower drag coefficient.