Rico's rants: The Super Guns

Rico's friend Kelley, also a military history nut, forwards this article from CombatAce.com:

The Paris Gun (Paris-Geschütz, in German) (photo) was the name given to a type of German long-range siege gun, several of which were used to bombard Paris, France during World War One. They were in service from March to August of 1918. When first employed, Parisians believed they had been bombed by a high-altitude Zeppelin, as neither the sound of an airplane nor a gun could be heard. They were the largest pieces of artillery used during the war by barrel length if not caliber, and are considered to be superguns. The Paris Guns hold a significant place in the history of astronautics, as their shells were the first man-made objects to reach the stratosphere.
Also called the Kaiser Wilhelm Geschütz (Emperor William Gun), they were often confused with Big Bertha, the German howitzer used against the Liège forts in 1914; indeed, the French called them this, as well. They were also confused with the smaller Langer Max (Long Max) cannon, from which they were derived; although the famous Krupp family of artillery makers produced all these guns, the resemblance ended there.
As military weapons, the Paris Guns were not a great success: the payload was minuscule, the barrel required frequent replacement, and its accuracy was only good enough for city-sized targets. The German objective was to build a psychological weapon to attack the morale of the Parisians, not to destroy the city itself.
The Paris Gun was a weapon like no other, but its capabilities are not known with full certainty. This is due to the weapon's apparent total destruction by the Germans in the face of the Allied offensive in 1918. Figures stated for the weapon's size, range, and performance varied widely depending on the source; not even the number of shells fired is certain. With the discovery in the 1980s and publication in the Bull and Murphy book of a long note on the gun written shortly before his death in 1926 by Dr. Fritz Rausenberger, who was in charge of its development at Krupp, the details of its design and capabilities were considerably clarified.
The gun was capable of firing a 106-kilogram shell to a range of 130 kilometers and a maximum altitude of 42.3 kilometers— the greatest height reached by a projectile until the first successful V-2 flight test in October of 1942. At the start of its 182-second trajectory, each shell from the Paris Gun reached a speed of 1,640 meters per second.
Seven barrels were constructed. They used worn–out 38 cm SK L/45 Max gun barrels that were fitted with an internal tube that reduced the caliber from 380 millimeters to 210 millimeters. The tube was 21 meters long and projected four meters out of the end of the gun, so an extension was bolted to the old gun-muzzle to cover and reinforce the lining tube. A further, twelve-meter long smooth–bore extension was attached to the end of this, giving a total barrel length of 34 meters. This smooth section was intended to improve accuracy and reduce the dispersion of the shells, as it reduced the slight yaw a shell might have immediately after leaving the gun barrel, produced by the gun's rifling. The barrel was braced to counteract barrel droop due to its length and weight, and vibrations while firing; it was mounted on a special rail-transportable carriage and fired from a prepared, concrete emplacement with a turntable. The original breech of the old 38 cm gun did not require modification or reinforcement.
Since it was based on a naval weapon, the gun was manned by a crew of eighty Imperial Navy sailors under the command of Vice-Admiral Rogge, chief of the Ordnance branch of the Admiralty. It was surrounded by several batteries of standard army artillery to create a "noise-screen" chorus around the big gun so that it could not be located by French and British spotters.
The projectile was the first object to reach the stratosphere. The historian Adam Hochschild put it this way: "It took about three minutes for each giant shell to cover the distance to the city, climbing to an altitude of 25 miles at the top of its trajectory. This was by far the highest point ever reached by a man-made object, so high that gunners, in calculating where the shells would land, had to take into account the rotation of the Earth. For the first time in warfare, deadly projectiles rained down on civilians from the stratosphere." This reduced drag from air resistance, allowing the shell to achieve a range of over 130 kilometers. The Paris Gun was the largest gun built at the time, but it was surpassed by the Schwerer Gustav of World War Two. This fired shells up to seventy times heavier, but with only around half the muzzle velocity and less than one third the range.
The Paris Gun shells weighed 106 kilos. The shells initially used had a diameter of 216 mm and a length of 960 mm. The main body of the shell was composed of thick steel, containing seven kilos of TNT. The small amount of explosive (around seven percent of the weight of the shell) meant that the effect of its shellburst was small for the shell's size. The thickness of the shell casing, to withstand the forces of firing, meant that shells would explode into a comparatively small number of large fragments, limiting their destructive effect. A crater produced by a shell falling in the Tuileries Garden was described by an eye–witness as being four meters across and a meter deep.
The shells were propelled at such a high velocity that each successive shot wore away a considerable amount of steel from the rifled bore. Each shell was sequentially numbered according to its increasing diameter, and had to be fired in numeric order, lest the projectile lodge in the bore, and the gun explode. When the shell was rammed into the gun, the chamber was precisely measured to determine the difference in its length: a few inches off would cause a great variance in the velocity, and with it, the range. Then, with the variance determined, the additional quantity of propellant was calculated, and its measure taken from a special car and added to the regular charge. After 65 rounds had been fired, each of progressively larger caliber to allow for wear, the barrel was sent back to Krupp and rebored to a caliber of 238 mm with a new set of shells.
The shell's explosive was contained in two compartments, separated by a wall. This strengthened the shell and supported the explosive charge under the acceleration of firing. One of the shell's two fuses was mounted in the wall, with the other in the base of the shell. The shell's nose was fitted with a streamlined, lightweight, ballistic cap, a highly unusual feature for the time, and the side had grooves that engaged with the rifling of the gun barrel, spinning the shell as it was fired so its flight was stable. Two copper driving bands provided a gas-tight seal against the gun barrel during firing.
The Paris Gun emplacement was dug out of the north side of the wooded hill at Coucy-le-Château-Auffrique. The gun was mounted on heavy steel rails embedded in concrete, facing Paris. The gun was used to shell Paris at a range of 120 kilometers. The distance was so far that the Coriolis effect— the rotation of the Earth— was substantial enough to affect trajectory calculations. The gun was fired west-southwest from Crépy-en-Laon.
The gun was fired from the forest of Coucy and the first shell landed at 0718 on 21 March 1918 on the Quai de la Seine, the explosion being heard across the city. Shells continued to land at fifteen minute intervals, with twenty counted on the first day. The initial assumption was these were bombs dropped from an airplane or Zeppelin flying too high to be seen or heard. But, within a few hours, sufficient casing fragments had been collected to show that the explosions were the result of shells, not bombs. By the end of the day, military authorities were aware the shells were being fired from behind German lines by a new long-range gun, although there was initially wild press speculation on the origin of the shells. This included the theory they were being fired by German agents close to Paris, or even within the city itself, so abandoned quarries close to the city were searched for a hidden gun. However, the actual gun was found within days by the French air reconnaissance aviator Didier Daurat.
A total of about three hundred shells were fired, at a maximum rate of around twenty per day. The shells killed over two hundred and fifty people and wounded over six hundred, and caused considerable damage to property. The worst incident was on 29 March 1918, when a single shell hit the roof of the St-Gervais-et-St-Protais Church, collapsing the entire roof on to the congregation then hearing the Good Friday service. A total of ninety people were killed and seventy were wounded. The gun was taken back to Germany in August of 1918 when the Allied advance threatened its security. The gun was never captured by the Allies, and it is believed that, near the end of the war, it was completely destroyed by the Germans. One spare mounting was captured by American troops near Château-Thierry, but the gun was never found; the construction plans seem to have been destroyed as well.
In the 1930s, the German army became interested in rockets for long range artillery as a replacement for the Paris Gun, which was specifically banned under the Versailles Treaty. This work would eventually lead to the V-2 rocket used in World War Two.