The Secret of the Paris Gun

The Paris Gun Test Firing

During my Bat Soup Plague incarceration, my better half issued orders for me to commence de-cluttering my office forthwith. Unable to evade the mission, I soon found myself looking through my back issues of Military History Quarterly, and I re-discovered  this interesting entry from Major General David Zabecki. He rather concisely reveals the secret to  the Krupp-built Paris Gun's phenomenal 78-mile range (theoretically 81 miles according to the Encyclopedia Astronautica).

Designed by Krupp’s Professor Fritz Rausenberger, the officially designated Wilhelmgeschütz (Kaiser Wilhelm Gun) was one of the most remarkable artillery pieces ever built. Its maximum range of 126,000 meters far exceeded that of any gun built before. Or since. The Germans used three of them against Paris between March and July 1918, earning them the name Paris Guns. Very few conventional artillery pieces fired in war have been able to achieve even half their range.

The Paris Gun was constructed by inserting a 210mm liner tube into a bored-out 380mm naval gun barrel. The liner extended some 39 feet beyond the muzzle of the base barrel. A 19-foot smooth-bore extension was then added to the front of the extended liner, giving the composite barrel a length of 130 feet. The entire composite barrel required an external truss system to keep it straight.

Virtually all artillery pieces achieve their maximum range when the barrel is elevated to an angle of 45 degrees. Anything over 45 degrees is classified as high-angle fire, and as the elevation increases the range decreases. The Paris Gun, however, appeared to defy the normal laws of ballistics by achieving its maximum range at an elevation of 50 degrees. The reason was that at 50 degrees the round from the Paris Gun went significantly higher into the stratosphere than at a 45-degree elevation. The reduced air density at the higher altitudes caused far less drag on the body of the projectile, which resulted in the greater horizontal range.

Read our earlier article on the operation of the Paris Gun HERE.

Source:  Military History Quarterly, Autumn 2014.