In a pair of previous articles, we covered some oddities in weapons design, involving pneumatic/air pressure systems to propel projectiles, sometimes of significant weight. In contrast, this week, we will look at something simultaneously advanced, yet strangely kitschy and primitive:
The patent for the Fahrbare Panzerlafette für leichte Geschütze (in English: movable armor carriage for light guns) was originally filed in Germany in 1880, although the patent would be approved until 1885 (1887 in the United States), by inventor Hermann Gruson. The Fahrpanzer (which is what it was quickly abbreviated to) was essentially a light artillery gun carriage. Gruson created a kind of “semi-mobile” (to use modern terminology) pillbox that could be quickly transported around the battlefield by a team of horses (like the other varieties of field artillery of the time), to strengthen local defenses.
Gruson’s design was essentially an armored pillbox, with a rotating turret, accessed by a tiny armored “closet”-like box to the rear. The turret could mount either a Maxin-type machinegun, or a very lightweight 53- or 57mm cannon, also designed by Gruson, the Cannone da 57/25 Gruson.
Gruson’s turret design was unique, in that rather than relying on a central column to support the weight of the turret, the Fahrpanzer’s turret rested on the upper portion of the inside of the turret, transferring its weight to the upper portion of the cylindrical casing via a set of roller bearings, which was rotated through a full 360° using a hand-crank wheel at the gunner’s station creating, in effect, a modern turret. This had the side effect of freeing up space on the floor of the fighting compartment to fix a rubber roller (made specifically of “Indian Rubber”, according to Gruson’s recommendation) in place to stabilize and cushion the 53- or 57mm gun’s mount, whose trunnions were placed behind the center of gravity of the mount. The gun, as well as the turret, could be adjusted internally by a hand-crank, but could also be elevated similarly, allowing for limited elevation of about –5° to +10°.
If the turret had any defect, it was that the turret was made of cast iron. The resulting brittle nature of the metal left the Fahrpanzer with acceptable protection against rifle fire, but a hit from any kind of artillery would rip through the turret like paper. However, on the plus side, the system’s design offered only a very small opening for the cannon and its sight, significantly reducing the danger of infantry fire to the crew.
The gun itself, while an admitted lightweight, was no slouch: with a maximum range of c.5,500 meters it could drop a shell loaded with over 600 grams of black powder; that is not a charge a person would want to be next to. The gun was fast, quick and simple to move around the battlefield, and did very good work on its own, mostly throughout Europe and Russia, but also managing to find a home in the Chilean Navy.
With about two thousand units ultimately being produced, Gruson’s mobile turret lasted in military service throughout the world, from the 1890’s to well after World War 1, finding use on early armored cars, as well as being fitted into permanent positions guarding critical points. Those turrets were hidden in small caves dug into mountainsides, in positions that offered a clear field of fire when the pint-sized turrets were run out for action, in a manner not dissimilar to the cannons of a warship of the Age of Sail.
Ultimately, technological evolution passed the Fahrpanzer by. Later self-propelled vehicles would effectively duplicate the turret, to make the first real tanks; more effective models supplanted its gun; and finally, its armor – while cheap and effective for the 1880’s and 1890’s – was virtually worthless by 1914. While a few units survive in places, mostly in Greece and Bulgaria, most have long ago been either destroyed, sold for scrap, or rotted away on forgotten battlefields…
…But – you never know: someone might just decide to build a modernized version, because it’s not as hard a thing to do as one might suspect.