Steam launched harpoon

A steam launched harpoon is exactly what it sounds like. A spear like object sharpen, launched by steam power. The goal of the harpoon is to penetrate the balloon of an enemy airship, to be sharp enough to penetrate the hardened, armoured, outer layer and continue with enough momentum to penetrate several gas bags. Which will cause the air ship to sink. Sinking being the technical term for free falling to the surface of the earth, and stopping it from being an effective fighting machine.

Maker

Almost all steam launched harpoons are made by the Etherington Arms Production and Development company. They make harpoons in most weight classes, and are often the first to develop a new version with improvements. Multiple companies produce mounts though, but hey almost all exclusively launch Etherington harpoons from those installations.

Version 1

The first version had a steam cylinder mounted on the launching pod, this cylinder was pressurised with steam from an external boiler. The harpoon formed the seal of one side of the cylinder. Releasing the lock that held the harpoon in place, made the steam expel the harpoon forwards. The steam was wasted. If this harpoon was mounted on an airship or other craft, it could take steam from the vehicles steam system. Costing the vehicle precious steam.

Version 2

Later versions had a longer barrel which the harpoon slid through, more effectively absorbing the energy of the expanding steam in the launch pod mounted cylinder. Reducing the steam cost, and extending the range and accuracy.

Version 3

The next version, had a major change the steam cylinder is mounted on the harpoon itself. It flies with the harpoon. This cylinder is pressured by the external boiler, and when the harpoon is released the steam expels out of the back through a nozzle, pushing the harpoon forward over a far greater distance and time then when it slid out of a barrel. There is still a barrel to guide the harpoon when it just starts accelerating, to aid in it's accuracy. This version extended the range by a factor of three. as well as creating a greater impact, due to the increased speed and weight of the harpoon.

Version 4.1

Then when oil burners became more prevalent, the steam cylinder on the harpoon was initially charged with boiler steam. Then sealed, and the outside of the cylinder heated with extra burners, raising the pressure significantly. Higher the safe for a boiler, but good enough for a single use harpoon. This vastly complicated the launching system, and it took longer to get harpoons ready to shoot.

Version 4.2

Also versions exist which do not need to be connected to an external steam supply at all. They come pre-charged with a volume of water, which then is boiled to steam by the external burners. But this is even slower to get ready, and after the burners have heated the cylinder it cannot be trusted anymore, and even if the harpoon is not shot, the harpoon has to be discarded, for the cylinder walls have become to wea to survive the pressure of a second heating. In contrast a harpoon that has been brought to boiler pressure can be safely de pressurised and used again later.

Version 5

The steam cylinder with nozzle is separate from the harpoon, they no longer form a single unit and build are in two pieces. The harpoon is attached to the cylinder with a very strongly tensioned spring. The spring is held under tension by a latch. In cold, un-pressurised status the latch keeps the spring. When the cylinder is heated up and the steam creates pressure, the latch moves to the armed position. Now the spring will release as soon as the pressure drops below a certain level. This is matched to the point where the steam expelling trough the nozzle is no longer propelling the harpoon. This way the weight of the cylinder is shed. And the harpoon is given a final push towards its target. Creating a slimmer profile for easier penetration. Tools exist to safely cool down a harpoon that has a version 5 release, and to reset the latch system.

Classes

Several classes of harpoons exist, they are separated by weight, the heaviest you can find on shore based installations, and some ships of the Imperial Eglonian Navy. And the smallest are launched from hand held units, ackin to archaic crossbows. Harpoon launchers come in several shapes and sizes as well, most carry a single harpoon. But also installations with up to twelve harpoons exist. Those with a lot of harpoons are usually found on land and are used as anti-air defence system.