Airships of the Nine Empires – Part 1

Following this paragraph is a summary I previously wrote regarding the various types of airships used in the story of the Nine Empires (I copied a Microsoft Word document and pasted it, alright).  Some of these types are obsolete by the time that the story takes place, but they are still relevent.  The “new type” that I mention at the very end is described in a different document, and I will post its contents later.  This post is relevent to several of my future posts, regarding airship models that I am having printed at Shapeways.  Before concluding this paragraph, I should mention that I will also make a future post regarding the War of Rhûnnish Succession, which is helpful lore for the story.

Air travel on Rossbera began during the final days of the Rhûnnish Empire.  Historians agree that, by this time, Bulmut had surpassed Rhûn in level of technology.  However, while Bulmut may have exalted in technological innovation, Rhûn still had the mightiest industry on the continent.  Thus, the curiosity of two Bulmutian chemists became a great military asset to the Rhûnnish.  This curiosity, of course, was the hot-air balloon.  While the Bulmutians developed it as a means for wealthy landowners to travel in style back to their manors, which were very frequently built atop steep hills, the Rhûnnish made balloons for the military.  Balloons were vastly superior to towers for scouting, and proved invaluable in many circumstances.  Like towers, balloons also had carrier pigeons for relaying information to commanders.  Balloons were used extensively during the War of Rhûnnish Succession, and actively contributed to the stalemate.  After all, neither side could hide their movements or numbers from the other.  With the information from the balloon scouts, generals on both sides were able to muster optimum defences well ahead of any impending attack.  There was hardly a move that either side could make.  Thus, the War of Rhûnnish Succession went down in history as the strangest war ever, for it was exceedingly long, not very bloody, not a single battle was fought, and the conflict was never resolved, all thanks to the hot-air balloon.  In short, it was a Renaissance version of the Cold War.

Balloons were useful for travelling short distances in the exact same direction as the wind.  They are cramped, cannot carry very much weight at all, and have no means of navigation.  Scout balloons, in fact, were usually transported on the ground, then tethered and launched, in that order.  As for those wealthy landowners in Bulmut who were too weak or lazy to climb the hills to their manors, many times they tied the balloon to a cart that was destined for the hilltop, as the wind rarely cooperated.  In order to navigate the balloon somewhat, one of these landowners attached eight sails around the basket, and would furl or unfurl different sails depending on what direction he wanted to go.  This was the first sail-balloon.  Little time passed before other balloonists started doing the same, and some even took to replacing the cylindrical basket with a rowboat, arranging the masts in two rows.  With its huge surface area, the balloon itself always ran with the wind, but the additional sails, including a spanker, allowed for some rudimentary navigation.

One physicist’s experimentation and mathematical analysis of kites led him to add wings to a sail-balloon, giving it greater lift.  Wings constructed like sails act as a primitive airfoil, allowing sail-balloons to lower their fuel consumption while moving.  In many ways, it was a great convenience that the new sail-plane-balloon could launch, deploy its sails, turn down the burners to cruise, then turn off the burners entirely to slowly descend to the landing zone.  In later decades, steam power began to develop.  The effectiveness of the screw propeller on surface ships merited experiments with it on sail-plane balloons.  A hot-air engine, heated with burners using the same fuel supply as the balloon burner, would drive a larger, wooden version of a ship’s screw in order to generate thrust, and by extension, lift.  The idea seemed daft at the time, but the innovation eliminated the need for conventional sails on airships, just as it had on surface ships.  Of course, the plane-balloon still needed the fabric wings and rudder in order to function, but the higher speeds and ability to take off on its own meant that the new design could have a much smaller balloon in relation to its mass than previous designs.

For all its innovation, the plane-balloon was still not very practical for transporting anything other than small numbers of people short distances.  It was certainly not favourable by most measures over rail travel, which had become quite prolific by this point.  However, there were certain places that trains could not reach, and for the final leg of a long journey to such a place, one would have no options other than to hike up a hill or take a ride in a balloon.  Plane-balloons were not at all efficient for this, since most of them had balloons of insufficient size to take off vertically, and thus needed huge open areas.  Of course, such areas were usually farm fields, and farmers do not take kindly to balloonists mucking around in their crops.  Thus, as the now-prolific railroads were allowing industry to spread rapidly, accelerating technological advancement, a new opportunity for airship design presented itself.  It took the observations of yet another physicist to determine that the most efficient type of screw propeller has a blade cross-section like an airfoil, creating lower pressure in front of it.  Rather than “blowing the air back,” a properly-made screw “lets the air suck it forward.”  Rotating the screw upwards would create lift, rather than thrust, he thought, and tested this by mounting a small, engine-driven screw on a balloon.  Once the balloon had been weighed down such that it was neutrally buoyant in the air, the engine was turned on, and the screw pointed in different directions.  As expected, the balloon moved in whatever direction the screw was pointed.  Why no-one had thought to do this before seemed astounding to this physicist.  However, in order for a vertical-facing rotor to be practical, it would either have to be very big, or have lots of help.  Since an engine powerful enough for the former option simply didn’t exist, lots of help from a big balloon was the route taken.

Though it was seen as a step backward, requiring such a large balloon to be light enough for vertical rotors to lift, the caravel turned out to be a huge development.  The first of the type had only two rotors, which were mounted on trunions to the side of the gondola.  The rotors could be tilted slightly, to provide forward or rearward motion, as well as lift.  By tilting one rotor forward and the other rearward, the caravel would turn in place, much like a surface ship with side paddlewheels.  An alternative design was proposed around the same time, known as the carrack, which had all of its rotors fixed in place, some of which were used for lift, and others for propulsion.  This meant that carracks never lost lift when cruising at full speed, and were generally much faster than caravels.  Caravels, however, were much more manoeuvrable.

Naysayers remained unconvinced until they noticed that caravels were not only becoming popular for transporting passengers from rail stations to mountain villages, but cargo as well.  This gave some shipping companies an idea: keep the balloon the same size, but make the gondola bigger, and add more engines to let the airship carry more weight.  Little by little, caravels kept getting bigger until the gondola was the same length as the balloon.  With the introduction of counter-rotating propellers, one on either side of each engine, some wondered if the balloon was even necessary.  By replacing the hot-air engines with steam engines, eliminating the balloon, and making the rotors larger, the largest of the heavy caravels became the galley, and carracks underwent a similar development.  Sadly, although there was a good use for it, the galley was not profitable enough to merit production, and only two were built.

Though caravels and carracks continued to be used in small areas, they never reached any level of popularity as passenger transport, simply because of the much quieter dirigible.  By the time that the first caravel was built, advances in metallurgy allowed the construction of much larger light framework than ever before.  Balloons needed no longer be kept small in order to be streamlined.  Thus, with the technology perfected, dirigibles were finally a commercially viable means of transportation, even though the concept was almost as old as the balloon itself.

The Taressimians perfected two types of rigid-balloon airships, carracks and dirigibles, to the point where their military value was unparalleled.  Not only could they relay information with on-board wireless communication, but they could carry bombs and machine guns.  The Sondorians thought of redesigning galleys for military use, as they were much more solidly-built and could knock out rigid balloons with ramming manoeuvres and by slicing them open with their rotors, but Taressim suffered a defeat which caught much attention and had a great impact on future airship designs.  The Karadenian Empire developed an entirely new type of airship, with a source of lift so powerful that the ship’s hull could be properly armoured.  Armed with cannons firing incendiary shot, a single Karadenian flying galleon was able to wipe out the Taressimian airship fleet during the Battle of Xiamazdu.