This interaction has the isue of stating Skytears have a line from where heating them makes them less dense, then more dense. Superheating them is likely to have some containment problems though. Along with just sinking the ship entirely? Density heavier than air will cause it to be heavy.
Maybe change it to spongy, but then we get into floating in the air.
As for something simple-ish.
Military: SkyshipWhen Skytears are frozen in water, and then superheated, it cracks apart into gas. And when mixed with Helium, the resulting gas is lighter than Hydrogen when heated. He-St is also non-flammable, so it became the go to method for lifting airships. Just fill the canopy with it, and use Sunseeds to heat it through a circulating water system. This will boost it's buoyancy, lifting the ship into the sky.
Combined with steam-screw propellers for propulsion, we took to the air in Skyships. And these Skyships held the Artillery we had produced, launching explosive rounds down onto the battlefield and sea both. And another aspect of HE-St made itself known. When the heated form found a hole, the outside cool air actually kept a good deal from escaping immediately, creating a type of density seal. This did cause the Skyship to tilt and lose buoyancy, but allowed for it to land safely.
From this, a Skyship made full use of our metalworking to be covered in armor and supports rather than pure cloth, protecting the lifting mechanism, with decks hanging down from it where the rest of the Skyship's mechanisms were, including the Artillery cannons. With the propellers hanging out near the back and the sides.
He-St, commonly known as Hest in common speak. The Helium ends up taking on some of Skytear's properties. Heating it cause buoyancy(from density change), while cooling it condenses it's density. Fundamentally, it's rather light, acting mostly like a slightly heavier helium when at normal temperatures. Temperature differences, such as Hot Hest meeting cold air, can cause it to solidify like an air wall. Though this doesn't last as the temperature normalizes over time.
Theoretically, if Cooled Hest met hot air, it would cause a sudden burst of expansion. Though that is only theoretical at this point, and may not be true.
Interestingly, it doesn't actually affect humans in it's heated state or normal state. Though it does cause suffocation if no air is nearby for one to breath. It just doesn't enter the lungs at all due to trying to escape the heated body. Will cause a buildup of CO2 in the body if surrounded by it.
Note the notes below the line are mostly fluff... Physics and it trying to float upward when heated.
Military:
Sky CarrierIn this age, we succeeded at mixing Skytear dust into Iron, changing it. Sky Iron is interesting, maintaining Skytear's properties. Beams of the stuff could be heated, giving an amazing amount of lift to the structure it was attached to. This was used to build the sky carrier, a ship made up of crisscrossed Sky Iron beams heated through Sunseed water circulation. Steam-screw powered propellers shaped for air propelled it through the sky effortlessly.
The shape was curved with gentle slopes on the bottom, with the propellers protruding from it's sides. The rest of the ship looked more like other regular Galleons of old, with wood being key, mixed with metal armor. They were powered modernly for it's time of course, as mentioned using the method for turning propellers. It's balance was perfect for flight.
Atop the ship rested the various guns of the ages, being updated as new versions came to be. As for the rest, it had the masts and sails for sailing on the sea, though when airborne, they would be furled most of the time, only being unfurled slightly when making turns and correcting course, the wind coming into them allowing for the ship to make good turns. On the sea, it registered 7 knots. During flight, the furled masts acted to help keep the ship steady.
Later one, with the creation of steel by Etroa, the Sky Iron process was used, making Sky Steel and mostly replacing the iron version. The Sky Carrier throughout all it's versions allowed Etroa to loom over the land and sea, raining down destruction on ships and armies alike. As well, cargo versions existed, and the Sky Carrier fulfilled Etroan dreams of flight.
Reaction Note: Mixing the Skytear powder into iron confers Skytear's properties to the result once cooled. As steel has iron as a major component, this would naturally lead toward Sky Steel becoming a factor later on when steel was created. Though for the current Phase, Sky Steel is not yet a thing.
Note that the self-upgrade aspect is more tilted toward advancement over the ages. The first version would only have weapons of that time, while later versions would be made with newer weapons.
Also normal, the fact that being able to fly effectively made these ships the cargo carriers of their time, bypassing water trade routes most times.Military
Railwalker: ()
Reaper Gatling Gun: (1) Stirk
War-Airship: ()
Skyship: ()
Sky Carrier: (1) TricMagic
Civilian
Eclipse Engine: (2) Stirk, TricMagic
Potential revision
Frozen EarthThe FE Shell is made up of crushed moonseed and oil, turned into a gel, that when sufficient impact occurs, drains all heat in the surrounding area in one burst. This creates a Frozen Earth effect, in which everything in that area has the heat leached out of it, water freezing to ice in the process.
Used on ships in the water, it turns them into literal icebergs, freezing the surrounding water, cooling the metal to cracking, and generally halting all operation. On land though, the effect is mostly limited to the area it hits. Though in cases of rain or high humidity the effect is amplified.
As a weapon, it is especially effective against ships and aircraft. On ground targets, less so than an explosive round, which is cheaper to produce. Anything hit directly will be effectively stalled and dead on the ground though.