Heavenium Jet Engine
The theory of this engine is based in the Archemidean principles, and while it would first be used by civil engineers for fountains and other waterworks) and shipwrights (of seas) it could eventually be adapted for airships.
The principle behind it is simple - a still fluid stays still because every other bit of fluid above and to the sides of it presses it down with the same force of gravity. But what would happen if we put a vertical pipe of heavenium into that fluid?
The fluid inside the pipe would get much lighter and the surrounding fluid would force it upwards, just like a piece of cork under water. And it would draw with it a new amount of fluid, which would get lighter and be forced upwards in a constant stream.
This upwards motion of fluid alone would be godsend for civil engineering - a pump with no moving parts! But that is not all - the fluid that has started flowing still has some momentum to it that can be redirected. Just put a bend in a pipe and it will now flow out sideways propelling the engine and anything that is attached to it sideways.
Air is just a form of fluid - and as boat can float on a water - so can balloon on the air. 1018
And in the same way the heavier water would force lighter water upwards - so would air.
Of course there are differences. For one - air is about thousand times less dense than water which means that it will propel the ship with much less force. On the plus side, that means that heavenium will need to be recharged less. Also air unlike water can compress, which means that to get a good flow you instead of a simple pipe you would need a much wider funnel in the intake.
Pros:
* No moving parts
* Simple construction
* Easily controlled (rudder + lid or just mount the whole thing on a swivel)
* Useful in other applications (lower cost and quicker R&D)
Cons: - Very low thrust in the air - Difficult to recharge
Possible improvements (possibly incompatible): - Replace the Heveanium funnel with ordinary funnel + Heveanium mesh on the intake for better pressure profile and efficiency - Place re-loadable heaveanium bunker above the funnel for easier refuelling - Add access and fittings for in-place recharging - e.g. burning a breazier of coal right below the funnel 479