The Rune Airship
What makes it go up? Rune plates of levitate. Each rune plate individually lacks the power to lift the whole ship (they are created a Caster level 3 to keep math simple and nix permanent hit point loss for creating 200+ exp items) each plate contributes to lifting 300lbs
The construction of one of the rune plates would require a wizard (or other class of caster) with scribe scroll and etch rune plate. They cost 1,650gp in materials and 132exp and 3 days to create.
However: the spell harnessed by the rune plate is power hungry, every five minutes of operation the rune plate draws a charge from its power source, you will see the dilemma soon
Displacement is a measure of how heavy a ship is sort of: its really a measure of how much water is not in the space taken up by the boat and therefore how much lighter the boat is than the water it has displaced, I will use this to calculate the number of rune plates needed to provide lift.
(For the mathematically savvy you will realize a ship is by definition lighter than its displacement, plus the air in the space held apart by the hull has a bit of something to do with buoyancy. But for the sake of argument we will assume that providing the lift to equal the ships displacement in water will provide enough force to hold the ship in the air too with enough wiggle room to mess around with a bit of extra weight here or there)
The USS Monitor (an early American Ironclad) displaced 776 tons (roughly 1,552,000 lbs) it would require 5,174 rune plates to lift (but it has a whopping 8 inches of iron plate armor…)
The USS Constellation with 1,278 tons displacement would require 8,520 rune plates to lift.
Both of these ships are prime examples of vessels available in the Iron Kingdoms.
Now we can fudge the plates a little to boost there lifting power but increase there cost dramatically or ‘GM Fudge’ the power out put of the plates for the sake of flight.
An alternate plate design calling for a casting of empowered levitate (making it a level 4 spell cast by a 7th level caster has a lifting power just over 1,000lbs [.5 tons] each of these plates would cost 7,700gp in materials + 616exp and 7 days to create.
Back to the Monitor, with its 5,174 rune plates it would need another 5,174 series conduits to link them all together 100gp + 8 exp to create each.
On to a source of power (bwa haha!)
The monitor had 2 steam engines (adequate for outrigger props but what about the rune plates?) each rune plate needs to suck up a charge ever 3 minutes (30 rounds) now comes in the arcane turbine(s) if the rune plates are linked together into banks that draw there charges at the same time (during the same round) we still need a way to generate 173 charges a round, as the rune plates are bundled into 30 sets of 173 plates; also requiring 30 mechanical triggers to start each bank Every 6 seconds another bank is turned on until all 30 banks are running and full lift is generated. Note that all 30 banks must be running at all times the rune ship is in flight, losing just one bank turns your flying ship into a 51,900 lb rock. Warcaster arcane turbines build 6 charges a round but only power 5 items we would need 21 of them just to power the rune plates or a larger arcane turbine or two (or five) LM describes larger turbines providing more charges but not being practical for warcaster armor, but we aren’t making warcaster armor we are making a Runeship.
Looking at arcane turbines I surmise the following: it generates one charge for every 1,333.3r gp + 106 exp to create in cost and they weigh 15 lbs at 6 charges but as a warcaster could easily lift 30 lbs for 12 charges/round I must assume they become weight prohibitive on a compounding scale so I would factor the weight if a player was making the turbine (probably by adding = 15 lb for ever extra charge so: [15 lb at 6 charges would be 30 lb at 7 charges and 45 lb at 8 charges ect.]
The turbines I am fitting my runeship with will be 450 lbs each there are five of them powered by two steam engines they cost 46,690 gp + 3736 exp to make. They generate 35 charges per round.
The Runeship can ascend/descend 20ft per round with the use of a control surface and there’s a single extra rune place mounted on the dead center of the keel and one amid ship on the top to provide sky ballast (a fraction of weight to pull the ship towards the earth or heavens that is neutralized by the other plate pulling in the opposite direction when/if it starts to roll on its axis. The amount of force that can be generated is 300 lbs in each direction, these plates could also be used to force the ship to roll but why would you want to do that?)
That all together creates the bare bones of a Runeship based on the Monitor
It would cost
- 233,500gp + 18,680 exp to make the arcane turbines (467,000gp to contract there construction and 56 days to make each one)
- 8,540,400 gp + 683,132 exp to make the rune plates (17,080,800 gp to contract there construction and 3 days to make each one [or 15,528 days consecutively just under 43 Iron Kingdom years for one person])
- 517,400 gp + 41,392 exp to make the series conduits connecting the rune plates to one another (1,034,800 gp to contract the construction)
- 500 gp + 40 exp to link the arcane turbines to one another with series conduits (1,000 gp to contract the construction)
- 3,000 gp + 240 exp For 30 mechanical triggers to turn the series connected rune plate banks on and off (10,000 gp to contract the construction of these)
- Control surfaces to manipulate all of the rune plates (part of the cost to link them all together)
- And the cost of the ironclad to which it is all attached. The USS monitor cost $195,000 US$ to build in 1862 the price of gold was $35 an ounce that works itself out to being 560$ / 50 gp
That works out to costing 17,410.7 gp to make the ship all the mechanika is attached to.
It took the US 4 months to make the Monitor
A player making this ship would be spending on the order of 9,312,210 gp and about 744,977 exp, it would take him/her about 18,625 days [about 51.3 years]
A nation contracting this project over a large number of workers would be spending about 18,624,420 gp
Could a nation make one? Hell yes!
Movement would be based on the props connected to the steam engines and its mass, I imagine it would move at around 16 knots (double what the monitor could pull off in the water, not factoring in wind) it would ascend descend at up to 20 ft/round (200 ft a minute)
Cargo: 15,000 cu ft
I would build it into a ship shape to allow for its already natural displacement to keep it afloat allowing one to land in rivers, lakes and what not.
It would probably have a 16 hour coal endurance (based on the Monitor and it’s endurance) fuel stores for 47,920 lbs.. When the coal runs out the arcane turbines would spin down and the ship would become a rock (unless you also added 130 heavy accumulators to power the rune plates, you would need 130 of them for every three minutes you wanted to stay aloft)