• Welcome to the Fantasy Writing Forums. Register Now to join us!

Physics of a sky ship?

Skyfarer

Dreamer
Sky ships. Flying boats. I'm just about willing to call them objectively cooler than regular water ships, and I'm damn sad that dirigibles are out of fashion. It's so cool to happen upon seeing one, on those rare moments they do.
Naturally then, I want to add them to my stories in some way. For today, I was wondering about how the traditional fantasy sky ship, the ones that look like regular sail ships but in the air, could feasibly work. I imagine that some suspension of disbelieve gonna be needed, but still, is it possible?
Could a regular wooden ship hold itself together in the air?
What would the sails accomplish?
How high could it go before the sailors couldn't stay on deck?
Of course, I intend to look more thoroughly into this matter myself, but I'd also like to get everyone's opinions as well. Let this be a fun discussion!
 

pmmg

Myth Weaver
Well...I think there would have to be some stuff you just take as a given, such as the ship down not sway or roll too much.

If you want to maintain the actual look of a ship from the water, and not a ship with a giant balloon above it, the ship itself would have to have an air tight nature to it, and a container that held a gas that let it float.

The internet says the zone where masks are needed is about 25000 ft, but I can assure there are effects of it long before that. One like me, would have trouble just being active on Pike's Peake for example. I am not used to high altitude oxygen levels.
 
Studio Ghibli guy absolutely loves anything like that and put a lot of flying ships, blimps etc in his films.

I think they went out of fashion because they were giant flying flammable nightmares, and tended to go boom.
 

CupofJoe

Myth Weaver
Sky ships. Flying boats. I'm just about willing to call them objectively cooler than regular water ships, and I'm damn sad that dirigibles are out of fashion. It's so cool to happen upon seeing one, on those rare moments they do.
I think it might be a reaction to Steam and Dieselpunk where just about everyone seemed to have airships, blimps and Zeppelins
Naturally then, I want to add them to my stories in some way. For today, I was wondering about how the traditional fantasy sky ship, the ones that look like regular sail ships but in the air, could feasibly work. I imagine that some suspension of disbelieve gonna be needed, but still, is it possible?
Could a regular wooden ship hold itself together in the air?
Probably but the hulls are built to keep water out so they might have to be braced differently.
What would the sails accomplish?
The wind would still push you along especially at height where the winds can be far stronger. You could make them more like wings to soar and dive...
In the water, America's cup yachts can take a 30knt wind and get up to 60knt speed because they use "wings" rather than sails.
Do that in three dimensions and things could get interesting.
How high could it go before the sailors couldn't stay on deck?
I'd say not much more than 10,000 ft, if you are not used to it or are carrying passengers that aren't. You can go higher, much higher, but that takes training and experience. And there is a chance you would need a pressurised hull for people and cargo.
Of course, I intend to look more thoroughly into this matter myself, but I'd also like to get everyone's opinions as well. Let this be a fun discussion!
 
Last edited:
I've written a book with sky ships in it. Pirates, sails and all.

I don't go into too much detail about how it works in the books. In short, it's tied to the magic system. In my magic system, you can use Fae dust to make things move. Fae live in forests in a newly discovered continent. The trees they live in become so saturated with Fae dust that the wood becomes Fae wood, which has the ability to fly. And you can then build ships with it, though it's rare, so there aren't too many flying ships.

The sails are there to make the ship move, since they don't have anything like engines or propellors to do so.

I'm not sure what you mean with could a ship hold itself together. There isn't that much difference between being in water and being in air in my view. Though I guess part of that is because my flying ships don't differ all that much from regular ships in term of speed etc. So there aren't really many other requirements on the ship.

As for height, I don't really specify it. Since there's no oxygen supply or source of heating on board, you'll run into the standard limits in terms of how high the people will want to go. Anything over 4km is probably out of the question, since going from sea level to 4km in one go is a good way to give people altitude sickness. And temperatures drop a lot at that height already. But in the story, they don't go more than a few hundred meters above sea level.

Bonus: cover image, just because I like it ;)

embed
 

Queshire

Auror
Presuming that the ship in question isn't airtight then those on it would still have to deal with the effects of the air thinning the higher you go, though on the other hand that means you don't have the risk of the ship blowing up as a result of rapid depressurization.
 

pmmg

Myth Weaver
You would actually have the opposite problem. The ship would not have to be pressurized to avoid implosion but to avoid explosion. Contained air and gases would have to be built to remain contained. Probably not a severe problem, but if the ship was to fly with pressure concern being to prevent explosion and then also to be sea worthy, or submerged, it would completely change the stress it was under.

If i was writing it, id probably just gloss over it.
 

Gospodin

Troubadour
[...]

If i was writing it, id probably just gloss over it.


Ditto because if you attempt to contextualize or rationalize it too much, I’m gonna follow you down that rationalization rabbit hole, and my scrutiny will be withering because I figure that’s why I was invited down the hole. Someone up-thread mentioned the flying ships found in many Miyazaki films, and I think those are a great example because they are not remotely genuinely airworthy, but Miyazaki also never forces me to engage that unworthiness. He doesn’t make it part of the narrative that I understand lift and thrust in Miyazaki Land. He just asks that I accept them in all their cool, gargantuan, lumbering glory.

It’s like in the film The Chronicles of Riddick. Riddick goes to that prison planet called Crematoria and part of his escape plot is that the underground prison has to periodically refresh the atmosphere via a large snorkel-like structure that opens to the surface. He's gonna use the snorkel as his escape route. The problem is that another feature of this planet is that the sunrises are so violent, they literally ablate the surface in pyrotechnic explosions. Never mind oxygen - there shouldn’t even be an atmosphere at all on this little rock in space, and I likely would have just let it slide under the umbrella of suspension of disbelief were it not for that snorkel atmosphere exchange event calling attention to it.
 

Skyfarer

Dreamer
Yeah, I more or less intend to skip over it But I figure it's good info to keep on the back burner anyway.
 
You would actually have the opposite problem. The ship would not have to be pressurized to avoid implosion but to avoid explosion. Contained air and gases would have to be built to remain contained. Probably not a severe problem, but if the ship was to fly with pressure concern being to prevent explosion and then also to be sea worthy, or submerged, it would completely change the stress it was under.
I disagree. A sufficiently leaky ship would have the same pressure on the inside and the outside. No pressure difference, hence no implosions or explosions. A sailing ship with an open hatch would be fine. The only thing to watch out for are enclosed air pockets in things like bottles, though I think you'd run into trouble breathing etc before those become a big issue (unless you're dealing with faulty materials of course).

It would of course be different if you'd have flying submarines. Since they're meant to be airtight, you would get a pressure difference, and all the issues that would bring up.

Like I said, I think the main worries are more about the people on board than about the ship itself. Though of course, if you need air to support your ship then you run out of air at some point, and if you're using a balloon to lift the ship, then you need to watch out that the balloon doesn't explode as you go higher.
 

pmmg

Myth Weaver
I am not sure that we really disagreed...but...

There would be some construction differences for a flying ship, over an in the water one. But anything that had to be kept contained on the ship would need to be made to keep its contents. A balloon is a good example, cause its fragile both directions....too much pressure and it loses its contents to pressure coming into it, too little and it may expand to rupture. Materials on a boat at not as fragile, but the same forces are at play.

If the ship wanted to keep its helium, for instance, it would have to be build to not leak helium.
 

Gospodin

Troubadour
Yeah, I more or less intend to skip over it But I figure it's good info to keep on the back burner anyway.
There are flying airships that seem like sea-worthy ships, so I’m assuming there is at least a bit of room for magic in your setting? Can that be applied in some way to the trees from which these ships are built? Is there room in the narrative for jet streams and air currents and cold fronts abutting warm fronts to take on nautical, marine aspects? There are plenty of stories where ships ply oceans of sand. Can yours ply oceans of air? If you take me in that direction, if we avoid the mixed epistemology of Real World Science vs Fantasy World Features, as a reader, I would not be looking for altitude sickness or the problems with depressurization, or the frigid temperatures experienced at high altitudes. In a Fantasy story, my concern is ever on internal consistency. I have no expectation that the setting will be consistent with the one I actually occupy - unless the writer gives me cause to expect it.
 
Top