Sails?

[Yeratel]

I have the mental picture that an airship acts much like a submarine, in a sea of moving air. The lift and trim crystals are like ballast tanks, moving the ship up and down, where it can take advantage of different air currents or aether currents at different altitudes. Without the aetheric webbing to provide propulsion, the ship is carried like a cork on the air currents, and it's streamlined shape means it actually moves a little slower than the air current, unless it extends its sails to provide more surface area and get up to the speed of the air. And with regular sails, it can only move in the direction of the airflow. With the aether silk sails extended, actual thrust is provided, which can move the ship in any direction, including against the flow of the air.
Was there not also mention made of ships with steam engines? Perhaps with propellers like a dirigible, or was that just for running the windlass barges that traveled up and down the spire?

[Quantus]

Was there not also mention made of ships with steam engines? Perhaps with propellers like a dirigible, or was that just for running the windlass barges that traveled up and down the spire?

There was, they are the more popular choice than wind for a backup engine. They use "steam-driven propellers and the new screw-like turbines."  But they are both heavier and louder than wind power.  Not to mention the fact that a pile of canvas very rarely explodes...

[knnn]

The difference, I think, is that the trim and Lift crystals are not actual thrusters, they are anti-gravity pumps.  They can tilt a vessel by applying less lift to a port-side trim crystal than the starbard-side, but the forces are always acting only in the vertical plane in direct opposition of natural gravity, and so they cant actually apply force in a horozontal direction.  I think the horozontal rotation (ie "Yaw", for those that dont want to look it up like I had to :p) comes from teh interplay of the "Control planes" (wings) and the asymetric pulling from the various Etheric Webs.

I think I agree with this, though  I personally don't think "control planes" are enough given the reasons I mentioned above.
FWIW, you've got the following quote:

"Grimm saw the enemy ship sturggling to stabilize itself with it's trim crystals alone - a tricky proposition without enough forward momentum to allow the more responsive manuevering planes to assist with the task".

This directly confirms that the "manuevering planes" are what counts.

But then you've got the following:

(during final battle with Itsaca, one set of web destroyed, other reefed, and one set of trim crystals burned out):

"Hard to port at flank speed, Mister Kettle!  Stay ahead of her turn!"

Basically, Predator is managing to make a circle around Itsaca (and keeping ahead of the battlecruisers' steam-powered turn) despite having no sails out, no web, and only half her crystals working....  I don't think I can explain it unless we're saying there was enough residual speed to do this.  Even then. how are they going to turn?  I can't imagine that the control planes are big enough to do anything -- wind resistance is simply not going to be enough.

[Maredudd]

Hi Folks!

I looked up "Trim" as it relates to aeronautics and based on what I saw, are we certain that the Trim Crystals do not provide the same function for Jim's airships as they do for aircraft today?

You want to go in a particular direction and set the trim crystals and the produce the forces necessary in the airship to move it to the desired orientation, Not that they provide no motive force though so whether you are using the etheric web or the sails, its business as usual. Technically this could compensate for the what is missing when compared to a surface ship.

[Shecky]

The difference, I think, is that the trim and Lift crystals are not actual thrusters, they are anti-gravity pumps.  They can tilt a vessel by applying less lift to a port-side trim crystal than the starbard-side, but the forces are always acting only in the vertical plane in direct opposition of natural gravity, and so they cant actually apply force in a horozontal direction.  I think the horozontal rotation (ie "Yaw", for those that dont want to look it up like I had to :p) comes from teh interplay of the "Control planes" (wings) and the asymetric pulling from the various Etheric Webs.

That's if you're assuming that lift and trim crystals work in precisely the same manner, which I'm not. But you're certainly correct to point out the control planes; while they wouldn't provide the same order of magnitude of effect as a keel in a denser medium, there'd certainly be torque available.

[Maredudd]

With respect to the Trim Crystals, perhaps the trim crystals serve the function of a control surface. I suggest this because modern aircraft use a trim control to help hold the various control surfaces in the set position, to make it easier for the pilot, and its not a big leap to say lets just loose the middle man and say the trim crystal provided the function of the control surface . . .

[Quantus]

That's if you're assuming that lift and trim crystals work in precisely the same manner, which I'm not. But you're certainly correct to point out the control planes; while they wouldn't provide the same order of magnitude of effect as a keel in a denser medium, there'd certainly be torque available.

That's true, I'd thought the line that mentioned inverted gravity said both trim and lift crystals, but it doesnt mention trim crystals at all in the list of energy conversion types. Looking into it: earlier, Grimm refers to the new trim crystals as lift crystals in his internal monologue when they first arrive and journeyman is looking them over; that could be indicative of a trim crystals as a subset of Lift Crystal, or just a typo. 

I'd say it stands to reason, regardless, that they are simply smaller versions of the same, because from what I can tell, a crystal that could apply thrust directly in the horizontal would be a game-changing technology.  It would be core-powered thrust that is entirely protected by the shroud, and if they can be made anywhere near as strong as the main Lift Crystal, they'd be able to accelerate the ship to G's at the limits of their crew's endurance.  It's the lack of that sort of horizontal thrust that makes the Dive maneuver so important, because it's the only way they can get that sort of speed.

With respect to the Trim Crystals, perhaps the trim crystals serve the function of a control surface. I suggest this because modern aircraft use a trim control to help hold the various control surfaces in the set position, to make it easier for the pilot, and its not a big leap to say lets just loose the middle man and say the trim crystal provided the function of the control surface . . .

Reasonable, but the airships do also have control surfaces, though I think they are stationary, so if the trim crystals contribute is only part of it. 

[Shecky]

I'll freely admit that I've been assuming a particular set of things:

1) That the lift crystal is the big one because that's the one that deals with the biggest force: gravity. It makes structural sense to have a single large one at the center of gravity; it's easiest to design a support system that hinges on one point of force instead of multiple. Having multiple smaller lift crystals distributed throughout the ship would supply a lot of redundancy, true, but it would also make designing supports far more complex and make managing their output perhaps beyond the capacity of a single pilot. It's the way I would do it, anyway. May also have something to do with the higher efficiency/effectiveness of a single large crystal as compared to those of multiple small crystals.

2) That the attitude crystals can't be set to provide force along varying vectors, not just with or against gravity. I've personally seen no reason to think that something that applies a force must be limited to one axis (again, I may easily be wrong on this, so grain of salt, etc.), and with the lift crystal's support system supplying a central axis point, it would therefore be easy to distribute attitude crystals to work around that rotational point in all three dimensions. (Again, see maneuvering thrusters on, for example, Apollo spacecraft.)

A lot of assumptions, I know. But they make engineering sense to my eye.

[Quantus]

I'll freely admit that I've been assuming a particular set of things:

1) That the lift crystal is the big one because that's the one that deals with the biggest force: gravity. It makes structural sense to have a single large one at the center of gravity; it's easiest to design a support system that hinges on one point of force instead of multiple. Having multiple smaller lift crystals distributed throughout the ship would supply a lot of redundancy, true, but it would also make designing supports far more complex and make managing their output perhaps beyond the capacity of a single pilot. It's the way I would do it, anyway. May also have something to do with the higher efficiency/effectiveness of a single large crystal as compared to those of multiple small crystals.

That's fair.  The assupmtion I was under was more or less the same, except that the they were all Lift Crystals in that they are all anti-gravity pumps.  The /Main/ Lift crystal is the largest only because it has to take the full load coming out of a Dive, which to do efficiently requires a massive and precisely made, whereas the Trim Crystals are just smaller/younger and easier to mass-produce.  They could (barely) hold the load on their own but would be burned out by even light manuevers; the rest of the time they are only there to pivot the ships mass around the Main lift crystal. 

At one point gwen lists categories of crystal (Lift, Weapon, Cannon, Power/Core).  In another line Folly lists some types and their energy conversions.  From the two I come up with the following list of crystal types:

Lumen Crystals:  Etheric to Light

Weapon Crystals: Etheric to Heat & Force

Core Crystals: Etheric to Electricity

Cannon Crystals: Electric to Heat & Force

Lift Crystals: Electric to "Inverted Gravity"

2) That the attitude crystals can't be set to provide force along varying vectors, not just with or against gravity. I've personally seen no reason to think that something that applies a force must be limited to one axis (again, I may easily be wrong on this, so grain of salt, etc.), and with the lift crystal's support system supplying a central axis point, it would therefore be easy to distribute attitude crystals to work around that rotational point in all three dimensions. (Again, see maneuvering thrusters on, for example, Apollo spacecraft.)

A lot of assumptions, I know. But they make engineering sense to my eye.

The only way I can see that the lift crystals would be limited to a single axis is if they are all (main and trim) limited to reversing gravity along it's natural vector, rather than being able to redirect it omni-directionally.  But I freely admit that Im looking for a reason, if only to explain why anyone would bother with wind sails (or steam turbines or such flammable and tangle-prone systems like Etheric Webs) if you could channel the electricity that would otherwise be used to charge web into a direct thruster.  I dont think it's 100% clear from the text so far, but it's the only way Ive come up with to reconcile the two things in my mind, and has the added bonus of simplifying the 'magic system' of the crystal types.  Hopefully we'll get more details next time around.  If it centers around airship races as I hope, it would have plenty of reason to pontificate on the technology. 

[knnn]

1) That the lift crystal is the big one because that's the one that deals with the biggest force: gravity. It makes structural sense to have a single large one at the center of gravity;

One thing for sure, if the main lift crystal is actually an engine that just happens to be perpetually pointed straight down, then that a is a colossal waste of energy/power.  At the very least, since we know that the crystal can violently slow down a dropping ship, that means that it has enough power to both keep the ship in the air and move it forward.  All you would need to do is increase power to the crystal and angle it so that 90% of the thrust is pointing downward and 10% forward.  Heck, you could just mount two lift crystals and go zooming around as fast as you want.

That's why I very much agree with Quantus, that the crystals (lift and attitude) can only control up/down.  "Inverted Gravity" is probably the best name for it, since it actually uses negative gravity to create the lift.  Though even this would have weird physics.  Remember that there is an apparent limit to how high the crystal would work (7-8 miles), despite the fact that gravity goes "forever".

[Quantus]

One thing for sure, if the main lift crystal is actually an engine that just happens to be perpetually pointed straight down, then that a is a colossal waste of energy/power.  At the very least, since we know that the crystal can violently slow down a dropping ship, that means that it has enough power to both keep the ship in the air and move it forward.  All you would need to do is increase power to the crystal and angle it so that 90% of the thrust is pointing downward and 10% forward.  Heck, you could just mount two lift crystals and go zooming around as fast as you want.

That's why I very much agree with Quantus, that the crystals (lift and attitude) can only control up/down.  "Inverted Gravity" is probably the best name for it, since it actually uses negative gravity to create the lift.  Though even this would have weird physics.  Remember that there is an apparent limit to how high the crystal would work (7-8 miles), despite the fact that gravity goes "forever".

Gravity is directly proportional to distance though, it's not truly "forever." It was mentioned that the lift crystal would be far more efficient at lower altitudes, so I think it just has to work harder the higher you go, until a breaking point is reached.  That may have to do with distance from the main "aerosphere" level of the planet, which seem to be where the etheric currents exist in sufficient density for airship web use. 

[knnn]

Gravity is directly proportional to distance though, it's not truly "forever." It was mentioned that the lift crystal would be far more efficient at lower altitudes, so I think it just has to work harder the higher you go, until a breaking point is reached.  That may have to do with distance from the main "aerosphere" level of the planet, which seem to be where the etheric currents exist in sufficient density for airship web use.

Unless the radius of the planet is very small, an extra 7-8 miles is pretty negligible in the scale of things, at least with respect to pure gravity.  If the crystal gradually stopped working as you went higher, then I think it would be pretty much at it's limit already.  The fact that crystal can lift the Predator so quickly implies to me this is not the case. 

On the other hand, I seem to recall that sails/steam are supposed to be the prime means of propulsion when you are out of the aerosphere.  This implies that the lift crystal works out of the aerospere (otherwise the ship would simply fall).   I suppose it's possible that the crystal simply gets weaker as you move further away from the range of the aerosphere...

Still, the fact that ships are built to have means of propulsion out of the aerosphere implies that it's a place that you would normally be required to reach in a ship.  To me this all seems to imply that the aerosphere is a narrow band, say 2-4 miles thick floating a mile over the ground.  Thus, ship that go to the bottom level need to have steam/wind.  This combined with the idea that lift crystal work less well out of the aerosphere might be part of the reason big ships can't do power-dives.  If they try to regain lift too slowly, they get to places where the lift crystal is no longer strong enough to slow them down before they hit the ground.

[Quantus]

Unless the radius of the planet is very small, an extra 7-8 miles is pretty negligible in the scale of things, at least with respect to pure gravity.  If the crystal gradually stopped working as you went higher, then I think it would be pretty much at it's limit already.  The fact that crystal can lift the Predator so quickly implies to me this is not the case. 

On the other hand, I seem to recall that sails/steam are supposed to be the prime means of propulsion when you are out of the aerosphere.  This implies that the lift crystal works out of the aerospere (otherwise the ship would simply fall).   I suppose it's possible that the crystal simply gets weaker as you move further away from the range of the aerosphere...

Still, the fact that ships are built to have means of propulsion out of the aerosphere implies that it's a place that you would normally be required to reach in a ship.  To me this all seems to imply that the aerosphere is a narrow band, say 2-4 miles thick floating a mile over the ground.  Thus, ship that go to the bottom level need to have steam/wind.  This combined with the idea that lift crystal work less well out of the aerosphere might be part of the reason big ships can't do power-dives.  If they try to regain lift too slowly, they get to places where the lift crystal is no longer strong enough to slow them down before they hit the ground.

That seems generally sound.  Do we know for sure that the currents are actually gone at the lower altitudes?  I want to say there was a mention of not using webs down in the mists because they attracted giant predator monsters. 

Either way, there are two separate energy paths at play here, I think.  Lift crystals get electrical power from the core, which in turn converts ether to electricity, and the older it is the more of one you get from the other, so the efficiency is determined by the crystal properties as much as anything.  By contrast the Web requires both electric current from the Core as well as actual Etheric currents for the energized web to interact with.  I imagine there is simply a breaking point where the Core can no longer convert enough ether to electricity to drive both the lift crystals and still energize the web enough to get reasonable speed. 

[knnn]

That seems generally sound.  Do we know for sure that the currents are actually gone at the lower altitudes?  I want to say there was a mention of not using webs down in the mists because they attracted giant predator monsters. 

This is from chapter 1.   Seems pretty conclusive to me:

Few airships utilized wind-sails these days. Steam-driven propellers and the new screwlike turbines were the preferred means of locomotion in the event that a ship dropped out of the aerosphere or was becalmed in some portion of the sky without etheric currents strong enough to propel a vessel.

I imagine there is simply a breaking point where the Core can no longer convert enough ether to electricity to drive both the lift crystals and still energize the web enough to get reasonable speed.

Are we saying that the Core gets less powerful as you go out of the aerosphere or that the lift crystal needs more power to maintain altitude as you go further away?  I was thinking the latter, but if a core crystal converts etheric energy to electricity then it obviously needs to be in a place where there is sufficient ether.

[Quantus]

This is from chapter 1.   Seems pretty conclusive to me:

That's what I was looking at too, but it still doesnt clarify if dont use them lower because they do not function, or because they are beacons to giant etheric monsters that would eat any ship that attracts its attention with active webs.  It said in Ch.2 two that the Mistmaws are attracted to powered webbing.  The Webbing was being used during the dive, and he said he expected that Journeyman cut the line asap /after/ tehy pulled out of the dive.  This implies to me that it is technically possible to use the Webbing for motive force down in the Mists, and that it's just not smart too far from the Spires because of the danger of attracting predators.  The fact that barges and Windlaces can float themselves all the way up from the surface would tell me there is at least a little Ether there.  Though it's possible that the Spire is actively pulling it down (by Folly's sight) so it may only exist at low altitudes near a spire. 

Are we saying that the Core gets less powerful as you go out of the aerosphere or that the lift crystal needs more power to maintain altitude as you go further away?  I was thinking the latter, but if a core crystal converts etheric energy to electricity then it obviously needs to be in a place where there is sufficient ether.

Both, I think, maybe (depending on the definition of Aerosphere).  Gwen says of the first gen core: "IF the crystal was as old as journeyman claimed, it would be able to produce more electricity from less etheric energy than almost any crystal gwen had heard of-- which would mean that the ship could sail to more places, farther and farther from the main etheric currents, and do it more swiftly.  Im not clear on how the ether varies with altitude, but it seems to flow around the planet in large, jet-stream style currents by the sound of it, something relatively stable and/or mapable