The Conundrum of Conjoiners: an Analysis of Navani's Airship

[+Oltux72]

6 hours ago, Jofwu said:

I feel like "arbitrary" vs "fixed" are rather mutually exclusive, but I guess I see your point?

Not really. It may be arbitrary unless you are subject to an external force or inside a gravity well. And then both of you must align according to that force or gravity.

6 hours ago, Jofwu said:

I'm just trying to get to the heart of the argument here, without all the frills.

Certainly, but the assumption that that is the breakthrough that aluminium allowed is a bit strange.

6 hours ago, Jofwu said:

Sure. I don't read it that way because "temporarily disjoined" implies to me that they conjoin them again as soon as they "turn around". Meaning the same gems. And I think the context of her bringing up aluminum as a way to redirect force vectors would be irrelevant if that's not what's going on?

No, it would not be irrelevant. The exact wording is alter, not redirect. For example it could allow you to move your ship around horizontally while the anchor in Urithiru remains stationary and the connection switched on.

6 hours ago, Jofwu said:

They had to build a tower for the counterweight and pull that down to lift the archer platform up. Why do that if you can just have chulls pull a lattice sideways to lift the archers up? The ability to do this is a significant technology with zero mentions in the text.

That is correct, but built on the assumption that gravity does not matter.

2 hours ago, Pagerunner said:

This is, in fact, inconsistent with the text. We're told, expressly, that the ship flies through alternating uses of the horizontal and vertical lattices. They are not both active at the same time.

This is the core so let me quote it literally:

Quote

Alternating between those two lattices—one to control altitude and a second to control horizontal movement—let Navani’s ship soar.

What does alternate mean? Do they really switch them off or do they move them only one at a time? And what does soar mean? Being aloft or being raised?
I am afraid at this time these are real differences not just details of wording.

1. It must be possible to have both connections on, at least briefly. You need to be at rest. If the chull platform needs to bear the ship's weight, the ship cannot be falling.
2. You cannot signal both ground stations at once, except at a dead stop. The spanreed must be at rest.

 

 

Quote

 

2 hours ago, Pagerunner said:

It seems the largest source for this idea is the phrase "isolate motion along a plane," which has been elevated to the single most important phrase in the entire passage. But I see it being interpreted in a vacuum. "What could 'isolate motion along a plane' mean? Ah, it must be that a conjoiner only responds along one axis." But the phrase is actually part of some classic technobabble: "they’d learned to use aluminum to isolate motion along a plane, and even change the vectors of force." How are you supposed to know what that means?

By extrapolating from Navani's old platform.

2 hours ago, Pagerunner said:

By looking at the very next sentence, which is what I think is the most important phrase in the passage. "The end result was chulls that could pull for a while, then be turned around." That's the only place that aluminum is brought up, that it lets them pull this trick with the chulls. The mechanisms for vertical and horizontal motion had already been established prior, with no mention of aluminum.

Well, no. Let me quote again

Quote

as all the while the airship continued in a straight line.

That is impossible under the old scheme. During that time the ship must be held aloft by the Urithiru base support. But that is not moving. The airship could not be continuing. It would have to hover. And that is not a question of orientation. That is solvable. The problem is that they switch the connection to the chull platform off during the turn.

2 hours ago, Pagerunner said:

Now, this isn't to say that partial inhibition is impossible. It would certainly be a very useful advancement. But we can achieve a complete explanation of how this particular airship functions, and we can do it without utilizing this phenomenon, so I don't think it's been accomplished yet by Navani and her team.

Well, no. Not unless you are at a complete stop while the chulls turn.

2 hours ago, Pagerunner said:

Side note, I'm seeing some terminology used inconsistently within the thread. (I probably contributed without realizing it, but I'm not gonna reread my OP right now with an eye towards it. Have you seen how long that thing is?) Disjoining is what Navani says they can do with aluminum,

Well, no. The isolation along a plane and the change of vectors comes first. Disjoining comes later. There is no indication it is done with aluminium.

2 hours ago, Pagerunner said:

and that lets you misalign your force vectors. Just regular turning off a spanreed isn't disjoining; I guess that would be deactivating?

Well, that is difficult. You can certainly switch on your spanreed, yet it does not join because it is improperly aligned or not at rest to its counterpart. It looks like there is no way to actively disjoin it without switching it off (or using aluminium) but the reverse is not true

2 hours ago, Pagerunner said:

I'll keep an eye out next time I'm rummaging through the relevant passages to see if we have something more specific. But let's make sure that we all mean the same thing when we say "disjoin."

Great notion, but potentially we are looking at three states not two.

1. off
2. on but not joined (due to either speed or aluminium)
3. joined

2 hours ago, Pagerunner said:

And there are subtle differences in a reoriented conjoiner, vs a reverser. Like I showed in my original post, a conjoiner will only act in the opposite direction for 2 axes; you can't get all 3 inverted. This is actually going to be what kills the suggestion of a conjoiner/reverser double lattice pulled by chulls.

If you assume that the connection to Urithiru is switched off

2 hours ago, Pagerunner said:

Yes, this thing would be an ungainly beast, moving in fits and starts like a Driver's Ed student in a stick shift. That's going to be the case no matter how you slice up the aluminum applications; the motion of the chulls and the ship are tied together,

As long as the connection is joined in all axes. Which according to the weirder part about aluminium it is not.

2 hours ago, Pagerunner said:

so when you stop the chulls to turn them around, you stop the ship. We're not applying pure force to the ship; we're tying the ship's motions to the motions of another object. It's not an RC car with an engine; it's that plastic popper pusher thing. (My secondary goal of this thread is to fill everybody's Amazon suggestions with the most bizarre items.)

And that is deeply problematic. The ship is basically tethered while the chulls are being turned. There is no way around that, as the connection to the chulls is off. It will now start twisting as the wind is buffeting it. And that is deeply problematic, as the chull cart is not. How do they reestablish the connection? It seems to me that the answer again is aluminium.

2 hours ago, Pagerunner said:

The speed they went is 5 knots, which is just under 6 miles per hour. That's not very fast.

That is insanely fast if that object massing - let's guess - a hundred tons is magically tied to a cart going towards a chasm

2 hours ago, Pagerunner said:

This is actually faster than a horse-drawn carriage, which according to the Internet can pull about 4 miles an hour maybe. So these chulls are pulling at a good clip, and they must not be wasting a lot of time turning the ship around.

Indeed. And chulls are not known for fastness. Hence we must conclude that the Fourth Bridge does not stop while the chulls are turning. It coasts and that is possible only because the Urithiru anchor is always connected and the ship is coasting along a plane while the chulls are being turned thanks to aluminium.

[Gisaku75]

Not being a native English speaker, I find it difficult to understand too technical texts but it seems to me that the principle behind Navani's ship is unnecessarily complicated and impractical. A group of windrunners could simply lash the hull of a ship and obtain a kind of zeppelin powered by the Stormlight. And it would make it move thanks to the force of the wind or by changing the direction of the lashes. What is the advantage of Navani's system? the least use of Stormlight?

Edited July 30, 2020 by Gisaku75

[rjl]

7 minutes ago, Gisaku75 said:

Not being a native English speaker, I find it difficult to understand too technical texts but it seems to me that the principle behind Navani's ship is unnecessarily complicated and impractical. A group of windrunners could simply lash the hull of a ship and obtain a kind of zeppelin powered by the Stormlight. And it would make it move thanks to the force of the wind or by changing the direction of the lashes. What is the advantage of Navani's system? the least use of Stormlight?

Advantages of Navani's system:

1. Does not require a radiant -> free up the radiant(s) for other duties whilst the ship keeps moving
2. Power requirements - this ship is ENORMOUS - the amount of Stormlight needed to do it only with lashings would be immense -> possibly would only work in front of a Highstorm.

[+Oltux72]

1 hour ago, Gisaku75 said:

Not being a native English speaker, I find it difficult to understand too technical texts but it seems to me that the principle behind Navani's ship is unnecessarily complicated and impractical. A group of windrunners could simply lash the hull of a ship and obtain a kind of zeppelin powered by the Stormlight. And it would make it move thanks to the force of the wind or by changing the direction of the lashes. What is the advantage of Navani's system? the least use of Stormlight?

Windrunners would have to lash ship, passengers and cargo. All of whom would be in free fall when they are lashed. If you are a Radiant I am sure Stormlight will keep your lunch down. For normal people the consequences will be worse.. In addition an air barge is virtually immune against counter lashings. or rammings. It is potentially absolutely stable a platform for fighting.

[theTruthshaper]

3 minutes ago, Oltux72 said:

Windrunners would have to lash ship, passengers and cargo. All of whom would be in free fall when they are lashed. If you are a Radiant I am sure Stormlight will keep your lunch down. For normal people the consequences will be worse.. In addition an air barge is virtually immune against counter lashings. or rammings. It is potentially absolutely stable a platform for fighting.

Actually, no. You can carefully bring up the speed using partial lashings, and on reaching terminal velocity, there would be no more acceleration of the ship. However, the main problem is that using lashings is very stormlight intensive, and requires a team of windrunners who would otherwise be free to fight the fused.

[+Oltux72]

5 minutes ago, The_Truthwatcher said:

Actually, no. You can carefully bring up the speed using partial lashings, and on reaching terminal velocity, there would be no more acceleration of the ship. However, the main problem is that using lashings is very stormlight intensive, and requires a team of windrunners who would otherwise be free to fight the fused.

Only until you hover.

[+Child of Hodor]

30 minutes ago, The_Truthwatcher said:

Actually, no. You can carefully bring up the speed using partial lashings, and on reaching terminal velocity, there would be no more acceleration of the ship. However, the main problem is that using lashings is very stormlight intensive, and requires a team of windrunners who would otherwise be free to fight the fused.

Yeah it's not at all feasible right now for trips that last more than like a day, unless Dalinar is on the ship repeatedly renewing spheres via the perpendicularity or something. I guess he could do the touch on the chest he did to Kaladin. Not sure how often he can do that before he needs a rest. 

This ship is horribly inefficient and vulnerable. Like it would be nice if they could control the ship speed, altitude and direction via people doing things on the ship relying instead of two giant teams far away. Long term they'll need to use the surges.

I think multiple gravitation fabrials positioned at different points on the ship would be the way to go, once they figure out how to make more efficient large ones. No. I have no idea how they do that.  I'm just here to point out problems  

Edited July 30, 2020 by Child of Hodor

[+Oltux72]

19 minutes ago, Child of Hodor said:

This ship is horribly inefficient and vulnerable. Like it would be nice if they could control the ship speed, altitude and direction via people doing things on the ship relying instead of two giant teams far away.

What could be more secure than having your engines and lift cells in a deep, well defended bunker? This is Autonomy speaking, not safety or security.

[Jofwu]

Well, I tried to get Brandon to comment on the matter without much success.

Me:

Brandon:

My interpretation is more in line with Pagerunner's, but I can totally see why there's a different perspective on it. Guess we'll have to wait for more details to see if one way or the other gets confirmed.

[Watchcry]

My problem with these ships is how the heck can they mass produce these and,  most importantly,  how can two enemies fight a war between themselves without swathes of land / towers separate and protected from said enemies. Are they going to have a hundred chull teams out there and hundreds of mechanisms elevating and lowering along Urithiru? What is the culminating point?

[Pathfinder]

29 minutes ago, Watchcry said:

My problem with these ships is how the heck can they mass produce these and,  most importantly,  how can two enemies fight a war between themselves without swathes of land / towers separate and protected from said enemies. Are they going to have a hundred chull teams out there and hundreds of mechanisms elevating and lowering along Urithiru? What is the culminating point?

If you think about it, they essentially found a way to offload the engine room. So i would see subsequent advances focusing on miniaturizing the process. Depending on the direction they go and how they accomplish it, you could have a static building in a secure location providing locomotion for airships across the globe. 

[+Bzhydack]

4 minutes ago, Pathfinder said:

If you think about it, they essentially found a way to offload the engine room. So i would see subsequent advances focusing on miniaturizing the process. Depending on the direction they go and how they accomplish it, you could have a static building in a secure location providing locomotion for airships across the globe. 

Yeah, this is very good for transportships, but have no use for fighters or bombers. I know they have Windrunners or Skybreakers, but still possibility to free them to other tasks is too large. To serve at war, machine has to be independent.

BTW, I can imagine Lashing guns or fabrial bombs, so they dont need our technology.

[Pathfinder]

8 minutes ago, Bzhydack said:

Yeah, this is very good for transportships, but have no use for fighters or bombers. I know they have Windrunners or Skybreakers, but still possibility to free them to other tasks is too large. To serve at war, machine has to be independent.

BTW, I can imagine Lashing guns or fabrial bombs, so they dont need our technology.

True the biggest threat to these airships is cutting off the signal from their engine, but then that would be an issue for transport ships just as much as for combat ships. Assuming the signal could be maintained and protected, then I think it would actually be more beneficial to off load the engine room than "be independent". You wouldn't have to worry about your fuel exploding. Wouldn't have to worry about the added weight from engines and fuel. Would not have to worry about resupply in transit. To my knowledge we have not seen spanreeds having to be refueled with stormlight have we? Even if they would, stormlight storage is theoretically far lighter than other fuels, and once they get the hang of producing perfect gemstones, they wouldn't have to worry about a depreciating storage. 

Your air force would be lighter and or could hold more than it would otherwise. That would be a massive boon in my mind for commercial as well as warfare. 

Unless you think I am trying to argue that it would replace windrunners and skybreakers entirely in the war effort? Because that was never my intent. 

Edited July 30, 2020 by Pathfinder

[Jofwu]

Before things get too far down the road of speculation about where development of the airship will go next, be aware that this thread exists:

This one should probably stay focused on how it works in its current form.

[+Bzhydack]

11 minutes ago, Pathfinder said:

Your air force would be lighter and or could hold more than it would otherwise. That would be a massive boon in my mind for commercial as well as warfare. 

If you have to fight in sky, you are forced to do crazy maneuvrs. And without instant comunication with "Engine Room" and automatization allowing it ro response precise and fast on your comand, you will be dead.

Also remember, we are talking about world with Shardblades. Flying machine with engines inside can have hull fully armored with Aluminum, being immune to magical attacks. On the other hand, you cannot do this in current model, because you will disconect fabrials! So your ship will allways have weak spots.

Can Mod move our few posts into topic about updating Navanis work?

[Pagerunner]

18 hours ago, Oltux72 said:

This is the core so let me quote it literally:

What does alternate mean? Do they really switch them off or do they move them only one at a time? And what does soar mean? Being aloft or being raised?
I am afraid at this time these are real differences not just details of wording.

1. It must be possible to have both connections on, at least briefly. You need to be at rest. If the chull platform needs to bear the ship's weight, the ship cannot be falling.
2. You cannot signal both ground stations at once, except at a dead stop. The spanreed must be at rest.

 

I'm not sure what you're trying to say. Yes, words can have different meanings. But there is a a natural meaning to the word "soar" that I think everyone would agree encompasses any mechanism that keeps an airship aloft. Sure, it's possible that there's a specific, technical definition of "soar" that would specifically mean movement in both a vertical and a horizontal axis simultaneously - but in order for the word "soar" to be used against my model (or any model), there needs to be some indication from the text of that definition being the operative one.

"Alternate" is sort of the opposite case. There is a natural definition and use of the word, which does not fit with the model of two concurrently active lattices. (Specifically, with the vertical one always being on when it's in flight. There's nothing to alternate with.) Is it possible to redefine the word "alternate" to somehow encompass this? I mean, technically yes, anything is possible with the malleability of language. But, again, there would need to be some sort of indication in the text of that redefinition, this time to include the scenario you're describing; which there is not. (Everything I have seen draws from the "isolate plane of motion" phrase, which is not conclusive in and of itself, and I have presented an alternate interpretation of that phrase.) The natural sense is, however, consistent with my model. Yes, even if both lattices are active at the same time while you're at rest (which is what I said in my original post), the fact that they overlap during the alternation doesn't mean it's not alternation.

When theories and the text are in contradiction, you should not deconstruct the meaning of the text so that the theory can fit into an expanded definition. Instead of twisting the text to fit theories, you need to twist theories to fit the text. When I first read the chapter, my initial impression was a partial disjoining, the same as the majority of people in this thread. But, as I studied the words of the passage more carefully and rigorously, I saw that it didn't actually fit with the descriptions. But I'm not using the theory as a foundation to change the interpretation of the descriptions, because that would be a backwards way to theorize.

19 hours ago, Oltux72 said:

By extrapolating from Navani's old platform.

What is this supposed to mean? What about Navani's previous platform experiments hints towards fabrials only acting in a single direction? You need to be specific in your references if you're going to use it as the foundation for your explanation.

18 hours ago, Oltux72 said:

That is impossible under the old scheme. During that time the ship must be held aloft by the Urithiru base support. But that is not moving. The airship could not be continuing. It would have to hover. And that is not a question of orientation. That is solvable. The problem is that they switch the connection to the chull platform off during the turn.

Well, no. Not unless you are at a complete stop while the chulls turn.

Well, no. The isolation along a plane and the change of vectors comes first. Disjoining comes later. There is no indication it is done with aluminium.

Well, that is difficult. You can certainly switch on your spanreed, yet it does not join because it is improperly aligned or not at rest to its counterpart. It looks like there is no way to actively disjoin it without switching it off (or using aluminium) but the reverse is not true

Great notion, but potentially we are looking at three states not two.

1. off
2. on but not joined (due to either speed or aluminium)
3. joined

And that is deeply problematic. The ship is basically tethered while the chulls are being turned. There is no way around that, as the connection to the chulls is off. It will now start twisting as the wind is buffeting it. And that is deeply problematic, as the chull cart is not. How do they reestablish the connection? It seems to me that the answer again is aluminium.

I'm having a hard time tracking your arguments here, but I'll take a crack at addressing what you've raised.

First, yes, disjoining is an unusual phenomenon caused by aluminum. That's explicitly laid out in the paragraph on aluminum: "The real advancement had come as they’d learned to use aluminum to isolate motion along a plane, and even change the vectors of force. The end result was chulls that could pull for a while, then be turned around—the gemstones temporarily disjoined—to march back the other direction, as all the while the airship continued in a straight line." The end result of aluminum is temporarily disjoining gemstones.

Second, I was not saying that there were only two states. I was saying that posters in this thread were using the same word, "disjoined," to apply to both the normal operation of a spanreed and to the phenomenon caused by aluminum. I didn't mention the third state, "on," specifically, but that was because nobody was using incorrect terminology to describe it, not because I don't believe it to exist.

Third, you're talking about how spanreeds work, but where are you getting information? You're saying that spanreeds won't join if they're not properly aligned. How do you know that they won't still join, but that the writing will be illegible because the pen's movements won't interact with its environment the same way on both ends? None of the passages I've looked at go that in-depth into the specific functioning of spanreeds.

Fourth, the start-stop method of movement is not inconsistent with the text. You say the phrase "in a straight line" contradicts it, but you need to look at the entire passage; it says "while" the ship moves in a straight line. And what's the "while," the time period over which the ship moves in a straight line? "The end result was chulls that could pull for a while, then be turned around—the gemstones temporarily disjoined—to march back the other direction, as all the while the airship continued in a straight line." The chulls are not moving in a straight line; they're going back and forth. But the ship is not changing orientation. Sure, it's moving forward and stopping, but you can continue in a straight line with an irregular speed. And besides, even if you did disjoin the fabrials while the chulls and airship were still in motion (which I do believe is possible), and if you assume that you can keep the vertical lattice active at all times (which I don't believe is possible, but will entertain for the purpose of this example), you would still have to wait for both to be at rest before starting up again. The speeds of the two halves of the fabrial would not be aligned, which (like I said above) we don't know exactly what effect it would have. It might not rejoin at all, in which case you have to let the ship coast to a stop. Or it might rejoin, but the different speeds would mean you'd essentially have a car crash every time you had to turn the chulls around, which would be very bad for the structural integrity of the airship and the fabrial. Since, at this level of technology, there's no feasible way to match speeds of chulls and airship, the only way you know they're at the same speed would be when they're not moving.

[Four and a half, if your ship is too good at coasting, it's actually going to be more efficient to stop completely. Distance traveled is the integral of your velocity; so what does your velocity look like when you're coasting? It's a line with a decreasing slope; the area under the curve is a right triangle the height being v0 (your initial velocity), the base being t1 (the time it takes you to cost to a stop). The amount of distance "lost" during your maneuver would be subtracting the area under that curve from the area under the curve of steady movement over that time period; a horizontal line at v0 for t1. Since it's a right triangle, the amount of distance lost is the same as the amount of distance traveled, so you waste v0 * t1 / 2. However, if you come to a complete stop, you're distance travelled is 0 (since you're not moving) times t2, so the amount of distance lost is v0 * t2. When will it be more efficient to keep coasting? When v0 * t1 / 2 < v0 * t2. Which simplifies to when t1 < 2t. So, if your ship coasts to a stop in more than twice the time it takes to turn around, you're actually less efficient. Granted, we don't have any specific numbers to apply to this, but it's to give a general sense that coasting isn't necessarily more efficient than hitting the brakes.]

Sixth, I don't see what the problem is with the ship being pushed by the wind when the chulls are being turned. If it's anchored to the vertical lattice, that is against a cliff face, so it does have some resistance to turning that will keep the ship from spinning freely. But even if it does turn some, there won't be a problem rejoining, since the entire purpose of disjoining the horizontal lattice is so that you can turn the chulls independently from the ship and rejoin them at the end with both sides having different orientations. If the ship turned a little bit during that process, you just turn it back using whatever process you normally would use to turn it. (Which I assume would be just having the chulls rotate their lattice, but they might have other tricks involving their fans, for all I know.)

19 hours ago, Oltux72 said:

That is insanely fast if that object massing - let's guess - a hundred tons is magically tied to a cart going towards a chasm

Indeed. And chulls are not known for fastness. Hence we must conclude that the Fourth Bridge does not stop while the chulls are turning. It coasts and that is possible only because the Urithiru anchor is always connected and the ship is coasting along a plane while the chulls are being turned thanks to aluminium.

No, we cannot conclude that at all. You haven't provided any evidence. Chulls aren't fast, but at the bare minimum they're apparently faster than a horse-drawn carriage over a long distance (per the numbers I showed up above), and no amount of disagreement over the mechanics of aluminum interaction can make the ship move faster than the chulls can pull it. So the relevant questions here are "how much faster are chulls than a horse-drawn carriage" and "how much time is spent turning the chulls around with respect to how long they pull and how long it takes the ship to coast." We don't have specifics to put any actual numbers on any of those, so I don't see how you can conclude this is inconsistent with my interpretation.

22 hours ago, Karger said:

Newer idea.  Maybe they don't want to just re conjoin the fabrails later?  If they do that(the same thing you do when you turn off and turn back on a spanreed) unless the chull handlers manage to get those dumb animals to move in mathematically precise ways you will get slightly different alignments each time and that is going to interfere with steering.  Perhaps aluminum stops the connection but keeps the same alignment?

Another point is that you don't have to worry about friction with the ground.  If you can get the airship moving at top chull speed it will continue going at that speed in that direction for a considerable time.  You only need to give it an additional push now and then to maintain that speed against air friction.  In fact now that I think about it there is no way that any chull maintains a speed of 5 knots for any length of time considering they are slower then horses.  They must be using some kind of mechanical pulley system to increase speed.

The comparison I made wasn't chulls to horses - it was chulls to a horse-drawn carriage, where long-term endurance is going to be the big factor. We're given a more useful reference in the text - faster than "double speed" of a marching army, which will be about 4 miles an hour (the "forced march"). Now, the numbers aren't quite matching up for me here; you're not going to be able to march an army around the clock, so say we get down to 12 hours a day, which means a force march will average 2 miles an hour over its duration. A team of chulls, even if they move slower than humans, could pull around the clock, so even if they only pulled at 3 miles an hour, they'd be able to sustain that over the entire duration and result in being faster than a marching army.

And now I realize another one of my assumptions. I've taken the "5 knots" and assumed it means, exactly, the 5 knots as defined on Earth. But none of the other units of measure match up; Rosharan feet aren't Earth feet, Rosharan weeks aren't earth weeks, so on and so forth. So the 5 Rosharan knots, which seems unreasonable, might correspond to 2.6 Earth knots (which is 3 Earth miles per Earth hour).

In terms of a pulley system on the horizontal lattice. There is a pulley system required for the vertical lattice, and we're told about it. If there was a pulley on the horizontal lattice, it would have been mentioned as well.

[Karger]

36 minutes ago, Pagerunner said:

In terms of a pulley system on the horizontal lattice. There is a pulley system required for the vertical lattice, and we're told about it. If there was a pulley on the horizontal lattice, it would have been mentioned as well.

Maybe.  I still think it would be smarter to double the number of chulls and then increase speed be mechanically converting that extra power.  I wonder why they did not think of it.

 

[+Oltux72]

8 hours ago, Pagerunner said:

I'm not sure what you're trying to say. Yes, words can have different meanings. But there is a a natural meaning to the word "soar" that I think everyone would agree encompasses any mechanism that keeps an airship aloft.

Well, no. Not everybody would agree to that. Navani is poetic here, as she should. Soaring has two components, going up and staying up. They may be divided and it is unclear what she is refering to.

8 hours ago, Pagerunner said:

Sure, it's possible that there's a specific, technical definition of "soar" that would specifically mean movement in both a vertical and a horizontal axis simultaneously - but in order for the word "soar" to be used against my model (or any model), there needs to be some indication from the text of that definition being the operative one.

Let me quote it:

Quote

Alternating between those two lattices—one to control altitude and a second to control horizontal movement—let Navani’s ship soar.

She is alternating between "controls of movement". Now what does that mean? Granted the text is obviously not a technical treatise, but controlling at least horizontal movement means changing it, that is actively moving the ship. So to take controlling vertical movement meaning to keep the ship at constant height looks like the less likely reading. Nothing in that quote says that the lattices cannot be connected at the same time. They merely are moved at the same time.

 

8 hours ago, Pagerunner said:

(Everything I have seen draws from the "isolate plane of motion" phrase, which is not conclusive in and of itself, and I have presented an alternate interpretation of that phrase.)

Please elaborate. I understood your explanation just using "isolate plane of motion" as a precursor to the the phrase and even change the vectors of force, which rests on the condition that conjoined fabrials work on cardinal directions. This may be the core of the matter, so please explain again.

8 hours ago, Pagerunner said:

When theories and the text are in contradiction, you should not deconstruct the meaning of the text so that the theory can fit into an expanded definition. Instead of twisting the text to fit theories, you need to twist theories to fit the text.

I fully agree in theory. Yet I feel I must say that you are doing this by assuming spanreeds by working in cardinal directions, while the texts describe meticulous levelling with devices made for them but no effort to orient them north/south. The starting point for the reed is even the top left corner, not a geographical designation..

8 hours ago, Pagerunner said:

When I first read the chapter, my initial impression was a partial disjoining, the same as the majority of people in this thread. But, as I studied the words of the passage more carefully and rigorously, I saw that it didn't actually fit with the descriptions. But I'm not using the theory as a foundation to change the interpretation of the descriptions, because that would be a backwards way to theorize.

I would say that the

8 hours ago, Pagerunner said:

What is this supposed to mean? What about Navani's previous platform experiments hints towards fabrials only acting in a single direction? You need to be specific in your references if you're going to use it as the foundation for your explanation.

Sorry, the aluminium allows for something the old scheme cannot do, or will do much worse. It looks to me like we disagree on what that impossible feat is. Now, Under Navani's old scheme

• the chull lattice would need to do an empty run to the other edge (assuming cardinal directions apply) 
• both lattices could be active only at a dead rest
• Fourth Bridge could never drift

do we agree on what is impossible?

8 hours ago, Pagerunner said:

I'm having a hard time tracking your arguments here, but I'll take a crack at addressing what you've raised.

Sorry. I will try to do better.

8 hours ago, Pagerunner said:

First, yes, disjoining is an unusual phenomenon caused by aluminum. That's explicitly laid out in the paragraph on aluminum: "The real advancement had come as they’d learned to use aluminum to isolate motion along a plane, and even change the vectors of force. The end result was chulls that could pull for a while, then be turned around—the gemstones temporarily disjoined—to march back the other direction, as all the while the airship continued in a straight line." The end result of aluminum is temporarily disjoining gemstones.

Well, the full quote is: "then be turned around—the gemstones temporarily disjoined—to march back the other direction, as all the while the airship continued in a straight line."
(emphasis mine)

I am afraid our disagreement is on how literally we take "all the while"

If I understand your proposal correctly I think they must operate as follows

straight line    -  stop - ------------------------------------------------------------------ - straight line (Fourth Bridge)

forward leg      - stop - switchover and turn under aluminium and switchover  - backward leg (Chull Base)

While I propose

straight line -         coast               - straight line

forward leg - conventional disjoint  - backward leg

8 hours ago, Pagerunner said:

Second, I was not saying that there were only two states. I was saying that posters in this thread were using the same word, "disjoined," to apply to both the normal operation of a spanreed and to the phenomenon caused by aluminum. I didn't mention the third state, "on," specifically, but that was because nobody was using incorrect terminology to describe it, not because I don't believe it to exist.

Right, my apologies. I just think that if we propse a terminology, it better be as precise and comprehensive as possible

8 hours ago, Pagerunner said:

Third, you're talking about how spanreeds work, but where are you getting information? You're saying that spanreeds won't join if they're not properly aligned. How do you know that they won't still join, but that the writing will be illegible because the pen's movements won't interact with its environment the same way on both ends? None of the passages I've looked at go that in-depth into the specific functioning of spanreeds.

1. They are using carpenter's levels and recheck - it need not be horizontal to the plain eye
2. The spanreed will not work on a ship
3. No compass mentioned ever

8 hours ago, Pagerunner said:

Fourth, the start-stop method of movement is not inconsistent with the text. You say the phrase "in a straight line" contradicts it, but you need to look at the entire passage; it says "while" the ship moves in a straight line. And what's the "while," the time period over which the ship moves in a straight line?

Well, no, let me quote again

Quote

as all the while the airship continued in a straight line

I am taking that literally. The ship is moving all the time, including during the turns.

8 hours ago, Pagerunner said:

"The end result was chulls that could pull for a while, then be turned around—the gemstones temporarily disjoined—to march back the other direction, as all the while the airship continued in a straight line." The chulls are not moving in a straight line; they're going back and forth. But the ship is not changing orientation. Sure, it's moving forward and stopping, but you can continue in a straight line with an irregular speed.

Yes, but the conclusion that you need aluminium to do that rests on spanreeds needing cardinal directions, doesn't it?

8 hours ago, Pagerunner said:

And besides, even if you did disjoin the fabrials while the chulls and airship were still in motion (which I do believe is possible),

How? What holds the ship up when you do that?

8 hours ago, Pagerunner said:

and if you assume that you can keep the vertical lattice active at all times (which I don't believe is possible, but will entertain for the purpose of this example), you would still have to wait for both to be at rest before starting up again. The speeds of the two halves of the fabrial would not be aligned, which (like I said above) we don't know exactly what effect it would have. It might not rejoin at all, in which case you have to let the ship coast to a stop.

No. You just let your chulls accelerate and at some point in time they will sync. Yes, that depends on nothing happening at all when you try to sync at the wrong speed.

8 hours ago, Pagerunner said:

[Four and a half, if your ship is too good at coasting, it's actually going to be more efficient to stop completely.

That calculation is correct but depends on an inability to do a "running sync"

8 hours ago, Pagerunner said:

Sixth, I don't see what the problem is with the ship being pushed by the wind when the chulls are being turned. If it's anchored to the vertical lattice, that is against a cliff face, so it does have some resistance to turning that will keep the ship from spinning freely.

I was assuming a system of a freely swinging counter weight. You can attach it to a cliff wall, if you have Windrunners. My mistake. You are correct.

8 hours ago, Pagerunner said:

No, we cannot conclude that at all. You haven't provided any evidence. Chulls aren't fast, but at the bare minimum they're apparently faster than a horse-drawn carriage over a long distance (per the numbers I showed up above),

Well, no for we have no idea how often they are changing teams.

8 hours ago, Pagerunner said:

and no amount of disagreement over the mechanics of aluminum interaction can make the ship move faster than the chulls can pull it.

Not easily. You are correct.

8 hours ago, Pagerunner said:

So the relevant questions here are "how much faster are chulls than a horse-drawn carriage" and "how much time is spent turning the chulls around with respect to how long they pull and how long it takes the ship to coast." We don't have specifics to put any actual numbers on any of those, so I don't see how you can conclude this is inconsistent with my interpretation.

It is not inconsistent. Should I have implied so, sorry. But it is harder to achieve.

8 hours ago, Pagerunner said:

And now I realize another one of my assumptions. I've taken the "5 knots" and assumed it means, exactly, the 5 knots as defined on Earth. But none of the other units of measure match up; Rosharan feet aren't Earth feet, Rosharan weeks aren't earth weeks, so on and so forth. So the 5 Rosharan knots, which seems unreasonable, might correspond to 2.6 Earth knots (which is 3 Earth miles per Earth hour).

Right. Too many unknowns. If I may add, what is marching speed on a low gravity, high oxygen world?

8 hours ago, Pagerunner said:

In terms of a pulley system on the horizontal lattice. There is a pulley system required for the vertical lattice, and we're told about it. If there was a pulley on the horizontal lattice, it would have been mentioned as well.

Most likely.

[+Hoiditthroughthegrapevine]

I have to say first off, that I called this method of airship construction back in early 2018, but based on the critiques by @The One Who Connects of the the physics of this arrangement I also gave this method up for lost. But with a greater understanding of how conjoiner fabrials work thanks to the as usual excellent analysis of @Pagerunner and @Jofwu, I believe that I might have figured out what is going on and further how to extend and enhance Airships using conjoiner fabrials. One of the breakthrough realizations was that when objects are conjoined, they function as one single rigid body.

I think the mechanism that fits the evidence and most elegantly explains how spanreeds are able to synchronize without relation to cardinal directions is that a shared cognitive reference frame is created. The spanreed station at both points A and B have been set up and verified to be vertically, and horizontally level (for both x and z), and further the spanreed is placed in a specific location on each separate board. This creates a fixed frame of reference for each board that is the same, with only a translation of absolute coordinates to relative coordinates necessary (through the application of magic) in order to perfectly synchronize the movements of the spanreeds.This setup is shown in the following diagram.

The initial position of the vertically aligned spanreed would function as the common origin for both spanreeds, and the movement of 1 spanreed would be translated to the relative reference frame of the other. The reason that spanreed communication doesn't work when one of the spanreeds is in motion is because their shared fixed reference frame no longer exists, or more precisely because the moving spanreed is traveling away from it's origin point. The only reason I mention all of this is that I think this gets at the heart of what is happening when Navani and her artifabrians are using "aluminum to isolate motion along a plane".

From the description of the how the Fourth Bridge is made to fly by "Alternating between those two lattices—one to control altitude and a second to control horizontal movement...", I think Brandon's idea is to isolate the shared motion of conjoined fabrials along one axis, basically creating a 1 dimensional vector. I think that with the proper application of Aluminum this would be possible by shielding the 2 dimensions that you want to ignore. Here's a diagram about what I am talking about, the first picture is a fully unshielded conjoiner, showing the 3 axes that it can translate force and thus influence motion along. The second has all axes but the X shielded by aluminum, the third has all but Y shielded, and the third has all but the Z shielded.

So applying these fixed one-dimensional conjoiners to the Vertical and Horizontal lattices that move the Fourth Bridge, you basically have a system where Vertical and Horizontal movement can be controlled separately and independently.

Here's a diagram of how this is applied:

The purple dots are Amethyst reverser fabrials that are aluminum shielded to only transfer motion along the Y axis, the red dots are ruby conjoiners that have been shielded to only transfer motion along the X axis. When the Vertical lattice is lowered from the top of Urithiru, the airship rises an equal distance. When the horizontal lattice is pulled by the Chulls, the Fourth Bridge advances an equal distance. With the conjoiner fabrials that are only transferring force along the X axis, it is possible to see how the aluminum screened turn around would work, the diagram below shows the turn, and also shows vectors of motion for X during the stages of the turn for an aluminum shielded turn and for a non-shielded turn.

For the shielded turn, during the portion of the chull cart journey when the x movement is not being transferred to the Fourth Bridge, it would be possible for the momentum it experienced prior to the conjoiner being cutoff to continue to impel it in it's current direction because the motion of the shielded fabrials would not affect the Fourth Bridge's fabrials. If the turn occurred without aluminum shielding, the force in the direction of X is just the x component vector during the turn, and after the turn the force would be applied along the x axis but in the opposite direction.

The reason that using conjoined fabrials and reversers is such an appealing prospect is the extremely large amount of potential energy that objects at the top of Urithiru have. It should be possible using a system of conjoined weights to move the vertical lattice efficiently and quickly to control with precision the ascent and descent of the Fourth Bridge, the following diagram shows the minimum number of conjoined weights to operate efficiently, but extra massive weights and corresponding paired fabrials could be added to increase the on demand maneuverability of the Fourth Bridge.

The use of small lightweight conjoiners that apply force to lattices could be extended to the horizontal motion of the Fourth Bridge as well by using something as simple as a chute that drops down at a 45 degree angle, basically allowing for half of the force exerted in the drop to be applied to X direction (and after the lattice and lightweight conjoiner are dropped, the lightweight conjoiner attached to the lattice could be disconnected from the conjoined weight and drawn back up to the top of the chute, ready to perform an emergency speed maneuver again). And you could have batteries of these ready to go, giving the slow and very poorly maneuvering Fourth Bridge a bit of help in emergency evasive maneuvers.
 

Edited August 6, 2020 by hoiditthroughthegrapevine

[Quantus]

Im late to the party so not 100% sure where everybody is at this point in the discussion, so forgive me if this ends up just being a recap.  I more or less agree with @hoiditthroughthegrapevine's analysis.  The Spanreeds were the base technology, but they locked all relative rotation to each other, and the users had to go through that little alignment ritual we saw them doing.  As Navani said,

Quote

 

"The real advancement had come as they’d learned to use aluminum to isolate motion along a plane, and even change the vectors of force. The end result was chulls that could pull for a while, then be turned around—the gemstones temporarily disjoined—to march back the other direction, as all the while the airship continued in a straight line."

 

So there were two different Aluminum-based breakthrough's here:

• Isolation of motion along a single plane
• Change Vectors of Force

The first allowed them to use two different conjoiner webs on one object, by isolating them each to different directions of motion.  That way there is a Lift Fabrial rigged to rocks dangling off the tower, and a Drive Fabrial linked to the Chull teams.  By isolating the planes the elevation of the chulls makes no difference to the barge, nor does the horizontal motion of the Lift rocks, because those planes are not transmitted (entangled?).  

The second (which Id missed on my first read-through) allows them to transmit forward motion of the chulls as they march in both direction: they march them out, reverse the horizontal axis, and then march them back "as all the while the airship continued in a straight line."  I dont recall a specific mention, but I assume this also lets them steer the airship by changing the vector, allowing them to march the chulls back and forth in a single lane, rather than roaming all over a pasture.  

 

Side Note: 

On 7/28/2020 at 8:56 PM, Pagerunner said:

Conjoiner Basics

The way I understand conjoiner fabrials, when you draw a free-body diagram, you treat both halves of the conjoiner as the same object. There's no "force" between the two objects; any forces that act on one act on the entire set. There's an additional "magical friction" term that will act against the direction of movement, whose magnitude is determined by the distance between these fabrials. (This force does not have an equal and opposite, which means we're going to break energy conservation, but we're doing it the opposite way often enough that I think we'll be fine.) I'm going to ignore that for the time being in all of my drawings below, because I can and I feel like it and it won't matter for the sake of this analysis.

 

This isnt a problem, Friction never has an equal&opposite reaction force, and is not ever conserved as force.  Instead it's works under conservation of Energy, and represents energy lost from the system into other energy types (most typically mechanical heat, sound, and plastic deformation, but can be magnetic, etc too.)  So for the stormlight equivalent I'd image it to just an efficiency loss as some energy is leaks out at increased distances (or maybe is used up supporting/maintaining the connection?).  

[Master_Moridin]

So idk if this will mean anything to anyone's models, but I was rereading spanreed scenes and hit upon a thing that I think completely changed how we think of spanreeds.

(This is basically all copy pasted from messages I sent in Discord)

Shallan finds Tyn's spanreed blinking, and after setting it up and flipping the dial to indicate she's ready to receive...
It just hangs there immobile not moving, and Shallan assumes the person attempting to contact her stepped away
Which could mean  a couple things.
When set to the right setting a spanreed just, refuses to move unless moved by its pair, but that comes with complications.
Is the partner reed hanging in a rack? Then wont moving it move Shallan's out of position? Or is it able to move independently still while Shallan's is locked in place until the partner reed is set to the right setting?
(Perhaps the partner reed already is in correct position but is also hanging immobile, and will only move if the person moves it? I doubt this one)

--WoR Ch 42 btw

Aside from this, I went and broke back down how the settings if the spanreeds work.

So there's about 4 settings that we see from the perspective of someone receiving a message
Off, Request/Accept, Receiving, Sending

I assume that setting you switch to time accept someone's request is the same one they set their spanreed to to send said request, so that's why I have it labeled as I do.

It blinks in Off mode when someone is trying to contact you
Turns ruby one notch to acknowledge request, then after setting up board and putting reed in place, turns another notch
After the sender writing is finished, turn a notch to write a response, place back at the start location, then turn back to the previous notch

 --WoK Ch 28

the WoR scene only mentions Shallan turning the dial to indicate she had set up, and then the reed hangs there

I think it basically works like this:

You want to contact someone
Switch to what I call Request/Accept
When the person on the other end also switches to Request/Accept, I assume you get an indication.
Then, once theyve set up, they set themselves to Receive, and you get an indication.
Then you place your reed in the same spot, and switch to Send

Then you tradeoff back and forth to have a conversation

If conjoiners can be made to transmit in only one direction then that solves a couple problems with the ship and accidentally pulling and moving things

[Jofwu]

@hoiditthroughthegrapevine Woah, amazing graphics!

I don't quite follow on the shielding of the chulls. It seems like you're arguing that it enables them to keep the gems on and working as they make the turn, but doesn't the chapter specifically note that they don't do this? That they turn them off when they turn?

3 hours ago, Quantus said:

The Spanreeds were the base technology, but they locked all relative rotation to each other, and the users had to go through that little alignment ritual we saw them doing.

Unless I misread, I'm not sure you agree with Hoidit on this? They said:

"the movement of 1 spanreed would be translated to the relative reference frame of the other."

You said:

"The second (which Id missed on my first read-through) allows them to transmit forward motion of the chulls as they march in both direction"

I think this is the biggest thing that irks me. If spanreed board orientation (rotation around the Y axis) doesn't matter, then this second breakthrough seems irrelevant to me. I'm more in favor of saying it IS a breakthrough, and that spanreed board orientation did matter. But I guess we'll have to wait and see?

3 hours ago, Quantus said:

This isnt a problem, Friction never has an equal&opposite reaction force, and is not ever conserved as force.

That's not right. A "nonconservative force" is about energy in some defined system--not violation of violation of Newton's 3rd law. Friction ALWAYS has a reaction force. If you slide your finger to the right on a surface, the same friction force resisting that movement is applied equally and oppositely to the surface.

The energy issue isn't hard to get around though, in my opinion. Just handwave it as energy going to/from the Spiritual Realm as Investiture.

1 hour ago, Master_Moridin said:

If conjoiners can be made to transmit in only one direction then that solves a couple problems with the ship and accidentally pulling and moving things

I wondered this too, but the fact that we never see "one way" control being a thing elsewhere I'm skeptical. For spanreeds, I'm wondering if all the different settings are just about communication. They do have some kind of blinking-light mechanism, right?

So the process would be... We have two people with their spanreeds, call them A and B.

• Both start "off" at setting 0. Or rather, let's call it "standby" because it still needs to receive light blinks.
• A wants to talk, so they twist theirs from 0 to 1. Setting 1 is still not activated. It just sends blinking lights to it's pair.
• B sees their spanreed blinking, so they twist it from 0 to 1. This simply lets A know that they're getting ready.
• Both A and B (in either order) get their boards ready, put the spanreed in place, and turn it to setting 2. When both are on 2 they are "actively" conjoined.
• At this point, either A or B can pick up the spanreed and right. But as a matter of protocol perhaps 2 means it's A's turn to write. So A writes what they need to say, puts the spanreeds back in the corner, and then twists to setting 3.
• All setting 3 does is send a blinking light to communicate "I'm done". B turns theirs to setting 3 to acknowledge, and then writes what they need to write. Then they put it back and switch back to 2.

So basically what you've got is...

• On settings 0 & 1 the conjoined gems are "deactivated". On settings 2 & 3 they are "activated".
• Whenever one spanreed is on a different setting than it's twin, they both blink. Or maybe, when one changes it causes the other to blink until they are both at the same setting again.
• The only reason for two "deactive" setting and two "active" settings is for the sake of communication protocol. They're about different ways to control the blinking light.

[Quantus]

26 minutes ago, Jofwu said:

 

Unless I misread, I'm not sure you agree with Hoidit on this? They said:

"the movement of 1 spanreed would be translated to the relative reference frame of the other."

You said:

"The second (which Id missed on my first read-through) allows them to transmit forward motion of the chulls as they march in both direction"

I think this is the biggest thing that irks me. If spanreed board orientation (rotation around the Y axis) doesn't matter, then this second breakthrough seems irrelevant to me. I'm more in favor of saying it IS a breakthrough, and that spanreed board orientation did matter. But I guess we'll have to wait and see?

I thought Spanreed table orientation did matter, and there'd been mention of a bit of a back and forth ritual to get things aligned to hit the ink wells and things, but I would have to go looking for the actual passages.

 

Quote

That's not right. A "nonconservative force" is about energy in some defined system--not violation of violation of Newton's 3rd law. Friction ALWAYS has a reaction force. If you slide your finger to the right on a surface, the same friction force resisting that movement is applied equally and oppositely to the surface.

The energy issue isn't hard to get around though, in my opinion. Just handwave it as energy going to/from the Spiritual Realm as Investiture.

Friction doesnt have a reaction force, it is the reaction force.  Or more accurately it is a force-equivalent term for energy being lost to other domains.  I guess that was the main point I was trying to make: that even in normal physics calculations frinction is outside the Conservation of Force Equal&opposite force balance, it has to be captured in a wider Work-Energy calculation, but that doesnt violate Conservation of Energy.  

Edited August 6, 2020 by Quantus

[+Oltux72]

8 hours ago, hoiditthroughthegrapevine said:

 

 

The problem is that we have no evidence for the tY-axis level. In fact we have evidence for the spanreed placed by hand.

8 hours ago, hoiditthroughthegrapevine said:

 

The purple dots are Amethyst reverser fabrials that are aluminum shielded to only transfer motion along the Y axis, the red dots are ruby conjoiners that have been shielded to only transfer motion along the X axis. When the Vertical lattice is lowered from the top of Urithiru, the airship rises an equal distance. When the horizontal lattice is pulled by the Chulls, the Fourth Bridge advances an equal distance. With the conjoiner fabrials that are only transferring force along the X axis, it is possible to see how the aluminum screened turn around would work, the diagram below shows the turn, and also shows vectors of motion for X during the stages of the turn for an aluminum shielded turn and for a non-shielded turn.

Why do they not just turn off the conjoiners?

8 hours ago, hoiditthroughthegrapevine said:

For the shielded turn, during the portion of the chull cart journey when the x movement is not being transferred to the Fourth Bridge, it would be possible for the momentum it experienced prior to the conjoiner being cutoff to continue to impel it in it's current direction because the motion of the shielded fabrials would not affect the Fourth Bridge's fabrials. If the turn occurred without aluminum shielding, the force in the direction of X is just the x component vector during the turn, and after the turn the force would be applied along the x axis but in the opposite direction.

The reason that using conjoined fabrials and reversers is such an appealing prospect is the extremely large amount of potential energy that objects at the top of Urithiru have. It should be possible using a system of conjoined weights to move the vertical lattice efficiently and quickly to control with precision the ascent and descent of the Fourth Bridge, the following diagram shows the minimum number of conjoined weights to operate efficiently, but extra massive weights and corresponding paired fabrials could be added to increase the on demand maneuverability of the Fourth Bridge.

 

 

4 hours ago, Quantus said:

Im late to the party so not 100% sure where everybody is at this point in the discussion, so forgive me if this ends up just being a recap.  I more or less agree with @hoiditthroughthegrapevine's analysis.  The Spanreeds were the base technology, but they locked all relative rotation to each other, and the users had to go through that little alignment ritual we saw them doing.  As Navani said,

So there were two different Aluminum-based breakthrough's here:

• Isolation of motion along a single plane
• Change Vectors of Force

OK, so if you could not change the vector of force you might be able to move but the force would still be there. It would be bad if you could basically move Fourth Bridge down but the chull cart would still feel the force. The assumption that change means a turn within the isolated plane s not there.

4 hours ago, Quantus said:

The first allowed them to use two different conjoiner webs on one object, by isolating them each to different directions of motion.  That way there is a Lift Fabrial rigged to rocks dangling off the tower, and a Drive Fabrial linked to the Chull teams.  By isolating the planes the elevation of the chulls makes no difference to the barge, nor does the horizontal motion of the Lift rocks, because those planes are not transmitted (entangled?).

Then you have changed the vector of force already. If you movd the reverser, for example, down and left, Fourth Bridge would feel only a force up, not right.

4 hours ago, Quantus said:

The second (which Id missed on my first read-through) allows them to transmit forward motion of the chulls as they march in both direction: they march them out, reverse the horizontal axis, and then march them back "as all the while the airship continued in a straight line."  I dont recall a specific mention, but I assume this also lets them steer the airship by changing the vector, allowing them to march the chulls back and forth in a single lane, rather than roaming all over a pasture.

I don't see how you can require that advance without imposing an absolute frame of reference on the spanreeds. The problem with that is that they are aligned down. On a sphere however, down is not paralell.

2 hours ago, Master_Moridin said:

So idk if this will mean anything to anyone's models, but I was rereading spanreed scenes and hit upon a thing that I think completely changed how we think of spanreeds.

(This is basically all copy pasted from messages I sent in Discord)

Shallan finds Tyn's spanreed blinking, and after setting it up and flipping the dial to indicate she's ready to receive...
It just hangs there immobile not moving, and Shallan assumes the person attempting to contact her stepped away
Which could mean  a couple things.
When set to the right setting a spanreed just, refuses to move unless moved by its pair, but that comes with complications.
Is the partner reed hanging in a rack? Then wont moving it move Shallan's out of position? Or is it able to move independently still while Shallan's is locked in place until the partner reed is set to the right setting?
(Perhaps the partner reed already is in correct position but is also hanging immobile, and will only move if the person moves it? I doubt this one)

This is highly problematic. But it can be solved by the sender just using a holder for the reed, keeping it on the dot.

1 hour ago, Jofwu said:

@hoiditthroughthegrapevine Woah, amazing graphics!

Indeed

1 hour ago, Jofwu said:

So the process would be... We have two people with their spanreeds, call them A and B.

• Both start "off" at setting 0. Or rather, let's call it "standby" because it still needs to receive light blinks.
• A wants to talk, so they twist theirs from 0 to 1. Setting 1 is still not activated. It just sends blinking lights to it's pair.

I am afraid this protocol is not compatible with Shallan's experience using Tyn's spanreed. The reed could not be hanging in the air, if the sender's reed were still at position 1. It seems to me that you call somebody bu outright switching to 3 = "send"

1 hour ago, Jofwu said:

• B sees their spanreed blinking, so they twist it from 0 to 1. This simply lets A know that they're getting ready.
• Both A and B (in either order) get their boards ready, put the spanreed in place, and turn it to setting 2. When both are on 2 they are "actively" conjoined.
• At this point, either A or B can pick up the spanreed and right. But as a matter of protocol perhaps 2 means it's A's turn to write. So A writes what they need to say, puts the spanreeds back in the corner, and then twists to setting 3.
• All setting 3 does is send a blinking light to communicate "I'm done". B turns theirs to setting 3 to acknowledge, and then writes what they need to write. Then they put it back and switch back to 2.

So basically what you've got is...

• On settings 0 & 1 the conjoined gems are "deactivated". On settings 2 & 3 they are "activated".

Or we have an XOR. One reed needs to be in 2 and the other in 3.

1 hour ago, Jofwu said:

• Whenever one spanreed is on a different setting than it's twin, they both blink. Or maybe, when one changes it causes the other to blink until they are both at the same setting again.
• The only reason for two "deactive" setting and two "active" settings is for the sake of communication protocol. They're about different ways to control the blinking light.

Possible but not confirmable, it seems to me.

 

[Quantus]

7 minutes ago, Oltux72 said:

OK, so if you could not change the vector of force you might be able to move but the force would still be there. It would be bad if you could basically move Fourth Bridge down but the chull cart would still feel the force. The assumption that change means a turn within the isolated plane s not there.

Im not sure what you mean here?

7 minutes ago, Oltux72 said:

Then you have changed the vector of force already. If you movd the reverser, for example, down and left, Fourth Bridge would feel only a force up, not right.

I don't see how you can require that advance without imposing an absolute frame of reference on the spanreeds. The problem with that is that they are aligned down. On a sphere however, down is not paralell.

I propose that this is not a concern on Roshar, because as far as the collective consciousness of Roshar is concerned, the planet is a flat plane.  We know this by the topography of  teh Cognitive Realm, which surges generally do business with and which is literally the reflection of the collective idea of Reality.  All that to say that spanreeds are likely to operate using Cognitive Realm topography, where everything is projected onto a flat plane with (more) objective cardinal directions.