Navani’s flying palanquin physics

[CosmereMaths]

In the beginning of RoW, Navani flies from Alethkar to Urithuru with the wind runner in a spherical winged palanquin that is lashed. I find this to be inconsistent with what I understand about lashings for a few reasons.

Firstly and unimportantly, it appears to be far less aerodynamic than a human being falling headfirst so should travel much slower, but terminal velocity (at x lashings) is the speed at which they fly.

Secondly, it is unclear which part is affected by the lashings. As I understand Cosmere magic, perception is important so I would assume the vehicle experiences the lashings but not Navani nor her papers and fabrials inside as the Windrunner would not view them as all one object. Perhaps with the proper visualization and intent it can all be lashed at one touch and all fall as one. But this brings me to my biggest issue. If it is all lashed as one, then Navani and her papers should be weightless and she should have a tough time writing. More likely and evident by that she is writing is that only the palanquin is lashed and Navani insides experiences 3 G forces directly backwards (technically sqrt(10) G forces at an angle arctan(1/3) down from the horizontal) until terminal velocity is reached. I’m unsure about the interior forces to expect her to experience once terminal velocity is reached. Also on the way upwards she should experience at least 2 G forces or 4 if they used a triple lashing the whole time. Moreover, if the vehicle is lashed but Navani isn’t, and the vehicle is lashed horizontally, then shouldn’t Navani’s weight make the vehicle plummet or does it need an additional upward lashing to compensate.

I do not know a lot about pilots or race drivers withstanding g forces but I want to know if her device is as unpleasant as I first imagined. 

[Treamayne]

On 1/13/2025 at 4:39 AM, CosmereMaths said:

Firstly and unimportantly, it appears to be far less aerodynamic than a human being falling headfirst so should travel much slower, but terminal velocity (at x lashings) is the speed at which they fly

My understanding is that Sanderson was treating it more like a normal aircraft or car, in that accelleration is felt by those inside, but once a non-increasing cruising speed is reached, the internals are travelling at the same speed as the externals, and the frame of reference inside becomes a net zero (passenger's flying on commercial airlines do not experience G forces from cruise speeds at altitude - only in accelleration and deceleration). However @DrPhysics is probably the best person to discuss the issue.

Edited January 15, 2025 by Treamayne
SPAG

[DrPhysics he/him]

On 1/13/2025 at 2:39 AM, CosmereMaths said:

Firstly and unimportantly, it appears to be far less aerodynamic than a human being falling headfirst so should travel much slower, but terminal velocity (at x lashings) is the speed at which they fly.

Actually, a sphere is much more aerodynamic than a human: https://en.wikipedia.org/wiki/Drag_coefficient (Humans are close to a long cylinder. The rounding of the head helps a bit, but from what I could find on tests, our best drag coefficient ends up being around 0.7). A slightly pointed sphere would have even less drag.

 

On 1/13/2025 at 2:39 AM, CosmereMaths said:

Moreover, if the vehicle is lashed but Navani isn’t, and the vehicle is lashed horizontally, then shouldn’t Navani’s weight make the vehicle plummet or does it need an additional upward lashing to compensate.

Navani would be much lighter than the sphere (the sphere is probably around 1000 lbs), so the lashing would have to be angled up by less than 5 degrees, or if one of the points was tilted slightly up, it could easily generate enough lift to hold her up.

 

Everything else you describe would be correct, assuming they stayed at a constant 3 lashings, but we don't get many details on starting/stopping, so I bet they don't do that.

The boring version: as much as Brandon says lashing isn't flying, he treats it like flying an aircraft whenever they have extended flights*.  For example, Kaladin should never black out from G-forces while turning but would black out after about 10 seconds with a double lashing at terminal velocity.

It's a part that I've just learned to ignore (or at least not think too hard about) with my physics brain.

 

*This may be due to managing the reader's expectations as @Treamayne notes below. (This footnote was added after their comment)

Edited January 17, 2025 by DrPhysics
Clarity

[Treamayne]

1 hour ago, DrPhysics said:

On 1/13/2025 at 4:39 AM, CosmereMaths said:

I do not know a lot about pilots or race drivers withstanding g forces but I want to know if her device is as unpleasant as I first imagined.

The boring version: as much as Brandon says lashing isn't flying, he treats it like flying an aircraft whenever they have extended flights.  For example, Kaladin should never black out from G-forces while turning but would black out after about 10 seconds with a double lashing at terminal velocity.

He has also acknowledged that, sometimes, he factor's reader expectations against realistic portrayal (most readers would not have the physics background to realize the issue and expect that sharp turns cause physiological effects). WoB:

Spoiler

shinarit?

There is that scene where Kaladin takes a sharp turn at high speeds and he almost blacks out. That is normal for jet pilots, since they experience high G forces when their airplane tries to accelerate them by their backs and bottoms.

But Lashing doesn't work that way, it generates fake gravity. Accelerating your whole body shouldn't cause you anything, you can't even feel it.

Is this something that is an admitted physics hiccup or I misunderstood this kind of Investiture usage?

Brandon Sanderson

This one is actually in the process of flux, as I do more research on the effects of acceleration (including interviews with fighter pilots, which has been fun.) Basically, I realized I needed to beef up my understanding of all this, and then make some decisions on exactly how this all works, because I've been relying on instinct too much in some of these sequences.

So...that's a RAFO, I'm afraid. More because I'm still tweaking some of the little details of how I want this all to work. (In ways that become increasingly relevant as I look forward toward things like Windrunners in space.)

There are a ton of details to consider, even if I eventually hand-wave some of it with the magic. (For example, the heart pumping blood in a high-g environment. How does that interact, if at all, with stormlight? And the direct oxygenation of the brain implied by not needing to breathe while holding stormlight...)

We have several very large math-ish projects going on behind the scenes.

Phoenixdown

I think it depends on if lashing independently impacts each atom within your body simultaneously, or if it is only a subset.

Brandon Sanderson

There's one important fact you're not considering, but which is vital: reader expectation.

One of the questions I have to ask myself is this: What will the reader expect to happen? How will they expect to feel? Granted, none of us have ever flown like this before--but we generally imagine similar things, similar feelings.

As a writer, one thing I need to balance is when I go against reader expectations and when I don't. Going against the expectations can be interesting, but often takes a large burden of words and explanation to keep reminding them something is not how they'd imagine it to be.

For example, it took a relatively large amount of reader attention (and explanation) to keep reminding people in Mistborn that plants weren't green and the sky wasn't blue. In many ways, making something new (like a chull) is easier on readers than making something familiar into something strange (like the horses in Dragonsteel, which were smaller than Earth horses--and kept causing confusion problems in my alpha readers.)

As annoying as this example can be, this is why Lucas had sound, fire, gravity, etc in space. Starships banking in formation felt real to the viewers, even if it didn't make sense in context. I hope to not go that far, but these questions are something in my mind.

I try to be careful not to remove the sensations of magic, in order to keep the movements of characters grounded. Windrunning has left me having to decide how far I want to go with things like this, in order to preserve the visceral feelings for the reader.

General Reddit 2018 (June 6, 2018)

Hope that helps