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We are creating a world of floating islands, these vary in size from small outposts that are little more than a Dock and Watchtower, through independent farmsteads, to full Nations in which the majority of the population are unaware they are on a floating island.

A particular Nation has access to "magic" but it is treated as science as it is technically unlawful, so if it is quantifiable or repeatable it becomes allowed, but summoning a Demon to ask for directions would not be acceptable. They have developed Airship technology, and Ornithopters, and would be typically "human". The power is held by Universities and Guilds rather than a Feudal state.

In the rest of the world pretty much anything goes, so there are Pegasi, Goblin Hanggliders, Sky Whales etc...

The atmosphere is Earthlike, so high is cold and hard to breathe and low is hot and hard to breathe. There are winds that could be predictable. Birds are around. Clouds form and block visibility so you may not have 100% visibility. There is a celestial globe of stars and other objects that can be observed and measured.

Considerations from our Earth:

  • Islands in the Pacific Ocean can be identified by how they disrupt the wave patterns
  • You can follow Trade Winds to find entire continents and return to your own continent, can you do the same to an island
  • Altimeters use Air Pressure but are periodically zeroed at known heights/location
  • You can measure speed via a log
  • A compass can be used to give the direction to a known/assumed point
  • Devices can be used to measure angles for celestial bodies
  • Maps can be a list of distances and directions
  • Maps can be a representation of the area in pictographic form
  • Data can be pre-calculated and recorded in books of look-up tables; calculations, tides etc...

How would this nation that is self-limiting to technological methods map and navigate through 3D space? Would there be a way to do it if there was no compass?

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  • $\begingroup$ The question becomes, do the islands move or are they 'stationary'? $\endgroup$ – bowlturner Aug 11 '15 at 13:04
  • $\begingroup$ they can bob slowly under their own accord but currently seem fixed. Given enough impetous they could be moved by a determined faction... $\endgroup$ – Whinja Aug 11 '15 at 13:08
  • $\begingroup$ for your altimeters (which are nothing but calibrable barometers) : you can recalibrate them with a log line: drop it to the ground (no! only one end! dang... get a new logline...!) and measure it coming back up. Mind you: in some weather conditions you would need to repeat that every few hours. $\endgroup$ – Burki Aug 11 '15 at 14:51
  • $\begingroup$ If the islands never move then how is it any different from navigating on earth? $\endgroup$ – Tim B Aug 11 '15 at 20:30
  • $\begingroup$ @TimB the islands are in 3D space so its really about how they would map the different heights and navigate back to them $\endgroup$ – Whinja Aug 12 '15 at 8:44
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The best way would probably be to use a sextant. As long as you can see celestial bodies/the sun, you can navigate yourself to within half a mile. This is great for a 2D world, but adding in the 3rd dimension, you'd likely use an altimeter/barometer to determine your height as well. Coordinates would be 3 dimensional (latitude, longitude, and elevation).

You'd probably want a compass, but you wouldn't need it. As long as someone had a sextant, they can just note where they are now, and where they are in a few minutes, and get a direction of travel.

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    $\begingroup$ I have read your link, thank you, and came across this line "Sextants measure the angle between the sea horizon and a celestial body." and suggestions for how to measure celestial angles with no horizon? $\endgroup$ – Whinja Aug 11 '15 at 14:38
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    $\begingroup$ While in real life, especially at sea, you use the horizon as a baseline, this is not a strict requirement: you need to find the angle between a horizontal line through your sextant and the one through your observed object and a sextant. a bowl of water will provide a horizontal pane, and you can build something useful starting from there. $\endgroup$ – Burki Aug 11 '15 at 14:49
  • $\begingroup$ I didn't want to get too much into the details because honestly I don't know the math behind it. That being said, the "horizon" would just be holding the sextant still on a flat base. You can determine the offset of the horizon based on the altitude to get a reading of the ocean's horizon. It would probably just be some simple trigonometry so you'd likely also want to bring a calculator or a table of sines and cosines precalculated. $\endgroup$ – Thatguypat Aug 11 '15 at 14:53
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Celestial navigation is quite useful -- 1 NM accuracy 95% of the time (RNAV 1 in modern parlance) will get you close enough to your destination to find it and land there basically every time. However, it's not the only thing your aviators need.

Up? What's Up? Where's Up? WHERE IS UP!?!??!?!

Land creatures typically are given stabilizing systems that are designed for two-dimensional motion on a surface -- our inner ears are quite good at it. However, they aren't so good at ascertaining balance in a three-dimensional environment, especially when visual cues go away. Hence, some form of gyroscopic instrument would be needed in addition to the obligatory altimeter, compass, and airspeed indicator. At minimum, a simple one-axis gyro can be used in a system akin to "needle, ball, and airspeed" flying; however, two-axis gyros aka attitude indicators make the lives of your blind-flyers much easier.

Finding Your Way Through the Clouds and Fog

A prime drawback to celestial navigation is that you can't use it when you're in the middle of a big, fat cloud or fogbank. Some sort of system based on beacons (similar to today's radiobeacons such as VORs and NDBs) would be needed in order to let people at least find the nearest island and wait out the weather, if not navigate beacon-to-beacon in a fashion similar to modern air navigation.

Getting down to land

It could easily happen that one of your floating islands would become enshrouded in a cloud. Landing in that case would require something more sophisticated than a mere beacon to guide your aviators to the right spot at the right altitude -- the concepts behind an Instrument Landing System (using focused, crossed beams to provide azimuth and elevation guidance to the landing site) could be used to allow for safe landings in all weather.

Lights, Action!

Of course, lights can also be used to provide visual aids in night and even to some degree bad weather, similar to lighthouses in the naval world.

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They can place lighthouses on islands. On the Earth surface limits the range of lighthouse to be seen: Lighthouse on Earth In the sky, the range can be much more bigger, and is only limited by air transparency.

They can use some sort of bells and buzzers for audible navigation in foggy weather, and every airship has a special crew member - Listener, who determines the direction and range to near buzzers.

The air attenuates sound of high frequencies more, than sound of low frequency (Sorry, i don't remember this physics law name ;-( ). So, distant buzzers sound with more bass. If all buzzers use standard frequency, Listener can determine distance by change of tone of sound.

The Listeners use gadgets like this:

Listener from crew with his gadgets

Also every island has Listeners, that find approaching airships to notify watchmen:

Listener from island with fixed listening device

(In real life this gadgets was used in World War 2 to find approaching aircraft's and guide anti-air cannons.)

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  • $\begingroup$ Very cool gadgets! $\endgroup$ – Bookeater Aug 13 '15 at 8:13
  • $\begingroup$ "The air attenuates sound of high frequencies more, than sound of low frequency". Is the Doppler effect the physics law you're looking for? $\endgroup$ – Thatguypat Aug 13 '15 at 13:03
  • $\begingroup$ no, some physics laws from nonlinear acoustics, i have studied it at college in 2001 year... The Doppler effect (or Doppler shift) is the change in frequency of a wave (or other periodic event) for an observer moving relative to its source (c)en.wikipedia.org/wiki/Doppler_effect. $\endgroup$ – vodolaz095 Aug 14 '15 at 8:07
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Actually I think it would be easier to navigate if you constantly have landmarks visible from long distances. Who needs a compass when the Hohenberg's island to the north is visible for miles, even through the forests? That is how much of navigation was done. The stars became useful on open expanses such as the oceans where there are few to no landmarks over much of it.

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  • $\begingroup$ So rather than 'maps' you might have a list of landmarks or islands to hop from? I know that the first thing that might be considered maps were long strips showing points of interest along routes. $\endgroup$ – Whinja Aug 11 '15 at 14:44

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