KOSH Coffee Table

[Okayish Aviator]

Hello all,

This is my first post, and I do so both to share my work/thoughts, and to ask for ideas on how to solve certain problems.

My current project is one that is close to my heart. The EAA AirVenture airshow at Oshkosh WI, USA is one of the most spectacular aviation events in the world. Each year nearly a million people visit. I decided I wanted to make a coffee table with a scale model of the airport on the surface. In addition, I thought it would be an outstanding idea to also light the airport with proper lights, and markings. As I have some experience in AutoCad, I figured I'd start designing it there, and then build it after it's been designed.

Here's what I had in mind:

The runways and taxiways themselves are going to be a very thin sheet of aluminum cut with a milling machine I have located near where I live. On top of the table surface, I plan on placing a piece of glass, or filling with a liquid acrylic.

I do have a couple of problems I'm facing. Primarily, when lighting the airport, I need to have various colors, and some lights and runway markings are different on opposite sides. For example, runway end lights are green on the approach side, and red on the end side.


Do any of you know how to make dual color lights? These are quite small, as the actual scale of the runway is 26/10000. The total diameter of the fibers are .02in. You can ignore the inset, as I was using that only as a reference for where the aluminum will sit.

 

[Jens Andrée]

Cool project!

I regularly use RGB leds in various projects. They are programmable leds (light emitting diodes) and they can emit all possible colours, not just red, green or blue.
They come in various different packages but the most popular are the WS2812b or similar sizes. In modern electronics terms these are huge. Around 6x6mm-ish in size.

If you only need red/green you can choose a smaller, and cheaper, led that can switch between the two colours and they come in really small packages for smd. (surface mount)
The smallest I've used are 0503 but I suspect there might exist as small as 0201 dual coloured leds. They exists in old-school leds too for through hole soldering. 5 mm leds for sure but also perhaps 3 mm.

Are the leds going to be of a more static role or are they going to be programmed to run complex programs? (this is not that complicated to do with a microcontroller)

If you can tell me this in detail I can perhaps guide you to a solution. I'm also an EE engineer.

 

[Okayish Aviator]

The LED's are supposed to be more of a static role. Runway lighting doesn't change itself, but rather airport lighting looks different depending on which direction you are looking at it from.

For instance, if you approach runway 05, the lights at the beginning of the threshold are green and the end are red, however if you look at it from the other direction (runway 23), the lights are still green at the threshold and at the end they are red.

I'm trying to use the smallest LED's possible, or using fiber optic cables routed through the holes to create the lighting. Below is a picture of what a similar sized runway to what the models runways are would look like at night. The red at the beginning of THIS runway is a displaced threshold and doesn't exist on the KOSH runways, but the blue taxiway edge markers, green taxiway centerlines, white runway edge lights, green threshold lights and red end lights all will go into the build. The 2 red and 2 white lights on the right are called a PAPI, a Precision Approach Path Indicator. The last 1000ft of a runway have yellow runway edge lights, but if you look at them from the other direction, they are white. I'd like to figure out a way to make a PAPI, but that's a HIGHLY complicated device that changes from all red to slowly all white based on only 2.75 degrees of elevation angle on a flight path and probably isn't feasible for this build. I'm also probably nixing the idea of using green centerline lights for the taxiways and focusing on the runways and edge lights for the taxiways.

I'm not sure how to do dual sided lighting other than maybe doing 2 lights of different colors and block the light from the other one from one direction.

 

[Jens Andrée]

Ok. I think I understand what you want.

Dual sided lights should be simple to construct by gluing two smd leds to a plastic strip (for mounting) and you just have red on one side and green on the other, or whatever colours you need.
You also might want to shield the sides of the leds to minimise spillage because these leds aren't directional.

The smallest ones you realistically could use here are 0201 leds (2x1 mm size) but it might be tricky to solder loose wires to that.
Alternatively you could design a tiny pcb (dual sided) which acts as the light housing where you solder one led on each side and something you could solder a connector to the bottom for connecting, and mounting, on the runway table? Designing a pcb like that doesn't take many minutes.

Let me know if anything I'm writing is unclear and I'll try to draw a picture, or make a prototype to show you.

 

[Okayish Aviator]

A picture/diagram or prototype would be great. Like I said, initally I was thinking of just doing fiber optic cables through the table surface so they all would have a common light source, but if this works and will be simpler, then I'm game.

 

[Jens Andrée]

A picture/diagram or prototype would be great. Like I said, initally I was thinking of just doing fiber optic cables through the table surface so they all would have a common light source, but if this works and will be simpler, then I'm game.

To be honest with you - even though I'm an EE hobbyist who's done more than a few really complex led projects - fibre optics would be a much simpler solution on your build considering how many individuals leds that's going to need wiring up and controlled...
With fibre optics you can get away with just one led per colour and then some sort of light pipe that feeds into every individual fibre.

How many lights do you think is going to be needed? (counting the double ones as one)
If it's only a handful then the led option would be the easiest, but if we're talking about 50-ish lights or more then I'd probably go for fibre optics, if I did the project.

You're also going to have to take into consideration maintenance so you can replace a burnt out led at some stage.