Getting Lights on Your Plane

First, some inspirational images as to what is possible

The Demonstrator

The goal is to add very easy illumination to the Simple Delta Demonstrator. Warning: The Demonstrator is meant to be a begginer level plane to build, not fly. It requires intermediate flying skills to pilot. The finished Demonstrator looks like this:

Laying out power the power buses

Pretty cool eh? You are going to be able to say that your aircraft has not one, but two power buses. One is AC for the el-wire and the other is DC for the LEDs as well as the DC input power for the inverter that powers the AC powerbus. Pretty fancy for a scrap of foam. We put the DC bus on the top surface of our fanfold delta and the AC bus on the bottom.

Copper foil tape is your friend

A key innovation we came up with for night flying setups is the use of copper foil tape for power distribution. You can get it at stained glass stores for cheap and beats the daylights out of running wire all over the place because it lays flat, adheres to fan fold/epp/glass great.

Here is the DC bus layed out on the top of the wing:

The only downside is that it is uninsulated (easily fixed with some tape laid on top) and it likes to break on bumpy foam like Multiplex elapor foam. Take care with the copper tape, it is a short circuit waiting to happen--insulate with a layer of tape on top. We use clear so you can't see it clearly in the photos.

Connecting to the reciever power

Since our night flying setup is not going to draw much power and this is meant to be the simplest possible setup we use the power going to the reciver to run the illumination. That power will come from the battery elimination circuit (BEC) from the electronic speed control that is driving the motor. See the Demonstrator pages for how that all works.

Connecting LEDs

The LEDs need to have a resistor inline to work and it is a little complicated to figure our what resistor you need because different LEDs work at different voltages. The LED is soldered to the resistor (which wire doesn't matter) and then it is soldered to the power bus (polarity does matter here). You won't hurt the LED if you get it backwards, it just won't work.

How to calculate what resistor you need?

There are a number of online LED resistor calculators or you can do the math yourself. You will need to know the specificaitions for your resistors to use one, the input voltage is 5 volts given this setup. LEDs of the same color tend to use the same resistance. So working from a spec sheet for a red LED I get a forward voltage (not the reverse voltage!) of 2.1 volts at 20 mA (milliamps). Drop that into the led resistor calculator and we get a 150 ohm 1/8th watt resitor. You can use higher wattage resistors, but not less. A green LED with a forward voltage of 3.6 volts and 20mA needs an 82 ohm 1/8 watt resistor. So they are not all the same.

I stick with a standard green light on the right/red light on the left just to keep things consistent with big aviation. White lights towards the back would complete the setup but I didn't go that far this time. I do go that far with my 48" or larger planes.

Hooking up the Elwire

Elwire, aka LyTec Electroluminescent Wire is a very effective way to illuminate an aircraft. On the simple Demonstrator there is around 4 feet of 2.5mm aqua elwire taped to the leading edge and 2 feet taped juse before the elvons yielding a very easy to recognize triangle shape in the air. This is all run by a small DC to AC inverter which draws power from the DC bus that the LEDs are using. The underside of the wing shows the connections between the inverter and the AC bus.

Connecting the elwire to the inverter can be a bit of a hassle. Have a look at how to solder the elwire to regular wire. For the Demonstrator I just soldered the elwire directly to the AC bus.

Inverters/Sequencers

• Inverters For the Demonstrator I used a 3 volt inverter which seems to tolerate the 5 volt input well enough. The 9 volt and 12 volt inverters can be powered off of the motor battery pack easily depending on what that voltage is. They are rated by how much wire they will drive. They break so have backups.
• Sequencers These are good for more complex patterns. I used one of these to drive my wriggling animation of the sperm's tail
• El Wire This is the good stuff, beware of imitations. I used the Hi Bright 2.5mm the most. The double core looks interesting, but no experience yet.

Other elwire setups

Last year I lit the sperm by splitting the battery mains to a cheap parkflyer speed control with the BEC disabled. I used a separate channel to control how much energy to send to the el wire inverter and LEDs which I controlled with a slider on my transmitter. The whole display system was setup to run at the inverter voltage of 6 volts. This had the advantage that I could turn off the lights at will which was good if I didn't want to draw a crowd at launch.

I did the same thing on a separate channel for my navigation lights done with LEDs.