Alex Eames Nachtflug Mod


By Alex Eames (RCGroups alexeames)

Lighting the EasyStar required some thought.This is what I came up with...

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...Video of it flying is in the below link. It's a bit washed out, but you get the idea of the real colours and intensity from the photos. The video camera tends to go black and white in low light conditions...

Night flying EasyStar (2.8 MB / wmv)

And here's a short video of the EasyStar sitting on C of G jig, close-in so you can see it well...

Easystar Indoor.wmv (0.6MB / wmv)

Some of the Thought Behind My Way

I'll try to outline some of my thinking. Problems to overcome...

  • Curvy wings (upswept tips)
  • Two piece detatchable wing (connectivity)
  • Power source (flight pack or separate pack)
  • Wing color quite dark for reflecting light
  • Good all round lighting

The EasyStar is not really suitable for internal lighting as it's made of quite thick foam and not enough light gets through. It would probably be an ideal candidate for external glow wire. But not having a readily available source of that, superbright LEDs were used from the outside. These LEDs have quite a narrow beam and it was found best to get some distance between the LED and the object it illuminates.

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So the white tail fin is illuminated from each side by an LED sitting near the end of the blue horizontal stab and pointing back at the tail fin. The prop area is lit by an LED sitting at the top of the vertical stab pointing forwards.

I'm using superbright LEDs in white, pure green and red bought from maplin.co.uk part numbers N21BY, N23BY and N22BY. They're about a pound (GBP) each (~$1.80 USD) and pretty bright (~7000 mcd).

The whites have a viewing angle of 20 degrees. The green and red 30 degrees. The white and green ones are 3.2V forward voltage (max 3.6). So I'm using them without resistors. The red ones are 2.3V forward voltage (max 2.6) so I've got a 24 Ohm resistor on each of those in series.

Wiring Concept

I did a proof of concept over 3 evenings. Didn't need to finish it to see that the system would work. The only thing I wasn't sure about was whether or not the lower surface of the wings would be sufficiently lit. I'm happy with it for now though.

I was concerned if the wiring would cause radio interference. I used insulated solid core telephone wire. So far it doesn't seem to affect anything negatively. So that's good.

The best wiring plan uses the least wire (less weight and resistance).

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The power pack sits right at the rear of the cockpit with two main wires (One + & one -) going forward and two backward. These are the main parallel circuits. I took spurs off each of these for the tail upper and lower surfaces and the vertical stab fin. I also took another spur through the horizontal stab on each side for the two LEDs which light the underside of the stab.

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There's also a set for the two LEDs on top of each wing connected to the battery.

The underside of the wings are lit by a single LED mounted on the fuse and pointed at the wing. There's a spur for these from the main wires. On this side, the blue striped wire comes through the wing mounting hole from the other side and vice versa.

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All wire junctions were made by stripping back a small bit of insulation, twisting one wire around the other and soldering them together. All the LEDs are connected up in parallel. The circuit is nominal 3.6v using a 3 cell AAA NiMH 900 mAh. According to my calculations this should handle my 13 LEDs for nearly 2 hours.

The weight of the pack is about 45g. It's located behind the receiver, which minimises c of g issues as it's near to c of g. Did all my calculations based on NiMH nominal voltage of 1.2v per cell. But of course, the actual voltage of a fully charged 3 cell pack is 4v, but it doesn't stay that way for long in use.

Overcoming the Wing Problems

All the LEDs were CA'd in place while they were lit so that I could angle them precisely pointing where I wanted.

Lighting the wings was difficult because they sweep upwards and they're blue, which is not a very reflective color. So I decided to paint white stripes lengthways on the wings and stab in order to have better reflection, but not lose all the daytime visibility by painting them completely white.

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I also painted the upper wing tips white (the really curvy bits). I needed two coats of humbrol model enamel to get the desired effect.

The undersides are lit by single LEDs, one green one red. The photo in the previous post shows the location of these, just below the control rods. The topsides have two LEDs. One illuminating the upswept, white wing tip and the other at the end of the straight section, about 1cm from the leading edge, pointing forward for landing orientation. You can see those in the front view picture in the first post of this thread.

Landing Lights and Weight

Two white landing lights are placed on either side of the fuselage about 7 cm back from the front of the plane, angled parallel to the top of the fuse in that place and about half a cm from the top. The gently downward angle of these allows you to see the ground for landing (from several feet up).

The LEDs and wire weigh about 10g altogether. The battery pack and switch weigh another 50g. You can wire the rig into the receiver, but only if your BEC can support the extra amp draw. My rig draws about 0.4A, which on a 1A ESC, I thought was a bit dodgy, so I went for a separate pack.

If you do plug into the receiver (5v) you will need resistors for all the LEDs (~60 Ohms for white and green - 54 for red. Closest values in Maplin catalogue are... 56 and 51).

You could also use a 1s LiPo, at 3.7v it would be ideal and lighter. (But you would have to watch that you don't run it too low).

I hope you've enjoyed this mod. Now why not have a go?