Required LED power for dusk flying?

[Earthchill]

Flew around dusk last night and crashed when I lost orientation of the plane (no damage though). This made me realize that some sort of light will be needed if I'm to continue flying in the evenings (and that's when I have time).

I have a ton of brown foam board so I believe that three navigation lights will be easier to install than led strips.

So here's the question: What kind of of power (or candela/lumen) do I need? Since I live in Sweden at 58°N the dusk is quite long with slowly decreasing light, I suspect that that means that I need stronger LEDs than if it got dark quickly.

Any recommendations on specific systems would be appreciated but I'm happy to put something together myself. I'm looking at some 3W LED's, but then I likely need heat sinks and the weight starts to add up. On the other hand I could probably buy those, try with lower power and install the heat sinks if I really need them.

 

[leaded50]

heat sinks aint necessary with LEDs, they dont make heat. blinking leds would be easier to see, and of course you would need some resistor,and power.

 

[Earthchill]

heat sinks aint necessary with LEDs, they dont make heat. blinking leds would be easier to see, and of course you would need some resistor,and power.

An ordinary LED usually needs a current of 20 mA, the linked one handles 700 mA. The efficiency of a LED is much better than other light sources, but it's far from perfect. Even at 90% efficiency there's 0.3W that needs to go somewhere and LEDs seem to be quite temperature sensitive.

But I doubt I need that kind of power, letting it blink at 3W is probably the best. Then the average power will be low enough to avoid the heat sink. But if I can get away with four or five 20 mA LEDs instead that would be so much simpler.

Have you tried any dusk/night flying, I imagine we have similar light conditions? The people I talked to at my club only had lights for the scale looks, not to see the plane, so they didn't really know.

 

[leaded50]

An ordinary LED usually needs a current of 20 mA, the linked one handles 700 mA. The efficiency of a LED is much better than other light sources, but it's far from perfect. Even at 90% efficiency there's 0.3W that needs to go somewhere and LEDs seem to be quite temperature sensitive.

But I doubt I need that kind of power, letting it blink at 3W is probably the best. Then the average power will be low enough to avoid the heat sink. But if I can get away with four or five 20 mA LEDs instead that would be so much simpler.

Have you tried any dusk/night flying, I imagine we have similar light conditions? The people I talked to at my club only had lights for the scale looks, not to see the plane, so they didn't really know.

sorry, not any light on my planes at flying (yet) Conditions should be quite similar yes , but i lack much flying in dusk (yet) If you hold on a lighted LED, you will close to not find any heat, that shows need of any shielding, eg. against heatsensitive foam. The needed resistors can get a bit varm though, doubt enough there too to ruin any foam

 

[JasonK]

@leaded50 - small LED don't make any appreciable amounts of heat, but Earthchill is correct, larger ones do. I tried a few of those small LEDs on a plane and it would have had to been near pitch black before they would have shown up well. Earthchill is going to either need to use LED strips or a, if a single LED, a larger one.

@Earthchill - what I have seen done for night flying are LED strips in the wings to make the wings glow. if your just going to put on 'running' lights, make sure your lights have good 'all direction' light, most LEDs tend to be more of a cone (so won't be supper visible except in the way it is pointed).

 

[clolsonus]

We thought we had lit up an airplane pretty well for dusk flying, but when it turned towards us on short final it was still nearly impossible to discern the orientation. So for dusk+30 minutes type flying (a) you need to be lit up way better than you would think, (b) better to fly a self stable airplane like a 3-channel glider where you can steer the dot, but not have to worry about orientation, (c) pick an airplane that you can fly slow and close.

Fortunately this airplane can do a 100% autonomous landing.

This was for a joint University research project. University of Minnesota Entomology Dept + Aerospace Engineering dept. We setup the airplane with bug traps and flew a little before and after sunset when the bugs were most active to see whta we could catch at different altitudes.)

 

[leaded50]

best led light you can get, is by using a flashing SMD type. even if they get some heat, not as the 0-heat 5v standard led diode

 

[leaded50]

here, even showing dlash at daylight, ready for RC use : https://www.banggood.com/Xenon-LED-...eft-hotproducts__5&ID=516628&cur_warehouse=CN

 

[LitterBug]

I have used these "sequin" LEDs that MicroCenter sells on a few builds. They have a resistor built in and take 3-6V.
https://www.microcenter.com/product/456443/adafruit-industries-led-sequins-ruby-red--5-pack
https://www.microcenter.com/product/456450/adafruit-industries-led-sequins-emerald-green---5-pack
https://www.microcenter.com/product/456452/adafruit-industries-led-sequins-royal-blue---5-pack
https://www.microcenter.com/product/456453/adafruit-industries-led-sequins-warm-white---5-pack

I even used them on a sport cub S running off a single cell lipo

Cheers!
LitterBug

 

[Earthchill]

We thought we had lit up an airplane pretty well for dusk flying, but when it turned towards us on short final it was still nearly impossible to discern the orientation. So for dusk+30 minutes type flying (a) you need to be lit up way better than you would think, (b) better to fly a self stable airplane like a 3-channel glider where you can steer the dot, but not have to worry about orientation, (c) pick an airplane that you can fly slow and close.

Fortunately this airplane can do a 100% autonomous landing.

I've been looking for an excuse to run iNav or Ardupilot 😂. I was considering creating a wing with symmetrical airfoil and no dihedral to get something more interesting to fly. Perhaps I should put lights and ailerons on the Tiny Trainer's glider wing instead.

here, even showing dlash at daylight, ready for RC use : https://www.banggood.com/Xenon-LED-...eft-hotproducts__5&ID=516628&cur_warehouse=CN

Thanks! Will include a couple of sets of these the next time I order something from Banggood.

I have used these "sequin" LEDs that MicroCenter sells on a few builds. They have a resistor built in and take 3-6V.
https://www.microcenter.com/product/456443/adafruit-industries-led-sequins-ruby-red--5-pack
https://www.microcenter.com/product/456450/adafruit-industries-led-sequins-emerald-green---5-pack
https://www.microcenter.com/product/456452/adafruit-industries-led-sequins-royal-blue---5-pack
https://www.microcenter.com/product/456453/adafruit-industries-led-sequins-warm-white---5-pack

I even used them on a sport cub S running off a single cell lipo

Cheers!
LitterBug

Do you really see these at a distance? How many do you use? I know they are light (which makes it possible to fly low, slow and close) but it seems to contradict what @clolsonus says.

 

[Earthchill]

Found this crazy LED-strip. 18 W/m without heat sink. Is that what you used @clolsonus, or did you use one with sparser LEDs? Makes the single 3W LEDs seem small. I want 4 meters of these.

 

[Earthchill]

I tried flying this Wednesday with these LEDs running at 350 mA (i.e 1.26 W). I only ordered three of them (one green, one red and one white) to test if they where bright enough. I mounted the red and green underneath the wings and they where almost blinding when the plane was tilted in the right direction. As soon as I rolled the other way I couldn't see them at all though.

The fuselage is completely full of cables now though so my plan is to shorten all the cables and replace the thicker ones with softer silicone cables. I also need to switch from XT60 to XT30. That should make cables for another set of lights fit. Since I fly on 2S I can put two LEDs in series which means that I can get 6 LEDs in total on the constant current driver board (3S is nice, but that wont fit). If I can fit a micro processor as well I can make the top LEDs blink and the bottom have a constant light. That way it should be possible to see if I see the top or bottom of the wing.

It will still be completely impossible to see if the plane is 2 meters or 0.2 meters above ground when landing, but the Tiny Trainer is light and can handle dropping from a meter or two. I really want a LIDAR for that but I need to build a bigger plane then