Aircraft Landing and Navigation LED Lighting

[Everwild]

Hi. I'm in the process of building an experimental kit aircraft. A Vans RV-10. I'm thinking about designing my own landing and navigation lights. There are existing solutions out there but like most things in aviation, the cost is high for quality commercial options. I consider myself to be a quick learner, enjoy learning new things, but have a limited electronics background.

For landing and taxi lights, I'm thinking about using Cree XHP35.3, XHP50.3 or XHP70.3 LED chips available in 3v 6v or 12v, off the shelf optics, heat sinks and other components to make the system design simple and repairable should something fail. The aircraft will have a 12v system (12.4-12.9 fully charged, up to 14.4 volts when charging the battery). The main alternator can provide up to 60amps of current with a backup alternator that delivers up to 40amps if the main fails.

So far I'm thinking about using some combination of adjustable linear voltage and current regulators to drive the LEDs. Efficiency is less important than keeping RF noise to a minimum as to not interfere with communications or navigation radios. The idea is to use multiple LED projector units in combination to provide LOTS of light. Think 15-20k lumens. I would like each LED projector unit to have it's own driver for redundancy.

The Cree XHP50 at 6V has a maximum current of 3A and puts out 2300 lumens. The XHP70.3 can push a max of 7A at 6V and 5000 lumens.

I'm assuming I need to start by identifying the right linear voltage and current regulator for the job and then design my circuits around those? Any ideas on which linear regulators I should consider?

Thanks!

 

[ChrisP58]

I'm not aware of any monolithic linear regulators that can handle that much power.

I'd suggest using something like the LM723 (UA723C) to drive an external pass transistor on a heatsink.

https://www.ti.com/lit/ds/slvs057d/slvs057d.pdf

 

[audioguru]

Is it legal for you to tamper with airplane external lighting? It is illegal to tamper with vehicle external lighting.
The brightness, angles and colors are important.

 

[Diver300]

Most electrical modules for automotive use are specified for around 9 - 16 V. I don't know what voltage range you will be working to, but you should include voltages well below 12 V so that the lights will work with battery that isn't fully charged.

The Cree XHP70.3 are rated at a maximum of 3600 mA but a lot of their specification are quoted for 1050 mA. For reliability, efficiency and lifetime reasons, I would suggest running them at 1050 mA, although you will need more LEDs to get the same light output.

However, you really don't have enough voltage to run the 12 V ones. They are rated at 11.2 - 12.2 V at 1050 mA. Like most LEDS, they need to be run from a constant current supply, and the voltages are only mentioned so that the constant current supply can be specified to cope with the voltage and if you happen to get LEDs that are near to 12.2 V, they will be dimmer if the battery isn't charged. 12 V LEDs will go out completely when the engine is cranking if you are running from the starter battery.

You should use the 6 V version, with a constant current regulator for each LED. Do not put the LEDs in parallel, as the current may not be shared equally.

You could use three LEDs rated at 3 V each, in series, with a single constant current regulator. That would be more efficient.

Make sure that your regulators can handle the heating at the maximum alternator voltage. You should also consider what happens if an LED shorts out, or partially shorts out. The 6 V LEDs are actually two 3 V LEDs in series, so it's possible for one to be shorted and the other to remain illuminated. You need to make sure that the regulators won't be damaged or overheat something else when there is a short or a partial short, either of which would cause increased heating in a constant current regulator.

 

[ChrisP58]

Is it legal for you to tamper with airplane external lighting? It is illegal to tamper with vehicle external lighting.
The brightness, angles and colors are important.

Well, I don't know as i've never been involved with such a project but, since the original question was about use in an "experimental kit aircraft," there's probably some leeway to what is chosen for the initial installation.

 

[danadak]

LEDs in series costs effective approach, and benefit from better brightness matching
because all LEDs carry same current.

But reliability, one LED fails open all are offline. So consider driving in parallel, picking
matched LEDs where ever possible. And use ballast Rs in series with them to aid in
current balance. Not as efficient. Tradeoffs, always tradeoffs.

https://www.stanleyelec-stj-components.com/data/technical_note/TN003_e.pdf

Efficiently driving 6 LEDs in parallel

I have a display that has six white LEDs in parallel (common anode) as backlight. The LEDs' forward voltage is 3.2V, the current per LED is 20mA, so 120mA in total. The available voltages in the

electronics.stackexchange.com

Regards, Dana.

 

[For The Popcorn]

Has anyone noticed the original post is from December 6th, 2022, and the original poster hasn't been back since December 12th?

 

[Nigel Goodwin]

Has anyone noticed the original post is from December 6th, 2022, and the original poster hasn't been back since December 12th?

Yes, a spammer posted in the thread, and others followed suite.

Spammer has been deleted, and thread now locked.