Here is another question. I noticed that many of the LEDs with a high mcd rating have a narrow viewing angle. So I wonder if they are really brighter of if the same amount of light may simply be concentrated in a smaller area? Here are the specs for a couple LEDs I'm considering for the LED afterburner ring:

1) 5mm straw hat LED, 10,000 mcd, Vf 3.0-3.4v, Viewing angle 120 degrees, 20 mA
2) 5mm LED, 25,000 mcd, Vf 1.9-2.3v, Viewing angle 25 degrees, 20 ma

Which would be better? I'm guessing #1 may be better despite the lower MCD rating because of the wide angle. The airplane will seldom be seen level straight from behind so unless the LEDs have a wide angle, maybe they will not show up that well in the daylight?

 

Cheap old LEDs are made in a tightly focussed case so that their brightness number is high but you cannot see them a little off to the side.

Very bright LEDs can be seen in bright sunlight. All traffic lights in my city use LEDs.
Pixel screen ads use LEDs in bright sunlight.

 

I would just go for some in the 1W case. 1 led is easier then 20. You could literally just hang the LED case inset in the rear of the engine and let the engine cool it off. No heat sink required. Unless there is some limitation preventing this. Like maybe a high speed LED flying out the back of it if you didn't mount it well enough.
http://cgi.ebay.com/10x-1W-Red-Supe...671?pt=LH_DefaultDomain_0&hash=item3cb0f81367

 

Here is another question. I noticed that many of the LEDs with a high mcd rating have a narrow viewing angle. So I wonder if they are really brighter of if the same amount of light may simply be concentrated in a smaller area? Here are the specs for a couple LEDs I'm considering for the LED afterburner ring:

1) 5mm straw hat LED, 10,000 mcd, Vf 3.0-3.4v, Viewing angle 120 degrees, 20 mA
2) 5mm LED, 25,000 mcd, Vf 1.9-2.3v, Viewing angle 25 degrees, 20 ma

Which would be better? I'm guessing #1 may be better despite the lower MCD rating because of the wide angle. The airplane will seldom be seen level straight from behind so unless the LEDs have a wide angle, maybe they will not show up that well in the daylight?

The wider the dispersion angle the more area illuminated at a given length. The light divides up. Same as the difference between a spotlight and a floodlight of equal wattage.

It will take a fairly high output LED to be seen in daylight if it has a wide dispersion angle.

 

Well, high-wattage LEDs might be difficult (if not impossible) to fit in the space available. Power dissipation could get to be a real problem, too.

If you are going to glue the LEDs in a Plexiglas light diffuser ring, the focus angle probably won't make much difference. Not knowing what the actual dimensions are, I'd say offhand that even 5mm LEDs could be kind of tough to fit in.

I think it would be really cool to use RGB LEDs; have the reds start to come on at around 80%, fade to blue from around 85% to 95%, and then go to white from 95% to 100%. A microcontroller would simplify the electronics considerably.

But, rather than use RGB's, one might simply use discrete red, blue, and white LEDs that were sequenced; that way you could wire each color string in series and use a DC-DC boost circuit.

 

I know even less about high wattage 1W type LEDs than regular ones. It does appear the regular ones done right can be clearly visible in the air, as shown in this video:

http://www.youtube.com/watch?v=JdLPzBTAA_o

I did see a place selling a kit that came with 3 powerful LEDs to make an afterburner effect but there was no video of it to know what it looks like in the daytime up in the air.

I saw an airplane where the person used surface mount LEDs but the video was inside a house so no way to tell how it would look outside either. It did look fine indoors.

What I think I will do for now is get some of the bright 5mm amber wide angle LEDs and wire them up in a ring around the exhaust tube. I'll drive it right off the ESC power with appropriate resistors. If it works fine I may then adapt that to run it off the light kit I got but I don't know if I really even need the extra electronics in that kit. I could buy 2 flasher LEDs, one red and one green, for the side nav lights and wire them up direct to the ESC along with a light for on top of the vertical fin. They take up so little power there isn't much of a point to have the extra electronics to turn them on and off from the radio. (Unless I plan on a stealth night attack mission with the RC airplane where I need to black out all lights!) I do like the flicker effect on the light kit I have now, so I may adapt my custom ring to replace the red LED ring on the kit that is too large.

I'm sure I will have more questions when that time comes. Meanwhile I will read Bill's guide so maybe I can wire them up right the first time.

 

The 1W and greater tend to be a bit larger. This is probably why you don't see them in afterburner locations.

 

Hee, hee.
In the video those LEDs are extremely hot so that they are smoking!
They also make a loud racket.

 

I know even less about high wattage 1W type LEDs than regular ones.

You use them and calculate the resistor the same way as the small ones. they just get warm to hot depending on current.

 

You might consider doing what this guy did:
http://www.youtube.com/watch?v=YDvnhxdT_Bo&feature=related

He used the pre-fab SMD LED strip and just wrapped it around the inside.

Very realistic looking with flicker and color changing. Using the pre-fab strip stuff, you already have the resistors in line.

 

You might consider doing what this guy did:
http://www.youtube.com/watch?v=YDvnhxdT_Bo&feature=related

He used the pre-fab SMD LED strip and just wrapped it around the inside.

Very realistic looking with flicker and color changing. Using the pre-fab strip stuff, you already have the resistors in line.

I saw that one and liked it, but I assume you need some ICs to have it change color as the voltage goes up?

I need some more help from you guys. I hate being the dumbest one here, but I'm still real green at this. The LED ring in the kit I got has 28 LEDs. They appear to be setup as 4 sets of 7 LEDs. There are only 2 wires going to the ring. The maximum voltage from the battery is 12.6v. How can you drive 7 LEDs with only 12.6v max? When I try running 7 they light up but are very dim.

Here is a photo of the ring where you can see the circuit. I put a blue dot on the position of each LED on the opposite side.

AudioGuru - What is puzzling is how they don't melt on the airplanes that are flying with real kerosine burning turbines. Mine just blows cold air out the back.

 

The LEDs ring has four groups of LEDs in series. If the LEDs are 3V each then they light well with a 12V supply and are very bright (almost burning out) with 12.6V.

Each group of LEDs has 7 LEDs in parallel so they must be matched.

 

In first trying to keep it simple, this is what I did a few minutes ago. I cut the LED ring into 4 sections where there was only 1 trace on the ring and trimmed off the excess. Then I reconnected the 4 trimmed sections with small pieces of wire. That allowed me to fit them between the exhaust tube and cosmetic exhaust tube. They are still a little further inside than I would like, so I may put some slits in the cosmetic tube to give me more room to slide the lights closer to the exhaust tip. I also lined the inside of the cosmetic exhaust with aluminum foil. This greatly enhanced the reflection inside the tube making it look a fire inside. The real test will be how it looks tomorrow in the daylight. Very hard to video and photo the LEDS. For now I did a sloppy quick trial fit job. When I go to actually assemble it permanently I will do a better job. When my 5mm bright amber LEDs arrive I'll probably make a ring with them and compare to see if the existing or the amber LEDs work best. After that I will run out of excuses to not fly the thing and have to take it out for the white knuckles maiden flight. Always very tense the first time launching a new airplane.

Short video of lights in exhaust cone.
http://www.youtube.com/watch?v=mlXoTadpUPg

 

It looks very good. I think it is going to work well for you

 

Usually the ground jumps up and whacks a model airplane on its maiden flight before it is trimmed.
I launch at a fairly steep angle so the airplane can quickly climb away from the nasty ground.
Then I pass the transmitter to the nOOby who is learning how to fly and the ground is too far below to cause harm.
Watch out for birds.

 

Here are a couple photos and video taken this morning from about 50 yards. I think they will be visible in fight. The foil in the exhaust seems to help a lot. Color is okay too. Given most of the time it will be about 500' in the air and going by at 80 MPH, amber or red may not make that much of a difference.

I do want to return to my original plan to build a ring from scratch. The reason for that is to save weight and space. Those LEDs are still on the way from Honk Kong. In the meantime I'm going to work on getting this jet ready for flight. I'll come back here when I start working on a new scratch built LED ring.

http://www.youtube.com/watch?v=q8swd6Jo698

 

Is the Cayenne turbo?

 

Is the Cayenne turbo?

I wish! It's a Cayenne S - same V8 sucks up as much gas but not as quick. If I put a ring of LEDs around the exhaust tips maybe it can keep up with the turbo?

 

I wish! It's a Cayenne S - same V8 sucks up as much gas but not as quick. If I put a ring of LEDs around the exhaust tips maybe it can keep up with the turbo?

Nope, but you could probably get pulled over so the cop could check it out.

I've always liked the idea of Batman's turbo, perfect for those pesky tailgaters.

I thought I had asked this, but I don't see it. What part of the US are you?

 

I'm in Southern California, Orange County.

Funny you should mention Batman's turbo. Just yesterday I was thinking about packing the rear center brake light full of ultra bright LEDs and have them hooked up to a switch for tailgaters. I wonder if it could be made bright enough to cause a tailgater to want to back away from the light?

I have discovered that turning on the wipers and using a lot of water to clean my windshield is quite effective in getting tailgaters off my rear. But I don't like to do that when my car is clean. I drive rather sportingly so if someone is on my tail it is because there is something blocking me from going faster or moving out of the way. So the tailgaters really annoy me.