Jay wrote:

Using the web, I found in part 23 section 23.1391 a list of the
intensity (candels) by angle required. From what it looks like,
someone measured the system that was already being made (a bulb and
filter) and put in in the book. So what this means is that you're
stuck emulating a technology inferior in almost every way using a new
technology. The spec emphasizes what light bulbs do well (high flux,
even illumination) and de-emphasizes what it doesn't (spectral purity,
reliability).

You could probably do the math from the minimum guaranteed intensity
and the beam shapes and meet the spec on paper, but it would be nice
to actually measure it. You can buy equipment to do this if you want
to add to your tool box yet another single purpose tool.

The other issue is that the manufacturer beam shapes are really a
little bogus because the high intensity LEDs use clear lenses and
actually project an image of the semiconductor chip inside. So
instead of a nice round shape, you get a picture of a little bright
chicklet and reflector cup.

This is very true for the LEDs with a very narrow beam (half angles down to
8-degrees or so) - but luxeons give a much broader beam and for whatever
reason this isn't the case in my experience (lambertian beam pattern only).
You can buy an optical widget that fits over the LED to make a narrower
beam again, and IMO your criticism is very valid for this case.

A solution is to shine the LEDs through some five or ten-degree holographic
diffusing filter from the POC (Physical Optics Corporation - if memory
serves). They're nice people to deal with, and were giving out free 1"
samples last time I asked.

AC

So how many LEDs? Depends on if your using "typical" or minumum
guaranteed intensity. Depends on what direction you array them,
depends on what bin they came from, depends on a lot of things.




(Bill) wrote in message
. com...
To Jim Weir and Group

I am interested in using the new (to me) 1 watt and 5 watt LEDs for
nav lights.
Not having to worry about changing bulbs or the power requirements are
very attractive.

I have seen some posts about leds but would like to tie it all
together.
I know of two sites showing their versions and one is using 9 LEDs
while the other is using more.

What it boils down to is this: how many leds for the the right and
left wings, how many for the tail and can the leds be strobed or any
thing else I don't know?

Thanks
Bill