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irampil(at)notes.cc.sunys
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 Posted: Wed Jul 12, 2006 4:02 am Post subject: LED Landing/Taxi lights |
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Hi Ron,
I may be totally out to lunch on this, but I believe the standard 100W PAR bulb
puts out roughly double the mcd output claimed for the LEDs. Also, high output
LEDs generally have stringent cooling requirements emphasizing airflow close
to the emitter dies. Excessive heat can cause the rated life of the LEDs to shorten
even to far less than regular incandescent bulbs, sometimes dramatically
shorter.
It would be great if this LED system could be made bright and cool enough.
It might be worth noting that LoPresti should be offering their HID lighting
system with the new compact ballast at Oshkosk for $3-400. That is also
a potentially nice solution, if one can design an appropriate mount!
Ron, are you going to Osh?
Ira N224XS
Many notches in my soldering iron from LEDs
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rparigor(at)suffolk.lib.n
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| Posted: Wed Jul 12, 2006 8:09 am Post subject: LED Landing/Taxi lights |
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Hello Ira
Not going to OSH this year.
Its true 5 watt LEDs need great cooling. The LEDs I am proposing are not
drawing 700 mAs each, but 20 mAs each. Heat is not a problem with even
continuous use. That said, many new 5 watt LEDs as offered by Best Hong
Hong live on a fairly large star of aluminium (heat sink) and that
aluminium can live on a piece of conductive metal.
Its true that my idea of a removable landing/taxi light could possibly be
accomplished with some 5 watt LEDs with a 10 degree reflector, could put
in a tube in same area under cowl, and have some air pass through, larger
bump, a lot more heat and a lot more amp draw.
There is no question that a Beechcraft 100 watt, I think 5+1/2" landing
light does a great job. A 3.5" Cessna 100 watt does a good job. A 3.5"
Halogen Cessna 50 watt 3.5" does close to the net usable of the 3.5" 100
watt.
100 watt lamps, and 50s make heat, and lots of it, not great for
composites. Where do you put one on a Europa?
I am proposing a field of approx. 10 square inches of 20mA LEDs, ~240 10mm
12 degree 20mA, and between them ~60 5mm 20 degree 20mA. It will not light
up a path wide enough or forward enough for landing C-130s at Gabreski,
but probably adaquite for a Europa to do a low pass to see if there are
any deer on Gabreskis runway, and see well enough for take off, landing
and taxi.
The arrangement does not need to be square, it can conform to shape of
lower airscoop of cowl, narrow and long, will be adding bout thickness of
a finger to the cowl. Again only take the increase drag when you need
lights, and it will work on both short and long wings.
I have LEDs at hangar, come on over one night and tell me what you think.
The Net light output of the 10mm LEDs I want to use supposedly require
only 1/5th the power in compared to Halogen lamps. Can put 4 or 5 in
series when using ships power.
Ron P.
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ami(at)mcfadyean.freeserv
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| Posted: Wed Jul 12, 2006 3:24 pm Post subject: LED Landing/Taxi lights |
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HID lights are more efficient than high-brightness LEDS. So, for a given power input, there is less waste heat to dispose. It depends how much light you want. It would take a lot of LEDS to be equivalent to a 35W HID bulb; and you'd still get less light and more heat.
Duncan McF.
[quote] ---
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asarangan(at)YAHOO.COM
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| Posted: Wed Jul 12, 2006 7:50 pm Post subject: LED Landing/Taxi lights |
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The heat argument is a little misleading. These LEDs don't generate
much heat only because each unit consumes a mere 65mW. With 240 devices
they will be dissipating a lot of heat. Lamps are measured by luminous
efficiency. At 20-deg beam angle, 30000 mcd is equal to 2.8 lumens. So
the luminous efficiency is 43 lumens/watt. For comparison, fluorescent
lights are about 50 lumens/watt, and some HID lamps are 50-100
lumens/watt.
In addition, with 240 devices packed in close proximity, the efficiency
is unlikely to be the same as a solitary device. I would guess it would
be around 25 lumens/watt, in which case you will be pretty close to the
Luxeon V LEDs.
--- rparigor(at)suffolk.lib.ny.us wrote:
| Quote: |
Hello Ira
Not going to OSH this year.
Its true 5 watt LEDs need great cooling. The LEDs I am proposing are
not
drawing 700 mAs each, but 20 mAs each. Heat is not a problem with
even
continuous use. That said, many new 5 watt LEDs as offered by Best
Hong
Hong live on a fairly large star of aluminium (heat sink) and that
aluminium can live on a piece of conductive metal.
Its true that my idea of a removable landing/taxi light could
possibly be
accomplished with some 5 watt LEDs with a 10 degree reflector, could
put
in a tube in same area under cowl, and have some air pass through,
larger
bump, a lot more heat and a lot more amp draw.
There is no question that a Beechcraft 100 watt, I think 5+1/2"
landing
light does a great job. A 3.5" Cessna 100 watt does a good job. A
3.5"
Halogen Cessna 50 watt 3.5" does close to the net usable of the 3.5"
100
watt.
100 watt lamps, and 50s make heat, and lots of it, not great for
composites. Where do you put one on a Europa?
I am proposing a field of approx. 10 square inches of 20mA LEDs, ~240
10mm
12 degree 20mA, and between them ~60 5mm 20 degree 20mA. It will not
light
up a path wide enough or forward enough for landing C-130s at
Gabreski,
but probably adaquite for a Europa to do a low pass to see if there
are
any deer on Gabreskis runway, and see well enough for take off,
landing
and taxi.
The arrangement does not need to be square, it can conform to shape
of
lower airscoop of cowl, narrow and long, will be adding bout
thickness of
a finger to the cowl. Again only take the increase drag when you need
lights, and it will work on both short and long wings.
I have LEDs at hangar, come on over one night and tell me what you
think.
The Net light output of the 10mm LEDs I want to use supposedly
require
only 1/5th the power in compared to Halogen lamps. Can put 4 or 5 in
series when using ships power.
Ron P.
|
Andrew Sarangan
http://www.sarangan.org
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