Singapore 777
Topic Author
Posts: 980
Joined: Sat May 29, 1999 3:00 pm

LEDs As Airborne Indicators

Tue Jul 27, 2004 10:41 pm

A simple question - what were some of the problems associated with early LEDs as airborne indicators?

Thanks in advance for the replies! Much appreciated!  Smile
 
cancidas
Posts: 3985
Joined: Thu Jul 03, 2003 7:34 am

RE: LEDs As Airborne Indicators

Wed Jul 28, 2004 1:47 am

i'm not sure what you mean. are you asking why LED lights are not used in aviation more often? actually, they are. i have seen quite a few aircraft, bit GA and airliners using LEDs for position (anti-collision) lights. the strobes, well they have to be strobes. however, the reason LEDs are not used in landing/taxi lighting is twofold. partly, it's the same reason you won't find LED lamps for your house. they just don't put out good white light. the other is that they are not bright enough for use as landing lights.
"...cannot the kingdom of salvation take me home."
 
airplay
Posts: 3369
Joined: Sat Oct 25, 2003 1:58 am

RE: LEDs As Airborne Indicators

Wed Jul 28, 2004 2:10 am

they just don't put out good white light. the other is that they are not bright enough for use as landing lights.

Many designs for aircraft lighting now use high powered LED arrays. I have seen then in general cabin illumination, panel lighting, logo-lights and other external lighting. Its only a matter of time before we see an LED landing light.

The engineering hurdles have consisted primarily of heat dissipation but it is being addressed.

Also, additional optics can make relatively low brightness LEDs as bright as you want them to be.
 
BandA
Posts: 319
Joined: Tue Aug 03, 2004 6:34 am

RE: LEDs As Airborne Indicators

Thu Aug 12, 2004 12:29 am

Yeah the brightness of an LED shouldnt be an issue for too long... they already use LEDs in strobes on police cars around here... they are very bright and ommit accurate colors...
"They [Terrorists] never stop thinking about new ways to harm our country and our people, and neither do we." - GWB
 
User avatar
N328KF
Posts: 5810
Joined: Tue May 25, 2004 3:50 am

RE: LEDs As Airborne Indicators

Sun Aug 15, 2004 12:00 am

Som military aircraft use LEDs to emit a very pale blue light at night, to make the aircraft blend in with darkness better.
When they call the roll in the Senate, the Senators do not know whether to answer 'Present' or 'Not guilty.' -Theodore Roosevelt
 
MD11Engineer
Posts: 13916
Joined: Sun Oct 26, 2003 5:25 am

RE: LEDs As Airborne Indicators

Sun Aug 15, 2004 12:14 am

Considering the amount of "peanut bulbs" (387, 1864, etc) we change every day, I wonder why LEDs are not used more in cockipt indication lights. Also I can´t imagine LEDs getting as hot as those light bulbs.

Jan
Je Suis Charlie et je suis Ahmet aussi
 
Klaus
Posts: 20622
Joined: Wed Jul 11, 2001 7:41 am

MD11Engineer

Sun Aug 15, 2004 1:26 am

MD11Engineer: Considering the amount of "peanut bulbs" (387, 1864, etc) we change every day, I wonder why LEDs are not used more in cockipt indication lights. Also I can´t imagine LEDs getting as hot as those light bulbs.

No, especially the halfway modern LEDs use a lot less power than normal light bulbs. (And produce less heat in return.)

But (reliable) white LEDs aren´t around for all that long yet, and they´re still more expensive than the classic red, green and yellow ones.

You´d probably have to redesign the switches or instruments to accomodate the LEDs instead of conventional bulbs as well, so I guess it may not be seen as a high priority.

And you´ll lose the possibility to determine the status of an indicator light after a crash (characteristically broken filament). LEDs leave no such trace. Maybe that´s another reason, but I could understand why it might not be publicized a lot...
 
FredT
Posts: 2166
Joined: Thu Feb 07, 2002 9:51 pm

RE: LEDs As Airborne Indicators

Sun Aug 15, 2004 3:08 am

On one aircraft I'm very familiar with, we eventually got LED position lights. The fun part was that these LEDs were white until lit - i e, you couldn't see the colour of them when they were off! And naturally, the previously red/green glass was clear as well. This created a need for new procedures in maintenance that were not expected, in order to make sure the red colour lights went on the left side as the green lights were right and would have been wrong.  Big grin
I thought I was doing good trying to avoid those airport hotels... and look at me now.
 
Klaus
Posts: 20622
Joined: Wed Jul 11, 2001 7:41 am

FredT

Sun Aug 15, 2004 4:05 am

Yeah... you sometimes have to power them up to see what kind you´ve got.  Wink/being sarcastic

Since coloured LEDs generate only the "right" colour anyway (through the properties of the semiconductor materials), there´s no need for a filter to mask the other wavelengths. And that´s another reason why they´re more efficient: A normal lamp wastes energy on creating the full spectrum, even though the filters will block most of it again.

Who is online

Users browsing this forum: Afstand, rg787 and 8 guests