March 2009 Issue
LED Landing Lights: Better Than Expected
LEDs aren’t as bright as HIDs or conventional incandescents, but they’re durable and require minimal power.
Automotive technology trickles into aviation in fits and starts and with spotty success. HID lighting, for example, was practically standard equipment on some cars before it finally gained a foothold in the light aircraft GA market. Now LEDs—light emitting diodes—are undergoing a similar evolution. We’ve seen them in cars and on motorcycles for years and lately, they’ve found their way onto wingtip and nav/position lights. Next step: landing lights. In this article, we’re examining a new product recently sent to us by a company called AeroLEDs. AeroLEDs is by no means the only supplier of this technology. Whelen, for example, makes a line of LED landing lights and we know of some other similar products in development. We’ll do a detailed comparison of all the LED products in a future issue, but in this article, we’re interested in testing the concept itself. Landing and taxi lights are big draws on the airplane electrical system for a reason: You need a bunch of light to reach through the murk to find night details necessary to establish depth perception and hazard detection. Although they’re inefficient in terms of converting electricity to light, conventional incandescent bulbs are still more than bright enough to do the job, which explains why they’ve endured so long. At $20 a pop, they’re also relatively cheap, if not always reliable. Can LEDs hope to compare? We aimed to find out. LEDs are one of those alluring technologies that seem too good to be true. They deliver bright, cool light with a fraction of the power required for an incandescent lamp. This, more than anything, explains why LEDs are turning up in everything from flashlights to automotive tail lights. LEDs themselves have more to do with transistors than with traditional filament-type bulbs. LEDs have p-n or positive-negative semiconductor junctions, just like transistors do. When power is applied to the junction, electrons flow and drop into so-called electron holes—they actually revert to different orbits in the junction material. When that happens, energy in the form of photons is released. Physically, the p-n junction is small and so are LEDs. An individual LED is bright, but its overall light output is small, so to approach the requirements for something like a landing light or even a navigation light, multiple LEDs are ganged together. The SUNSpot product that AeroLEDs sent to us has 16 LEDs arranged in a circular lens assembly.
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