Avionics News August 2012 - 21

Thousands of years later, Thomas Alva Edison created previously relegated to a host of filament-based incandescent visible light out of the resistance glow of molecular-level bulbs. electrons squeezing through too small a pipeline. Decades Take 6.5 amperes of electrical current and double it, since the later came quartz halogen bulbs, a 20th century variation on aircraft we’re sampling today uses two landing-light bulbs. Add Edison’s original. another four amps for each of two strobe-light packages and six Today, a new illumination revolution grows from another more for two rotating beacons. Then, there are six amps for the 20th century technology just now trickling down to VHF nav/comm radios when transmitting, four for the mass-use prices: the light-emitting diode. display power, two for two GPS navigators, and LEDs appeal to aviation users for their double-digit more for panels illuminated light weight, tunable light qualities, with post lights. longer life spans and significantly In no time you’re well above lower power requirements. the limit for a standard-rating Consider that virtually all alternator – 50 to 60 amps – or, new-production general aviation particularly for an old generator, aircraft feature a solid-state well above its mere 35-amps electronic flight instrument basis. system, with digital electronic The LEDs do more than glass components displacing light the way on less; they spinning-mass air-driven also promise other benefits in gyroscopic attitude sensors and exchange for their higher initial analog air-data instruments. prices. Digital electronic navigators For example, LEDs last much with large, color displays, higherlonger – in most cases 10 to 50 times power VHF comm radios and digital longer, in large part because they enjoy engine-monitoring join flight-management greater durability than incandescent hardware and electrically powered glowing-filament light sources. EMTEQ’s PAR 36 landing and taxi lights autopilots to challenge the capacity of the They run cooler, as well. Yes, LEDs entire electrical system to keep pace with do get warm, but they stay far cooler than the electrical load demands. other light sources, which expend most It’s enough to make an alternator seem weak. of the energy they use as heat rather than light. LEDs provide relief by lowering the electrical loads of the LEDs properly designed for their roles simply need less lighting hardware. current to produce a given amount of light. The ambitious could find their way clear to go completely LED. But, the change wouldn’t be inexpensive, and it would Around and Around They Go preclude any further lighting costs for several decades. Position, recognition, anti-collision, strobe, landing and taxi; using incandescent bulbs add up to a lot of wattage. The Demands of the All-Electrical Panel LED options exist for all of these necessary roles, and The versatile LED has moved into roles as diverse and together, their power-to-light ratio is much better. They need a demanding as internal and external light sources, including Continued on following page position lights, anti-collision lights, landing and taxi lights – jobs
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Avionics News August 2012

Table of Contents for the Digital Edition of Avionics News August 2012