Source: Knoxville News Sentinel | Frank Munger | June 16, 2015
Researchers at Oak Ridge National Laboratory (ORNL) are working on prototypes for runway lights that combine various technologies to potentially improve visibility for airplane pilots, even in the worst conditions, and save energy, too.
The ORNL team is trying to help the Federal Aviation Administration overcome some of the technical challenges involved in replacing the 150-watt incandescent bulbs that are currently used at airports across the country.
James Klett, a senior research engineer in ORNL’s Materials Science & Technology Division, said there have been some runways converted to LED (light-emitting diode) lights on a test basis at airports in the north. He noted those runway lights reportedly received negative reviews from pilots for a couple of reasons.
Although the LED bulbs were energy efficient, their brightness apparently was too bright for some pilots, who experienced “blinding” or “blooming” from the emitted white light. Besides that, the LED lights reportedly didn’t show up on the infrared thermal cameras that are used on most commercial and military aircraft, as well as some passenger jets, to enhance vision during bad weather.
“They’re not putting off a lot of heat, so you couldn’t see them (using the infrared cameras),” Klett said.
The ORNL team, collaborating with industrial partner Spectrum FML, is testing concepts that reduce the energy use — compared to the incandescent bulbs — but maintain good vision of the runway during normal weather conditions and enhance the capabilities to track the runway from a distance during fog, snow, rain and storms of all sorts.
A rough prototype was tested for a few months earlier this year at Memphis International Airport, the hub for Federal Express, and there are plans to do additional tests as the working models become more refined.
The feedback has been positive. The prototype tested in Memphis was in Washington last week, reportedly being scrutinized by employees at the FAA.
A major focus of the ORNL team is to incorporate a light source that generates infrared energy that can be picked up by an airplane’s onboard camera during bad weather.
Klett has devoted his career to working with forms of carbon, including graphite foam — a lightweight material with high conductivity. In this system, a coil introduces a radio-frequency induction to a stamp-sized piece of graphite foam, heating it to a desired level — 400-500 degrees Celsius — that generates infrared signals across a broad range.
That would work side by side with LED lights within the housing that’s the size of a standard flood lamp, providing the needed white light for direct visuals of the runway and the signals needed for infrared cameras to pick up the runway outline in poor visibility conditions.
Klett praised the work of Roger Kisner, a distinguished research staffer in the Sensors and Controls Research Group, and his associates for their work on the electronics.
Once the basic components are shown to work as needed, the attention will turn to how to best package the multi-component runway light for optimum use. That incudes making it long-lived and capable of withstanding rain and snow, heat and cold, and keeping its energy use to the minimum.
“Taking all of those things into account has led us down this path,” Kisner said with a shrug.
The researchers indicated there was some urgency to the work, but they also noted there is no timetable for having a commercial product.