The Pentagon’s Naval Research office has selected Emteq to create a rotorblade tip lighting system. The program’s goal is to develop and build a reliable, lightweight system that can be modulated to provide red, green and white navigation lights at the appropriate position on the azimuth: a hover mode that clearly marks the rotor disk’s circumference to ground crews and a low-observable night-vision-goggle-compatible mode that could be used in night formation flight.
Over the next six months, Emteq will complete the program’s phase 1 feasibility study. Phase 2 of the program, scheduled for later this year, involves fabrication and testing, while phase 3 transitions to flight-qualified technology.
The technology is appealing, said Emteq government systems program manager Ryan Paffel, because it will enable flight crews and ground personnel to “visualize the complete span of the rotor blades in a variety of configurations” in low light and marginal weather and in crowded and chaotic environments such as those encountered during shipboard operations. The system is called the modulating rotor tip light (MRTL) and it sequentially flashes the appropriate color LED tip light at the correct rotor positions of the rotating blade (red on the left, green on the right and white to the rear).
The MRTL enhances rotor blade visibility three ways, Paffel said.
“The tip light path appears as long stripes of light rather than individual beacons. The improved LED technology offers high intensity light output and a minimal weight and installation footprint, he said. “Finally, the lateral separation between red and green lights can be as large as the rotor diameter. In some cases that is five times larger than the width of the fuselage.”
Paffel said the system will not induce flicker vertigo because the passage frequency of the rotor blade exceeds the critical flicker fusion rate. “Moving tip lights from successive blades appear to the human eye as continuous bright stripes of light on the rotor disk.”
The MRTL can also enhance mission safety by providing enhanced modes of tip path lighting such as white for civil operations or infrared for covert missions, making the tip path highly visible during taxi, takeoff and landing, as well as during sustained formation flight.
While significant, Paffel said these benefits are secondary to the technology’s primary mission of developing position lights that provide increased operational safety.