helping you keep an eye on things...
One very effective way in which to cloak an Unmanned Aircraft is to apply a light emitting material to the underside of the Unmanned Aircraft. The important thing seems to be the emission of light from the underside of the Unmanned Aircraft to match the background light intensity, with the exact colour of the light emitted being less important.
Above: strips of electroluminescent material that can be used to line the underside of an Unmanned Aircraft, from the presentation by Dr Ron Barrett of Kansas University at the 23rd Bristol International Conference on UAV Systems.
Visual Signature Suppression of an Unmanned Aircraft
From a presentation by Dr Ron Barrett titled "Hypermaneuverability and Visual Cloaking" at the 23rd Bristol International Conference on UAV Systems on 8th April, 2008.
Unmanned Aircraft can be "downed" by a variety of weapons, as shown above. To increase the survivability of Unmanned Aircraft, one needs to reduce the Visual Signature.
Blue-Sky Overhead Visual Cross Section (BSOVCS):
The Blue-Sky Overhead Visual Cross Section of an aircraft at a given flight state is deemed to be:
- the area of a silhouetted lamp black disk at 100m altitude directly overhead
- against a cloudless blue sky at less than 50% humidity
- with the sun at a 40° to 50°angle to the disk-aircraft-observer plane
- such that the majority of a statistical sample of no less than 10 observations
- from individuals with 20-20 vision declares the disk to be just as obvious as the observed aircraft
- given a 10 second observation time
- and a flight motion of the aircraft and the disk at arc rates with respect to the observer which are representative of the aircraft at the given flight state
- considering the disk and aircraft traveling in the same direction as they pass overhead.
Above: an example of an electroluminescent strip. Such strips can be used on the underside of an Unmanned Aircraft wing and body to dramatically reduce the visual observability of the Unmanned Aircraft.
Above: with a sufficient intensity, the electroluminescent layer on the underside of the Unmanned Aircraft renders it very difficult to see the Unmanned Aircraft against the background sky.
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Flexible OLEDs Double Efficiency as Organic Light Prices Decrease |
- from http://www.popularmechanics.com/science/research/4254221.html
Sheets of this OLED material could possibly be used to line the underside of a stealth Unmanned Aircraft.
By Emily Masamitsu
Published on 12 March 2008
Artificial lighting is delicate in its current forms—bulbs encased in rigid glass crack easily with anything stronger then a gentle grip. But imagine being able to shoot a bullet through a light bulb without plunging into darkness. That’s the promise of ultra-efficient organic light emitting diodes.
OLEDs lit up the buzz machine when Sony debuted an 11-in. television panel that uses the technology at the Consumer Electronics Show earlier this year. But the applications for OLEDs reach beyond the living room, with everything from solar collectors and sensors under development, in addition to lighting. And this week, General Electric announced a major manufacturing feat: Researchers in the megacorp’s industrial arm have created flexible sheets of OLED lighting using a process similar to modern newspaper printing.
“Basically, you start with a roll of plastic material that, by the end of the process, is a sheet of OLED lighting,” explains Anil Duggal, manager of GE’s Advanced Technology Program for Organic Electronics. The organic polymer that produces light when connected to a power source bonds with the plastic like ink bonds to paper.
GE teamed with Energy Conversion Devices and the National Institute of Standards and Technology to develop the process. The result of this first test is an 8-ft. strip comprised of 6 x 6 in. lighting panels (pictured above). When electrified—Duggal’s group used simple alligator clips for the demo—the result is thin, flexible, efficient lighting.
The new roll-to-roll process is one step toward making the technology affordable. Sony’s new TV sells for $2500, and only cheaper building processes for OLEDs will bring down prices for bigger TVs, solar sheets and other products down the line. “Right now manufacturing costs are measured in the thousands of dollars per square inch,” Duggal says. “Our goal is to reduce that cost measure to price per square meters.”
The U.S. government made efficient, bendable displays a priority by providing funds to establish the Flexible Display Center at Arizona State University in 2004. With an output of approximately 30 lumens per watt, GE’s lighting panels are twice as efficient as incandescent lamps. They can’t fold in half like a sheet of paper, but the panels can bend around a 1 to 2 in. radius, Duggal says.
The GE team plans to continue tweaking its process and explore roll-to-roll manufacturing for other forms of OLED lighting. “There are so many possibilities for this technology, it’s truly exciting,” Duggal says.
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