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March 7, 1997

Release: 97-09

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A new antenna system which could revolutionize airborne communications achieved remarkable results in its first flight tests at NASA's Dryden Flight Research Center, Edwards, Calif. Tests of the "Smart Skin" antenna system aboard Dryden's F/A-18 Systems Research Aircraft (SRA) demonstrated a five-fold increase in voice communication range and a substantial improvement in the quality of radio transmissions from the aircraft when compared with transmissions from the F/A-18's standard blade antenna. Initially sponsored by the U.S. Air Force's Wright Laboratory, the new technology was jointly developed by Northrop-Grumman Corporation and TRW's Avionics Systems Division using internally-generated company funds. Two test flights were flown recently with the Smart Skin antenna embedded in a specially-built tip mounted on the SRA's right vertical stabilizer. Joel Sitz, Dryden's F/A-18 SRA project manager, said the new antenna system has the potential to greatly improve the range and quality of air-to-air and air-to-ground communications. It could also result in improved maintainability, reduced aerodynamic drag as external antennas are removed and a smaller radar signature for tactical military aircraft, he added. The concept has potential applications not only to military and commercial aircraft but also to "smart" automobiles and other forms of transportation requiring high-efficiency communications capabilities.

Allen Lockyer, Smart Skin Antenna program manager for Northrop-Grumman's Integrated Product Team, called the development a significant breakthrough in antenna system structural integration technology. Lockyer said the system is electrically as well as physically connected to the airframe, making the aircraft skin operate as an antenna along with the antenna structure itself.

During the two flight tests of the Smart Skin Antenna, NASA Research Pilots C. Gordon Fullerton and Mark Stucky flew circular flight patterns about 10 miles in diameter while flight test engineers Eddie Zavala and Dave Webber transmitted signals from the aircraft's radios at frequencies of 33 and 65 mhz. to a receiving station at Edwards Air Force Base. The two Dryden pilots flew the circles at bank angles of 0, 15, and 30 degrees in order to evaluate the range, gain and radiation patterns of both the Smart Skin and the standard blade antennas. The patterns were first flown at a distance of about 35 miles and then repeated at about 20 miles from the ground receiving station.

Dr. Allan Goetz, TRW's Smart Skins program manager, said the Smart Skin antenna demonstrated a 15 to 25-decibel improvement in signal-to-noise ratio at the lower frequency. "That equates to more than a five-fold increase in voice communication range and a substantially more symmetric radiation pattern," Goetz said.

The concept was first broached by the Air Force in the late 1980's. Its development came with several technological breakthroughs recently achieved by the TRW/Northrop-Grumman team.

"The idea of using the tail as an antenna had been attempted before," Lockyer explained. "The problem has been choosing the right materials and design to make it happen. You need materials whose properties will give you both electrical and structural performance at the same time."

Lockyer said some of the new thermosets and core materials now becoming available combine low-loss, high-conductivity electrical properties which stimulate surface current flow, along with high strength to survive twin-tail buffet loads.

"Some said this test wouldn't work, but flight research has proved them wrong," said Sitz.

Smart Skin antenna systems not only have the potential for enhanced voice communications and higher-quality navigation, but could also lead to a 65 percent reduction in airframe structural cutouts for external antennas and a weight savings of 250 to 1,000 lbs. per aircraft.

The Smart Skin antenna hardware developed by engineers at TRW Avionics Systems Division in San Diego was integrated into the custom vertical stabilizer end cap by Northrop-Grumman using production tooling at the firm's Pico Rivera, Calif., facility. The proof-of-concept test article was installed on the right vertical fin of NASA's F/A-18 SRA by Dryden technicians.

"The team did an excellent job of getting the experiment installed and checked out," Sitz said. "We're happy that we can make Dryden's Systems Research Aircraft available as a testbed to industry. It makes it possible to validate these concepts."


Note to Editors: NOTE TO EDITORS: Several photos are available from the NASA Dryden External Affairs Office to support this release, among them:

EC97-43950-1 F/A-18 vertical fins with Smart Skin antenna mounted. EC97-43950-2 NASA Dryden technician checks out antenna on F/A-18 vertical fin. EC97-43950-3 Smart Skin antenna end cap on F/A-18 vertical fin. EC97-43950-4 (Vertical) F/A-18 right vertical fin with Smart Skin antenna. EC97-43950-5 F/A-18 vertical fins with Smart Skin antenna mounted, NASA hangar. EC97-43958-1 F/A-18 SRA in flight with Smart Skin antenna on right vertical fin These photos will also be available on the Internet under NASA Dryden Research Aircraft Photo Archive, Dryden News and Feature Photos, URL: /centers/dfrc/Gallery/Photo/index.html

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