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Up, up and away

By Maj. Joe Mecadon
HQ AIA/PAO
Kelly Air Force Base, Texas

Some sharp-eyed San Antonians first spotted the mysterious object hovering high in the clear Texas sky around 2:30 p.m., April 27.

Thirty minutes later, alerted news crews were filming the “UFO,” which appeared to shine brightly one minute and vanish the next, when a smaller object separated and began a slow, steady descent to earth. Was “Independence Day” coming to the Alamo City?

Fortunately, for a team from the Joint Command and Control Warfare Center, Kelly AFB, Texas, there was nothing at all unidentified about this particular flying object. They had launched Sounder, an experimental communications relay platform, from the Hondo, Texas, airport earlier that day.

Being studied for development for the U.S. military, Sounder is a prototype, solar-powered, lighter-than-air vehicle designed to fly at altitudes of 60,000 - 80,000 feet, where the air is wispy thin and winds are relatively calm. Its airframe is a helium-inflated hull made of a thin, transparent plastic film – very similar to the material used to wrap cigarette packages. When fully expanded at its operating altitude, Sounder is 124-feet long and 24 feet in diameter.

“It appeared to be more or less visible – intensely bright or nearly invisible — depending on how it was orientated to the sun,” said Navy US Commander Gary “Bud” Abbott, JC2WC project leader.

“If it had stayed up after twilight, it probably would have been visible to everybody in South Texas.”

Developed for the JC2WC by San Antonio’s Southwest Research Institute, Sounder is unique in several respects, and has achieved a number of firsts, according to Abbott.

“Sounder is the first vehicle designed to be launched and ascend like a balloon, and then fully expand and pitch over as the surrounding air pressure reduces at altitude,” Abbott said. “Once that happens, Sounder is instrumented to fly like a blimp. When on station 11 to 15 miles up, Sounder fills out to about 55,000 cubic feet – about one third the size of the Goodyear blimps.”

Batteries charged by a single solar array positioned inside the transparent envelope power Sounder. The batteries drive an electric motor and propeller in the back of the balloon-turned-blimp.

The Sounder vehicle is designed to loiter and maintain a pre-determined position for extended periods of time.

Sounder carries an electronics equipment pod under its hull, which can be configured to perform a variety of functions, such as communications relay. Sounder could be used to extend ground-based, line-of-sight communications systems to reach anywhere within a 300-mile radius.

“From 72,000 feet, the line-of-sight distance is incredible,” Abbott said. “One indication of just how high that is, is that cameras placed aboard for the test transmitted back pictures in which the curvature of the earth was clearly visible. SR-71 pilots operating at similar altitudes could view San Francisco, Los Angeles and Las Vegas all at the same time.”

If Sounder becomes operational, it could become a major communications enabler for all U.S. military forces, according to Abbott.

“Additionally, it has the advantage of relatively low cost — $50,000 to $100,000 each, depending on what it carries — when compared to the cost of satellites,” he said.

“Further pluses include the ease of launch, minimal ground support requirements, and a recovery system which allows the instrumentation packages – the most expensive part — to be recovered and re-used.”

Although the 11 a.m. launch appeared to be picture-perfect, with ideal ground level and winds aloft, the test team believes one of three fragile tail fins may have been damaged during the launch, according to Abbott. Sounder’s flight was terminated due to system failures around 5:15 p.m.

“Our initial thought was that one fin was damaged and detached around 3 p.m.,” he said. “Unfortunately, in addition to compromising the overall aerodynamic stability, the fin also served to partially support the motor assembly, which then became miss-aligned. After that, the vehicle could no longer maintain its position.

“We sent a destruct signal, which split and deflated the hull, and released the instrument package on a parachute,” he said. “ It came down south of Jourdanton, Texas, and we went out and picked it up.”

This fourth and final Sounder test-of-concept flight completed the contract between the JC2WC and the Southwest Research Institute. Although his team won’t see Sounder become operational, and the unique craft didn’t stay aloft as long as anticipated, it was well worth the effort, according to Abbott.

“Each flight provided valuable data on the flight and performance characteristics of the platform, and overall viability of the concept,” he said. “Our work dovetails with research other agencies, including NASA, are doing. The down-linked data and the information we recovered from the instrument package will allow Southwest Research to work with other service branches, government agencies and private organizations interested in pursuing the concept.”