As you read this story, a silent sentinel surely soars skies above the U.S. Navy’s Pacific Missile Range Facility at Barking Sands, near Kekaha. Though the bird might look a bit different now that it’s equipped with fuel cells that
As you read this story, a silent sentinel surely soars skies above the U.S. Navy’s Pacific Missile Range Facility at Barking Sands, near Kekaha.
Though the bird might look a bit different now that it’s equipped with fuel cells that will keep it aloft even without its normal solar fuel, the Helios Prototype that two summers ago at PMRF set a world record for sustained, solar-powered flight altitude, has returned for an encore.
The unmanned aircraft, controlled remotely by humans on the ground, was supposed to lift off from the PMRF runway around 8 a.m. today for a 20-hour shakedown, checkout flight, to make sure it can remain flying without sunlight.
That’s possible because the craft, known as a flying wing because that’s what it looks like (one, 247-foot-long wing), has been modified with installation of an experimental, hydrogen-fuel-cell system developed by AeroVironment, Inc., the craft’s Monrovia, Calif. manufacturer.
The craft flies with propellors driven by solar power converted by panels on the wing by day, and is designed to also fly by night using onboard hydrogen mixed with atmospheric oxygen.
Most of today’s test flight, to end early tomorrow morning, will take place at around 50,000 feet above PMRF and its ocean range. If all goes well, a test flight of 40-hours’ duration could happen at the base as early as mid-July.
“The Helios Prototype has proven its capabilities to conquer the day on solar power,” said John Del Frate, Helios project manager at NASA’s Dryden Flight Research Center in Edwards, Calif.
“Now, to fulfill the long-term vision for it to fly routinely for extreme duration, the next challenge is to conquer the night,” he said. “The key to that is development of the fuel-cell system. It’s the necessary next step to extreme endurance.”
The Helios Prototype research is designed among other things to test the feasibility of using renewable-fuels-powered aircraft (solar and fuel-cell) to replace satellites for telecommunications and other applications.
In the summer of 2001, the solar-powered Helios Prototype set a world altitude record for non-rocket-powered aircraft in sustained horizontal flight, at 96,863 feet above PMRF.
If this summer’s 40-hour flight is successful, it “would meet a NASA milestone for the solar-aircraft technology development under NASA’s Environmental Research Aircraft and Sensor Technology (ERAST) project,” said Alan Brown of the public affairs office of NASA’s Dryden Flight Research Center.
A preliminary liftoff test at PMRF last month showed the craft is stable despite the increased weight and load distribution of the fuel-cell system, Del Frate said.
The system combines advanced automotive-fuel-cell components with proprietary control technology designed for the harsh environment above 50,000 feet.
The ERAST program is scheduled to end in September, but not before another Helios Prototype test is scheduled that month at PMRF, when telecommunications equipment will be added to the wing’s payload.
The flight demonstration planned for September at PMRF will see Helios Prototype carry advanced broadband Internet connectivity and antenna systems developed by Japan’s Communication Research Laboratory and the Telecommunications Advancement Organization of the Japanese Ministry of Public Management, Home Affairs, Post and Telecommunications.
Japanese government and private-sector officials are interested in the technology to eliminate cellular-phone “dead spots” in Japan, and for other purposes.
The AeroVironment system consumes no fossil fuels, emits no atmospheric pollutants, with water vapor and heat the only fuel-cell byproducts.
“The challenge is to operate the fuel-cell system in a high-altitude flight environment,” said AeroVironment engineer Bill Parks, who led the development effort.
“We had to learn a lot about operating in that environment. There were a number of tradeoffs, in terms of weight versus efficiency, all of which were optimized for this (high-altitude-flight) application,” said Parks.
In August 2001, flying on electrical power generated solely by the 62,000 silicon solar cells mounted across the upper surface of its 247-foot-long wing, Helios soared to an altitude of 96,863 feet, maintaining stable horizontal flight above 96,000 feet for more than 40 minutes.
It was a world record for all winged aircraft except those powered by rockets.
Although the ERAST project will end this fall, further development of the fuel-cell system is likely to continue under a follow-on NASA project to perfect a regenerative version of the system.
“A mature, non-regenerative system similar to the one we are flying this summer has the potential to fly continuously for two weeks in the stratosphere,” Del Frate explained.
“It can give the Helios year-around global coverage, not limited to temperate or equatorial climes or latitudes.
“After testing on this system is finished this summer, we will focus on development of a fully regenerative system that could fly up to six months or more,” he added.
Del Frate said a production version of the Helios with the regenerative fuel-cell system is of interest to NASA officials for environmental science, and to military and AeroVironment personnel for various uses, primarily as a stratospheric telecommunications relay platform.
Digital photos of the Helios Prototype may be available a few hours after takeoff of today’s checkout flight, at http://www.dfrc.nasa.gov/gallery/photo/helios/index.html.
Business Editor Paul C. Curtis can be reached at mailto:pcurtis@pulitzer.net or 245-3681 (ext. 224).
