Transfer of solar aircraft technology to the commercial market has moved a step closer with the recent signing of an agreement between NASA's Dryden Flight Research Center and AeroViroment, Inc., to jointly sponsor further development of AeroVironment's Helios Prototype and Pathfinder Plus solar-electric flying wings.
The Joint Sponsored Research Agreement (JSRA) was signed recently by Kevin Petersen, director of NASA Dryden, and Timothy Conver, president and chief executive officer of AeroVironment, on the occasion of the final flight in a three-mission series of high-altitude telecommunications relay demonstrations by the Pathfinder Plus from the U.S. Navy's Pacific Missile Range Facility (PMRF) on the Hawaiian Island of Kauai.
At the same time, the two entities revealed that a second supplemental energy system is being perfected by AeroVironment that will give the Helios the ability to fly multi-week missions at high latitudes.
"Not only does this agreement help focus the ongoing NASA-sponsored development efforts, it also forms the framework for enabling the commercialization of the solar-electric platforms to support various commercial, government, and university needs," said Petersen.
"This NASA-AeroVironment collaboration offers a huge advantage to the nation of accelerating access to the revolutionary low-cost benefits of communication and remote sensing from the stratosphere to both the government and private sectors," added Conver.
Commercialization of high-altitude remotely piloted or autonomously operated unmanned aerial vehicles (UAVs) has been a high priority for partners of the Environmental Research Aircraft and Sensor Technology (ERAST) alliance since its inception in late 1993. The new agreement builds upon a similar JSRA pact between NASA and several small high-technology firms that forms the basis for the ERAST project.
"This new arrangement streamlines existing efforts-both commercially and federally sponsored-by AeroVironment and NASA's ERAST project to merge solar powered UAV development into a single solar/electric platform program aimed at developing multiple aircraft," said John Del Frate, project manager for solar powered aircraft at NASA Dryden. "The agreement also sets forth a framework for future partnering in commercial activities related to the Helios solar-electric family of aircraft."
As part of the agreement, AeroVironment will provide program management personnel; expertise in energy storage systems, fuel cell propulsion and solar-electric airframes; design and flight teams; and facilities, such as their UAV Development Center, Fuel Cell Lab, and Mobile Test Facility.
The agreement calls for NASA Dryden to maintain safety oversight for flight and ground testing for all solar aircraft as well as for energy storage and power systems, stationary and mobile ground support systems. Dryden will also provide support for flight demonstrations, including provision of the Pathfinder Plus and Helios Prototype aircraft and their flight kits, support for technology development for next-generation Helios aircraft and components, and facilities and equipment such as PMRF, environmental test, simulator facilities and range equipment.
AeroVironment and NASA Dryden Flight Research Center have been collaborating on development of solar-powered UAVs since 1993. These efforts were initiated with the Pathfinder, which set a series of altitude records as it underwent extensive modifications and upgrades over the next five years. In its latest form, the Pathfinder Plus, it is capable of altitudes up to 80,000 feet.
Also being worked as a collaborative effort is the development of the Pathfinder's follow-on, the Helios Prototype. Originally named the Centurion, Helios first flew in 1998 and currently holds a world altitude record for its flight to 96,863 feet in August 2001, also flown out of PMRF.
Initially, AeroVironment and NASA are commercializing two versions of the Helios solar/electric extreme-endurance UAV. One version will be able to fly at lower latitudes for up to six months without landing by employing a regenerative fuel cell-based energy storage system to provide power at night. The regenerative system uses excess power from the solar arrays during the daytime to power an electrolyzer that breaks down water into its component gases, hydrogen and oxygen, which are then stored in pressurized tanks. At night, the process is reversed, with fuel cell stacks recombining the gases into water, producing electricity as a byproduct to power the aircraft.
The other version will use a similar fuel cell-based energy system without the regenerative feature to power the aircraft at night. Designed to allow Helios to fly for one to two weeks at all latitudes any time of the year, this system combines stored hydrogen with oxygen collected from the atmosphere. Initiated by AeroVironment and now a joint effort by NASA and the Monrovia, Calif., -based firm, development of the non-regenerative system has accelerated rapidly over the past nine months. AeroVironment is currently operating developmental versions of both fuel cell-based energy systems at its California development facility.
The Helios Prototype is currently being modified in preparation for a series of experimental long-endurance demonstration flights late next summer, which will use the primary non-regenerative system to provide power for night operations.
"The measured performance of both our primary and regenerative fuel cell systems is very good, and indicates that years of hard work on these complex and often under-estimated systems is paying off," said Robert Curtin, vice-president and director of AeroVironment's UAV Design Development Center in Simi Valley, Calif. "The integration of these systems with our proven stratospheric solar aircraft will enable a global, low-cost, extreme-endurance UAV capability."
Both the Pathfinder Plus and the Helios Prototype have been developed as platform aircraft to test unique technologies and demonstrate a variety of potential applications. Among proposed uses are earth monitoring for climate, environmental changes and natural disasters; "last mile" connectivity for systems such as TV, cell phone systems and the Internet; and surveillance applications for border patrol, port and pipeline security and the military.
"Fundamentally, affordability is why we're building the Helios," Curtin added. "Cost is very important to potential military and commercial users. The extreme endurance of Helios will result in a short logistics "tail," a very small operational infrastructure and low operational costs. The bottom line is much lower operational costs than any conventional UAV."