John Hicks, BS ASE 1969

Most of the summer from mid-May to mid-August 2001 was spent on the island of Kauai in Hawaii. As NASA’s project manager of the ERAST (Environmental Research Aircraft and Sensor Technology) project, one of the airplanes in this project was the unique AeroVironment-NASA solar-electric Helios that was flown from the Naval Pacific Missile Range on Kauai.          

The Helios was an unmanned solar-electric powered aircraft. The ultra-lightweight 1600 lb. aircraft was a 247 foot long by 8 foot wide wing-only aircraft made of thin plastic sheets stretched over a plastic and carbon composite airframe. The top of the wing was covered with about 1700 sq. ft. of over 62,000 solar cells. Propulsion was furnished by fourteen 2-HP dual-prop motors that were about the size of salon hair dryers.  Aerodynamic lift gave the lightweight design a built-in flexibility for control purposes that bent into a "smiley face" U-shape as it flew. The aim of the flights was to set a new absolute world’s altitude record for any type of aircraft.  This was done August 13th to 14th with a new record of 96,863 ft., some 12,000 ft. above the 25 year old record set by the SR-71 Blackbird.  It flew with backup lithium-ion batteries to power it for landing after dark.

One of the key technology objectives was to develop a new hydrogen-powered fuel cell energy system on board. In order for the system to be as lightweight and compact as possible for flight application on such an aircraft, development was centered on a new high-pressure 400 psia system that could easily fit on a card table. It is designed to be a closed system (that is, it doesn’t have to be recharged or refueled) that uses the excess solar energy from the solar cells to split water into hydrogen and oxygen gases stored in tanks, which at night is used to produce energy by putting the hydrogen and oxygen back together to make water and electricity. Theoretically, this would allow the Helios to stay up indefinitely. The aircraft would need to come down every 6 months for preventative maintenance and health checkup but otherwise is virtually a "perpetual motion machine". And, of course, as with most R & D the spin offs for this fuel cell technology include application in automobiles, homes and commercial buildings, remote sites, etc.       

The next question, by most people, is what use is the Helios? One of the basic uses is as a science platform to carry scientific instruments to high altitudes above the weather and all other aircraft to study ozone or global warming. It could also track weather patterns or hurricanes, act as a fixed telecommunication platform, for disaster or forest fire monitoring, or monitor agriculture, fisheries and forests. Its basic value is to fly over fixed regions above the earth for very long periods well above any weather or aircraft interference.           

As with flight test of any new, unique aircraft, the Helios had numerous problems to overcome that required a multi-discipline engineering team. This remotely controlled giant aircraft support covered engineering disciplines of structures, mechanical systems, aerodynamics, electrical systems and computers, and flight controls. Such a delicate aircraft demanded careful flight planning and operations to minimize wind and turbulent atmospheric conditions that could overload the aircraft structure and flight control requirements.

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