Helios solar powered UAV
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The Helios Prototype is an enlarged version of the Centurion flying wing, which flew a series of test flights at Dryden in late 1998. The craft has a wingspan of 247 feet, 41 feet greater than the Centurion, 2 1/2 times that of its solar-powered Pathfinder flying wing, and longer than either the Boeing 747 jetliner or Lockheed C-5 transport aircraft.
The solar cells generate about 40 kilowatts of power -- about the amount used each day by four to six homes -- to drive 14 propellers on the craft.
Helios is developed by AeroVironment inc. under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) project, this program was started by NASA in 1994 to develop unmanned aerial vehicle (UAV) technology and the miniaturization of science instruments.
The unique craft is intended to demonstrate two key missions:
The ability to reach and sustain horizontal flight at 100,000 feet altitude on a single-day flight, and to maintain flight above 50,000 feet altitude for at least four days, both on electrical power derived from non-polluting solar energy.
During later flights, AeroVironment's flight test team will evaluate new motor-control software which may allow the pitch of the aircraft-the nose-up or nose-down attitude in relation to the horizon-to be controlled entirely by the motors. If successful, productions versions of the Helios could eliminate the elevators on the wing's trailing edge now used for pitch control, saving weight and increasing the area of the wing available for installation of solar cells.
Project Milestones:
August 18, 2024 Functional ground checkout
September 8, 2024 Low-altitude maiden checkout flight
September 29, 2024 Second flight
August 13, 2024 Achieved Record Altitude of 96,863 feet
Although the NASA scientists aimed for an altitude of 100,000 feet, the flight of August the 13th still was a huge succes.
the altitude is the highest ever flown by a non-rocket powered aircraft in sustained horizontal flight, and well above the current world altitude record of 85,068 feet for sustained horizontal flight by an aircraft, set by an SR-71A Blackbird in July, 1976.
The maximum-altitude flight was one of two major flight milestones set for the craft by NASA. The project's focus has now shifted to the achievement of a four-day non-stop endurance demonstration flight above 50,000 feet planned for 2003.
The solar panels on Helios' wings produce 37 kilowatts of power, but the plane only needs 10 kilowatts to fly. The rest is wasted as heat. The ability to capture as much of this extra energy as possible would enable the plane to fly for months at a time.
Development of a regenerative hydrogen-oxygen energy storage system which would make the multi-day continuous flight possible is progressing at AeroVironment. The system uses excess power generated by the solar arrays during the daytime to run an electrolyzer that separates water into its component parts, hydrogen and oxygen, which are then stored under pressure in specially-designed tanks. At night, the hydrogen and oxygen are recombined by the fuel cells, producing electricity as a by-product to power Helios' motors and systems.
For those flights, eight motors will power the prototype and more than 500 lbs. of ballast will be added to simulate the weight of the energy storage system now being designed for Helios. Fewer motors are needed for the Helios mission due to the lesser altitude requirements.
Production variants of Helios might see service as long-term
Earth environmental monitors or as communications relays,
reducing dependence on satellites and providing service in
areas not covered by satellites. The successful flight at
high altitude also provides NASA with information about
flight on Mars, since the atmosphere at that height above
Earth replicates the atmosphere near the Martian surface.
