Alternative Energy

Recently we posted an article announcing the production of a portable solar charger for airplane avionics. At the end of that article we asked if you thought airplanes could one day be powered by solar. Since then we discovered a whole slew of existing solar airplane concepts and projects that we thought we’d share with you. Click through the following links to visit the related websites. At the bottom of this article you’ll find another opportunity to vote your opinion and leave your comments about the feasibility of solar powered flight.

The Helios Prototype solar-electric flying wing was one of several remotely piloted aircraft, also known as uninhabited aerial vehicles or UAVs, that were developed as technology demonstrators under the now-concluded Environmental Research Aircraft and Sensor Technology (ERAST) project. Prior to its loss in an in-flight mishap in June 2003, the Helios Prototype set a world altitude record for propeller-driven aircraft of almost 97,000 feet.

Pathfinder was first developed for a now-cancelled classified government program in the early 1980’s to develop a high-altitude, long-endurance aircraft for surveillance purposes. Known as the HALSOL (for High-Altitude SOLar) aircraft, its eight electric motors — later reduced to six — were first powered by batteries. After that project was cancelled, the aircraft was placed in storage for 10 years before being resurrected for a brief program under the auspices of the Ballistic Missile Defense Organization (BMDO) in 1993. With the addition of small solar arrays, five low-altitude checkout flights were flown under the BMDO program at NASA Dryden in the fall of 1993 and early 1994 on a combination of solar and battery power.

The Centurion is a lightweight, solar-powered, remotely piloted flying wing aircraft that is demonstrating the technology of applying solar power for long-duration, high-altitude flight. It is considered to be a prototype technology demonstrator for a future fleet of solar-powered aircraft that could stay airborne for weeks or months on scientific sampling and imaging missions or while serving as telecommunications relay platforms. Although it shares many of the design concepts of the Pathfinder, the Centurion has a wingspan of 206 feet, more than twice the 98-foot span of the original Pathfinder and 70-percent longer than the Pathfinder-Plus’ 121-foot span.

The “Hy-Bird” project plans to fly around the world with a 100% clean electric airplane powered only by renewable energies: solar energy and hydrogen. The goal is to design an airplane, which will use only renewable energies with no greenhouse gas emission, and, to decrease dramatically noise pollution, which airplanes do normally engender.Indeed, photovoltaic cells affixed on the wing and on the horizontal tail will supply sufficient energy for the take off and for on-board power supply. Besides, a fuel cell will fuel the aircraft for cruise flight. An electric engine (more silent than heat engines) will propel Hy-Bird. Inhabitat Article

After four years of research, studies, calculations and simulations, the Solar Impulse project has entered a concrete phase with the construction of an initial prototype with a 61-metre wingspan, referred to by its registration number “HB-SIA”. Its mission is to verify the working hypotheses in practice and to validate the selected construction technologies and procedures. If the results are conclusive, it could make a 36-hour flight – the equivalent of a complete day-night-day cycle – in 2009 without any fuel. EcoGeek Article

Eric Raymond’s dream of a solar powered airplane began in 1979, when Larry Mauro demonstrated his solar powered ultralight glider, named SOLAR RISER. Eric began construction of his design in late 1986. Progress was slow until 1988, when support was found in Japan. With the help of Sanyo and several other corporations the SUNSEEKER was test flown at the end on 1989 as a glider. The motor and prop mechanism were not satisfactory, so an A.C. brushless motor and a folding prop were installed. After many long test flights, a series of flights were initiated across the country. During August of 1990, The SUNSEEKER crossed the country in 21 flights, with 121 hours in the air.

The Sky-Sailor would be carried to Mars in a small aeroshell that would be attached to a carrier spacecraft. Upon reaching the red planet, the aeroshell would be released for direct entry into the Martian atmosphere. From this point, the operations could be decomposed in different phases. It can cover a distance of ~1700 km during a 12-hour period. This allows the airplane to reach many different areas of interest. The exploration mission will end when the airplane crashes normally due to the batteries life cycle and dust deposition on solar panels.

The SoLong is an electric-powered UAV (unmanned aerial vehicle) that collects solar energy from photo-voltaic arrays laminated into its wings. It uses energy so efficiently that it can fly all night on energy it gathers from the sun during the day. Remaining aloft for two nights is the milestone for sustainable flight. One night is possible just by discharging the batteries, but two or more nights means that the plane has to fully recoup and store the energy used at night while flying in the sunlight the following day. Once that is achieved, the cycle can repeat continually, and keep the plane airborne indefinitely.

Called the Zephyr, it’s an aircraft that can fly continuously using nothing but solar power and “low drag aerodynamics”. The combination of solar panels on the upper wing surface and rechargeable batteries allows Zephyr to be flown for many weeks and even months. The first flight trial of the Zephyr were conducted recently by QinetiQ in White Sands Missile Range, New Mexico. Two aircraft were flown for four and a half and six hours respectively, the maximum flight times permitted under range restrictions.

A Venus exploration aircraft, sized to fit in a small aeroshell for a “Discovery” class scientific mission, has been designed and analyzed at the NASA Glenn Research Center. For an exploratory aircraft to remain continually illuminated by sunlight, it would have to be capable of sustained flight at or above the wind speed, about 95 m/sec at the cloud-top level. The analysis concluded that, at typical flight altitudes above the cloud layer (65 to 75 km above the surface), a small aircraft powered by solar energy could fly continuously in the atmosphere of Venus. At this altitude, the atmospheric pressure is similar to pressure at terrestrial flight altitudes.