Solar explorer

A solar-powered aircraft with flapping wings could be used
for exploration of the Earth, Mars and Venus by 2020, US researchers claim.

A solar-powered aircraft with flapping wings could be used for exploration of the Earth, Mars and Venus by 2020, US researchers claim.

The plane will be built from a polymer that deforms when exposed to an electrical charge, and returns to its original shape when the charge is removed.

This deformation causes the wings to flap without the help of conventional mechanical parts, according to NASA-funded researchers at the University of Missouri-Rolla.

The plane will be launched from a hot-air balloon for mineral research or military reconnaissance on Earth. For research on other planets, it will be launched from another spacecraft.

But the range of the plane in space is limited to Mars and Venus because there is too little sunlight beyond Mars.

The wings are made from an ionic polymer-metal composite – a family of materials with the unique ability to bend, twist or flap when exposed to an electrical charge.

The polymer has electrodes attached to it and a specific voltage is passed through them. The electrical charge induces attraction and repulsion in the polymer that results in deformation. By controlling the voltage the researchers have been able to control precisely the amount of deformation required for a flying motion.

The solar cells will power the flapping motion of the wings during the day. But to enable long flight durations, the plane will glide without flapping its wings during the night, so not using any energy.

The researchers placed a scaled-down model of the wing into a 10-gallon tank of salt water to mimic precisely the effects of air resistance on a full-sized wing. They used the system of deformation with electrodes to move the wing back and forth, and monitored the bubbles given off by the wing in motion.

From this information, the researchers have been able to develop the aerodynamics of the wing and calculate the exact flapping frequency needed to sustain the flight.

Leading the research, Kakkattukuzhy Isaac, professor of mechanical and aerospace engineering at the university, said the research will be refined over the coming year.

‘Wind tunnel tests are planned for next year and my colleagues are working on reducing the number of electrodes attached to the wing. Even with four pairs of electrodes they can complete very complex movements,’ he said.

The research is funded by a grant from the NASA Institute of Advanced Concepts.Joe Boyle