Flying toward all-electric airplanes.

The in-flight movie may be airplane passengers' prescribed form of entertainment, but those who score seats above the wings can watch an alternative show. The wing flaps rise and fall, extend and retract, in a carefully orchestrated dance that helps control the flight of the plane. Complicated hydraulic systems running throughout the plane transmit the pilot's commands to actuators that move the wing parts.

Now, engineers at NASA's Dryden Flight Research Center in Edwards, Calif., have successfully tested a device that may help eliminate a plane's reliance on heavy, temperamental hydraulic systems. The device, an electrohydrostatic actuator, moves wing components called ailerons that control the side-to-side movement of the plane. The new actuator responds to commands by using an electric motor to pump a small amount of hydraulic fluid to the aileron.

Replacing many of the hydraulic control lines with electric wires would save weight, making military aircraft easier to maneuver and commercial planes more fuel-efficient, says David Voracek, chief engineer for NASA's F/A-18 Systems Research Aircraft, the plane used to test the device.

Electric systems also need less maintenance than hydraulic ones, which require "a lot of tender loving care," adds engineer Stephen Jensen. The Dryden team also plans to test an electromechanical actuator, one that eliminates hydraulic fluid altogether.