During normal cruise the outer wing panels of Helios are arched upward and give the aircraft the shape of a shallow crescent when viewed from the front or rear. This configuration places the motors on the outer wing panels higher than the motors on the center panels. If the upper motors are speeded up they are expected to cause the aircraft to pitch down and begin a descent. Conversely, motors in the center panels turning faster are expected to cause Helios to pitch up and begin climbing. During these tests, the trailing-edge elevators are disengaged, but not deactivated.
Flight controllers have the capability of re-engaging the elevators at any time.
If the tests are successful in providing adequate and safe pitch control for all flight operations, the elevator servo motors and all of their electrical wiring could be removed from the production Helios design, giving it an additional 25 to 30 lb of useful payload on future flights. The wing space now being used by the elevators could also be covered with solar arrays for additional power. The Helios Prototype will return to AeroVironment's Simi Valley facility following the 1999 series of test and development flights. Current plans call for the installation of the solar arrays on the upper wing surfaces as they are delivered from the manufacturers and various electrical and avionics system upgrades in preparation for the 100,000-ft altitude flight tests planned for 2001. All 14 motors, and minimal ballast, would be used on the altitude mission.