It had already passed hover tests -- flying like a helicopter -- with flying colors. But now was the big hurdle -- the transition from vertical to forward "wing-borne" flight. As engineers who have designed full-scale vertical take off and landing tiltrotors such as the V-22 Osprey will tell you -- that is no easy task because of the challenging flight aerodynamics.
"During the flight tests we successfully transitioned from hover to wing-borne flight like a conventional airplane then back to hover again. So far we have done this on five flights," said Fredericks. "We were ecstatic. Now we're working on our second goal -- to demonstrate that this concept is four times more aerodynamically efficient in cruise than a helicopter."
Zack Johns is the GL-10's primary pilot. He says flying the ten-engine aircraft has its ups and downs, but it really flies more like a three-engine plane from a control perspective.
"All four engines on the left wing are given the same command," said Johns. "The four engines on the right wing also work in concert. Then the two on the tail receive the same command."
The prototype successfully transitioned from hover to wing-borne flight during several test flights.
Credits: NASA Langley/Gary Banziger
One other advantage to the GL-10 besides its versatile vertical take off and landing ability is its noise or lack of it. "It's pretty quiet," said Fredericks. "The current prototype is quieter than a neighbor mowing the law with a gas-powered motor."
The next step in the GL-10 test program is to try to confirm its aerodynamic efficiency, but first is a stop at the Association for Unmanned Vehicles Systems International 2015 conference in Atlanta May 4-7. The GL-10 will be the centerpiece of an exhibit showcasing some of NASA Langley's UAV research. Read More