NASA researchers have confirmed that the Greased Lightning (or GL-10) battery-powered concept UAV has completed a series of successful flight tests.
Currently in the design and testing phase, Greased Lightning has 10 engines, can take-off like a helicopter and fly efficiently like an aircraft. The remotely piloted plane has a 10-foot wingspan (3.05 meters), eight electric motors on the wings, two electric motors on the tail, and weighs a maximum of 62 pounds (28.1 kilograms) at take-off.
Having already passed hover tests, flying like a helicopter, the team have now completed tests assessing the transition from vertical to forward “wing-borne” flight.
“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.”
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 neighbour mowing the lawn with a gas-powered motor.”
The next step in the GL-10 test program is to try to confirm its aerodynamic efficiency.
Bill Fredericks, an aerospace engineer at NASA’s Langley Research Center in Virginia, said “The GL-10 could be used for small package delivery or vertical take-off and landing, long endurance surveillance for agriculture, mapping and other applications. A scaled up version — much larger than what we are testing now — would make also a great one to four person size personal air vehicle.”
Update: The Greased Lightning UAV design is now licensed to Advanced Aircraft Company.