Imagine a battery-powered plane that has 10 engines and can take off like a helicopter and fly efficiently like an aircraft. That is a concept being developed by NASA researchers called Greased Lightning or GL-10.
NASA Langley researchers designed and built a battery-powered, 10-engine remotely piloted aircraft. The Greased Lightning GL-10 prototype has a 10-foot wingspan and can take off like a helicopter and fly efficiently like an airplane. In this video, engineers successfully transition the plan from hover to wing-borne flight in tests at Fort A.P. Hill in Virginia.
The team, at NASA's Langley Research Center in Hampton, Virginia, is looking at the idea initially as a potential unmanned aerial vehicle (UAV). "We have a couple of options that this concept could be good for," said Bill Fredericks, aerospace engineer. "It 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.""
The GL-10 is currently in the design and testing phase. The initial thought was to develop a 20-foot wingspan (6.1 meters) aircraft powered by hybrid diesel/electric engines, but the team started with smaller versions for testing, built by rapid prototyping.
"We built 12 prototypes, starting with simple five-pound (2.3 kilograms) foam models and then 25-pound (11.3 kilograms), highly modified fiberglass hobby airplane kits all leading up to the 55-pound (24.9 kilograms), high quality, carbon fiber GL-10 built in our model shop by expert technicians, " said aerospace engineer David North.
During a recent spring day the engineers took the GL-10 to test its wings at a military base about two hours away from NASA Langley. 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.
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."
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.
Credits: NASA Langley/Gary Banziger
SOURCE -NASA, Youtube