【科技动态】NASA研制10发动机电动无人机 可垂直起降
GL-10是一种旋翼可倾转飞机，旋翼可垂直倾斜，用于垂直起飞和降落。旋翼随后向前倾斜，用于水平翼载飞行，此时的主机翼保持固定状态。宇航局的最初计划是研制一款翼展约合6米的无人机，采纳柴油和电动发动机。项目组已对一个小型遥控版进行测试，翼展只有3米。
GL-10的机翼装有8台发动机，机尾装有2台发动机，重62磅（约合28公斤）。宇航局的技术人员共制造了12架原型机，其中包括5磅（约合2公斤）的泡沫原型和55磅（约合25公斤）的高品质碳纤维原型。
航空航天工程师大卫-诺斯表示：“每一个原型都帮助我们以较低的成本解答技术问题。一些早期原型在硬着陆时损坏，帮助我们了解如何完善飞行操纵系统。每次缺失原型都让我们学到不少东西，让我们保持前进步伐。”
GL-10的主操纵员扎克指出操控一架10发动机无人机更像是操控一架3发动机飞机。他说：“左机翼的所有4台发动机接收到同样的指令，右机翼的4台发动机也是如此，机尾的2台发动机随后接收到相同的指令。”GL-10能够在狭窄的空间起飞，拥有飞行时噪音低的优势。
(来源：新浪科技，编译：孝文)
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原文链接：
Ten-Engine Electric Plane Completes Successful Flight Test
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.
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.
"Each prototype helped us answer technical questions while keeping costs down. We did lose some of the early prototypes to 'hard landings' as we learned how to configure the flight control system. But we discovered something from each loss and were able to keep moving forward."
Engineers David North (L) and Bill Fredericks (R) carry the Greased Lightning before one of its flight tests.
Credits: NASA Langley/David C. Bowman
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."
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.
Part of that UAV research is for NASA Aeronautics' Unmanned Aircraft Systems Integration in the National Airspace System Project, led out of the Armstrong Flight Research Center in Edwards, California. Engineers from Armstrong will highlight project accomplishments and upcoming work in a booth in Atlanta. The goal of the project is to provide research results to reduce the technical barriers associated with integrating unmanned aerial vehicles into the skies.
Researchers from the Wallops Flight Facility in Wallops Island, Virginia will also be at the conference, highlighting unmanned aircraft for use in science missions. "Remotely piloted aircraft are enhancing NASA science investigations and serve as a platform to expand technology development for aircraft, cubesats and other platforms," said Wallops Director's Office official Mike Hitch.
Kathy Barnstorff
NASA Langley Research Center
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