Saturday, March 12, 2016

Electric Airplanes Getting Closer To Reality

Electric airplanes are closer to reality today, thanks to DARPA and some intrepid dreamers. DARPA is the Defense Advanced Research Projects Agency. It was established in 1958 after the US was shocked to find that the dastardly Russians had actually placed a satellite in orbit before we did. Through the years, it has experimented with all sorts of goofy devices that were supposed to be able to find their way from Point A to Point B using only computers and sensors. At first, they were hardly capable of finding their way out of small room. Today, the technologies they pioneered are making autonomous driving possible.
DARPA VTOL Electric airplanes
Autonomous cars are now the private domain of Google and Tesla, but DARPA hasn’t stopped experimenting with weird transportation ideas that may impact the future. According to Gizmag, one of them is an electric vertical take off and landing (VTOL) airplane. It started that project back in 2014 with the X Plane project. Now it has begun Phase 2, which seeks to  construct a demonstrator aircraft that can reach a top sustained speed of 345 to 460 mph, hover with an efficiency of at least 75% instead of the current 60%, reduce the cruise lift-to-drag ratio from six to 10, and carry a payload equal to 40 percent of the X-Plane’s gross weight of 12,000 pounds.
The design for the Phase 2 X Plane is from Aurora Flight Sciences Corporation. It features wings that look like a collection of box kites assembled together — 9 in each of the rear wings and 3 in each of the smaller canard wings in front. Each section has its own electric motor which is controlled by a central computer. Electricity is generated by an engine borrowed from a V-22 Osprey. It is capable of producing 3 megawatts of electricity, which is the equivalent of 4,000 horsepower.
What’s the point? Keep in mind that the D in DARPA stands for defense. There are any number of scenarios around the world where a plane that needs no conventional runway would offer a significant advantage to our military forces. DARPA is not ruling out the possibility that a similar airplane could carry human passengers at some point in the future. The first test flights for prototypes are scheduled for 2018.
Zee Aero Electric Airplanes
The DARPA Phase 2 X Plane is not fully electric, but a proposed VTOL airplane from Zee Aero definitely is. Founded by Ilan Kroo, who is a professor of aeronautics and astronautics at Stanford and former NASA researcher, Zee Aero has recruited a team of talented engineers, according to Electrek. Together, they are focusing on improving battery technology and control systems so the idea of an electric airplane can get closer to reality.  Elon Musk has talked about building an electric airplane. He says batteries that have a at least 400 watt-hours of power per kilogram will be required before electric airplanes are a realistic possibility. At present, the maximum power of lithium ion batteries is around 270 Wh/kg.
The Zee Aero electric plane also uses large rear wings and smaller canard wings up front with an array of motors for vertical lifting and forward motion. Kroo’s 2013 patent application describes it as follows:
“A safe, quiet, easy to control, efficient, and compact aircraft configuration is enabled through the combination of multiple vertical lift rotors, tandem wings, and forward thrust propellers. The vertical lift rotors, in combination with a front and rear wing, permits a balancing of the center of lift with the center of gravity for both vertical and horizontal flight. This wing and multiple rotor system has the ability to tolerate a relatively large variation of the payload weight for hover, transition, or cruise flight while also providing vertical thrust redundancy.
Will either of these electric airplanes ever fly? Maybe not next year. Maybe not in the next 10 years. But electric propulsion is clearly the way forward for human transportation. Don’t dismiss either of these projects just because they look like something from a another world. People once felt the same way about automobiles.

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