The Future of Flight: Hybrid-Electric VTOL Aircraft

nasa-greased-lightning-10-foot-drone-640x480It may look like something a dedicated hobbyist built, and sound like something cheekily named, but NASA’s new electrical vertical take-off and landing (VTOL) machine is a very serious venture. Known as the GL-10 Greased Lightning, this unmanned hybrid-electric aircraft is the agency’s proposal for a vehicle that one day replace the reigning champion of VTOL – the helicopter.

 

The G-10 is in part the result of the recent strides made in electric propulsion, which is made possible thanks to the growing power and energy density of batteries allows for some very efficient hybrid-electric aircraft designs. With eight prop engines mounted on the two main wings and another two mounted on the tail, the vehicle swivels them into vertical position for takeoff and landing, and then horizontal for conventional flight.

nasa-greased-lightning-prototype1While it’s not particularly hard to create an aircraft capable of VTOL, it has so far proven to be very tough to create an aircraft that can also efficiently cruise through the air after taking off vertically. The helicopter is the only common example of a VTOL aircraft that can also cruise acceptably, but at a cost. Compared to other aircraft, an everyday helicopter has a much lower-lift-drag ratio, which means it burns more fuel, has less range and can carry less weight.

However, electric propulsion allows for much more efficient designs, since vehicles no longer have to accommodate large fossil fuel-powered engines or manage the mechanical stress across the airframe. Instead, they can rely on smaller, more efficient, optimally placed electric motors, and without the mechanical complexity of big jet engines, it suddenly becomes a lot easier to have wings and propellers that can swivel between horizontal and vertical.

https://i0.wp.com/www.extremetech.com/wp-content/uploads/2014/08/nasa-greased-lightning-ground.jpgWhile pure-electric aircraft do exist – in the form of quadcopters – hybrid-electric designs with longer range are generally of more interest to military and commercial groups. In the case of NASA’s Greased Lightning, there are two small diesel engines in the body of the aircraft that turn electric alternators that constantly recharge the lithium batteries. This theoretically gives the GL-10 the same range and duration as a modern plane alongside its VTOL capability.

Interestingly, NASA also says that such a hybrid-electric design is “scale free” — meaning the same principles could be used to revolutionize everything from helicopters, to military UAVs, to massive jetliners. Much like hybrid-electric cars, the concept is set to revolutionize an entire fleet of aircraft designs that could be far more efficient than they currently are. One party who is sure to be interested in the possibilities is the US military, with its ever growing fleet of UAVs.

For now, Greased Lightning only has a wingspan of 3 meters (10 feet), and on its first test flight  – which took place on National Aviation Day, August 19 – it was tethered. Untethered flights are planned for later in the year, an event which is sure to be a media sensation and produce some viral videos!

 

 

Source: extremetech.com

SpaceShipTwo Makes First Flight!

For years, Richard Branson has been promising the world commercial spaceflight with his proposed aerospace line, Virgin Galactic. And with the advent of SpaceShipTwo, the rocket-powered vehicle designed for this end, the company has been promising to conduct a successful test flight by the end of the year. This past Wednesday, Virgin and the development company – Scaled Composites – delivered on that promise, as SS2 conducted its first fully-loaded glide test successfully and landed safe and sound.

Granted, the company has yet to test out the ship’s rocket motor, the propulsion that will be used to put the ship into the Earth’s atmosphere. However, it was the first flight where the space craft was deployed by itself, without assistance from its carrier, WhiteKnightTwo. It was also the first time the vehicle conducted a glide test with all its components and fuel tanks installed. By showing that it is capable of gliding while fully-loaded, Virgin Galactic has proven that SS2 is capable of making safe landings, which is just as important as getting into space when you think about it!

“It was also the first flight with thermal protection applied to the spaceship’s leading edges,” said Virgin in a press statement. “It followed an equally successful test flight last Friday which saw SpaceShipTwo fly in this configuration but remain mated to its WhiteKnightTwo carrier aircraft.”

Virgin also claims it intends to conduct two more glide tests before attempting a powered flight, where the rocket motor will be put to the test and the ship will finally acheive suborbital flight. And once all the bugs are ironed out, Virgin Galactic will then be able to finally offer the sub-orbital rides that have been the subject of talk for many years. One of the first to go with be Branson himself, along with five others who will travel aboard SS2 as it acheive a suborbital flight which will take it over 115,000 meters (350,000 feet) above the Earth and acheive weightlessness for the crew.

Source: Wired.com