Ten-engine electric plane prototype takes off

May 8, 2015

Credit: NASA Langley/David C. Bowman

By Kathy Barnstorff

A team at NASA’s Langley Research Center is developing a concept of a battery-powered plane that has 10 engines and can take off like a helicopter and fly efficiently like an aircraft. The prototype, called Greased Lightning or 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.

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, . “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 .


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37 comments on “Ten-engine electric plane prototype takes off

  • While not being critical in the slightest, I feel there must be a more elegant solution to combining the advantages of helicopter and aircraft flight.



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  • Multi electric motors and a bit of on board battery storage not only give redundancy and therefore safety but also allow very great finesse in the balancing act that take off and landing constitute.



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  • Would it not be greener to combine balloon and aircraft flight? Take off via helium balloons attached to the craft then, once an appropriate height is reached, the helium is released, a bit of gliding to pick up speed and then into standard aircraft mode.



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  • @OP – A team at NASA’s Langley Research Center is developing a concept of a battery-powered plane that has 10 engines and can take off like a helicopter and fly efficiently like an aircraft.

    There have been several variations on this tilt-rotor theme over the years!

    http://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey

    Darpa X-plane to radically rethink vertical takeoff – http://www.bbc.com/future/story/20130228-x-plane-plans-for-radical-takeoff



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  • 6
    NearlyNakedApe says:

    While it could be argued that a more elegant solution is always possible, aeronautical engineers haven’t come up with one so far. Combining vertical take-off capability with fast horizontal flight is a much more difficult challenge than many people realize.

    Helo’s take off vertically but are severely limited in forward speed by the aerodynamic drag of the main rotor. Tilt-wing designs like the Osprey (and the above GL-10) overcomes the forward speed limit with variable geometry but at the cost of mechanical complexity due the extremely high load-bearing on the wing’s pivot mechanism during take-off (plus the torsion caused by the torque of the engines, etc..). But it’s a relatively successful recipe because a lot of experimental data and technical know-how is already available.

    Conventional aircraft using turbines and vectored thrust to take off vertically (Harriers for eg.) can somewhat overcome the mechanical complexity problem (although not completely) but at the cost of exceeedingly high fuel consumption (which reduces effective range) and significantly higher piloting skills required for take-off and landing (which increases the likelihood of accidents). This design is obviously not an option for an electric powered plane however.

    In engineering, everything is a trade-off. You almost always gain a feature at the expense of an another. But the reality of it is that there aren’t a whole lot of options available when it comes to designing an electrically powered airframe with those design goals.



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  • 8
    NearlyNakedApe says:

    @Ewan

    Would it not be greener to combine balloon and aircraft flight? Take off via helium balloons attached to the craft then, once an appropriate height is reached, the helium is released, a bit of gliding to pick up speed and then into standard aircraft mode.

    Yes that is possible and I thought about it but there are several obstacles:

    Weight.

    A really heavy airframe will require a really large Helium balloon which in turn require a really large amount of helium to inflate. A large baloon will take a long time to inflate (which severely lenghtens deployment time) and is not reusable.

    Resources.

    Helium while one of the most abundant elements in the universe is actually quite scarce on earth. And our helium reserves are dwindling. Consequently, helium has become severely rationned and very expensive. Plus, since the balloon is released every time the plane takes off, all that helium is wasted. Not green at all really.

    Practicality.

    The baloon takes a long time to inflate, cannot be carried aboard the airplane, complicates infrastucture because balloons, helium and inflating equipment have to be available wherever the plane lands which pretty much cancels its operational autonomy.



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  • We’ll never run out of energy as 1.5 trillion barrels of oil energy equivalent fallout of the sky every day. We have dwindling stocks of helium on the planet, so we cannot throw the stuff away if it is to be important to us. (Disgracefully we squander the stuff at the moment, failing to notice that it is seriously needed elsewhere).

    The amount needed to lift an aeroplane is not only immense but immensely bulky. One litre of He lifts one gram in weight. A fully loaded 747 say would need half a billion litres of gas (the size of thre R101s) to reliably ascend if put into a magically strong and weightless balloon. (Three empty R101s weigh two thirds as much as a fully loaded 747. So we’ll need almost as much gas again to lift them and more weighty containers etc….) We need to figure out how to pump billions of litres of gas quickly back into bottle and bundle up the ballon. The gas back in bottles weighs a third of a fully loaded 747. And what about landing?

    Twenty R101s (filled with heavy lifting hydrogen) could lift themselves and a fully laden 747 into the air, drop it from say 10,000 feet and it could fly after an initial plummet morphing into a rather profound dive. At the other end the twenty R101s have a catching net between them. The deceleration from landing speed to zero in a few seconds would probabaly kill the remainder that hadn’t perished from the heart attacks after take off…



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  • Plus, since the balloon is released every time the plane takes off, all that helium is wasted.

    Couldn’t you have permanent lifting balloons which are attached to the craft to lift it and then returned to the ground ready for the next job?



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  • This would take a LOT of Helium. And it is expensive. And it would have a lot of drag at high speed.
    A booster aircraft would be better- one that could release the payload aircraft, turn around and land. Something similar to Elon Musk’s booster rockets.
    Wait- they already have this- RATO rockets. Except that they are junked afterwards. Especially when they power a Chevy Nova down the road at 400 mph! 😉 (yes- I know it’s an old urban legend)



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  • Ewan
    May 8, 2015 at 1:52 pm

    Would it not be greener to combine balloon and aircraft flight? Take off via helium balloons attached to the craft then, once an appropriate height is reached, the helium is released, a bit of gliding to pick up speed and then into standard aircraft mode.

    The point of swivel rotors, is that fixed wing aircraft need a very considerable forwards speed, or they stall and fall out of the sky.

    Balloons and airships are exceedingly slow, so provide poor launchers for such craft. They are also voluminous, presenting huge wind resistance and a large heavy envelope.
    Helicopters are slower than fixed wing aircraft, but swivel rotor craft make the transition to high speed fixed-wing mode, and then back again to rotary lift for lower-speed or vertical landing.



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  • 14
    NearlyNakedApe says:

    Couldn’t you have permanent lifting balloons which are attached to the craft to lift it and then returned to the ground ready for the next job?

    Sure but like Phil mentions below, you would need humoungous sized balloons to lift even a moderately sized aircraft because of the relatively low lifting power of helium.

    If you used hydrogen instead, then you would gain in lifting power and hydrogen IS plentiful on earth (although extracting it from water or other hydrogen compounds like methane requires energy and is costly – which in the end throws efficiency out the window). Plus, hydrogen is highly flammable and thus a major safety hazard.

    But suppose for a moment that we could have reusable balloons filled with a gas that has all the qualities of H and He and none of their disadvantages, we would still have all our work ahead of us in addressing the other issues: increased demands on airport infrastructure, takeoff setup time and as Phil mentionned, passenger comfort.

    The main idea behind a vertical takeoff aircraft is convenience and cost saving: eliminating the need for long airstrips which take up a lot of real estate and cost a bundle to build and maintain.

    If every takoff of a plane requires a balloon that takes a long time to fill and costs a bundle to do so, then a self-contained airplane that can take off on a dime at a moment’s notice using rechargeable batteries and a large number of electrical motors seems like a much more attractive solution.

    An added advantage for a high-altitude flying electric plane is the option of adding large solar panel arrays. It’s always sunny above the clouds during the day so whatever energy was spent for vertical takeoff runs a good chance of being recuperated during a long-haul flight.



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  • Helium is a finite resource. Once liberated from rocks, it escapes the earth’s atmosphere and disappears into space. It is extremely valuable for engineering and science reasons. Like all finite resources, it should only be used for the highest priority uses. It should be so expensive that it shouldn’t be used for a florist party balloon. We should value helium like gold.



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  • Much more than gold. From my link-

    Professor Robert Richardson, of Cornell University, New York, who won the Nobel physics prize in 1996 for his research on helium, argues that a helium party balloon should cost £75, to reflect the true value of the gas used.



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  • The amount needed to lift an aeroplane is not only immense but immensely bulky.

    I know you’re talking about helium but isn’t the question of weight ponderously more relevant to the battery powered plane itself? This thing weighs 55 pounds. What is the combined weight of the batteries? I also noticed the synergy motors are electric-diesel hybrid. How far can it fly on electricity alone? and how far with the “assistance” of the internal combustion engines? How “big” would the airplane including batteries + diesel motor + covered airframe have to be to carry four 200 pound marines – lifting an 800 pound payload?

    The article leaves many questions unanswered.



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  • Sorry, the plane is completely battery-powered -no diesel engine involved. Weight is also 62 -not 55- pounds.
    Does anyone know about payload and weight specifications for larger battery powered proto types? I understand ion lithium batteries are very heavy. And most crucially, what is the range under 100% battery power? I wish the article had provided such basic info. My neighbor plays with a small four corner prop “toy” version of this concept.



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  • The plane is diesel powered. This drives a generator giving the opportunity for very fine and instantaneous control of the ten motors. The very small battery I proposed (that I think) they would include would provide a few minutes only for a safe vertical descent in the event of a diesel genset failure. Diesel has the same energy density as jet fuels like Jet A.

    Generator and electric motors at these rating are in the high nineties of percent and electric transmissions are quite as efficient as mechanical ones with that much increased opportunity for finessed control but also the safety of better managed redundancy.



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  • 20 R101s’ and a 747’s worth.

    This could be the ultimate theme park ride.

    The French proposed people could get into box ten at a time and be dropped from the second stage of the Eiffel Tower into a very deep pond, when it first opened. Then they came to their senses.



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  • Sorry, Melvin, I didn’t really answer your question about batteries. Lithium is still currently the best for this. (Lithium is very lightweight. Its possible though that graphene electrodes may ace it in terms of conductivity and available surface area.)

    Energy density for diesel is 48MJ/kg. Rechargeable Lithium ion is currently about 1.3MJ/kg, but various varients have been demonstrated at 9MJ/kg. So short haul stuff only even when using these latter batteries.

    An astonishing fraction of longhaul aircraft weight is jet fuel (46MJ/kg). A third or so…



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  • 23
    NearlyNakedApe says:

    @Phil

    The plane is diesel powered.

    Which plane are you talking about?… The GL-10 prototype in the video is 100% electric.

    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…

    Could this be the sentence that misled you?



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  • The intended plane is diesel powered and that is the design I first commented on as it is the most rational and immediately useful. The battery powered model prototype only makes sense at present to quickly validate systems. Scaled up all electric has no commercial life pending the advent of viable (and huge ultra high capacity) battery systems except in some modest niche applications.



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  • Good niche application, Len!

    Its a great way to develop such technologies until better batteries come along. VTOL brings extra demands on the battery with very high powers being needed at take off and landing. This is akin to EV cars needing to be able to do regenerative breaking. Ultra capacitors do this (with added weight and cost). The ultra high charge (and discharge) rate batteries/capacitors like the new nano-dot and graphene batteries could be just the thing used alongside the new high capacity lithiums…



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  • 27
    old-toy-boy says:

    Would it not be greener to combine balloon and aircraft flight? Take off via helium balloons attached to the craft then, once an appropriate height is reached, the helium is released, a bit of gliding to pick up speed and then into standard aircraft mode.

    Not really, it would waste a lot of helium, However it does me an idea. How about a big helium balloon permanently tethered to the ground via a tetrahedron of cables to ensure stabolity in winds. Then aircraft could ride up one of the cables like an elevator to a decent height, (of say about 1 km) and let go. It would also help financially stimulate the developing technology for space elevators.

    Personally I think the idea of very large catapults at airports, with sufficient grunt to put a fully laden Jumbo jet (minus the take-off fuel) at an altitude of 1Km would be greener, quieter, and bloody spectacular. (Any rich person or organisation out there want to fund my research and development?).



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  • Kind of like the Osprey but uses 8 engines for lift 4 on each wing instead of having only 1 large prop on each wing. Possibly with computerised control it may be easier to control on take off and transitioning to level flight with the multiple engine configuration avoiding the type of problems that the Osprey experienced especially earlier on.



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  • 29
    NearlyNakedApe says:

    Sorry Phil, I thought you were responding to Melvin’s comment that the plane is all-electric. Melvin was, like me, referring to the GL-10 prototype while you were refering to the as-of-yet unbuilt full-blown diesel-electric model (GL-20?). We were talking about two different birds 🙂

    This makes me wonder though… Since the energy density of diesel fuel is about the same as that of jet fuel, what’s the advantage of opting for a diesel-electric system versus a conventional turbo-prop system? Wouldn’t the added weight of a diesel engine+generator plus the inevitable losses of chemical–>mechanical–>electrical–>mechanical energy conversion place the overall design at a disadvantage?

    Wouldn’t a multi-mini-turboprop airframe be more energy efficient since the conversion is a single stage chemical–>mechanical process?



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  • 30
    Andrew says:

    He mentioned the Harrier, and I would lump the Osprey in there as well, as being very inefficient. Wasting that much fuel is alright for the military, who can justify wasting that much money, but for practical applications it just isn’t, well, practical.



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  • 31
    Andrew says:

    When you start researching those catapults, be sure to start a youtube channel. You could probably fund half the project from the advertising hits you got from all the views of your early prototypes! 🙂



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  • 32
    Andrew says:

    I would also add, how do you generate enough forward momentum to keep the plane airborne after detaching the balloon? The drag of the balloon would negate most of the energy used to create that forward thrust, possibly to the point where you might as well have just taken off from the ground in the first place.



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  • 33
    NearlyNakedApe says:

    Kind of like the Osprey but uses 8 engines for lift 4 on each wing instead of having only 1 large prop on each wing.

    Yes, it makes sense to spread the workload of lifting the airframe over 8 smaller engines than 2 big ones. And computerized control for accurate power distribution across the engines makes it much easier to pilot.

    One design hurdle though: multiple motors on the wings means you have to go for a tilt-wing design (vs. the Osprey which is a tilt-rotor design). On a small lightweight prototype like the GL-10, this is easy to implement but on a bigger heavier airframe with more powerful engines, the load-bearing demands on the wing-to-fuselage hinge mechanism go up exponentially. Beyond a certain size and weight, the multiple engine tilt-wing approach could eventually become unworkable.



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  • @nearly

    Sorry for the confusion. I’d started by talking of the diesel design intention (then added some potential for more confusion by adding a little battery for backup) and in my usual aspie solepcism thought everyone knew what I was talking about as I had thought my thoughts quite clearly.

    Electric generators and motors at these powers are hugely efficient now and can quite match mechanical transmissions for efficiency especially if any gearboxes are involved. The power switching is awesomely good and the response time for altering the power of each motor is going to be an order of magnitude faster and with much greater resolution than a mechanical system. This will make the inherently unstable machine a doddle to bring under computer control, deskilling the pilots task also.

    Using electrickery in this way also opens out the engineering effort to multiple implementations as time and invention unfurls. Electricity might come from a diesel genset, a turbine and genset, a fuel cell using hydrogen or methane or ammonia, a Polonium 210 stirling engine and genset (well…) lithium+ batteries, ultracapacitors, flow batteries, zero point casimir generators (welllll…). AA cells…inertial storage…ATP/glucose drawn from the weightier passengers…

    I have to live with this brain.



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  • It seems the electric plane is moving from concept prototype to commercial development!

    https://www.bbc.co.uk/news/science-environment-44853242

    A solar plane which can stay aloft for weeks at a time is to be manufactured by Airbus in the UK.

    The unmanned craft flies high in the atmosphere to avoid commercial air traffic and adverse weather.

    Known as the Zephyr, its remote-sensing potential has already seen the UK MoD invest, but Airbus also hope to develop the craft as a communications platform.

    The Zephyr will now begin industrial production in Farnborough, after several years of testing.



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