back to article Rolls-Royce, Airbus, Siemens tease electric flight engine project

British aero engine maker Rolls-Royce will team up with Airbus and Siemens to develop hybrid electric-powered flying machines, it has been announced today. Speaking at the Royal Aeronautical Society in London, the trio said their intention was to have a demonstration engine ready by 2020, called the E-Fan X. The BAe 146 demo …

  1. Anonymous Coward
    Anonymous Coward

    Advantages

    Assuming they can do this are there advantages to a hybrid powered electric jet engine?

    Or is it just greenwash?

    1. Steve Todd

      Re: Advantages

      They can use a smaller generator and run it continuously at it's most efficient speed. Extra power needed for take off can be stored in batteries and replenished while in flight, and you need run only a single generator rather than two or more engines in order to qualify for multi-engine operations requirements.

      1. wayne 8

        Re: Advantages

        Single generator is a single point of failure. Which defeats the purpose of multiengine.

        1. Steve Todd

          Re: Advantages

          >Single generator is a single point of failure. Which defeats the purpose of multiengine.

          They only need to RUN a single generator. A smaller, lighter backup generator could be fitted that is started in case the primary fails. While it is cycling up the batteries can take the load. It should still be a lighter system than having two or more full power engines.

          The other option is to have enough battery capacity to allow flight to an emergency landing site (you don't need anything like full power for that).

          1. macjules Silver badge

            Re: Advantages

            Ah, a bit like a Boris Bus then?

            1. 1Rafayal

              Re: Advantages

              What about the weight of the batteries?

              I am not nay saying the idea of an electric plane, I quite like the idea personally. But what is the landing weight of a long range jet liner at the moment? Surely they burn most of the take off weight during the long flights they undertake?

              If you start flinging batteries into the equation, wouldnt that make the landing weight of the plane heavier than a traditional fuel burning plane? Especially given that it would also carry a generator and the fuel to power it? Or is all of this balanced out so the total weight of the plane plus fuel is less than that of a fuel burning plane with its tanks full?

              Need a ginger ale now...

              1. SkippyBing Silver badge

                Re: Advantages

                'But what is the landing weight of a long range jet liner at the moment? Surely they burn most of the take off weight during the long flights they undertake?'

                That is a pertinent point, currently a lot of long range airliners have to either burn off or dump fuel if they have to make an emergency landing early in the flight as it's not designed for the stresses of landing at Max All Up Mass (MAUM). So they either have to make the aircraft capable of landing at closer to their MAUM, which adds weight to the airframe and reduces the cargo capacity (fuel & passengers) or they have to accept a lower MAUM which means reduced cargo capacity...

              2. Yet Another Anonymous coward Silver badge

                Re: Advantages

                Conceivably it would make sense to run the bypass fan electrically with the compressor stage driving the generator. Might be cheaper / lower maintenance / better control than the gearbox needed for a 3 spool engine

          2. Mark 85 Silver badge

            Re: Advantages

            The other option is to have enough battery capacity to allow flight to an emergency landing site (you don't need anything like full power for that).

            Unless of course, the plane misses the threshold and needs a go around.

            1. scarper

              Re: Advantages

              >> The other option is to have enough battery capacity to allow flight to an emergency landing site (you don't need anything like full power for that).

              > Unless of course, the plane misses the threshold and needs a go around.

              And this is worse than a jet gliding into the airport, you're saying ?

          3. Alan Brown Silver badge

            Re: Advantages

            "The other option is to have enough battery capacity to allow flight to an emergency landing site "

            EBOPS ?

      2. Alan Brown Silver badge

        Re: Advantages

        "They can use a smaller generator and run it continuously at it's most efficient speed"

        Aircraft engines are sized for this anyway. It might make sense to use one core to directly (or electrically) drive a fan in front whilst electrically driving another but that's the kind of added complexity you probably don't want on a wing (you'd need a 10-20MW generator on the back of the core) and putting the core inside the fuselage comes with a staggering set of negatives (the weight on the wing and positioning of the engines happens to be "just right" to keep flutter in check so major redesigns would be necessary and that's quite apart from losing space for revenue cargo and the added risks if there's a turbine failure)

        One of the simplest ways of improving gas turbine efficiency both on AND off-max-load performance is to fit a recuperator but that's only ever done on Marine and land-based turbines (weight isn't the issue, they're bulky but not heavy) - because an aircraft engine is usually operated at full load for most of its cycle the recuperator doesn't get nearly as much benefit as in ground-based applications (especially boats, which seldom run at full power for prolonged periods.)

        1. Anonymous Coward
          Anonymous Coward

          Re: Advantages

          "...because an aircraft engine is usually operated at full load for most of its cycle..."

          This isn't the case, at least for multi-engined commercial aircraft. The performance required at take-off and during climb is greater than that needed for cruise1 and furthermore, the aircraft needs a surplus of performance during take-off and initial climb to cope with engine failures during these phases.

          1 During take-off and climb you're accelerating and lifting weight against gravity, increasing both your potential and kinetic energy states; during cruise you're just sustaining those states.

      3. PNGuinn
        Coat

        Re: Advantages

        "you need run only a single generator rather than two or more engines"

        = single point of failure. Just sayin'.

        And where do the passengers sit?

        >>Thanks, it's the long silk one neatly packed up on the shelf above the hook.

    2. Anonymous Coward
      Anonymous Coward

      Re: Advantages

      Or is it just greenwash?

      A combination of that and niche applications. Even if you could get the energy density of jet fuel in a battery, the size and mass of an electric drive of equivalent power to a gas turbine would be prohibitive. Peak power from a big turbofan is around 50 MW, and a 747 or A380 uses four of those.

      If people want renewable aviation, then the simple and perhaps only answer is to have gas turbines running on jet fuel synthesised from renewable sources, whether that's renewable powered dissociation of water to give hydrogen, and processing that into some liquid fuel, or starting from vegetable oil or algal biofuels and refining accordingly. RR and Siemens know that, but since there's currently no efficient way of making renewable jet fuels in volume, it may be more expedient to go with the greenwash. You're probably aware that vegetable oil based jet fuels have already been proven, but the problem is finding the sorts of volumes that the aviation industry need (currently growing on course to reach a million tonnes of aviation fuel a day globally by 2020). From a UK perspective, our airline fuel use is equal to about one third of the fuel use of all UK road vehicles.

      1. Camilla Smythe

        Re: Advantages

        Or is it just greenwash?

        #Ledswinger

        "A combination of that and niche applications. Even if you could get the energy density of jet fuel in a battery, the size and mass of an electric drive of equivalent power to a gas turbine would be prohibitive. Peak power from a big turbofan is around 50 MW, and a 747 or A380 uses four of those."

        1HP = 750W

        2MW = 2,700HP

        https://www.energy.siemens.com/mx/pool/hq/power-generation/gas-turbines/RB211/industrial-rb211-gzero.pdf

        ... This is from Siemens, one of the partners.

        "For global oil & gas mechanical drive and power generation applications, the Industrial RB211 gas turbine systems have earned a market leading reputation as the most reliable and efficient in their class. Available from 37,465 to 45,316 horsepower at ISO conditions, more than 700 units have been sold, recording over 30 million operating hours."

        Call it 40,000HP which works out to be 30MW. Just confirming the numbers and I'll qualify the difference between 50MW and 30MW by suggesting that something on the ground loses some efficiency by not travelling at 500MPH such that it can gulp more air.

        However... The 'test bed' is an BAe 146...

        https://en.wikipedia.org/wiki/British_Aerospace_146#Engines

        https://en.wikipedia.org/wiki/Lycoming_ALF_502

        RB211 240KN

        ALF502 30KN

        Take 50MW down to 6MW.

        I'd still call bullshit, including my own guesses, but it does not seem totally beyond the bounds of something worth having a shit at.

        1. Anonymous Coward
          Anonymous Coward

          Re: Advantages

          RB211 vs Trent/Industrial vs Aeroplane

          Trent is the renamed followon to RB211. There are (were?) industrial versions of both families.

          When comparing the numbers for power output between aviation and industrial versions of "the same" angine, please bear in mind that (a) the industrial ones are massively detuned so they don't cost a fortune in servicing every few hours, unlike their aeroplane siblings which are so finely tuned that flying them through a volcano cloud is a high risk/high impact operation (b) the detuning also means that the industrial ones are a lot less fussy about the kind of fuel they use (c) the industrial ones don't have quite the same certification requirements and costs (etc).

          So they do have a lot in common, but the power outputs aren't that similar.

          Incidentally, RR stopped making/selling Industrial RB211/Trent. That's now sold by Siemens.

          The planes being talked about for this project are smaller planes, whose engines tend to come from RR Deutschland rather than RR Derby. That may also help if there's any EU money involved in this exercise. RR HQ get the money (one way or another), RR Germany get the jobs and the skills.

      2. bombastic bob Silver badge
        Devil

        Re: Advantages

        "there's currently no efficient way of making renewable jet fuels in volume"

        true. synthetic oil can be made from organic garbage, but I think it would cost 2 to 3 times as much as drilling for it (currently) costs. Eventually this will be the ONLY option, but I don't see THAT happening within the next 100 years...

        and by then, I'd hope we would have fusion reactors small enough to fit on a plane.

      3. John Crisp

        Re: Advantages

        "From a UK perspective, our airline fuel use is equal to about one third of the fuel use of all UK road vehicles."

        From a global perspective this is a much bigger problem:

        http://www.industrytap.com/worlds-15-biggest-ships-create-more-pollution-than-all-the-cars-in-the-world/8182

        That's just 15. A lot more where they come from.

        To keep a global economy running it is one that needs fixing sooner rather than later.

        1. Richard 12 Silver badge

          "15 biggest ships" - good headline, is false

          The headline was based on a prediction that in the near future the few biggest ships might emit more sulphur dioxide than all the cars in the world.

          Because they burn bunker fuel, which at the time had a very high sulphur content.

          It never considered any other pollutants or emissions.

          Bunker fuel now has a much lower sulphur content (though still much higher than road fuels) - which was what the original prediction was trying to achieve.

          In other words, the headline was utter tripe.

        2. Jim84

          Re: Advantages

          ""From a UK perspective, our airline fuel use is equal to about one third of the fuel use of all UK road vehicles."

          From a global perspective this is a much bigger problem:

          http://www.industrytap.com/worlds-15-biggest-ships-create-more-pollution-than-all-the-cars-in-the-world/8182

          That's just 15. A lot more where they come from.

          To keep a global economy running it is one that needs fixing sooner rather than later."

          Yes you are correct to point out that shipping is an even bigger problem than cars or planes.

          There is a proposed solution - use the 500 degree plus heat from a (yet to be built) molten salt reactor to produce ammonia from air and seawater. Then use that in planes and ships.

          1. Anonymous Coward
            Anonymous Coward

            Re: There is a proposed solution

            Stop importing finished product by boat from the other side of the world? Accept that "the polluter pays" isn't just a good idea, it's the only way that our kids kids will still be able to live here?

            Just sayin'.

    3. Anonymous Coward
      Anonymous Coward

      Greenwash?

      I think that this is more of a research project to develop and prove the electric engine and it's control systems, while we wait for battery technology to improve, than a proposal for a viable replacement engine for current or near-future aircraft.

      Basically, they're going to use a jet engine to power a generator, to power an electric motor, which means that you're going to need an additional nacelle for each generator1 as well as the normal engine nacelle, and this will mean additional drag. Then there's the weight trade-off: will the total weight of the electric engine, batteries and generator weigh less than the single engine it replaces?

      1 The generator, as well as needing its own inlet, will also need to dump its exhaust gas and although it could be buried in the fuselage, that would in turn mean lost fuselage volume and even more additional weight for the trunking and insulation.

      1. brain_flakes
        Boffin

        Re: Greenwash?

        > although it could be buried in the fuselage, that would in turn mean lost fuselage volume and even more additional weight for the trunking and insulation.

        That used to be a common configuration - https://en.wikipedia.org/wiki/Trijet

        1. Alan Brown Silver badge

          Re: Greenwash?

          Trijets were a pain in the arse to service due to the height of the rear engine above the ground.

          In the case of the DC10/MD11 that was a _very_ long way above the ground and the L1011's inlet duct came with its own sets of problems whilst only lowering the engine a small amount and significantly increasing cabin noise at the rear of the plane.

          The tristar was relatively sucessful because of its autoland and autopilot features, not the engine layout (and was nobbled by underpowered engines anyway - necessitating a 4th engine at the rear for takeoff on the later stretches)

      2. Doctor Syntax Silver badge

        Re: Greenwash?

        "Basically, they're going to use a jet engine to power a generator, to power an electric motor, which means that you're going to need an additional nacelle for each generator"

        It would depend on how big the motor is. Possibly the entire assembly could fit into a single nacelle.

      3. Anonymous Coward
        Anonymous Coward

        Re: Greenwash?

        It might have some use as a research project but it is pure greenwash. Too many people have been sucked in to the UN green agenda and think that being green is the way to go.

        All this does is add extra weight to the airframe for no useful purpose as you say. Large banks of lithium batteries are heavy and are a fire hazard that needs special treatment for safety, all of which adds weight which is not wanted in an aircraft because it reduces the amount of revenue generation for a given volume.

        The only thing going for this is that it appears to be 'a good thing' for these companies shareholders.

        1. Tom 64
          Facepalm

          Re: Greenwash?

          >" lithium batteries are heavy and are a fire hazard"

          And aviation kerosene isn't either of those things I suppose?

    4. Hairy Spod

      Re: Advantages

      Its a different set of pros and cons to the electrification of road transport. Any real world efficiency advantages (if there are any) probably wont be as big as they are on the ground. In aviation the real advantage of electic power will be a reduction noise espectially on take off and landing

      Battery weight is much more of a disadvantage in the air than it is on the ground. On the ground you mostly pay penalty for extra weight in the form of using extra energy to accelerate, but in the air you also have pay penalty in energy for every second you remain aloft.

      If the planes can take off and land on electric power alone, all of a sudden lots of airports can allow a larger number of flights especially at night which means lots more operational profits even if there no profits to be had from efficiency.

      1. Anonymous Coward
        Anonymous Coward

        Re: Advantages

        HS, I don't understand this "If the planes can take off and land on electric power alone, all of a sudden lots of airports can allow a larger number of flights especially at night"

        Can you elaborate?

        1. scarper

          Re: Advantages

          >> HS, I don't understand this "If the planes can take off and land on electric power alone, all of a sudden lots of airports can allow a larger number of flights especially at night"

          >> Can you elaborate?

          Noise.

          Dunno about 90-passenger regional transports, but two-person electric planes have been flown, and multiple reviewers (of multiple planes) all were thrilled about the reduction in noise.

          1. Hairy Spod

            Re: Advantages

            >> HS, I don't understand this "If the planes can take off and land on electric power alone, all of a sudden lots of airports can allow a larger number of flights especially at night"

            >> Can you elaborate?

            Planning regs and local legislation often limit the number of flights coming in an out of an airport out of consideration for local residents especially at night. This is especially true of city airports, which are precisely the sort of places the first smaller electrified (not fully electric) aircraft will excell.

            Wright electric think their electric aircraft reduce noise by 50% and fuel by 10%

      2. Alan Brown Silver badge

        Re: Advantages

        "In aviation the real advantage of electic power will be a reduction noise espectially on take off and landing"

        Turbofan cores are already remarkably quiet. The only way to make them quieter (and more efficient) is to spin the fans slower - which is why geared turbofans such as the LEAP are flavour of the decade and being fitted to newer airframes despite the weight and complexity of a planetary gearbox transmitting 50MW being fitted in front of the core.

        Slower fans also mean wider chord blades are doable (quieter) and variable pitch fans become possible (even quieter, can be feathered in the event of a failure = greater range in the event of an engine failure AND can be reverse pitched, which means no more heavy and noisy thrust reversers, which means mroe range or more revenue capacity.)

        Geared fans means that the rear turbine disc can be spun at a more efficient (higher) speed (the current speed is a compromise between efficiency of pickup and not spinning the fans too fast), which in urn means that a bunch of other optimisations can be made along the entire core, possibly including higher compression ratios and making the hot exhaust even quieter by extracting more energy from it.

        _Everything_ about aviation propulsion is a compromise. Gas turbines are 20-30% less efficient than piston engines, but they're lighter, more powerful and far more reliable.

    5. Paul Hovnanian Silver badge

      Re: Advantages

      One advantage not being investigated in this test is the flexibility in configuring the fans. Instead of two or four big turbine/fan combinations, one could have a series of smaller fans positioned in lower profile cowlings along a wing. They would be supplied by one or two (for redundancy) gas turbines that provide thrust as well as drive generators.

      Typical high bypass engines have a very large diameter dictated by the turbine core size surrounded by a single ducted fan. The electric drive moves the function of the ducted fan to where it can be configured optimally.

    6. bombastic bob Silver badge
      Meh

      Re: Advantages

      well, as I understand things, you'd need a "jet engine sized" generator to power electric jet engines, so I'd expect it adds weight to the plane.

      If, on the other hand, the engines are lightweight enough to allow OTHER materials to be lighter (such as the engine support brackets), it might be "a wash". But probably not.

      Until we've got small nuclear reactors that are capable of making the electricity to efficiently propel the plane through the air, I expect that pure mechanical systems (like turbofans) are better than hybrid electrical ones.

      1. IGnatius T Foobar

        Re: Advantages

        Until we've got small nuclear reactors that are capable of making the electricity to efficiently propel the plane through the air, I expect that pure mechanical systems (like turbofans) are better than hybrid electrical ones.

        You're correct, of course, but the same people who hate hydrocarbon fuels also hate nuclear fuels because they labor under the mistaken assumption that wind and solar are scalable, and will fight/tax everything else until they get their way.

      2. Alan Brown Silver badge

        Re: Advantages

        Flying nuclear reactors are a non-starter. The USA tests showed that by the time you added enough shielding so the crew wasn't killed, you had no payload. The Soviets just radiated their crews, who didn't last long.

        HOWEVER, the aircraft nuclear reactor research program begat the Oak Ridge Experimental molten salt reactor and these run hot enough to drive a Haber process efficiently enough to make hydrogen and then tack on a few carbon atoms for stability/handlability (ie, synthetic jet fuel).

        Which means in a roundabout way you _CAN_ have a nuclear powered aircraft.

    7. Anonymous Coward
      Anonymous Coward

      Re: Advantages

      Ha Ha. Ok, so in an industry where they try to literally shave every ounce off the weight of an engine in order to squeeze more bodies into a giant toothpaste tube, removing a direct drive mechanism and instead having a few tons of batteries, inch thick cabling, generator, backup generator and two giant electric motors really makes loads of sense.

      "But it's electric, so it's green, innit" Ha ha ha.

      So how will the "lightweight"(chortle) backup generator keep the batteries going? and how long would the batteries be able to provide 50MW? - I take it they'll be using Duracells.

      The difference between a car and an aeroplane is that aeroplanes don't tend to have to stop at traffic lights or junctions,which is where battery power in cars excels - i.e. in town driving.

      What a stupid stupid idea.

      I take it the companies are getting huge grants to develop these technologies? (Because if they are stupid enough to invest their own money, they'll be out of business in 10 years). Well, Rolls Royce will - Airbus and Siemens will be rescued by the EU.

      1. Alan Brown Silver badge

        Re: Advantages

        The shorthaul aircraft market is booming at the moment. The problem is that this is also a prime target for being eaten by electric high speed rail as fuel prices go back up to the levels they "should" be (about $200/bbl)

        Increasing oil costs and increasing pressure to decrease carbon emissions is going to push things like hyperloop closer to reality for passenger transport and even make the Silk Road Rail routes more practical than ships, despite the incredibly low cost per box of moving freight on a post-panamax boat.

        I wouldn't be at all surprised to see a Bering Strait rail tunnel for freight. The geology is more than suitable, what holds it back is politics and routing on the north american side.

      2. scarper

        Re: Advantages

        >> I take it the companies are getting huge grants to develop these technologies?

        No need for grants. Not everyone misunderstands the weights of things as badly as you do. A jet engine is much bigger than a turbine, and a gearbox that can transmit megawatts isn't light. Electric motors are light. Check out the NASA X-57 project. They expect a 60 kilowatt electric motor, plus its propellor, to weigh 57 pounds.

        In the states, the FAA has actually had meetings with all the companies exploring similar designs, trying to work out the regulatory framework before the tsunami hits. Heck, there's a startup that has pre-sold its first 25 planes.

      3. PNGuinn
        Joke

        Re: Advantages "I take it they'll be using Duracells." @AC

        So, only for short hops then.

        >> We need a wabbit icon.

    8. rh587 Bronze badge

      Re: Advantages

      In the case of Diesel-electrics (as used on trains, some large mining trucks and Cat's D7E dozer), it means you can tune the engine more finely to the target RPM of the generator instead of having to cope with a range of operating speeds.

      Additionally, in those cases you get the goodness of the electric motor's high torque, which tends to be better than the equivalent sized diesel.

      I assume they are looking at a similar principle here (smaller, better-optimised engine than otherwise needed), and perhaps the use of batteries can buffer the power spike on take-off/climb, reducing noise pollution?

    9. strum Silver badge

      Re: Advantages

      >are there advantages

      Quiet operation - especially useful near airports.

      1. Richard 12 Silver badge

        Re: Advantages

        Nearly all of the noise of a high-bypass jet engine comes from the large mass of air it moves.

  2. Christoph Silver badge

    Is this actually practical? Can they power electric aircraft over a reasonable range without either too much weight of batteries or a really long extension cord?

    1. Alister Silver badge

      @Christoph

      That's not what they are proposing, the electrical fan will be powered by an onboard gas-turbine generator.

    2. Anonymous Coward
      Anonymous Coward

      Possibly

      El Reg did this one before. The answer is a qualified - maybe. With current battery watts/kilogram you could, conceptually [subject to about a million ifs and buts and depending on inventing unicorn substitutes], do short range inter city style hops with reasonable payloads, defining reasonable as flying a 737/A320 weight aircraft, with normal passenger load, from London to Paris without exceeding the allowable all up weight of the aircraft. With improvements in watts/kilo in the future no doubt the practicality will increase.

      However the standard El Reg answer will be to say it's all pointless because it won't get from London to Sydney non-stop while carrying 1 tonnes of luggage per passenger, unlike the SS Unsinkable in 1904, etc etc.

    3. macjules Silver badge

      Well, yes they can. It's known as RyanAir.

      "STFU and pedal faster"

    4. PNGuinn
      Joke

      @ Christoph

      "Is this actually practical? Can they power electric aircraft over a reasonable range without either too much weight of batteries or a really long extension cord?"

      That's the advantage of hydrogen powered aircraft. The supply hose would be self levitating.

      Patent it. Form a company to develop it. Sell it to a gullible VC. KER-CHING!

  3. Jess--

    I suspect the jet powered generator will be running at a fixed speed / output and anything not consumed by propulsion will be dumped into batteries.

    for takeoff I would guess power would come from both batteries and direct from the generator but once airborne (where the power would usually be dialled back) the generator will provide enough power for flight and recharging of batteries (ready for the next takeoff or high power demand time)

    basically it's the plane version of a prius

    1. ArrZarr Silver badge
      Boffin

      No. A Prius has a direct powering of the wheels from it's engine, supplemented by an electric engine. This is more akin to a Fisker karma (or the Hammerhead Eagle i-Thrust) where the drive is purely electric with an onboard generator to power the batteries.

      Connecting the jets to a generator that would have to sit in the fuselage mechanically would be a nifty trick.

      1. Steve Todd

        Me thinks you don't know how a Prius works

        It has a planetary gear box with an input shaft from the IC engine, two input/output shafts connected to motor/generator units and an output shaft connected to the wheels.

        At low speeds, and with enough battery power in reserve, the MGs turn the wheels only. At higher speeds the ratio of power added or removed by each MG is used to control the speed of the vehicle (providing a CVT style transmission). When the IC engine is needed the MGs spin it up (along with keeping the wheels moving) before it is fired, thus removing the need for a starter motor and giving a smooth transition from pure electric to IC.

        There is no point at which both the IC and the electric motors aren't connected to the wheels, but the IC is only running part of the time.

        As for equivalent car type transmissions, the Chevy Volt/Vauxhall Ampera is probably the closest.

        1. bombastic bob Silver badge
          Devil

          Re: Me thinks you don't know how a Prius works

          the Prius' solution to electric hybrid drive is BRILLIANT. It solves nearly all of the problems [except cost].

          [eventually, I'd expect nearly ALL (decent) cars to be hybrids]

      2. themodeller

        BMW i3 REX

    2. Anonymous Coward
      Anonymous Coward

      basically it's the plane version of a prius

      Or a locomotive, which run diesels to turn a generator which powers the electric motors driving the unit.

      1. Alistair Silver badge
        Windows

        Re: basically it's the plane version of a prius

        there are a *lot* of watercraft going this route -- for some values of "efficient" (i.e where we have two straight props for propulsion and say four or six lateral props for positioning/manoeuvring) this is a far more efficient use of diesels. -- one needs two or three diesels turning gennny's charging batteries, the overall ship and powering the props. Most of these are cruise ships, but it is becoming common on large container craft due to sheer size. The diesels run at peak efficiency 100% of the time, and power is available on demand.

        1. Yet Another Anonymous coward Silver badge

          Re: basically it's the plane version of a prius

          I can't think of any big container ships that use azipods. Single speed props + direct drive diesels are way more efficient if you only travel at one speed and never need to maneuver.

          Cruise ships have azipods because they: reduce vibration, save internal space, are maneuverable to dock quickly in tight resort harbors and you need to generate metric fsck tons of electricity for all the shiny stuff on a cruise ship anyway.

  4. Graham Hawkins
    Coat

    Is the next version...

    ...going to be called the 'E-Fan(n)Y'?

    1. MyffyW Silver badge

      Re: Is the next version...

      If we're going with church names it's "M-Y-F-A-N-W-Y" and I claim prior art.

  5. Milton Silver badge

    "powered by batteries and an onboard generator using jet fuel"

    "The BAe 146 demo aircraft will at first have one of its four gas turbine engines replaced with an electric engine, powered by batteries and an onboard generator using jet fuel. The team will then move to two electric engines once the technology is stable."

    So—what's the point? A gas turbine generator, like the APU that provides auxiliary power for every modern airliner, is a machine for turning kerosene into electrical power. It's generally some form of turboshaft system. The turbofan engines you see under the wings of modern airliners are also a form of turboshaft, increasingly so depending on the bypass ratio: the more cold air shovelled round the core, proportionally the more work the fan is doing and less of the thrust comes directly from hot jet exhaust.

    Which leads to the obvious question: why use a kerosene fuelled gas turbine to generate electricity which you're then going to turn fans/props with, when you've already got a system for doing it *without* a generator and electric motors?

    Today's high bypass turbofans run at extremely high core temperatures to achieve unprecedented fuel efficiency. A gas turbogenerator will sacrifice some efficiency in converting its energy to electricity, and electric motors will sacrifice some in turning the freshly-minted electricity back into rotational energy. It's extremely difficult to see how you'll get more fuel efficiency by introducing extra conversion losses.

    The only light I can see here is if the turbogenerator has outstanding efficiency for recapture of energy and/or the engine's fans/props are regenerative, e.g. generating some electricity during descent. But I confess I am still deeply sceptical. What am I missing? Perhaps this is intended only for relatively slow, smallish prop planes ...?

    (And what kind of phenomenal electric motor can keep up with a turbofan pushing over a tonne of air every second—up to 100,000lb thrust?)

    1. Jonathan Schwatrz

      Re: Milton Re: "powered by batteries and an onboard generator using jet fuel"

      ".....But I confess I am still deeply sceptical...." A more sceptical mind might note the presence of Airbus and jump to the conclusion this is more EU protectionism/funding being passed off as "scientific investment". Personally, I'd be a lot more impressed if the wings and upper fuselage had embedded solar panels to help generate cruising power, but that might be the next planned stage of illegal EU subsidization - sorry, I meant scientific development!

      1. Def Silver badge

        Re: Milton "powered by batteries and an onboard generator using jet fuel"

        A more sceptical mind might note the presence of Airbus and jump to the conclusion this is more EU protectionism/funding being passed off as "scientific investment".

        Because Boeing never received any handouts from the US government in the past. And they most certainly didn't have Concorde banned from flying over the continental United States because their supersonic projects crashed and burned long before they even got off the ground. (They probably didn't directly, but I wonder whether that ban would have been pushed so aggressively if it had been a Boeing supersonic aircraft flying from coast to coast.)

      2. Lars Silver badge
        Thumb Down

        Re: Milton "powered by batteries and an onboard generator using jet fuel"

        "A more sceptical mind might note the presence of Airbus and jump to the conclusion this is more EU protectionism/funding".

        Sorry I don't quite get you message, give me your less sceptical take then. The simple fact is that the airline industry is international. The Boeing Dreamliner is produced in apart from the USA in Italy, Japan, Mexico, the UK and probably in a few other countries too. You find that on YouTube. Could it be that you have pulled your head up into the Royal British arse looking for an all British airline industry.

        Good luck, it doesn't work like that. RR knows it and so does Airbus and Siemens.

        Be happy as long as RR understands it too, (they will).

    2. Jess--

      Re: "powered by batteries and an onboard generator using jet fuel"

      I think the efficiency will come from running the single generator engine at it's most efficient speed / loading, where it can provide enough power for flight and some battery charging.

      if we assume that there will be on generator per electic motor on the plane we may end up with a plane flying on 4 electric motors but only running 2 generators rather than 4 jet engines

      with regard to the electric motor the plan is for seimens to build a 2MW motor (assuming 2MW = 2 MegaWatt rather than 2MW being a model No)

    3. graeme leggett

      Re: "powered by batteries and an onboard generator using jet fuel"

      Perhaps, and these are off-the-top-of-my-head,

      1) optimum engine-generator design for generating electricity plus electric motor has some advantages over optimum turbofan engine layout

      2) redistributing weight from engine pods to fuselage is good for "reasons"

      3) easier to put electrical fans in more advantageous locations on aircraft design

      4) it looked like a fun thing to try

      5) you can use additional sources other than volatile fuel for the electricity - coal, nuclear, solar

      1. Anonymous Coward
        Anonymous Coward

        Re: "powered by batteries and an onboard generator using jet fuel"

        you can use additional sources other than volatile fuel for the electricity - coal, nuclear, solar

        or, in the case of Ryanair, passengers on some sort of treadmill or exercise bike, hooked up to the engineering

      2. Charlie Clark Silver badge

        Re: "powered by batteries and an onboard generator using jet fuel"

        Perhaps, and these are off-the-top-of-my-head,

        And, perhaps, going forward avoids some of the compromises required in jet engines associated with the need to cool stuff right down and heat it right up.

  6. Anonymous South African Coward Silver badge

    Sceptical too - and from a safety point of view, the single generator = single point of failure.

    Wonder if the pilots will allow this sort of thing. Oh wait, they'll be replaced by an avionics computer flying the plane...

    Somebdoy's been watching too many podracing events on Tatooine...

    1. Neil Barnes Silver badge

      Avionics computer and four electric fans. Does that make it a drone?

      1. Charlie Clark Silver badge
        Thumb Up

        Avionics computer and four electric fans. Does that make it a drone?

        Yes, just don't tell the pilots!

    2. Charlie Clark Silver badge

      Sceptical too - and from a safety point of view, the single generator = single point of failure.

      You can easily have too of them and you also have battery backup. It won't get a licence for test flights without really convincing back up plans.

  7. Anonymous Coward
    Anonymous Coward

    When Frank Whittle looked at replacing a propeller on a plane - his first thought was to drive a fan inside the body***. It was quickly decided that this did not generate more thrust than a propeller. As it lacked the added lift from the propeller airflow over the wings - then it was probably a less efficient method.

    The design breakthrough was to inject and burn fuel after the fan. That thermal expansion is where the power is developed.

    The electric engines seem to be following the original path.

    ***Other designers had already tried that idea.

    1. John Sager

      Well, fan designs have improved a bit since Whittle's time so, as others have said, most of the thrust on a high-bypass turbofan comes from the fan. It's not outrageous to replace the jet core with an electric motor. I wonder why they haven't proceeded with a motor/generator integrated with the wing-mounted jets? That would give the same sort of hybrid performance as the approach that BAe are taking. Perhaps it compromises too many things (weight, diameter, length, etc) on the jet to do that.

  8. ijustwantaneasylife
    Happy

    And don't forget...

    If you have electricity on tap, it will probably be straightforward to put electric motors in the undercarriage. This means all ground based movement is much more economical and would significantly reduce airport pollution.

    Just a thought...

    1. Nial

      Electric motors in the undercarriage.....

      There's already enough juice to do that...

      http://www.wheeltug.com/

      I worked on the early electronic control for this. :-)

  9. Chris Miller

    Diesel-electric locomotives and petrol-electric cars have some efficiency advantages (mainly that the engine speed is decoupled from the wheel speed, so the engine can run in its most efficient range more of the time), but require significant extra weight compared with a mechanical transmission. Extra weight isn't a huge problem for ground transport, but is a massive (sorry) issue in the air.

    1. kmac499

      Diesel Electric trains also allow massive torque at the traction motors, enabling the initial move on big trains. (imagine slipping the clutch on a few hundred tonne)

  10. steelpillow Silver badge
    Facepalm

    Not a production design!

    This hybrid is about getting electric fans into the air and shaking down the technology, while keeping a pair of turbofans as safety backup. It is not a production design!

  11. MrKrotos

    So....

    Toyota prius with wings?

  12. MJI Silver badge

    I like the 146

    Great little plane

    And some big names behind this project.

    This is a test aircraft to trial the technology.

  13. kmac499

    I can imagine this hybrid tech appearing in drone aircraft well before passenger aircraft. Especially if offered with a stealthy battery only mode.

  14. noideas
    Holmes

    Elementary dear readers

    This test bed ticks a lot of boxes in the aviation world at the moment. Aircraft are swapping hydraulic power for electrical power (especially the military who want power for laser weapons and such like) so there is great interest in high output electrical generators. There is a lot of interest in electric propulsion, whether as a primary or supplementary source, though its anybody's guess as to how effective it would be in practice for other than niche applications. Finally, there is concern over the corona effect and other issues with running Mw of power around an airframe.

    If the three partners involved in this project were not doing this their investors would be asking why not!

    1. pmb00cs

      Re: Elementary dear readers

      Indeed. All the comments of "but efficiency" or "battery weight" why are we not happy with a technical demonstrator/research test-bed being used to move the state of the art forward? It's not like any of the partners in this process are saying that they are going to start mass producing this configuration for commercial operations. It is an attempt to develop the technology, and demonstrate it's feasibility.

  15. Stevie Silver badge

    Bah!

    The aircraft will be made lighter by filling the passenger compartment with hydrogen. Passengers will be required to use the oxygen masks throughout the flight, or breathe hydrogen for a 10% discount on ticket price. Passengers will also be required to wear (hydrogen-inflated) life vests for the flight's duration.

    Also, luggage will be sealed in airtight bags and injected with hydrogen before loading in the luggage bay.

    Which will then be filled with hydrogen.

    Also: Special hydrogen-filled "air-soled" Doc Martens air-travel boots.

    Undercarriage: Filled with hydrogen.

    Avionics bay: all hydrogen, all the time.

    All unused internal airframe spaces not dedicated to fuel and/or batteries will be filled with hydrogen. Fuel tanks will be purged with hydrogen as the fuel is burned.

    All courtesy of Siemens Chemical Division Applied Hydrogen Project.

    1. bombastic bob Silver badge
      Devil

      Re: Bah!

      "Filled with hydrogen"

      I assume it's a non-smoking flight? (for 'no smoke' I'd put up with the hydrogen)

      1. Stevie Silver badge

        Re: Bah!

        I haven't flown on an aircraft where smoking was permitted in over 20 years. I don't doubt that the airlines and airspaces in which one can light up are those in which no sane person would be caught dead anyway.

        So, not a problem.

  16. TechDrone
    Pint

    Just need to invent a real gigaconductor

    How may MAh would you need to run say a dozen flights of a 146 around Europe? Somehow I suspect even if using superconducting cable to recharge it will make the problem of recharging a street of electric cars look simple.

    Hats off to Mr Hamilton for the idea all those years ago.

  17. Wolfclaw Silver badge

    First step would be a hybrid multi-engine, two jets to do the heavy lifting and then electric while in flight, using the jets in a low power/fuel usage/emmissions mode to provide electricity.

    You could even go the old Tristar/DC10 config, jet in the tail and electric on the wings.

  18. Ken Hagan Gold badge

    No. Failure of the generator would not result in loss of power. You'd have however long the batteries lasted to make a safe landing.

    1. Anonymous Coward
      Anonymous Coward

      About 10 minutes, then.

  19. YARR
    Boffin

    Reusable ejectable assist fan

    If the objective is to allow smaller jet engines by assisting takeoff with electric motors, the saving will be offset by carrying the weight of the batteries and electric motor + generator for the full flight.

    To overcome this, the batteries could be jettisoned after they have done the assisted take-off. Going one step further, if the batteries, electric motor and assist propeller(s) were one unit they could detach after take off, switch into autogyro mode and perform a controlled landing, similar to a reusable SpaceX rocket. They would have to clear the air-corridor quickly to avoid delaying the next take off.

    1. Anonymous Coward
      Anonymous Coward

      Re: Reusable ejectable assist fan

      "the batteries could be jettisoned after they have done the assisted take-off."

      Where's Gerry when you need him? Anderson, obviously.

      Launch from rails and jettison booster mechanism at take-off was Fireball XL5 wasn't it?

      And nuclear powered aircraft was Thunderbirds,

      Where are the folding palm trees in this picture?

      1. Yet Another Anonymous coward Silver badge

        Re: Reusable ejectable assist fan

        Or just a giant elastic band - like the one they are going to use for navy's new carrier

  20. John Smith 19 Gold badge
    Unhappy

    Bottom line. It's a big ass hybrid.

    With all their strengths and weaknesses.

    It also demonstrates (like it was needed) that the most efficient store of electricity is in fact a room temperature liquid hydrocarbon connected to a turbogenerator, probably with a battery for load leveling.

    Which really should not come as a surprise.

    Now let's see how close this can get to M1.

  21. bep

    A pilot friend of mine told me

    that the 'BAe' part of BAe 146 stood for 'Buy Another Engine' but I don't think that is what is intended here. The modern high bypass turbofans seem to take up a lot of space, to the extent that the nacelles are flatter on the bottom to stop them striking the tarmac, so something like this might help with design. As others have said, potentially burying the fans in the wings, for example.

  22. DougS Silver badge

    Distribute electricity using cables?

    Too bad no one has figured out room temperature superconductors yet, so high amperage wires could be light. Since that's not the case, they'll have to carry extremely high voltages to distribute multiple megawatts or use very heavy thick wires. Either has its own set of problems to consider.

  23. x 7

    Electric transmission, not electric powered

    So the power is still going to be generated by a gas turbine, but the drive to the props will be by an electric transmission, not mechanical via a gearbox.

    Hard to see where the advantage is unless there's a big weight saving

  24. Aquatyger

    Jet fuel?

    Another advantage is that when the world's oil runs out, the aircraft could be converted to run on coal-fired electricity. To make it environmentally sound you could use clean coal.

  25. x 7

    Electrically powered aircraft are a technical dead end

    What is required is an more environmentally friendly jet fuel, like Boron hydride (Diborane)

    We know it works - the SR-71 used it, and the Russians also experimented with it.

    Make it via chemical synthesis, using renewable or nuclear to provide the power. OK it creates some interesting handling issues, but they are known and surmountable.

    The only exhaust from the Boron hydride would be water and inert finely particulate boron oxides, which would settle to ground.

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