back to article NASA charges up 18-prop electric X-plane

NASA is working towards getting an electric-powered multiprop experimental aircraft off the ground, with an eye to future "greater fuel efficiency, improved performance and ride quality and aircraft noise reduction". The Sceptor (Scalable Convergent Electric Propulsion Technology and Operations Research) project will …

  1. Voland's right hand Silver badge

    It will be interesting to see the results...

    I find it difficult to believe that a gazillion of propellers do not create a hell of a drag.

    Granted, you can play with the boundary layer around the wing this way which you can do only to a very limited extent with a normal prop, but still... this looks like a contraption from a Studio Gibli flick

    1. phuzz Silver badge
      Boffin

      Re: It will be interesting to see the results...

      I'm guessing that the drag due to a propeller is related to it's surface area? As all the propellers are very small I'm guessing there could be even less drag than a single large prop.

  2. Eddy Ito

    "Tests so far show the distribution of power among the 18 motors creates more than double the lift at lower speeds than traditional systems."

    Shouldn't that be expected since essentially the entire wing now experiences a higher airflow over the wing due to it being almost entirely in the propwash?

    I look forward to the results of this research as I expect the asynchronous thrust across the wing to produce interesting data.

  3. Daedalus Silver badge

    100 kW?

    "To put that in perspective, 500 kilowatts (nearly 700 horsepower) is about five times as powerful as an average modern passenger car engine."

    Actually better than 15 times more powerful, based on your average 1-litre 30 kW engine. Of course these are American engines they're talking about, but even so 140 hp is one heck of a motor. You could put it in a light aircraft.

    1. Rabbit80

      Re: 100 kW?

      Since when was the average horespower around 40? Would barely get you up to motorway speed!

      1. SkippyBing Silver badge

        Re: 100 kW?

        I've got a 2 litre diesel in my car which allegedly produced 160hp when new. A Mini 1000* might produce about 40hp but that has an engine from the stone age.

        *The original British one with a 998cc engine not the German thing the size of a small county.

      2. Captain Scarlet Silver badge

        Re: 100 kW?

        "Since when was the average horespower around 40? Would barely get you up to motorway speed!"

        *Sure you can, my old banger (Nissan Micra with a manual 4 speed gearbox and 1.0 engine) could get to 70mph (*With careful timing of going to the next gear to keep momentum going.)

    2. Anonymous Coward
      Anonymous Coward

      Re: 100 kW?

      I think it's a reasonable comparison. A good modern family car has at least 100kW.

      A 1 litre 30kW car is a low-end vehicle for teenagers, pensioners and people who can't afford to run a proper car. It's a thoroughly miserable driving experience that struggles to pull its own weight up any kind of hill in any gear.

      140hp maybe have been considered "one heck of a motor" back in 1982. But a normal 1.6 or 1.8 litre hatchback will do that nowadays. My wife picks the kids up from school in an ordinary family estate car with 240hp.

      1. This post has been deleted by its author

      2. ravenviz
        WTF?

        Re: 100 kW?

        family estate car with 240hp

        That's handy then.

    3. Sorry that handle is already taken. Silver badge
      Headmaster

      Re: 100 kW?

      So the definition of "average modern passenger car" obviously depends on which country you're in when you ask the question. But the "modern" part excludes a lot of old and hilariously underpowered junk.

      However, if you ask an Average Australian what an Average Car is, they'll rightly say "Toyota Corolla" (Auris to you Europeans), which here has 103kW.

      QED!

      (They might say Holden Commodore though, which starts at 185kW, but let's forget about that one.)

      Also, no modern naturally aspirated 1L engine should have much less than 75kW.

      1. Jan 0

        Corolla vs Auris

        ? "Toyota Corolla" (Auris to you Europeans)

        Wot? What is this Europe that you speak of? Autotrader is full of Corollas, but I've never heard of an Auris. However, I see that Autotrader is also full of Aurises. I conclude that an Auris is not a Corolla. Disclosure: I'm in the UK, which has been part of Europe since time immoral.

        1. x 7

          Re: Corolla vs Auris

          as far as I'm aware, most Corollas are built at Sunderland

          1. werdsmith Silver badge

            Re: Corolla vs Auris

            @x7 "as far as I'm aware, most Corollas are built at Sunderland"

            I'm looking hard at this trying to get the joke, but it's flying over my head I think.

            Are you saying Toyota Corollas are built at a Nissan Factory ? Or is there a hidden joke?

            Toyota UK manufacturing is Burnaston, Derbyshire for cars, and North Wales for engines.

            1. x 7

              Re: Corolla vs Auris

              werdsmith

              no not a joke......I got my Jap plants mixed up. I meant the Derbyshire plant

              apologies for the confusion and thanks for picking up my mistake

        2. PJF
          Joke

          Re: Corolla vs Auris

          ? "Toyota Corolla" (Auris to you Europeans)

          "Wot? What is this Europe that you speak of? Autotrader is full of Corollas, ..."

          I'm sure he made a mistake, it's not a Corolla, but a "creamed-over". Lil'l things like that, like a stone in your tyre ,a "Fit", "Smart", or a "Leaf" make that unforgettable sound.. tick.. tick.. tick.. thunk, when it finally flies out...

          (still drivin' the '91 Cheby 3500 4x4 w/5.7l [350 c.i.] {with MAYBE 20 BHP, down hill, with a tail wind} gas guzzlin, oil eatin, grease drippin, anit-freeze spewing, brake-line leakin', pay-check robbin, winter-beater, POS...[can't find ONE panel that's not rotted out])

      2. Sorry that handle is already taken. Silver badge

        Auris? Corolla?

        I didn't realise that the sedan hadn't changed name but the hatchback appears to have been badged as an Auris over in that part of the world for almost ten years now. Do you still call these ones Corollas?

  4. Richard Scratcher
    Boffin

    "Specially modified truck"

    Seriously? There's no way that thing is going to get airborne, not with all those people in it.

    1. 's water music Silver badge

      Re: "Specially modified truck"

      Seriously? There's no way that thing is going to get airborne, not with all those people in it.

      I assume it "transforms" into a more aerodynamic configuration before it takes off

  5. Jagged

    First flight of hydrogen-powered drone with water vapour exhaust

    More interested in this:

    https://www.newscientist.com/article/2076536-first-flight-of-hydrogen-powered-drone-with-water-vapour-exhaust/

    1. inmypjs Silver badge

      Re: First flight of hydrogen-powered drone with water vapour exhaust

      Hydrogen is a stupid chemical fuel, but at least it is chemical.

      Lithium batteries have a 60:1 energy density problem compared to chemical fuels. Even with the relatively high efficiency of electric motors you are left with a worse than 10:1 problem (you use more fuel to carry more fuel).

      Electric planes will have less than 1/10th the range or carry more than 10 times more fuel. Being mostly charged with coal they are not green and unlikely to be for years. All round stupid.

      1. Shadowmanx2012
        Happy

        Re: First flight of hydrogen-powered drone with water vapour exhaust

        Ah, but when we get over our "phobia" about nuclear energy, then this plane could be powered by a compact reactor.

        Probably a fusion one but this will be a *little* way into the future.

        1. Sorry that handle is already taken. Silver badge

          Re: First flight of hydrogen-powered drone with water vapour exhaust

          Nuclear reactors are heavy, and that's without the radiation shielding!

          1. allthecoolshortnamesweretaken
            Coat

            Re: First flight of hydrogen-powered drone with water vapour exhaust

            Duh, just use unobtainium... *rolls eyes*

          2. Shadowmanx2012
            Boffin

            Re: Nuclear reactors are heavy, and that's without the radiation shielding!

            Yes fission reactors are now. Fusion reactors of the future may not be!

            And even fission reactors may get smaller and lighter, though what they will use for shielding I have no idea!

        2. Alan Brown Silver badge

          Re: First flight of hydrogen-powered drone with water vapour exhaust

          "this plane could be powered by a compact reactor."

          Or it could be charged by a much bigger reactors driving a Haber process that makes synfuels.

          Making a compact nuclear reactor was always easy. The hard part in aircraft has always been making radiation shielding effective enough to keep the meatsacks alive whilst light enough to allow the aircraft to actually leave the ground.

          1. x 7

            Re: First flight of hydrogen-powered drone with water vapour exhaust

            the russkies did actually have a bomber flying with a nuclear power plant fitted as a trial installation, though I don't believe it powered the aircraft

            As you say, shielding was an issue, as also apparently was premature fatigue of the airframe structure due to the irradiation

      2. PJF

        Re: First flight of hydrogen-powered drone with water vapour exhaust

        "Being mostly charged with coal they are not green .."

        Totally agree with you, BUT, the US uses mostly "Black Gold" to run the spinning parts in electrical generation. The other part of "mostly" is natural gas, and hydro (Niagara, Hoover)

      3. John Brown (no body) Silver badge
        Joke

        Re: First flight of hydrogen-powered drone with water vapour exhaust

        "Lithium batteries have a 60:1 energy density problem compared to chemical fuels. Even with the relatively high efficiency of electric motors you are left with a worse than 10:1 problem (you use more fuel to carry more fuel)."

        Maybe it needs to be a multi stage aircraft? Have a bigger "lifter" to get the whole lot into the air, then the smaller part can separate off and do the actual flying and landing part. NASA have form with this type of design. They might want to have a word with Elon Musk about getting the 1st "lifter" section back on the ground in a way that it can be re-used again though.

        NOTE: See icon. I'm not being serious. I know about White Knight, modified 747s carrying shuttles, B52's carrying/launching rocket "X" planes and even biplanes launching from airships.

  6. Chemist

    " but even so 140 hp is one heck of a motor."

    I'd imagine it's about high-ish average-ish even in the UK . But more to the point where are they going to get 500 kW of battery power that will get them a reasonable range as well. It's about 5/6 Tesla batteries at ~500kg each for about 1 hrs duration flight ( I know doubtless cruise will be much lower consumption )

    1. werdsmith Silver badge

      142PS, or 140BHP is pretty average in the UK, even a bit low now.

      1. Sorry that handle is already taken. Silver badge

        I think it depends on the motor. A 750cc sports bike engine producing 140hp is definitely one heck of a motor, but you probably wouldn't put that motor in a car. Could make fun out of a kei or supermini though.

        But a 140hp motor in a normal car built in the last 30 years is not likely to be one heck of a motor.

  7. Graham Cunningham
    Joke

    The goal is a worthy one, and you won't solve the problems by not trying ... so "props" to them.

    1. Anonymous Coward
      Anonymous Coward

      Enough props to make at least 4 decent-sized drones apparently ;)

  8. fishman

    Merican HP

    In the US, the average car would be like the Toyota Camry, with 178 HP. 140 HP is typical for the next size down.

    Gas was $1.63 / (US) gallon at the local station yesterday. It's even cheaper in some parts of the country.

    1. John Brown (no body) Silver badge

      Re: Merican HP

      Cheapest UK price I've seen is £0.977 per *Litre*, about $1.46 or $5.53 per US gallon or £4.44 per UK gallon (A UK gallon is about 20% bigger than a Texan gallon :-))

  9. Michael H.F. Wilkinson Silver badge
    Pint

    I do want to compliment these boffins

    both with the creativity of their research, and their creativity in cooking up acronyms

    BRains Invent Lasting Legacy In Artistic Names for Technology (BRILLIANT)

    Raises pint and doffs hat (the black Mayser Trekking today)

  10. Evil Auditor Silver badge
    Trollface

    TL;DR but that truck is never going to take off.

    On a more serious note, this looks like a variation of blowing your own sail. Except this seems to work somehow.

    1. Eddy Ito

      Blowing against your own sail does actually work if it's done right. The comic interpretation is to blow directly into the sail in an attempt to derive force from drag alone which obviously doesn't work. What does work is if the sail is angled and treated like an airfoil which provides force, effectively lift, in a direction largely orthogonal to the prevailing wind. Of course some of the wind has to actually fill the sail so it forms an airfoil but the principle is the same. It actually works a treat on wingsails of the type used in the America's Cup.

  11. Cynic_999 Silver badge

    I'd be interested in what they propose to use to supply that sort of power, what range they predict the aircraft will have, and what recharge time it will need (assuming rechargeable batteries rather than fuel cells).

    1. MD Rackham

      Hybrid!

      Most of what I've seen talks about actual use of this is in a hybrid configuration. Use batteries to power the motors for takeoff, then switch to conventional turbofans for cruise at which time they can also recharge the batteries.

      Or use both electric motors and turbofans for takeoff. That allows the turbofans to be optimized for cruise without the high-power requirements that takeoffs currently require. The idea being improved fuel burn and less noise.

      And probably coming to commuter planes a long time before you see an electric A-380.

    2. John Brown (no body) Silver badge
      Mushroom

      "what range they predict the aircraft will have"

      I hope it has good gliding characteristics.

  12. Turtle

    Or...

    "Sceptor (Scalable Convergent Electric Propulsion Technology and Operations Research) "

    Or...

    Sceptre (Scalable Convergent Electric Propulsion Technology and Operations Research)

    "Operations" can really be omitted entirely.

    1. John Brown (no body) Silver badge

      Re: Or...

      SPECTRE - Scalable Propulsion, Electric Convergence Technology REsearch

      Every villain should have one.

  13. x 7

    1) An asynchronous motor is a specific type of induction motor, nothing to do with them being independent.

    See

    http://machinedesign.com/motorsdrives/whats-difference-between-asynchronous-and-synchronous-motors

    and

    http://www.groschopp.com/synchronous-vs-asynchronous/

    Quite common on railway locomotives. Its basic technology that a tech journal should be aware of.

    2) With that number of props, I'm surprised there's enough clean air going over the wing to generate lift. I really would have expected the airflow to be too turbulent to be any use

  14. TJ1

    Folding props, less drag, more lift, lower stall, smaller wing

    LEAPTech:

    "In this design, eighteen electric motors are mounted in nacelles regularly spaced spanwise along the wing leading edge and drive propellers that increase the dynamic pressure over the wing during takeoff and landing. The propellers spin at relatively low tip speeds to minimize noise. Propulsion in cruise flight is outside the scope of this analysis, but is intended to be fulfilled by a combination of some of these propellers, separate propellers mounted on the wingtips to take advantage of the wingtip vortex, and/or a separate propeller mounted on the tail boom to take advantage of the fuselage boundary layer. Any of the leading edge-mounted propellers not required for cruise propulsion fold at against the respective nacelles to minimize drag."

    ...

    "One distributed electric propulsion (DEP) configuration that shows great potential is named Leading Edge Asynchronous Propellers Technology (LEAPTech) and features many small propellers distributed spanwise along the wing that blow the wing during takeoff and landing. This increases the dynamic pressure over the wing, facilitating lower stall speeds and/or reduced wing area without the need for structurally complex traditional multi-element high-lift systems. If the stall speed requirements are retained, a significantly smaller wing may be employed, because the wing is typically sized to meet takeoff and landing constraints. This smaller wing can result in a large reduction in cruise drag as well as substantially improved ride quality due to decreased gust sensitivity."

    Aviation Technology, Integration, and Operations Conference, 16-20 June 2014, Atlanta, Georgia

    "Drag Reduction Through Distributed Electric Propulsion"

    See: http://www.jobyaviation.com/LEAPTech%28AIAA%29.pdf

  15. TJ1

    Design Roadmap, Testing, in-depth technology insight (schematics, etc.)

    "Hybrid Electric Integrated System Testbed (HEIST) and Full Scale Testing Update of the LEAPTech Wing"

    http://nari.arc.nasa.gov/sites/default/files/attachments/Gibson-TVFW-Aug2015.pdf

  16. Pen-y-gors Silver badge

    That reminds me of something

    With all those props should it be called the Spruce Gosling?

    1. allthecoolshortnamesweretaken

      Re: That reminds me of something

      Me too... weirder things have cruised the skies:

      http://www.aviation-history.com/articles/nuke-american.htm

      http://www.scientificamerican.com/article/nuclear-powered-aircraft/

      or may be someday:

      http://www.businessinsider.com/boeing-just-patented-a-jet-engine-powered-by-lasers-and-nuclear-explosions-2015-7?IR=T

    2. druck Silver badge
      Coat

      Re: That reminds me of something

      It reminds me of the old pilot joke about how many engines a plane should have. The captain says well if there is an engine failure, I want the co-pilot to tell me that it was engine number 9, and then I'll ask is it number 9 on the left or right wing?

      Still not keen on flying anything batter powered though.

      1. x 7

        Re: That reminds me of something

        "Still not keen on flying anything batter powered though."

        that sounds a bit fishy

      2. Anonymous Coward
        Anonymous Coward

        Re: That reminds me of something

        That's what she said!

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