Electra Tests Hybrid-Electric Propulsion System


Electra.aero announced last week that it has successfully completed a fully integrated test of its hybrid-electric propulsion system. According to the company, the technology was developed for its nine-passenger electric short takeoff and landing (eSTOL) aircraft concept. Propulsion system testing was conducted at Electra’s facility in Switzerland.

“Tightly coupling airframe and propulsion systems is the hallmark of Electra’s unique and scalable approach to providing net-zero emissions for regional and transport-category aircraft by 2050,” said JP Stewart, Electra vice president and general manager. “Electra’s eSTOL aircraft uses this patent-pending technology for the urban and regional aircraft market, allowing a reduction of the 5 billion tons of CO2 created by inefficient ground transport in personal cars every year.”

Electra says its hybrid system, which is currently being integrated into the company’s demonstrator aircraft, uses “a combination of high-power battery packs and a turbogenerator to power eight electric motors and propellers.” For its nine-passenger hybrid eSTOL design, Electra is targeting a 400-NM range, 2,500-pound payload and 175-knot cruise speed. The company is participating in initiatives including NASA’s Advanced Air Mobility (AAM) National Campaign and the U.S. Air Force’s Agility Prime program.

Kate O'Connor
Kate O’Connor works as AVweb's Editor-in-Chief. She is a private pilot, certificated aircraft dispatcher, and graduate of Embry-Riddle Aeronautical University.

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  1. “Electra says its hybrid system, which is currently being integrated into the company’s demonstrator aircraft, uses “a combination of high-power battery packs and a turbogenerator to power eight electric motors and propellers.”


    So its a gas turbine engine with added weight and expense and complexity?

    • Yes, which allows it to distribute power the eight propellers, which in turn allows for considerable design versatility.

  2. “unique and scalable approach to providing net-zero emissions”
    Probably an electric motor driving a generator producing electricity to drive the motors hooked up to some propellers . . . and there ya go. “net-zero emissions” Heck . . . I thought that idea up as a kid. Dad told me it wouldn’t work so I didn’t pursue it.

  3. If the batteries are recharged on the ground, using good Swiss hydro electricity, (no means sure, the country suddenly realised this year how dependent on Russian gas it is), it seems one auxiliary power unit sized turbine, plus batteries, will be enough to turn eight props, instead of one large turboprop or two medium sized ones. So kerosene burn and CO2 produced cut by 50%? Probably not more. Still better than nothing.

    • The batteries are undoubtedly charged on the ground, and are probably well drained during the power intensive “V” part of the eVTOL cycle. The advantage of hybrid power is that the batteries can be recharged during level flight when the vertical thrusters aren’t required, to be ready for use during the vertical landing phase.

      This all means that you can substantially reduce the size (and weight!) of your battery pack.

      • Solution in search of a problem. Ditch the ‘V,’ and use a normal runway. Otherwise this will be a slightly more efficient helicopter, but still less efficient than an airplane.

        • I didn’t realize it before, but this already ditches ‘V’ in favor of ‘S’ and does use a short runway. Their secret sauce is to use full width blown flaps, with four props on each wing distributing the propwash along the width of each wing.

  4. “Notice they no longer state “carbon dioxide” but only “carbon”, most government school educated people think there is a difference.”

    Probably because it’s been called “The Carbon Cycle” since the 18th-century. But then I went to a “government school” but we always called it “public school”. Which I guess means a “non-government school” would be “private school” where out-of-touch liberal elites get their training according to prevailing ‘wisdom’.

    • Let’s examine the edumakashun of our most recent United Skates Precedents, shall we ?
      Richard Nixon went from a Quaker college (undergraduate…which he attended after rejecting Harvard College of Harvard University to help at home in Kalliphornia) then on to Duke Law School.
      Gerald Ford’s law degree was from Yale University Law School [you know, that place Justices Kavanaugh and Thomas matriculated after graduating from (please research their educational “bona fides”) Private Elite Colleges]. By the way, Ford worked his way through Yale Law coaching two sports, one being Football).
      George Herbert Walker Bush attended Yale College of Yale University after serving as The Youngest Navel Aviator in combat flying from aircraft carriers in the Pacific Theater during WW II. Prior to Military Service he graduated from an Elite Boarding Prep School for which his Father wrote tuition, room and board checks! (Look up the School; I will not do all the research for you.)
      TubeSteak Willie Clinton graduated from Georgetown University (Not that Kentucky college of the same name!) then went to Yale Law where he obtained a degree (do you perceive a pattern here) after being a Rhodes Scholar at Oxford U in LimeyLand (uh…nothing Elite there, correct?).
      George W. Bush (he who once or twice or three times pronounced “election” as “erection”…really, he was caught on video and film doing so), graduated from one of the two Phillips Academy institutions (his alma mater was the Massachusetts one not the New Hampshire off-shoot). Then Georgie Porgie went to Yale College for his Bachelor’s degree and Harvard for an MBA.
      Obama Rama went to Punahou School In Hawaii (the oldest private Preparatory School in all of the U S of A; even older than Boston Latin and Germantown Friends Academy in that Quaker State City…shudder). Then he attended Occidental College in Kalliphornia until he was discovered for his mental acuity and received a full ride to Columbia University (not a college in Chicago) in New York City (which institution claims to be older than Harvard, having begun as Kings College in the early 1600’s). Hint Columbia is Also Privit. Then, ObiWan graduated with a Bachelor’s from Columbia and later took a law Degree from Harvard Law (you know, the place where Chief Justice John Roberts and others on the High Court…as well as Ted Cruz obtained Juris Doctor degrees.)
      Let’s pause a moment and recall that Justices Gorsuch and Kavanaugh graduated from Georgetown Prep before going on to Ivy League institutions such as Columbia (Gorsuch) and Yale (Kavanaugh) for Bachelor’s degrees and Harvard Law (Gorsuch) and Yale Law (Kavanaugh). Oh, that’s correct, Neil Gorsuch took a Doctor in Philosophy (D.Phil) degree from Oxford University (no, not in Mississippi) in Oxford, England on a (General George C.) Marshall Scholarship.
      Now let’s move on to President Tremendous (the self-avowed most Intelligent Prexy ever). Donald Johnson-Bar Trumpeter attended New York Military Academy in New Windsor, New York (can you say Cornwall-on-Hudson, boys and girls?) where he received an award for being the most tidy Cadet (mainly for bed making and being neat and orderly). Following NYMA, DonJohn (a name his Federal Judge sister gave him at some point), matriculated at Fordham University (private and Jesuit Roman Catholic), supposedly transferring to the University of Pennsylvania’s Wharton School of Business from which he said he graduated. Penn, as it has become known over the years since being founded by Benjamin “Kite-Flyer” Franklin in the 18th Century, is private and one of 7 Ivy League Universities; it ain’t Penn State, mate!
      Now, Joby Bidun has a law degree from another Private Law School known as Syracuse Uni (the school that has given Jim Brown and Ernie Davis of Football and Lacrosse fame; every significant Sports Announcer and Aaron Sorkin, screenwriter extraordinare, to the world.
      So…Tucker, or is it Sean, please do your research on The Elites (both Presidential and Educational) before talking trash.

    • There seems to be a general consensus building that hybrid makes more sense for aviation. It’s too bad the “Climate Change” grift obscures the real advantages of electric propulsion. As for the next 30 years: The V-12 Liberty engine of 1917 developed 400hp and weighed 400lbs. Twenty-two years later in 1939, the Pratt & Whitney R-2800 radial engine produced 2000hp with a weight of 2,350lbs. R&D is sort of like compound interest; it works away in the background until suddenly you’re happily surprised.

      • Hybrid systems that I’m familliar with work best for intermittent (burst mode) applications of power. My airplane on the other hand does it’s flying thing at around 75% continuous power. Maybe “aviation hybrids” are needed simply because batteries are so much heavier than fuel?

      • So…one pound per horsepower during WW I went downhill to (let’s see HP divided by Pounds…or is it Pounds divided by HP). And then Torque turns propellers, doesn’t it? If accurate, we experimentalists have been eating the incorrect Kibbles ‘N Bits nourishment all these years in order to save money for Prius-like conversions of Jodels, S-19’s
        and CH650’s !!!

    • The best possible theoretical battery, according to the laws of physics, will only be about 1/10th the energy density of jet fuel.

  5. Personally, I think they need more steel in their test platform! One thing is for sure – problems are scaleable!

  6. It’s no dumber than the pictures floating around the internet of a Tesla Model S being recharged on the side of the road by a generator on a flatbed.

  7. From the looks of it, that contraption will never fly. Ah, I say it’s a joke son. Anyone who minimally follows the international news knows that Europe is in a deep energy crunch and headed for an even bigger one, and will be using coal, methane, diesel, wood and just about any combustible material they can find to heat their homes run their factories and charge their electric cars. Cars that themselves may be free of direct carbon dioxide emissions if you do not account for all the petroleum energy it takes to produce them and their batteries and the charging source energy. The whole concept of a fossil fuel free energy world is so far from reality and practicality that it just as farfetched and impossible as pregnancy in men.

    • Well, those kilt-wearers in Scotland have been fiddling around with wave-action power generators for Years (as they and Norway engage in even more North Sea oil extraction!). Wave Action sounds and looks like a dynamite idea; but, then, so is solar-powered desalination of Pacific Ocean water for California farmers now dependent upon the Colorado River (and South African cities such as Capetown which sits on the south Atlantic Ocean and appears to have a water crisis from time to time to time to time…).

  8. Somehow I fail to see how a 9 passenger commuter aircraft is going to replace the approximately 150 million personal cars and light trucks on US highways. It’s not like I am going to take it to run errands or even drive it to work. Some of these PR guys get a little carried away with their hyperbole. Plus, he is assuming that we will all be using that mythical “sustainable aviation fuel” that is supposed to replace the roughly 300 million gallons of gasoline and diesel fuel burned in the US every day. I’m still waiting for the plan on how we accomplish that without using all of our available farm land to produce fuel instead of food.

  9. Another stupid (or intentional) misuse of the term “net-zero”. It isn’t truly net-zero unless the source of ALL its power is “carbon-free”, and nothing practical is, except nuclear power, which the European greenies don’t like.
    Unless they’re going to scam us with the “carbon offset” fraud, that turbine engine is going to produce some CO2 emissions, whether they admit it or not.
    Are that many people really dumb enough to buy into this crap?
    The story might be reasonably interesting if they come up with a decently efficient hybrid setup, which is how “electric” aviation will HAVE to be done for the foreseeable future. The only other alternative is a quick-change battery pack that can be swapped out as quickly as a liquid-fueled airplane can refuel. Then multiple packs can be swapped around and charged while the airplane is flying on one of them.
    Otherwise, it’ll fly once, and sit for 12-18 hours recharging (NOT “carbon free”) while the plane is useless.