Why Electric Airplanes Face Such A Tough Haul: Joby Edition


Electric airplanes are coming at us a mile a minute with claims that seem to defy the laws of physics and maybe even Ohm’s Law. In this AVweb video, Paul Bertorelli takes a critical look at what most people in the industry consider to be a leading contender to own the urban air mobility market: the Joby S4. It’s a remarkable design and appears surprisingly mature. But can it make it through FAA certification on Joby’s claimed schedule? And will the imagined volume in the thousands ever materialize?

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  1. Great even-handed video. More unknowns still exist than known for a new air taxi system. One note though, Lord Kelvin was wrong. Heavier than air flying machines were gliding before 1895 so I get tired of the irony of it being used to put down knowledgeable people.

  2. It’s all about money Paul. Always has been and always will be. Even the feds don’t have enough to make this thing happen. If there was a remote glimmer of hope here, by the time you see the light you won’t know if it’s dawn, or, dusk. You can’t wait forever for a return on investment. Even the feds have their limitations.

    • The idea that the word “sustainable” is being tied to a technology that is based on RARE Earth metals overlooks one salient point: REM’s are rare.

      The limiting factor has always been that electric is voracious fo a very limited resources that cannot be replaced, synthesized, or grown. It’s a dead end.

      • “REM’s are rare”

        Except that they aren’t – see Wiki’s REM article (with citations, of course).

        REMs are reasonably plentiful, but haven’t been economically attractive to mine in the past.

        • “ REMs are reasonably plentiful, but haven’t been economically attractive to mine in the past.”

          Translation: they are in the earths crust, either so deep or scattered that they cannot be economically obtained. If they are too expensive now to strip mine out and process, guess what happens when 93 million new cars a year demand them?

  3. Very well done analysis. One aspect of electric vehicles that is rarely discussed is where will the electricity come from for all these electric vehicles? The sun? Wind? Coal? Natural Gas? Nuclear? If you look at the latest legislation before Congress, it is filled with measures to kill off fossil fuels, so that leaves sun, wind and nuclear. How many solar panels will be required to charge a VTOL? What size windmill? What if the sun is not shining or there is no wind. These are very unpredictable sources of energy. That leaves nuclear. When was the last time we heard of a nuclear power plant being built? Then you have the NIBY (Not In My Back Yard) syndrome.

    • People should ask Germans how they feel about energy supply this winter – running quite short because:
      – solar and wind fail to produce a lot
      – Germany rashly shutting down its nuclear power plants
      – France does not have enough nuclear power capacity to help everyone enough
      – Germany restarted coal plants but ran out of coal
      – dependent on ex-KGB goon Putin not shutting off natural gas taps a she salivates ‘re-uniting’ Ukraine with Russia (though he does need the income from NG sales)

      Perhaps the new Chancellor will be wiser.

      (As for intermittent power sources, big battery banks are needed for a cost. (Germany does have many coastal areas suitable for some wind power, but how much is that of total need?)

      Almost amusing is that a key executive of the terrorist group Extinction Rebellion has flipped to supporting nuclear power. Quite a few eco-goons like it as better than fossil fuels (in their minds at least).

  4. I agree with the economic challenge and I think it eventually will be an eclipse type story. however I think there may be a smaller niche for this technology if only for the wealthy user where time is really worth a lot of money and getting from down town to the airport is worth a lot. . but the really big obstacle is the battery technology. until we develop a technology with at least 4X the power pr pound and quick charge or quick change batteries this is a long way from being useful for the average person.

    I think what may eventually kill this application is when we get the ability to transmit our three D image and feel electronically so we can actually be at a meeting virtually and shake hands with a person and have that same feel as if we were actually there in person. web transmission of us is not limited by the physics of weight and distance.

  5. the crazier and more outlandish the claims the easier it is to get money from clueless investors that somehow believe that the Apple miracle is possible any where with any impossible design that looks strange and violates the laws of physics. a good example in the diesel engine world is the “ecomotor” that was a remake of an old idea but looked very strange. it received lots of money because it looked different and had a good promoter in the front.

    If you compare it to the EPS diesel aircraft engine saga that actually was tested and met its design objectives but looked too normal and did not have the grand visionary promotor running the show you can see the effect. EPS augured in because it did not make outlandish claims and it had a non promoter at its head who refused to work with outside money

    • Is there more to the EPS story? I couldn’t understand how it could fail if it lived up to the published specs.

  6. Red ink will wash runways, as hasty developers and outright slimy promoters take advantage of naivite.

    I call it ‘DelCom’. 😉

    That’s on top of the restaurant-like phenomenon – everyone wants to have their own (design), few succeed, even those who do sell few. (A few are smarter – Ranns for example, another I forget name of, I don’t know how many kits Darryl Murphy has sold but 129 Renegades in 1989 was a good start. (Business was for sale as Darryl wants to retire. Emphasis is on utility for the boonies and more, relatively recent option was racks to carry bicycles, I presume already had canoe racks for larger airplanes, planned to get LSA approval for one model.)

  7. I believe in the Power of the ‘Homebuilder’. One of the eVTOL outfits need to introduce a kit and show some black ink on their books. Give us naysayers something to chew on.

  8. Good presentation with a well rounded narrative and data. I think the e-contraption, as is, will dissolve. The idea 💡 will stay.

  9. I wondered where you were and why we here had to endure a protracted period and an all time high blog count arguing over whether to mask, or not, on airliners prior to the Holiday. Now I know … you were assembling still another educational, entertaining, interesting and — best of all — totally relevant discussion of the foibles of eAV’s … at this time. I especially enjoyed the reference to ‘Harry Hair-on-Fire;’ I see a lot of him in myself. 🙂 GREAT job. Do YOU do the cartoon work or do you have it done by others?

    As good a job as you did — number one being the accident rate discussion — I see still other areas of concern not addressed. Dana Nickerson brought up one of ’em … where is all the juice gonna come from when all the vehicles needed to run the world are sucking off the teat of an antiquated electric transmission grid powered by a part time supply of fairy dust ? Beyond that, what’s the plan to recycle all the tens of thousands of used Joby batteries, et al? And, here’s another. Just yesterday, I retired my old iPhone for a new one after just four years. So what will become of all the worn out (by all the use they envision) and no longer state-of-the-art Joby’s? At least aluminum can be reclaimed; what about composite structures? I still have my first Packard Bell 1GB computer available if anyone is interested? And what happens to support for these flying ubers when Joby folds? These entrepreneurs who are blinded by their own pie in the sky ambitions are starting to wear thin on most of us. There are SO many yet unanswered questions.

    See: wired.com/story/cars-going-electric-what-happens-used-batteries/?

    I spent over 25 years supporting flight test at Edwards AFB. In all that time, I never heard of or saw a chart graphically depicting empty weight fraction as a function of takeoff weight as a qualitative depiction of structural integrity. I’m gonna run that by one of my test pilot buddies to see if the Test Pilot school used such an analysis in their curriculum. Excellent depiction of why we all know that LSA’s are just … too damned light! I KNEW they shoulda called ’em Flycatchers. 🙂

    • Battery recycling–so-called circular manufacturing–is just coming out of the ground and will be the only way EVs sustain and grow. I’m not a customer for an EV until that is in place and all the external costs are incorporated. Right now, most Li-Ion is disposed and that just can’t go on. I’d just as soon have a more efficient ICE.

      To answer your question…I have no help on any of these videos. I do every f^%$**& pixel push myself. Which is why they take so long.

      • You do a superb job and I figured you’d say that. And, you make me laugh, too 🙂 Esp the subtle humor. I — for one — appreciate your hard work. Thanks.

        Some guy in Finland took his Tesla in for service and was told the car needed a new $23K battery. It peeped him off so he took the car to a safe place and blew it up !!


        Wait til they start blowing up useless Joby’s! I’m with you. IF it becomes necessary, I’ll get a super efficient car. AND … I’ll be judicial in how often I drive it. I already am. I predict that at some point, the regulators will start taxing us by the miles driven.

        • They already do tax us that way, Larry, except that they do it indirectly by how many miles/gallon our vehicle gets through the gasoline tax. Unfortunately, as ICE vehicle get more fuel efficient and hybrids and full electrics use little or no fuel, the highway trust fund is no longer able to pay for highway maintenance and construction. So at some point they will have to switch to a tax based on miles driven to keep money flowing into the trust fund. That is fine by me, because, like you, I put only about 4,000 miles a year on my vehicle. The big losers there will be hybrid and electric vehicles that get a free pass under the current system, and no, they shouldn’t get a break because they emit less air pollution.

      • Found this AM … “20 Drawbacks of of Electric Vehicles Drivers Overlook”


        Square it — or more — for eAV’s !! MOST predominantly … energy density as discussed ad nauseum and the impact of induced and parasitic drag on any vehicle at higher speeds.

        • I read through your linked article, and I can honestly say that I’ve never read such an ill-informed, ludicrous, moronic, just-plain-false smear job on electric vehicles – ever.

          Do you honestly believe those claims?

      • Brilliant video Paul. You nailed it.

        Keep your eye on Redwood Materials for battery recycling. Led by Tesla’s long time CTO and close to their Reno gigafactory, expect them to lead the way. https://www.redwoodmaterials.com/about

        Personally I’m going to slap my old EV battery on the side of the garage and use it for back-up power if I ever need to replace it. 9 years and 172k so far with 8% degradation, so not sure I ever will.

  10. Improving the large cargo trailer I use as home at Airventure late last summer, I bought an inverter to turn 12 volts dc into 115 volts ac for a few items that need that form of power. Then, it hit me … why couldn’t I just plug a battery charger into the inverter to REcharge the battery? I would no longer be dependent upon the grid; the process would be an endless loop of power! I wonder if Mr Joby has thought of this? His flying ubers could fly forever and the range problem would be solved 🙂 I better patent the idea before he steals it. Seeking venture capitalists!

    • Larry, if you’re going to be ‘Green’ about it. Put a light bulb over the solar panel and a fan blowing on the wind-generator. I’ve had the windmill on the roof while driving a Tesla conversation several times. Physics class is just not what it use to be. 🙁

      • Actually, I think Joby could accomplish a similar objective by putting one of those old fashioned wind generators on the Joby. While they’re flying the things, they could be recharging the batteries. It’d be a bit like regenerative braking on a Prius. Great idea, Klaus.

  11. Electric driven airplanes, there may be a few around saved for a collector, (EDSEL) but will not survive the long haul. Vehicles, yes because the government wants EVs. The government don’t give a rats a@## about planes.
    If electric vehicles are so great where are all the electric Harley Davidson Live Wire for $30K. The only reason Harley is still producing the Livewire is because they finance it with the gas motorcycle sales.
    Some people are so rich they can afford to go to space, not because it’s a good idea, because they have lots of money. Kinda like our Government.

  12. A US professor published the “hype curve” for the usual trajectory of the next new great technology. I would suggest EVTOL is at the very beginning of the curve, so it will be interesting to see how this plays out.

    One item not mentioned was the inconvenient fact that most part 135 accidents involve bad weather. Today I am looking out the window of my apartment. It is snowing lightly, with a howling wind and SIGMETs for severe icing and severe turbulence. On demand means the Joby shows up every time you get the iPhone out an order one. Not a problem in sunny California, a potentially big problem in the NE and NW.

    Finally finds folks to drive (I won’t deign to call it “flying”) a Joby probably won’t be that hard, finding folks to maintain the thousands of these things is another matter. As a certified Part 23 aircraft used in Part 135 operations they will have to be maintained by certified technicians working at a FAA approved repair station.

    The so what for traditional GA is, IMO , non trivial as I can see them basically sucking up most of the people who maintain our airplanes

    Finally there was no mention of segregation of airspace. GA is going to get squeezed out of urban airspace as the deep pockets of EVTOL and drone operations, grab it all

    • Good point about hype curve.

      ‘There’s a sucker born every minute.’ comes to mind.

      (Technically, Mr. Barnum said ‘There’s a customer born every minute.’ Same thing since out of many births there’ll be a sizeable quantity of suckers.)

  13. You didn’t mention fuel burn. As the aircraft burns fuel, it gets lighter. Dead batteries weigh just as much as a fully charged battery.

    • Excellent point about weight of batteries.

      I don’t understand why previously sensible operators like Harbour Air and Helijet are dabbling in electric airplanes, other than they depend on BC Gummint employees to fill their seats VancouverVictoria BC.

      That’s why some people promote the other fools’ game of hydrogen fuel.

  14. So many commenter on “will electric airplanes ever be practical.” So many would be EV aircraft producers claiming a practical aircraft is “right around the corner”—and of course, soliciting “development funds.”

    Time to put old-fashioned Capitalism to work. Las Vegas has legal betting—you can wager on most any outcome—and the “house” will set odds (and of course, keep a percentage for themselves). You can even bet on the performance itself—like the point spread in a sporting event—the “Over—Under” spread.

    What are the odds that Joey (or anyone else?) demonstrates a practical craft that will fly 4 people 300 Mn at 160 knots or more?

    What are the odds in getting it certificated within the stated time frame?

    What are the odds on getting it into production in the stated time frame?

    The betting market will put a stop to wild claims. If anyone REALLY BELIEVES the claim—they stand to make a fortune. If nothing else, it will discourage these wild claims—and stop those unfamiliar with the aircraft certification and marketing processes from losing their investment.

    For me—I’m inclined to “short” the investment.

  15. Although I find the whole electric airplane thing interesting, and follow it, the reality is that however it turns out is immaterial to me because (a) the timelines dictate that I’ll be dead before anything is resolved and (b) I likely wouldn’t ever have any real reason to participate in the urban air mobility thing anyway.

    Still, what does bother me as being a potential disaster for my children and their children is the growing socio-political acceptance of embarking wholesale on “electric” initiatives which have one obvious show-stopper problem that as yet has no clear pathway to solution. I speak, of course, of the energy storage issue. While the implications of the storage problem are easy to see when analyzing the practicality of electric airplanes, it is equally problematic with the plan to basically remake civilization by going 100% solar/wind as mankind’s primary energy source. Yes, there are ways to temporarily store power on a national-grid scale but all are inefficient and at the required scale immensely costly and resource intensive. Danger, Will Robinson!

    • Problem is irrationality of climate catastrophists, who operate on emotions from a very negative psychology toward other humans.

      With a controlling do-gooder mentality.

      Humans cannot cause runaway climate warming, because the ‘saturation effect’ of emissions of the greenhouse gas molecules carbon dioxide and dihydrogen monoxide vapour limits temperature rise from more CO2 to a small amount most of which has already been realized.

      Humans are not causing runaway climate warming, according to accurate thermometers such as weather balloons and satellite sensors, and tide gages collated in PSMSL.org.

      Climate continues a slow rise from the end of a cool era circa 1750AD, the end of a period that drove Viking farmers out of southwest Greenland. Warmer is better for humans and our food source – plants (whether directly or via converters such as animals, birds, and fish). More CO2 is good for plants.

  16. Great, balanced and insightful as always, Paul.

    I wonder how much if the eventual market for eVTOL will simply be traditional urban helicopter users transitioning to what may eventually be a lower-cost (and at least seemingly higher-tech) solution? Will these be new customers or simply existing customers moving in a slightly different way, making legacy helicopters obsolescent?

    • Well, perhaps very small helos, as people are using small electric cars for short-distance commuting.

      Recharging is key, some automotive fleets can recharge often. Some automotive uses do not need much range – postal deliverers now have little vans from which they walk around the neighbourhood, servicing people stay in one place for hours. (University of Washington has long used modified golf carts for servicing and minor landscaping work. Golf is an excellent example of the usefulness – frequent starts without need to warm engine up.)

      • If you go to the golf cart stores in The Villages, FL and ask ’em whether electric or gas carts are more popular … they don’t even have to think about it … “gas.”

        And, replacing all six batteries costs as much as $1,500 or more. Not as bad as a Tesla but — still — ya better have a battery replacement fund in a jar somewhere. For a “small electric car for short distance commuting,” I’d imagine replacement would ‘hurt.’ Therein lies the conundrum.

        • Flooded lead acid has been around for a very long time, gelled lead acid for a long time.

          (Gel used in motorcycles and mobility scooters.)

          Fancy dancy newer battery technologies are expensive.

      • Have to hand it to Elon ‘The Mouth’ Musck – Tesla has put money into charging stations.

        A Flying J truck stop at the top end of the Fraser Valley of BC has a bank of Tesla-branded EV charging stations, perhaps 8 or more.

        Conveniently situated before substantial stretches of mountainous highways with long stretches between anything that could recharge you. (H1, H3, H5.)

        Smartly located where there are:
        – gas and diesel pumps for small vehicles (side area has pumps for big trucks)
        – convenience store in building
        – restaurant in building

        In more populated areas I’ve seen recharging stations with signage of other car brands like Honda/Nissan.

    • Great articles. Finally some common sense brainpower put down on paper. Or, I guess I should say, a computer screen. I’m showing my age…🤷‍♂️

    • The Part 23 rewrite was a consortium of interests including the international regulators and the manufacturing industry.

      • The reason I asked is — well — the influence of the manufacturing industry.
        My understanding is that one driver (formally stated or not) behind the rule change was to improve the certification prospects of aircraft that were not entirely fixed-wing — but were part of this hybrid model proposed by the eVTOL stakeholders (hope I have my acronym correct) as well as Urban Air Mobility.

  17. Fantastic analysis and video Paul. Conjecture aside, we flew into SGH last weekend to find Joby Aviation and Beta Air (N250UT) logos throughout the FBO, an EVTOL charging station on the ramp, a space-age styled Joby construction office trailer parked behind the FBO along with a Tesla/EV charging station and a Beta Flight Recharging Station (https://www.youtube.com/watch?v=eHoar1cCE54) that appeared ready for service. FBO staff said they’re launching in 2023. It’s called the Springfield-Beckley Advanced Air Mobility Project and a large sign credits multiple public and private funding entities including JobsOhio. SGH is pretty much in the sticks just NE of Dave Chappelle’s comedy theater in Yellow Springs and 20 miles from nearest major city Dayton, OH. FBO staff claims they’re going to deliver anyone to any major city in OH for $150.00. What they’re really planning we won’t know for a while, but if it’s about money, and it’s always about money, it’s probably going to happen. Revitalization and maybe evening reopening of some closed GA airports could be a huge win for all even if EVTOLs don’t reach the masses anytime soon.

  18. Lest we forget, vertical lift aircraft, “sky cars” have been in development for 40 years. The Mollar M400 Skycar is an example. It used gasoline powered Wankel engines not electric. However, after forty years and $100M, the Skycar only demonstrated tethered hovering capability in 2003. Gasoline still has the superior energy density as Paul has pointed out in several discussion on electric aircraft. 6 lbs of gasoline takes up 230 cubic inches and contains the equivalent of 36 kWhs of electrical energy. EVs store no more than the equivalent of 16-24 kWh of energy in a single charge.

  19. Thank you, Paul for pointing out that modern lithium batteries are actually rather delicate and temperamental devices. They don’t like to get hot, they don’t like to be deep discharged and they don’t like to be overcharged. Any of those three conditions will permanently shorten the life of the battery. Do it often enough and you will be facing an expensive replacement. Chemistry being what it is, we have taken the lithium style batteries about as far as they can go, at least on an econonomical production basis. There will be incremental improvements, but nothing that will put them on par with gasoline or jet A. So, unless or until a new storage technology is developed, electric aircraft will suffer from limited range and long recharge times. To paraphrase Bill Clinton, who always campaigned on the slogan, “It’s the economy, stupid”; it’s the batteries, stupid.

  20. Battery technology is the limiting factor in all electric vehicles. Today’s batteries all rely on chemical reactions which cannot match the power-to-weight ratio of internal combustion engines. We will need a completely different non-polluting power source before electric vehicles will become widespread and economically viable. I’m thinking of miniature fusion reactors or matter-antimatter annihilation engines, which we probably won’t see soon.

    Electric motors convert energy to motion about 3 times more efficiently than internal combustion engines, are much simpler and cheaper to manufacture, are much more reliable and interface with computer systems more readily. Hydrogen fuel cells produce about 10 times more energy than lithium ion batteries. Hydrogen is difficult to produce, store and work with but it seems to me that we would be better off focusing on and investing in hydrogen fuel cell technology powering electric vehicles rather than lithium ion battery technology.

      • Not really a fair comparison, Larry. Compare the explosion or fire danger of hydrogen to gasoline and your favorite 100LL loses every time. Airplanes won’t be flying around with a giant gas-filled bag made of canvas coated with a highly combustible paint. (The actual primary fire on the Hindenburg probably started with the canvas covering that then spread to the gas bags). If stored in a pressure tank using metal hydride technology, the gas would be released at a relatively slow rate. If stored as liquid hydrogen, any liquid spilled in an accident would quickly vaporize and float away. Gasoline, on the other hand, stays on the ground or covers occupants with flaming liquid. Hydrogen burns with a relatively low luminosity flame compared to gasoline that emits high levels of radiant heat to injure nearby people. About half the occupants on the Hindenburg survived the wreck due to that factor. As Andrew said, the main problem with hydrogen is producing and distributing it on a large scale. The technical hurdles for using it have largely been solved by NASA for use as a rocket fuel. Having said that, I wouldn’t look for airplanes using hydrogen fuel cells any time soon. I can just imagine the hoops the FAA would impose on that technology!