Bye Aerospace claims to be able to make a 3-hour electric airplane

The founder of Bye Aerospace has written an IEEE Spectrum article about a 2-seat 3-hour trainer: “Cheaper, Lighter, Quieter: The Electrification of Flight Is at Hand”

I’m skeptical that this small company, founded in 2007, can do what has eluded Airbus and Pipistrel. But the editors of Spectrum are supposed to know stuff about electricity. So maybe this isn’t crazy.

It starts with a huge weight savings on the engine:

You rev the motor not with a throttle but a rheostat, and its high torque, available over a magnificently wide band of motor speeds, is conveyed to the propeller directly, with no power-sapping transmission. At 20 kilograms (45 pounds), the motor can be held in two hands, and it measures only 10 centimeters deep and 30 cm in diameter. An equivalent internal-combustion engine weighs about seven times as much and occupies some 120 by 90 by 90 cm.

Then there have been big improvements in batteries, supposedly, since 2007:

Bye Aerospace has worked with Panasonic and Dow Kokam; currently we use a battery pack composed of LG Chem’s 18650 lithium-ion batteries, so called because they’re 18 millimeters in diameter and 65 mm long, or a little larger than a standard AA battery. LG Chem’s cell has a record-breaking energy density of 260 watt-hours per kilogram, about 2.5 times as great as the batteries we had when we began working on electric aviation. Each cell also has a robust discharge capability, up to about 10 amperes. Our 330-kg battery pack easily allows normal flight, putting out a steady 18 to 25 kW and up to 80 kW during takeoff. The total energy storage capacity of the battery pack is 83 kWh.

A little fantasy doesn’t hurt:

Should something go wrong with the batteries in midflight, an alarm light flashes in the cockpit and the pilot can disconnect the batteries, either electronically or mechanically. If this happens, the pilot can then glide back to the airfield, which the plane will always be near, given that it is serving as a trainer.

This isn’t true even for pattern work at a typical busy training airport where the control tower might say “extend upwind two miles.”

13 thoughts on “Bye Aerospace claims to be able to make a 3-hour electric airplane

  1. I suggest if it is to serve as a trainer near airports, in case of battery mailfunction plain is guided automatically back by a software app controlled by the tower or Waze-style having inputs from planes around. Electricity can be too supplied tesla coil maner from the ground. Wish I had time and resources to work on this in my backyard

  2. I got my private pilot license in gliders and then did an add on for single engine land. Much of the “new to me” skills learned during my single engine land training were focused on checking, using, managing the gas engine; planning and flying cross country; and communicating with the right people along the way. With an electric trainer limited to pattern work, none of that is possible.

  3. @Philg: Not quite on topic but avionic related question.

    This week, I watched the movie Aftermath [1] which is based on the true events of Überlingen mid-air collision [2]. I don’t get it how such a thing can happen in mid air. Sure, I see airplanes flying at a fix altitude, but what are the chances of 2 or more plains meeting up in the air at a fix point?! Cannot this issue be avoided or its chances almost zeroed out by simply, making it a requirement that the altitude of one of the planes is 50 ft above / below of other planes in the area of a crowded airspace? I.e.: Once a plain is within 25 miles of landing, it has a fix altitude to say at which is different from all other plains within that 25 miles rads.


  4. Really? Only 1/45 the energy density of kerosene and it’s still viable? Their 330kg pack is the equivalent of 7.3 kg of regular fuel, or about 9 gallons of the stuff. How much less does the engine weigh? A 20kg engine plus 330 Kg in a battery pack wouldn’t be able to compete unless the regular engine was really heavy.

  5. Isn’t 3 hours plenty of range for tons of stuff? Airnav shows 121 airports within 200NM of where I am now. If even 10 of those had Superchargers for these things, I could really get places. Much more fun than a Tesla.

  6. superMike, this blog is worse than an opioid addiction.

    On topic, isn’t this the second dubious-endurance electric plane proposal lately? They may be on to something. At least these guys are specifying their hardware for the challenge.

  7. Oops, math error, I meant to say 9 liters, not 9 gallons! That seems like almost nothing! Does this really make sense economically? How much of a range will a plane have on that much fuel, even assuming greater efficiency from the electric motor?

  8. Update: this is the same plane announced earlier by “Aero Electric Aircraft Company” as the Sun Flyer with $250k price and $19 per hour operating cost. We’ll see I guess.

  9. 18650s are not some mysterious exotic battery. They are the same Lithium batteries that are found in the battery pack in your laptop. Because they are cheap and plentiful, they are also the same batteries used in Teslas.

    The thing about electric planes/cars/ etc. is that it is really very simple. An electric motor is a simple off the shelf device that has been well understood for 100+ years and operates at very high efficiency (almost 100% of the energy input is converted to motion – only a few % gets lost). It hasn’t been cost/range efficient because of battery technology (and probably still isn’t). If the batteries ever get good and cheap enough, then it would be relatively trivial for all the existing manufacturers to switch to electric power and eat the lunch of any new entrant. Car mfrs make their own engines but it has always been the tradition in the aircraft industry to rely on outside suppliers for engines. The real expertise is in building the aircraft and then you can hang whatever motor you want (of suitable power) in there. These new entrants will only be around long enough for the technology to be viable (if it ever becomes viable) and then they will get squeezed out by the established players who have much greater expertise and economies in building the rest of the aircraft.

  10. Joe S, the efficiency improvement at the propellor shaft is about 3x, so 9 gallons was pretty close. Still doesn’t add up right, especially with the claimed payload.

  11. Shipman –

    “Energy density” of the fuel does not tell the whole story. To start with, up to 80% of the energy in a gallon of fuel is wasted as waste heat and only 20% is converted to rotary motion (vs. an electric motor which is close to 100% efficient). Gasoline and kerosene are wonderfully energy dense fuels and make nice hot fires when burned but turning them into motion is no trivial task – no one has ever figured out a way to do it without wasting most of their energy. The Rube Goldberg method of spinning a shaft by setting off a series of explosions in a tube and converting the linear motion to rotary is crazy but they have been working on it for 150 years so it sorta works by now, but not really that well.

    2nd you have to look at the weight of the whole system and not just the weight of the fuel. Electric motors weigh much less than gas engines.

    They are claiming 3 hours flying time and a small plane might use 7 gals./hr so the charge must be somehow equivalent to approx. 20 gallons of fuel (while presumably costing much less to charge than that). So 9 liters (a little over 2 gallons) is way off. Just based on energy efficiency, you would need 10 gallons of fuel to produce 2 gallons worth of actual propeller spin and the rest of the savings is from the weight of the motor and other factors. The proof of the pudding is in the eating – if the thing really flies for 3 hours then it is somehow doing the same work as 20 gals. of fuel does in the real world. In any case your numbers are way off.

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