9 ms·

Bye lands orders for nearly 300 electric planes

102 points by gscott 8y ago

sremani 8y ago
I am curious, the aero-engines are know to be reliable but electric engines are considered to be good too. What kind of complexity variation does a battery introduce in providing reliable power vs gas tank. What can be possible weaknesses if any with electric planes?
- csours 8y ago
  Liquid fuel is volatile, but generally does not catch on fire on its own. Batteries can catch on fire if over or under charged. Batteries can catch on fire if punctured - liquid fuel can as well, but batteries do not need an external source. This means you need thermal management for your energy source and your power unit. It's not as applicable for this class of aircraft, but batteries do not get lighter as they are expended. Liquid fuel provides the same amount of unit energy until it is completely gone; batteries lose power over time, leading to lower horsepower at the end (this is a simplified point of view).
  - VectorLock 8y ago
    Also you can't shoot batteries out the back of your plane to create thrust like you're doing with liquid fuel.
    - AnimalMuppet 8y ago
      Sure you can. Encase them it metal, and use the remaining batteries to power a railgun...
  - aeternus 8y ago
    The per-unit energy is the biggest issue. It's true that fire is a problem for batteries, but that is manageable with very small sensors and casings. There are many more systems required to deal with the many failure modes of internal combustion engines: - Heating systems to address carburetor icing. Typically manually activated by pilot since they have a performance cost. - Fuel pumps since gravity cannot always be depended upon especially in acrobatic airplanes. - Fuel sump systems which must be checked before every flight to address water in the fuel tanks & lines. - Lubrication systems which require pre-flight fluid level checks. - Magneto system to ensure that sparks can be generated independently from the electrical system. - Redundant magneto system since carbon tends to build up and prevent proper sparking. - Possibility of an engine running rough/cylinder firing out of sync due to carbon or other issues. - Fuel/air mixture control so that the optimal mix can be selected based on altitude. Requires pilot intervention. - Extreme thermal stresses on the engine, requiring engine run-up checks before takeoff. - Radiators, and airflow rediretion to address cooling issues resulting in loss of performance and weight. - Exhaust system, and noise vs. weight tradeoff
    - Robotbeat 8y ago
      Indeed. ICEs only don't catch fire constantly because of a century of safety improvements.
      - mannykannot 8y ago
        Outside of combat, fuel fires are very rarely in the fuel tanks (TWA 800 being a notable exception, and there are ways it could have been avoided), and a for a fire in an engine, the fuel can be cut off and fire extinguishers used. On the other hand, liquid fuel is probably much more dangerous in a crash.
- asparagui 8y ago
  Electric engines have a number of properties that are great for aviation, namely the ability to provide torque at low speeds and easily handle high rotation rates, which removes the need for complicated gearboxes and simplifies design. They have been proposed a number of times over the years, the historical problem has always been getting the electricity to drive things: batteries are heavy and diesel->electric converters (eg. hybrid trains) are too large to be practical.
  - Zak 8y ago
    It's worth pointing out that piston aircraft engines usually don't use gearboxes. Instead, they drive the propeller directly, which dictates very low engine speeds relative to where car engines usually produce their peak power since any part of the propeller blade nearing the speed of sound results in a loss of efficiency.
  - chungleong 8y ago
    I wonder if progress being made in micro-turbine generators would one day allow them to be used in planes. Having a bank of generators inside the fuselage could making flying a lot safer. I imagine planes can be made much more aerodynamic as well.
    - starpilot 8y ago
      Turbines are more efficient with larger sizes due to the fluid mechanics, and they need air, so then you end up at gas turbine engines externally mounted.
- rmah 8y ago
  I imagine the primary weakness is the rather low energy density of li-ion batteries vs gasoline. This means less energy per kg of battery/fuel, which means lower power (speed/payload) or range or both.
- ccleve 8y ago
  I remember reading that electric motors are much lighter than gas engines for the same amount of power. This difference can at least partially offset the added battery weight. Also, it's possible to have multiple, small electric motors with no loss of efficiency. That isn't possible for a gas engine. Multiple motors could add some redundancy, and therefore reliability. I think we're going to see a lot of interesting designs over the next few years.
  - nbadg 8y ago
    > electric motors are much lighter than gas engines for the same amount of power That varies wildly based on what kind of engines and motors you're talking about; it's not consistent enough to be applied as a generalization, especially when it comes to aircraft (turbines are some of the most power-dense engines available). See here [1] for examples. [1] https://en.wikipedia.org/wiki/Power-to-weight_ratio#Examples https://en.wikipedia.org/wiki/Power-to-weight_ratio#Examples
  - ScottFree 8y ago
    Something else to keep in mind: a plane gets lighter as it burns fuel. Electric batteries don't get lighter as they expend energy. Chip Yates flew a few experimental electric airplanes a few years back. The last I heard, he had devised some sort of battery hot-swap system so he could fly from NY to England in one go. I don't think that one ever made it off the drawing board.
  - mikeyouse 8y ago
    Smaller motors unfortunately means smaller propellers which means smaller swept area and a large decrease in available power.
    - thrill 8y ago
      Propellers are generally limited by torque, which is something that electric motors excel at.
  - WrtCdEvrydy 8y ago
    > are much lighter than gas engines for the same amount of power The issue will always be that fuel is consumed and causes the aircraft to be lighter the longer you fly.
- itsyaboi 8y ago
  Off the top of my head, both lithium polymer/lithium ion cells are much more temperature sensitive when compared to most liquid fuels. When flying fpv quadcopters in cold weather, (speaking from a anecdotal hobbyist experience here), I get a much lower maximum current for the first minute or so until the individual cells warm up due to the internal resistances. This translates to less total raw wattage. Total battery capacity is reduced as well. I imagine a big challenge would be keeping the batteries at a happy temperature. A quick google search shows the Solar Impulse team ran into this problem: (https://www.theverge.com/2015/7/11/8933295/solar-impulse-sustains-battery-damage-after-record-flight https://www.theverge.com/2015/7/11/8933295/solar-impulse-sus...) Edit: The above in regards to providing reliable electric power. Disregarding this, the main downside by far is energy density of currently available batteries. From https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density, a kilogram of gasoline has about 53x as much energy as a comparable 1 kilogram lithium ion battery. Gasoline 46.4 Lithium-ion battery 0.36–0.875 (MJ/Kg)
- sowbug 8y ago
  These are some differences that I can think of after mentally running through a C172SP checklist. In a gas plane, checking fuel level during preflight is a matter of direct observation. It's at a certain level, it's the right color, and it doesn't have any gunk in it. In an electric plane, you can't directly observe a battery's state of charge; rather, you can measure the voltage using a device of some kind, and then extrapolate range/capacity from that. That's not hard to do correctly, but it does involve more moving parts than just looking at the gas. Batteries don't change their weight based on state of charge, which is nice for flight planning that normally has to take into account a heavier plane at takeoff than landing. But it is nice to be able to trade off range for performance by fueling to different levels in a gas plane, and you can't do that in an electric one. Batteries perform worse in the cold. Gas engines don't (though normally aspirated/carbureted engines do). The eFlyer is a pretty small plane, though, and it probably won't go high enough to reach altitudes that are consistently very cold. If your gas engine catches fire, there are a bunch of things you can do to put it out without killing yourself. But I'm not sure what you do if your batteries catch fire, except hope you're very close to a surface you can land on.
- cmurf 8y ago
  Cold weather operations might differ. It's not uncommon to heat a fuel powered engine in the winter, whereas with battery it might be mandatory. Also, cabin heat affect on range will need to be well understood and incorporated in performance and endurance charts for flight planning purposes. For pressurized airplanes, the power cost of pressurizing and cooling. I'm not sure what that cost to endurance would be, but it would need to be accounted for.
JMTQp8lwXL 8y ago
Title is confusing until you understand "Bye" is a company/CEO's last name, and "lands" as in orders.
- NullPrefix 8y ago
  "Bye Aerospace lands orders..." would be easier to parse, given no prior knowledge of Bye.
- magicalhippo 8y ago
  Not sure I'd feel comfortable buying airplanes from a company named Bye...
spaceheretostay 8y ago
These are small, low-altitude, low-capacity planes - because this is a hard problem and you have to start small. I wonder though - does Bye have ambitions in creating larger ones that fly at higher altitudes? I've thought about this ever since Elon speculated that high-altitude electric planes could be insanely efficient: they don't require the intake that normal jet engines do, so they can fly in thinner air and thus require less power to overcome air resistance. The main problem being battery density, IIRC. I wonder how that has changed since the ideas were floated some years ago. I want the super-fast, high-flying, supersonic electric planes please! That could do more to alleviate greenhouse gas emissions than even electric cars might!
- fwip 8y ago
  You also gotta spend more energy going up higher, though. If you take the idea to its conclusion you just end up with the solution of taking a rocket from China to SF.
  - spaceheretostay 8y ago
    Yeah, I guess that's where Elon ended up! SpaceX will do it in the extreme then, without batteries and with just rocket engines.
  - ogre_codes 8y ago
    That's what JATO is for. Just strap some rockets under the wings to get you up to altitude ;) https://youtu.be/97rSobuKBxI?t=27 https://youtu.be/97rSobuKBxI?t=27
- Retra 8y ago
  A propeller works by pushing off of the air. A jet works by exploding fuel. It's not clear how you'll get super-fast in thin air without the exploding fuel part?
  - Robotbeat 8y ago
    That’s not true. You’re describing a rocket, not a turbofan or even a turbojet. Fundamentally, modern high bypass turbofans are just shrouded propellers. Could reach supersonic speeds in the same way using electric. Lift to drag is about half as good at low supersonic speeds as transonic, so cut your range in half, but fundamentally there’s no reason you can’t achieve supersonic electric flight. Just need good batteries to get that range...
ortusdux 8y ago
Impressive stats on the 2-seater: 3.5hr flight time at 1/6th the hourly operating cost of a Cessna 172. Perfect plane for flight school.
- repiret 8y ago
  You think so until you look at TCO. A used 172 equipped for a superset of the training scenarios can be had for 1/5th the initial investment. You can buy a lot of operating costs with the savings.
  - VectorLock 8y ago
    Comparing a new 172 to a new eFlyer the price seems competitive ($300k vs. $350k it looks like?)
    - repiret 8y ago
      Indeed, which is part of why most flight schools don’t buy new planes at all. I was mostly trying to refute the grandparents assertion that it was a “perfect plane for flight school.” On the other hand, the discontinued Cessna 162 sold for $150k and is more similar to the eFlyer’s capabilities.
- ianai 8y ago
  Let’s also not forget that not everyone lives or has time to deal with a full size airport. I can imagine a future where it’s feasible to offset commute times with these instead of other options.
AWildC182 8y ago
Spoiler: These aircraft are almost entirely useless outside of limited pilot training applications. You might get 1-1.5 usable hours of flight time per charge. Battery density is not there yet and this is another fake it till you make it play. To further expand, these will cover about 90% of the hours needed for a part 61 private pilot licence and and another 80-90% for instrument and commercial. The issue is you'll still need a ICE aircraft for some of the XC flights which complicates training somewhat. Edit: Also, 3.5 hours is at barely-staying-aloft airspeeds riding the bottom of the drag curve. If you're maneuvering, doing practice landings, or actually trying to go somewhere you will not get anywhere near those numbers. The FAA also requires minimum 0.5 hours of reserve upon landing.
- djsumdog 8y ago
  How many students drop out after the first class or two, or how many just take a class for fun? Flight schools could still make this work depending on those ratios.
  - AWildC182 8y ago
    Don't get me wrong, these will be great for schools, but I don't think that's what the average HN reader is thinking about when looking at these. Bye is not publishing the important numbers so this whole thing looks a little too much like an attempt to say they're changing the entire aviation landscape when they're just another electric trainer (in a market that already exists and has more realistic contenders).
- Robotbeat 8y ago
  Huh? "Battery density is not there yet." "Fake it or make it" You know, it'd be helpful if you didn't accuse them of fraud without grounds. Battery density is only half the issue. The other one is efficiency. Half-century-old cessnas fly like a brick. State of the art aerodynamic performance can allow you to get two or three times the range you'd get just swapping out their engine for battery+electric. This aircraft can probably do about 400km range. With reserves, maybe 350km. That's not nothing, about Bakersfield to San Jose. And this thing is not fully optimized. If you REALLY wanted distance, you'd pressurize the cabin, use even higher aspect ratio wings, retractable gear, blend the body into the wing a bit, etc, and you could do up to about 1000km range with today's batteries (you'd be mostly battery by weight).
gmoore 8y ago
Let's see how many of these 'orders' actually get delivered.
Robotbeat 8y ago
3.5 hour endurance translates to about 500-800km range.
- AWildC182 8y ago
  Negative. 3.5 hours is at max endurance airspeed, probably 50-60 kts and only 3 of those is usable since the FAA requires you have 0.5 available upon landing.
  - Robotbeat 8y ago
    About 400km range, then.
    - AWildC182 8y ago
      Closer to 300km most likely.
      - Robotbeat 8y ago
        At maximum endurance speed, sure, but that's not likely to be the maximum lift to drag speed. The maximum lift to drag speed of the eflyer2 is 20.6. If we assume 35% of the in-flight vehicle's mass is batteries and the batteries have a 168Wh/kg specific energy at the pack level (same as the Model 3's battery pack), operating at the EMRAX motor (used for the prototype)'s peak efficiency with a high efficiency propeller, that gives about 400km range.
    - kgilpin 8y ago
      If you have a headwind, which is very commonly 30 knots or more, then in this plane you are barely moving. So, it would be hard to reliably get anywhere at all. Training flights are mostly in the vicinity of the airport so speed and range matters less. But you do still have to get places (eg the practice area and back) and a really slow plane is going to make a difference in the number of flight hours you need to accomplish the missions.
      - 8y ago
Alupis 8y ago
This is cool indeed, but don't get too excited - this is a puff piece touting (220, not 300) preorders that aren't yet real orders and might never be. The plane is not FAA certified yet (the first and only prototype flew in February), and the 4 seater (which accounts for half of the 220 preorders) won't fly until 2022, and then will have to seek FAA certification too.[1] Electric motors and batteries have a long way to go to even come close to power density and weight of kerosene or gasoline aviation engines.[2] Batteries also don't get lighter with reduced charge - something most aircraft rely on with designs and efficiency (ie. 500lbs of batteries weigh the same when nearly empty). It's also notoriously difficult and extremely expensive to certify new engine types for general aviation commercial pre-built's - which is part of the reason majority of modern GA aircraft still use very old engine designs (just not worth the investment from the manufactures). You can't just show it works... it has to be proven to work in a number of extreme situations and for very long duration with extreme reliability. Getting a new engine type into an Experimental Type Aircraft is much, much easier... I'd also hope the motor electrical system is fully isolated and separate from the aircraft's other electrical systems (maybe I missed it, but I haven't seen anything discussing this so far). Electrical problems happen, and losing all systems plus the motor at the same time would seriously jeopardize the safety of this aircraft. I wish Bye and his company the best, but I'm skeptical. [1] https://en.wikipedia.org/wiki/Bye_Aerospace_eFlyer_2 https://en.wikipedia.org/wiki/Bye_Aerospace_eFlyer_2 [2] https://aviation.stackexchange.com/a/26919/2294 https://aviation.stackexchange.com/a/26919/2294
- ip26 8y ago
  I left [2] unexpectedly excited for fuel cell flight perhaps with some form of battery or capacitor boost for takeoff. If it's a cap, you could even charge it while the plane taxis if an electric hookup was onerous.
- AWildC182 8y ago
  This. Don't get your hopes up until you see Experimental Amateur Built kit-planes running electric motors. There are already electric trainers on the market but FAA certification is a bitch...unless you're Boeing :)
skanga 8y ago
Why all the nay-saying? Give them credit for finding their niche and delivering (on the orders at least)!
Robotbeat 8y ago
Shout out to EMRAX, manufacturer of the motor for the prototype eFlyer2. According to the FAA filing: https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=502SF https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?N... https://emrax.com/products/emrax-268/ https://emrax.com/products/emrax-268/ Up to 98% efficiency. Up to 10kW/kg. Pretty impressive motor, and few electric motor makers like to compare their motors to this high of a standard.
- Alupis 8y ago
  > Shout out to EMRAX, manufacturer of the motor for the prototype eFlyer2 Doesn't seem to be true. The motor is a Siemens SP70D[1] [1] https://en.wikipedia.org/wiki/Bye_Aerospace_eFlyer_2 https://en.wikipedia.org/wiki/Bye_Aerospace_eFlyer_2
  - Robotbeat 8y ago
    It IS true for the prototype. Siemens is really good at grabbing these orders for production aircraft and getting their name in press releases, but the actual motor used for the prototype according to the FAA (who I don’t recommend lying to) is the EMRAX one. EDIT: And EMRAX motors have shown up on lots of other electric aircraft. My day job is making novel electric motors, and their motors are incredibly tough to beat. I have much respect.
newhotelowner 8y ago
What if the battery used in these planes are like my phone batteries. After using my phone for a few hours, the remaining battery will be down to 25%. And in 5 mins, my phone will be off due to the dead battery. Once it happened to my EV. The battery was down to 50%, and then suddenly drop to 10%. Luckily, I was very close to my home.
- davidrm 8y ago
  that’s because for those cases the power draw is hard to predict. in case of your phone, the BMS might be lying and also the state of health of the cell might not be accounted for, but it’s more likely that some apps are juat power hungry. as for the EV, it’s doing the same thing as an ICE car, it predicts the range based on your last x kilometers, if you step on the throttle your range will deteriorate as you reach higher speeds and drag increases. a traditional car will start reducing the estimated range as well. I imagine that the aviation industry is much better at predicting and controlling the power draw, therefore the range won’t be so unpredictable. it’s not the cells that are unpredictable, it’s their end user.
ChuckMcM 8y ago
Interesting product. All the discussion about training airline pilots makes me wonder if their value add is they can tune their fly by wire system to have the flight characteristics of a larger jet for familiarity with takeoffs and landings. That might make up for the relatively limited air time the plane can achieve (you don't need a lot of time for training flights per say). Turn around time would become an issue though in terms of how many you would need to sustain a full training day for a given number of students.
- bronco21016 8y ago
  The majority of flight training in the beginning is learning the basic ‘stick and rudder’ flying skills. This is the basic characteristics and relationship of pitch, power, roll, and yaw. Those basic skills and relationships help a pilot learn how to get out of unfortunate situations. Training in an aircraft artificially more similar to an airliner would not be productive as they tend not to be as forgiving when pushing the envelope.
apo 8y ago
> First deliveries of the $349,000 eFlyer 2 (the original price was $289,000) are anticipated in 2021. There's a lot going on with DIY electric flying craft as well. For example: https://www.youtube.com/watch?v=J7ykW4zk-Hk https://www.youtube.com/watch?v=J7ykW4zk-Hk Fascinating to see this problem attacked from the top and bottom of the market at the same time.
tamaharbor 8y ago
Could a hybrid plane receive the benefits of both a liquid fuel and electric battery?
bronco21016 8y ago
These aircraft may work as trainers because training aircraft come back to home base the majority of the time. This doesn’t solve any type of GA point to point transportation though until infrastructure is built out to accommodate charging. Land at any FBO today and they’re going to laugh you away if you ask for an electrical cord that charges these large batteries in any meaningful amount of time. Your product may be killer (Tesla Model S) but don’t expect any kind of uptake without the support infrastructure (arguably Tesla’s number one strategic move).
- curtis 8y ago
  Battery swapping and offline charging has not been successful in the automotive realm, but it might be a pretty reasonable alternative for aircraft. Even cheap aircraft are so expensive that the overhead of having two sets of batteries wouldn't make that much difference on the overall price, and you could probably rely on a shared pool of batteries anyway, since a lot of light aircraft aren't flown that much. If battery swapping works then that also opens up some interesting possibilities like aluminum-air batteries that have much greater energy densities than lithium-ion batteries but which aren't rechargeable.
  - bronco21016 8y ago
    I don’t disagree that there are many solutions to the problem. The issue isn’t a lack of solutions though. It’s a lack of implementation. Swappable batteries sound great but does say Million Air FBO at Chicago MDW have swappable batteries for my aircraft? If someone wants to really make a dent in this market they need to follow Tesla and build out the product and the infrastructure to make it practical. I have yet to see anyone come up with big enough investment to do that.

102 points by gscott 8y ago

I am curious, the aero-engines are know to be reliable but electric engines are considered to be good too. What kind of complexity variation does a battery introduce in providing reliable power vs gas tank. What can be possible weaknesses if any with electric planes?

csours 8y ago
Liquid fuel is volatile, but generally does not catch on fire on its own. Batteries can catch on fire if over or under charged. Batteries can catch on fire if punctured - liquid fuel can as well, but batteries do not need an external source. This means you need thermal management for your energy source and your power unit. It's not as applicable for this class of aircraft, but batteries do not get lighter as they are expended. Liquid fuel provides the same amount of unit energy until it is completely gone; batteries lose power over time, leading to lower horsepower at the end (this is a simplified point of view).
- VectorLock 8y ago
  Also you can't shoot batteries out the back of your plane to create thrust like you're doing with liquid fuel.
  - AnimalMuppet 8y ago
    Sure you can. Encase them it metal, and use the remaining batteries to power a railgun...
- aeternus 8y ago
  The per-unit energy is the biggest issue. It's true that fire is a problem for batteries, but that is manageable with very small sensors and casings. There are many more systems required to deal with the many failure modes of internal combustion engines: - Heating systems to address carburetor icing. Typically manually activated by pilot since they have a performance cost. - Fuel pumps since gravity cannot always be depended upon especially in acrobatic airplanes. - Fuel sump systems which must be checked before every flight to address water in the fuel tanks & lines. - Lubrication systems which require pre-flight fluid level checks. - Magneto system to ensure that sparks can be generated independently from the electrical system. - Redundant magneto system since carbon tends to build up and prevent proper sparking. - Possibility of an engine running rough/cylinder firing out of sync due to carbon or other issues. - Fuel/air mixture control so that the optimal mix can be selected based on altitude. Requires pilot intervention. - Extreme thermal stresses on the engine, requiring engine run-up checks before takeoff. - Radiators, and airflow rediretion to address cooling issues resulting in loss of performance and weight. - Exhaust system, and noise vs. weight tradeoff
  - Robotbeat 8y ago
    Indeed. ICEs only don't catch fire constantly because of a century of safety improvements.
    - mannykannot 8y ago
      Outside of combat, fuel fires are very rarely in the fuel tanks (TWA 800 being a notable exception, and there are ways it could have been avoided), and a for a fire in an engine, the fuel can be cut off and fire extinguishers used. On the other hand, liquid fuel is probably much more dangerous in a crash.
asparagui 8y ago
Electric engines have a number of properties that are great for aviation, namely the ability to provide torque at low speeds and easily handle high rotation rates, which removes the need for complicated gearboxes and simplifies design. They have been proposed a number of times over the years, the historical problem has always been getting the electricity to drive things: batteries are heavy and diesel->electric converters (eg. hybrid trains) are too large to be practical.
- Zak 8y ago
  It's worth pointing out that piston aircraft engines usually don't use gearboxes. Instead, they drive the propeller directly, which dictates very low engine speeds relative to where car engines usually produce their peak power since any part of the propeller blade nearing the speed of sound results in a loss of efficiency.
- chungleong 8y ago
  I wonder if progress being made in micro-turbine generators would one day allow them to be used in planes. Having a bank of generators inside the fuselage could making flying a lot safer. I imagine planes can be made much more aerodynamic as well.
  - starpilot 8y ago
    Turbines are more efficient with larger sizes due to the fluid mechanics, and they need air, so then you end up at gas turbine engines externally mounted.
rmah 8y ago
I imagine the primary weakness is the rather low energy density of li-ion batteries vs gasoline. This means less energy per kg of battery/fuel, which means lower power (speed/payload) or range or both.
ccleve 8y ago
I remember reading that electric motors are much lighter than gas engines for the same amount of power. This difference can at least partially offset the added battery weight. Also, it's possible to have multiple, small electric motors with no loss of efficiency. That isn't possible for a gas engine. Multiple motors could add some redundancy, and therefore reliability. I think we're going to see a lot of interesting designs over the next few years.
- nbadg 8y ago
  > electric motors are much lighter than gas engines for the same amount of power That varies wildly based on what kind of engines and motors you're talking about; it's not consistent enough to be applied as a generalization, especially when it comes to aircraft (turbines are some of the most power-dense engines available). See here [1] for examples. [1] https://en.wikipedia.org/wiki/Power-to-weight_ratio#Examples https://en.wikipedia.org/wiki/Power-to-weight_ratio#Examples
- ScottFree 8y ago
  Something else to keep in mind: a plane gets lighter as it burns fuel. Electric batteries don't get lighter as they expend energy. Chip Yates flew a few experimental electric airplanes a few years back. The last I heard, he had devised some sort of battery hot-swap system so he could fly from NY to England in one go. I don't think that one ever made it off the drawing board.
- mikeyouse 8y ago
  Smaller motors unfortunately means smaller propellers which means smaller swept area and a large decrease in available power.
  - thrill 8y ago
    Propellers are generally limited by torque, which is something that electric motors excel at.
- WrtCdEvrydy 8y ago
  > are much lighter than gas engines for the same amount of power The issue will always be that fuel is consumed and causes the aircraft to be lighter the longer you fly.
itsyaboi 8y ago
Off the top of my head, both lithium polymer/lithium ion cells are much more temperature sensitive when compared to most liquid fuels. When flying fpv quadcopters in cold weather, (speaking from a anecdotal hobbyist experience here), I get a much lower maximum current for the first minute or so until the individual cells warm up due to the internal resistances. This translates to less total raw wattage. Total battery capacity is reduced as well. I imagine a big challenge would be keeping the batteries at a happy temperature. A quick google search shows the Solar Impulse team ran into this problem: (https://www.theverge.com/2015/7/11/8933295/solar-impulse-sustains-battery-damage-after-record-flight https://www.theverge.com/2015/7/11/8933295/solar-impulse-sus...) Edit: The above in regards to providing reliable electric power. Disregarding this, the main downside by far is energy density of currently available batteries. From https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density, a kilogram of gasoline has about 53x as much energy as a comparable 1 kilogram lithium ion battery. Gasoline 46.4 Lithium-ion battery 0.36–0.875 (MJ/Kg)
sowbug 8y ago
These are some differences that I can think of after mentally running through a C172SP checklist. In a gas plane, checking fuel level during preflight is a matter of direct observation. It's at a certain level, it's the right color, and it doesn't have any gunk in it. In an electric plane, you can't directly observe a battery's state of charge; rather, you can measure the voltage using a device of some kind, and then extrapolate range/capacity from that. That's not hard to do correctly, but it does involve more moving parts than just looking at the gas. Batteries don't change their weight based on state of charge, which is nice for flight planning that normally has to take into account a heavier plane at takeoff than landing. But it is nice to be able to trade off range for performance by fueling to different levels in a gas plane, and you can't do that in an electric one. Batteries perform worse in the cold. Gas engines don't (though normally aspirated/carbureted engines do). The eFlyer is a pretty small plane, though, and it probably won't go high enough to reach altitudes that are consistently very cold. If your gas engine catches fire, there are a bunch of things you can do to put it out without killing yourself. But I'm not sure what you do if your batteries catch fire, except hope you're very close to a surface you can land on.
cmurf 8y ago
Cold weather operations might differ. It's not uncommon to heat a fuel powered engine in the winter, whereas with battery it might be mandatory. Also, cabin heat affect on range will need to be well understood and incorporated in performance and endurance charts for flight planning purposes. For pressurized airplanes, the power cost of pressurizing and cooling. I'm not sure what that cost to endurance would be, but it would need to be accounted for.

JMTQp8lwXL 8y ago

Title is confusing until you understand "Bye" is a company/CEO's last name, and "lands" as in orders.

NullPrefix 8y ago
"Bye Aerospace lands orders..." would be easier to parse, given no prior knowledge of Bye.
magicalhippo 8y ago
Not sure I'd feel comfortable buying airplanes from a company named Bye...

spaceheretostay 8y ago

These are small, low-altitude, low-capacity planes - because this is a hard problem and you have to start small. I wonder though - does Bye have ambitions in creating larger ones that fly at higher altitudes? I've thought about this ever since Elon speculated that high-altitude electric planes could be insanely efficient: they don't require the intake that normal jet engines do, so they can fly in thinner air and thus require less power to overcome air resistance. The main problem being battery density, IIRC. I wonder how that has changed since the ideas were floated some years ago. I want the super-fast, high-flying, supersonic electric planes please! That could do more to alleviate greenhouse gas emissions than even electric cars might!

fwip 8y ago
You also gotta spend more energy going up higher, though. If you take the idea to its conclusion you just end up with the solution of taking a rocket from China to SF.
- spaceheretostay 8y ago
  Yeah, I guess that's where Elon ended up! SpaceX will do it in the extreme then, without batteries and with just rocket engines.
- ogre_codes 8y ago
  That's what JATO is for. Just strap some rockets under the wings to get you up to altitude ;) https://youtu.be/97rSobuKBxI?t=27 https://youtu.be/97rSobuKBxI?t=27
Retra 8y ago
A propeller works by pushing off of the air. A jet works by exploding fuel. It's not clear how you'll get super-fast in thin air without the exploding fuel part?
- Robotbeat 8y ago
  That’s not true. You’re describing a rocket, not a turbofan or even a turbojet. Fundamentally, modern high bypass turbofans are just shrouded propellers. Could reach supersonic speeds in the same way using electric. Lift to drag is about half as good at low supersonic speeds as transonic, so cut your range in half, but fundamentally there’s no reason you can’t achieve supersonic electric flight. Just need good batteries to get that range...

ortusdux 8y ago

Impressive stats on the 2-seater: 3.5hr flight time at 1/6th the hourly operating cost of a Cessna 172. Perfect plane for flight school.

repiret 8y ago
You think so until you look at TCO. A used 172 equipped for a superset of the training scenarios can be had for 1/5th the initial investment. You can buy a lot of operating costs with the savings.
- VectorLock 8y ago
  Comparing a new 172 to a new eFlyer the price seems competitive ($300k vs. $350k it looks like?)
  - repiret 8y ago
    Indeed, which is part of why most flight schools don’t buy new planes at all. I was mostly trying to refute the grandparents assertion that it was a “perfect plane for flight school.” On the other hand, the discontinued Cessna 162 sold for $150k and is more similar to the eFlyer’s capabilities.
ianai 8y ago
Let’s also not forget that not everyone lives or has time to deal with a full size airport. I can imagine a future where it’s feasible to offset commute times with these instead of other options.

AWildC182 8y ago

Spoiler: These aircraft are almost entirely useless outside of limited pilot training applications. You might get 1-1.5 usable hours of flight time per charge. Battery density is not there yet and this is another fake it till you make it play. To further expand, these will cover about 90% of the hours needed for a part 61 private pilot licence and and another 80-90% for instrument and commercial. The issue is you'll still need a ICE aircraft for some of the XC flights which complicates training somewhat. Edit: Also, 3.5 hours is at barely-staying-aloft airspeeds riding the bottom of the drag curve. If you're maneuvering, doing practice landings, or actually trying to go somewhere you will not get anywhere near those numbers. The FAA also requires minimum 0.5 hours of reserve upon landing.

djsumdog 8y ago
How many students drop out after the first class or two, or how many just take a class for fun? Flight schools could still make this work depending on those ratios.
- AWildC182 8y ago
  Don't get me wrong, these will be great for schools, but I don't think that's what the average HN reader is thinking about when looking at these. Bye is not publishing the important numbers so this whole thing looks a little too much like an attempt to say they're changing the entire aviation landscape when they're just another electric trainer (in a market that already exists and has more realistic contenders).
Robotbeat 8y ago
Huh? "Battery density is not there yet." "Fake it or make it" You know, it'd be helpful if you didn't accuse them of fraud without grounds. Battery density is only half the issue. The other one is efficiency. Half-century-old cessnas fly like a brick. State of the art aerodynamic performance can allow you to get two or three times the range you'd get just swapping out their engine for battery+electric. This aircraft can probably do about 400km range. With reserves, maybe 350km. That's not nothing, about Bakersfield to San Jose. And this thing is not fully optimized. If you REALLY wanted distance, you'd pressurize the cabin, use even higher aspect ratio wings, retractable gear, blend the body into the wing a bit, etc, and you could do up to about 1000km range with today's batteries (you'd be mostly battery by weight).

gmoore 8y ago

Let's see how many of these 'orders' actually get delivered.

Robotbeat 8y ago

3.5 hour endurance translates to about 500-800km range.

AWildC182 8y ago
Negative. 3.5 hours is at max endurance airspeed, probably 50-60 kts and only 3 of those is usable since the FAA requires you have 0.5 available upon landing.
- Robotbeat 8y ago
  About 400km range, then.
  - AWildC182 8y ago
    Closer to 300km most likely.
    - Robotbeat 8y ago
      At maximum endurance speed, sure, but that's not likely to be the maximum lift to drag speed. The maximum lift to drag speed of the eflyer2 is 20.6. If we assume 35% of the in-flight vehicle's mass is batteries and the batteries have a 168Wh/kg specific energy at the pack level (same as the Model 3's battery pack), operating at the EMRAX motor (used for the prototype)'s peak efficiency with a high efficiency propeller, that gives about 400km range.
  - kgilpin 8y ago
    If you have a headwind, which is very commonly 30 knots or more, then in this plane you are barely moving. So, it would be hard to reliably get anywhere at all. Training flights are mostly in the vicinity of the airport so speed and range matters less. But you do still have to get places (eg the practice area and back) and a really slow plane is going to make a difference in the number of flight hours you need to accomplish the missions.
    - 8y ago

Alupis 8y ago

This is cool indeed, but don't get too excited - this is a puff piece touting (220, not 300) preorders that aren't yet real orders and might never be. The plane is not FAA certified yet (the first and only prototype flew in February), and the 4 seater (which accounts for half of the 220 preorders) won't fly until 2022, and then will have to seek FAA certification too.[1] Electric motors and batteries have a long way to go to even come close to power density and weight of kerosene or gasoline aviation engines.[2] Batteries also don't get lighter with reduced charge - something most aircraft rely on with designs and efficiency (ie. 500lbs of batteries weigh the same when nearly empty). It's also notoriously difficult and extremely expensive to certify new engine types for general aviation commercial pre-built's - which is part of the reason majority of modern GA aircraft still use very old engine designs (just not worth the investment from the manufactures). You can't just show it works... it has to be proven to work in a number of extreme situations and for very long duration with extreme reliability. Getting a new engine type into an Experimental Type Aircraft is much, much easier... I'd also hope the motor electrical system is fully isolated and separate from the aircraft's other electrical systems (maybe I missed it, but I haven't seen anything discussing this so far). Electrical problems happen, and losing all systems plus the motor at the same time would seriously jeopardize the safety of this aircraft. I wish Bye and his company the best, but I'm skeptical. [1] https://en.wikipedia.org/wiki/Bye_Aerospace_eFlyer_2 https://en.wikipedia.org/wiki/Bye_Aerospace_eFlyer_2 [2] https://aviation.stackexchange.com/a/26919/2294 https://aviation.stackexchange.com/a/26919/2294

ip26 8y ago
I left [2] unexpectedly excited for fuel cell flight perhaps with some form of battery or capacitor boost for takeoff. If it's a cap, you could even charge it while the plane taxis if an electric hookup was onerous.
AWildC182 8y ago
This. Don't get your hopes up until you see Experimental Amateur Built kit-planes running electric motors. There are already electric trainers on the market but FAA certification is a bitch...unless you're Boeing :)

skanga 8y ago

Why all the nay-saying? Give them credit for finding their niche and delivering (on the orders at least)!

Robotbeat 8y ago

Shout out to EMRAX, manufacturer of the motor for the prototype eFlyer2. According to the FAA filing: https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=502SF https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?N... https://emrax.com/products/emrax-268/ https://emrax.com/products/emrax-268/ Up to 98% efficiency. Up to 10kW/kg. Pretty impressive motor, and few electric motor makers like to compare their motors to this high of a standard.

Alupis 8y ago
> Shout out to EMRAX, manufacturer of the motor for the prototype eFlyer2 Doesn't seem to be true. The motor is a Siemens SP70D[1] [1] https://en.wikipedia.org/wiki/Bye_Aerospace_eFlyer_2 https://en.wikipedia.org/wiki/Bye_Aerospace_eFlyer_2
- Robotbeat 8y ago
  It IS true for the prototype. Siemens is really good at grabbing these orders for production aircraft and getting their name in press releases, but the actual motor used for the prototype according to the FAA (who I don’t recommend lying to) is the EMRAX one. EDIT: And EMRAX motors have shown up on lots of other electric aircraft. My day job is making novel electric motors, and their motors are incredibly tough to beat. I have much respect.

newhotelowner 8y ago

What if the battery used in these planes are like my phone batteries. After using my phone for a few hours, the remaining battery will be down to 25%. And in 5 mins, my phone will be off due to the dead battery. Once it happened to my EV. The battery was down to 50%, and then suddenly drop to 10%. Luckily, I was very close to my home.

davidrm 8y ago
that’s because for those cases the power draw is hard to predict. in case of your phone, the BMS might be lying and also the state of health of the cell might not be accounted for, but it’s more likely that some apps are juat power hungry. as for the EV, it’s doing the same thing as an ICE car, it predicts the range based on your last x kilometers, if you step on the throttle your range will deteriorate as you reach higher speeds and drag increases. a traditional car will start reducing the estimated range as well. I imagine that the aviation industry is much better at predicting and controlling the power draw, therefore the range won’t be so unpredictable. it’s not the cells that are unpredictable, it’s their end user.

ChuckMcM 8y ago

Interesting product. All the discussion about training airline pilots makes me wonder if their value add is they can tune their fly by wire system to have the flight characteristics of a larger jet for familiarity with takeoffs and landings. That might make up for the relatively limited air time the plane can achieve (you don't need a lot of time for training flights per say). Turn around time would become an issue though in terms of how many you would need to sustain a full training day for a given number of students.

bronco21016 8y ago
The majority of flight training in the beginning is learning the basic ‘stick and rudder’ flying skills. This is the basic characteristics and relationship of pitch, power, roll, and yaw. Those basic skills and relationships help a pilot learn how to get out of unfortunate situations. Training in an aircraft artificially more similar to an airliner would not be productive as they tend not to be as forgiving when pushing the envelope.

apo 8y ago

> First deliveries of the $349,000 eFlyer 2 (the original price was $289,000) are anticipated in 2021. There's a lot going on with DIY electric flying craft as well. For example: https://www.youtube.com/watch?v=J7ykW4zk-Hk https://www.youtube.com/watch?v=J7ykW4zk-Hk Fascinating to see this problem attacked from the top and bottom of the market at the same time.

tamaharbor 8y ago

Could a hybrid plane receive the benefits of both a liquid fuel and electric battery?

bronco21016 8y ago

These aircraft may work as trainers because training aircraft come back to home base the majority of the time. This doesn’t solve any type of GA point to point transportation though until infrastructure is built out to accommodate charging. Land at any FBO today and they’re going to laugh you away if you ask for an electrical cord that charges these large batteries in any meaningful amount of time. Your product may be killer (Tesla Model S) but don’t expect any kind of uptake without the support infrastructure (arguably Tesla’s number one strategic move).

curtis 8y ago
Battery swapping and offline charging has not been successful in the automotive realm, but it might be a pretty reasonable alternative for aircraft. Even cheap aircraft are so expensive that the overhead of having two sets of batteries wouldn't make that much difference on the overall price, and you could probably rely on a shared pool of batteries anyway, since a lot of light aircraft aren't flown that much. If battery swapping works then that also opens up some interesting possibilities like aluminum-air batteries that have much greater energy densities than lithium-ion batteries but which aren't rechargeable.
- bronco21016 8y ago
  I don’t disagree that there are many solutions to the problem. The issue isn’t a lack of solutions though. It’s a lack of implementation. Swappable batteries sound great but does say Million Air FBO at Chicago MDW have swappable batteries for my aircraft? If someone wants to really make a dent in this market they need to follow Tesla and build out the product and the infrastructure to make it practical. I have yet to see anyone come up with big enough investment to do that.