Originally published at: All-electric planes like this could change regional air travel | Boing Boing
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This is incredibly important to the future. We really need to work to keep the carbon footprint of air travel from returning to pre-COVID levels. Air travel is for a lot of people, the one place where they find it very difficult to reduce their own carbon footprint.
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The propulsion system is the least weird thing about that aeroplane.
The tail-dragger undercarriage arrangement and the V-tail are somewhat unconventional but the weirdest thing is the engine layout.
It looks to me that all those choices were made to reduce drag, but they give rise to other problems.
Pusher propellers are more efficient than tractor (puller) props 'cos they’re not pushing high speed air over the surface of the aircraft. But sometimes (slow flight) it’s desirable to have high speed air pushed over your tailplane and rudder because it makes them more effective controls. And having a propeller at the very back of the plane necessitates the tall tail-wheel so the prop doesn’t strike the ground. But tail-draggers have weird ground handling characteristics which is why tricycle gear is so much more common.
Having the (presumably heavy) motors arranged at the extremities like that will result in a large moment of inertia which is generally not desirable in a vehicle. The manufacturer claims that two outboard motors are there to provide yaw control which is cool so long as both motors are working. But if one of those motors fails, not only is yaw control compromised but you now have a radical asymmetric thrust problem and you don’t have a proper rudder, just a V-tail. Your fly-by-wire flight computer is expected to take care of this but physics is against you.
I dunno. It seems to me that the aircraft has been optomised for efficient cruise at the expense of practicality and redundancy.
Personally, I prefer the one-innovation-at-a-time approach of retrofitting an electric motor to one of the most dependable aeroplanes ever built…
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Yeah but pollution from air transport has a power distribution: a few people make the vast majority of it. A progressive tax, maybe even getting one trip without tax and sliding up so if you are on your hundredth it’s many, many times the cost of the ticket and that would sort that shit right out.
And nothing of value would be lost. We can no longer afford to prop up Boeing, airbus, Ryanair, Southwestern etc. Let them die.
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Which I would argue is especially important here because if the current electric planes are economically viable anywhere it’s in situations where speed and reach aren’t the most important factors. Mainly those are high frequency short trips such as island hopping (e.g. in the Scottish Northern Isles). In that case STOL capability is rather important.
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The battery weight is a big problem with electric planes, but likely solvable with a fuel cell instead. Fuel cells have much less power density than modern battery chemistries, but airplanes are a use case where the trade off for greatly reduced weight makes sense.
The deal breaker to the whole idea of electric planes is a thing nobody gives enough press to- the inverter. Electric vehicles need a huge inverter that is proportional in capacity to the horsepower required, and inverters get exponentially heavier the larger they get. The inverter keeps you on the ground long before you get near the power levels needed for big passenger planes. Little puddle jumpers like this one can get away with it, barely, but as stated above, the power ceiling keeps airspeed down.
The inverter is needed because batteries make DC power, but AC motors are where all the horsepower and efficiency are. It’s the great tragedy of the electric age. Brushless DC motors are doing impressive things now and could eliminate the inverter, but they are severely power limited by MOSFET switching capacity, which peaks long before you get to vehicle-levels of horsepower. There have been some promising developments in power conversion that might eliminate inverters, but nothing concrete yet.
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I don’t think inverter weight is a problem at all, especially if you use water cooled one.
Even transistors (typically IGBTs) that can switch loads in megawatt range are surprisingly tiny now.
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Just reporting what I’ve read on this issue.
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I designed inverters for synchronous motors, and I’m really surprised by this. Even with MOSFETs they were tiny, heat sink was typically the heaviest part.
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I look forward to your electric plane, then.
One way is to invest in alternatives to regional air travel, such as better rail services.
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I think you would have to look backwards for it instead, I’m not in aerospace business anymore, but when I was I participated in some cool electric UAV projects. While I didn’t participate in any project on manned electric aircraft, my friends did and following their progress was amazingly fun (it was a two person electric-powered sailplane, looked really cool).
The largest inverters I designed were for stationary applications, but their size or weight compared to the motors was never a problem. I’m pretty sure that with modern transistors they could get even smaller.
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I didn’t realize Alice has a tailwheel configuration. I agree that makes landing and ground maneuvers a lot trickier than the “trike” gear typical of commercial aircraft. And you make good points with the rest.
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I don’t know enough about the engineering aspects of this to really comment on the plane specifically. However, I think there is a big downside to dealing with our sources of emissions in isolation without thinking about the choices and systems that link everything. A very basic example of this is the materials themselves. Let’s assume that it’s economically feasible to replace our short-haul flights with the Alice. However, we need more planes to do this (because they don’t carry as many passengers), we need to unearth the raw materials to do this (or recycle them, which is also energy intensive) and the electricity used to charge everything needs to come from an emissions-free source. Building electric cars and planes is great, but the large scale mining required to find the raw materials for all this has a host of its own environmental issues (in addition to carbon emissions). We could reduce the number of flights people need to take, but that then threatens the economic case for electric vehicles and electric planes.
Humans just want to keep doing what we do, but in an emissions free way. I think we all need to level with the reality that our levels of consumption are not sustainable. I don’t think we’ll be able to solve the climate problem without moving to a largely post-consumer society.
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This is a little misleading because a propeller-driven craft will, for now, never be comparable to a jet. What we need to stress is that, in favor of going emissions free, passengers will be giving up commute time on short-haul flights.
Of course, there’s always the option of high-speed rail, which already has proven technology and no concern for batteries or weight.
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I wonder if a lightning strike would have an effect on this type of plane. I’m sure safeguards are in place but just curious.
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Considering amount of electronics on regular passenger aircraft, I think there would be no difference with this one.
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The video focused on short runs in the US coastal areas, but there could be big advantages to serving vast areas of the interior that have few major hubs but lots of regional airports.
Personal example: I live in central Missouri. Anytime (pre-pandemic, at least) I want to go almost anywhere by air, I have to drive 2 hours to St. Louis (STL) or Kansas City (MCI) airports. The same is true of everyone else in my city of 120,000. Think of all that carbon! We do have a regional airport, but it has only 2 flights a day each to/from Denver, Chicago, and Dallas. I’m sure there are many small cities that are similarly hobbled by distance from major hubs.
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It’s an Israeli company; can’t they beam power to them by the sinister Jewish space lasers discovered by Marjorie Taylor Greene? /s
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What about charge time? Airlines don’t like to have their planes sitting on the ground very long, so if it takes a few hours to recharge the batteries, the ability to earn revenue from the plane decreases.
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