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This graphic always reminds me why it's so hard to beat gasoline and that batteries kinda suck.

https://en.wikipedia.org/wiki/Energy_density#/media/File:Ene...

Energy density alone is a misleading metric, because what matters is how much energy actually gets delivered to the drive mechanism. It's actually not that hard to beat gasoline, because despite its excellent energy density, gasoline engines are only 30% efficient. First and foremost a gasoline engine is a machine for producing heat and noise, and only incidentally for producing forward motion.

I think lithium air batteries will be the real inflection point for aeronautics. Li-air has potential density 12 kWh/kg. CATL is focused on this tech. May be some years before they are able to achieve the full potential density. Still, as the other commenters said, the efficiency of electricity make make up that difference.

Also for traditional fuel you don’t have to carry half of the fuel - oxidizer comes from air. And then when you spend fuel, you have less weight to carry (which becomes noticeable on the plane).

If they can get the range to within what, for example, an Alaska Airlines/Horizon Q400 flies from Seattle for regional flights (with reserve for diversion airport), that may be sufficient for some purposes.

In terms of operating cost, not just cost of fuel, but if the electric engines can be much less costly in terms of periodic maintenance and overhaul. Maintenance and overhaul costs on turboprop and small jet turbine engines are not cheap.

So if they are doing the hybrid approach and just using the conventional engines during cruise they will have way reduced maintenance costs on them. The need for max thrust during takeoff drives a ton off wear and tear, so removing that would be big. If they are able to do electric only that is even better.

As a rule of thumb, when you find yourself looking at an existing internal combustion vehicle and converting fossil fuel energies and efficiencies using battery gravimetric densities, you’re almost always at the “garbage in” stage of GIGO.

This plane isn’t a 737, it isn’t even a jet, it doesn’t run the motors the same way, the flight profiles are all different.

The economics to do what planes do today make no sense; but i think that's making the analysis the wrong way around.

There are opportunities for which airplanes have never made economic sense because they have big fixed costs like pilot, hangar, fuel-infra, engine(-maintenance). So will small short haul (?pilot-less) rechargeable planes have enough allure to beat out alternatives where planes were never considered before?

probably not at any major scale in a future where it competes with other autonomous transport, but that's me guessing at numbers. There will be enough of a market to build these things for niche constraints (eg the fuel-infra if small modular reactors become widespread).

The big problem with autonomous airplanes is they still require airports. I don't have a runway in my backyard, and I can't build one because someone else has a house there. My closest runway is about 20 minutes away, and then once I get to the far airport it is another 20 minutes to get where I'm going. This is why commute by airplane will always be a niche only a few people can do. In turn this means airplanes will never scale to be as cheap as cars are (a new Cesna stationair HD MSRP is over $700k - I submit that if they were building 40 per hour like many SUVs are built the cost would be around $70k)

Even a farmer is unlikely to be willing to give up that much space from their farmer operation. I do know farmers who have their own private runways, but they love flying and so are willing to give up some income to have a runway. They are giving up thousands of dollars in gross income to have that runway.

I happen to have a backyard that is big enough for a helicopter (I think - I never measured but I think I'm at the minimums the FAA requires), but I have an oversized yard. There are a lot more places for a helicopter. Most local parks have enough space, but I think communities would object to regular use. (if used only a couple times a month no problem, but more that and the noise and need to clear everyone else out will make it an objection)

> Lets say we are using batteries that are 300 wh/kg (0.3 kwh/kg)

400 Wh/kg are almost there [1].

[1] https://youtu.be/nM86DBOqgPM?t=541

People are working on solid state batteries which puts you at 500-600 wh/kg.

For cars the economics is a dicey proposition. Because $/wh is important. The extra range (dubious) or lower weight has to cover the cost difference.

But for electric aircraft there is a lot to be gained by weight savings.

Also consider that an empty battery weighs the same as a charged one. Whereas empty fuel tanks don't.

I wonder how annoying this is for the engineers to stay within landing weight limits (MLW)

My guess (I'm not an engineer) is landing weight limits are more then because the airplane will never have more than that anyway. They need a little better suspension in case of a hard landing, and different training for the aircraft (which you need anyway) to account for it handling differently, but otherwise it is still an airplane. Maybe bigger spoilers or some other part as well to better bleed off speed.

They need to account for it of course, but it seems more like account for it, not difficult. Any engineer in this space able to comment?

Landing weight limits are less than takeoff limits because of the extreme stress it puts on the landing gear. This is why planes that have an issue right after takeoff often need to dump tens of thousands of gallons of fuel before they can land.

>Aircraft have two main types of weight limits: the maximum takeoff weight is composed of dry operating weight (DOW) plus payload (passengers and cargo), collectively the zero fuel weight (ZFW), plus the trip fuel, contingency, alternate, final reserve and the block fuel (taxi fuel), and the maximum structural landing weight, with the maximum structural landing weight almost always being the lower of the two. This allows an aircraft on a normal, routine flight to take off at a higher weight, consume fuel en route, and arrive at a lower weight. [0]

[0] https://en.wikipedia.org/wiki/Fuel_dumping

> an empty battery weighs the same as a charged one

Technically, an empty battery weighs less than a charged one.

In practice, the difference is negligible.

They discuss quite a bit of this in the video. I actually thought it was a decent walk through of why they're targeting the space they're targeting, and how they're thinking about exactly these problems.

Some items to consider from the video

1. short flights spend an large amount of energy simply having the engines running during taxi to/from the runway.

2. Take-off also consumes much more fuel than cruising.

3. 1 & 2 combine to push airlines to prefer larger & larger planes making longer trips when using fuel (it's how they're managing that 45.9 seat mile number - it get much worse for shorter trips).

4. They're already pushing the 400kwh/kg range for batteries (I believe he makes an offhand comment in the video that they're using 8 packs, with roughly the capacity/weight of 4 tesla battery packs - which would put their batteries in the ~4k lb range if we estimate by teslas pack weights. They are likely pushing to go lower than that. I think it's not crazy to consider they're targeting a production weight ~50% below your guess - in the high 3000s)

5. On top of fuel savings, one of his more compelling points is that maintenance on their engines will be much, much lower. Jet engines are expensive to service, maintain, and repair (thousands of parts, complicated designs, extreme operating conditions). Their motors are basically 450kg dc motors - it's a giant drone motor mounted on an airframe.

6. they seem to have quite a bit of interest from existing airlines (ex - united) so apparently this does seem compelling to them.

7. He quotes a $5 take-off cost in electrical power. Something like an Embraer ERJ-135 uses ~20 - 30 gallons of jet fuel for the same thing (~$100). If they target a plane that's doing very frequent takeoffs/landings, operating costs could be considerably lower, not just lower.

---

Personally - I don't know if they'll make it work, but it's definitely an interesting play, with more real thought put into it than most attempts I've seen.

1-3. Agreed

4. Remember my predicted number is on the low side of how much juice they would need. Of course they get much better efficiency than a conventional jet on taxi and takeoff, so maybe it ends up being closer to what you are saying. I wish they had some more hard data.

5. Yep, commented on this in another post but even just removing takeoff wear and tear on a conventional engine would be big.

6. I would take that with a big dose of salt. United has a deal with Boom (a complete fraud of a company in my view) to purchase planes. So maybe not the best metric.

7. I haven't done the math but the $5 takeoff doesn't pass the smell test for me. $5 doesn't buy much juice (50 kWh? So like a gallon of jet fuel?) and getting a 30k+ lb plane to cruising altitude is not trivial.

"Personally - I don't know if they'll make it work, but it's definitely an interesting play, with more real thought put into it than most attempts I've seen."

Totally agree, which I never thought I would say about an aerospace startup.

A businessman I talked to said that United is investing in smaller airplane manufacturers in hopes of breaking the Boeing-AirBus duopoly. Thus, giving commitments here and to Boom Supersonic.

There's a lot more to it than that. Just going around on the taxi, Take off and landing burns a ton of fuel for these for traditional jet engines.

This plane is designed specifically to cost less to operate. I'm pretty sure they figured it out, which is why they have over 9b in order commitments.

Check jet engine weight and include in the calculation. One weights 2200-3700 lbs according to same source that quotes 45.9 seat miles per gallon. Vs 125 pounds for electric engine.

I’d guess comparable for a 30-seat regional, you’d probably want to compare with a PT6, especially since this aircraft is prop driven. That’s only about 250lb dry.

It seems you're right. Would nice to see breakdown for this plane how it actually maps to real world prototype.

The thing I quoted is more for bigger jets with much larger engines (it was the first reasonable looking source I found). In any case their hybrid has four engines, two electric, two conventional, so you are really should think of it as needing to haul two extra engines on top of what a conventional only jet would have.

Yes, it doesn't even make sense to make electric trucks, let alone airplanes. Or they'd be mostly battery.

I read new truck sales in China are about 30% electric and climbing. Apparently it does make sense for them

What China does hardly indicates economic sense, and you can be sure you won't hear about the down sides or failures. They already very agressively hide car lithium fires but they're very frequent. Economics over there are mostly investment driven with a large dose of ideology and vanity, not demand driven. You can see it everywhere including the massive amounts of empty housings for example

This ignores the fact that there are also things that China does better or equal than Western companies. Like robots, solar panels, electric cars (?), AI models, electronics.

They must be good at something, otherwise China wouldn't be where it is.

So flat out dismissing anything from China is not enough of an argument.

Mind you, I'm not saying you're generally wrong, just your "generally" is wrong. ;-)

I'd dispute they do any of those better, they stole the IP, then used public funds to make cheaper versions in the hope of leading the markets, including by being artificially more affordable while there is any competition. Besides electric cars and solar, it's very debatable wether those will actually be ecological in the end. For ex. they are still opening massive amounts of fossil based electric plants, so the truck that is half battery is actually running on coal anyway. It would take an incredible re-work of the electric grids to accomodate actually transitioning away from thermal cars, including some solution for seasonal storage. If you're impressed by their robots, I don't know what you're looking at, they seem to be ridiculous, not even at the tech level that boston dynamics had decades ago. Finally keep in mind that electric cars are fantastic spying devices, for collecting data, and if you're nefarious, imagine hacking into them. That's why teslas are banned near anything governmental in China. So there is a huge strategic advantage to cornering that market, but not really to save the planet. The AIs are all distilled, USA still leads by far there, and they too are strategic weapons

> used public funds to make cheaper versions in the hope of leading the markets, including by being artificially more affordable while there is any competition

If you replace 'public' with 'VC', isn't that the exact same as the US does in Silicon Valley?

if VCs didn't care about making their money back, but instead had very different interests, then somewhat

You don't think China (as a whole and as the government) is making it's money back? If not now, then in a few years

They're really not, the tiniest bits have shown with evergreen for ex, all the ghost cities. We don't really see the people who's savings, which with kids is the only "pension", have been demolished, on an individual level Chinese tend to save way more than others, this is gone. There's the demographic issue on top, the famines, that they import 70% of their food, depend on trade which the americans are withdrawing for protecting the routes of, and other unadressed issues because the priority is this investment, the missing population, the utter lack of statistics, even internally. Most likely the biggest factor will be wether they try something in Taiwan next year as they warned.

> they stole the IP, then used public funds to make cheaper versions in the hope of leading the markets

If you steal my IP and you make a better - or at least comparative but cheaper - product, that's on me for not innovating further.

It's trivial to compete if you don't have R&D costs, and don't care about stuff like your employees, regulations or safety, or even sales since you can just use government money (this is not without consequence either). And it's not only about free market stuff, why do you think they're so excited for all countries to use their 5g products for example ? Don't think this is benign.

There are plenty of legitimate criticisms of Chinese policy, but you should probably reread your arguments and check for coherence.

Chinese EV trucks make no economic sense even though they're 30% of China's fleet but also they're only investing all that as a trojan horse even though they use them almost exclusively domestically, plus the old "Asians don't innovate they just copy" canard even though there wasn't much Western IP on electric trucks to copy in the first place and China's battery technology is somehow not Alibaba knockoffs but more performant than Western equivalents (whilst state sponsored Chinese industries remain generations behind in stuff that's actually strategically critical for them to clone via industrial espionage like semiconductors and jet engines)

I really don't see the contradiction, if that 30% was true, which, really... but ok, it still would normal for the CCP to do stupid stuff because they think it makes them look modern or ecological or similar. That's why there's no need for economic sense to explain that development at all. There are also excellent non financial reasons to want to dominate that market. So to circle back, their use of trucks, which if you buy the 30% "omg lol" as they say, is in no way an argument to them making sense, neither economically nor ecologically.

You're making a lot of assertions without citations here.

If I look at a BYD at my local dealership, and compare it to a comparable spec German car (I live in the UK, so tariffs are not the thing shifting the needle here), I can see where the cost savings are and the trade-offs.

I don't think they're artificially more affordable. I just think they're more affordable.

Using public funds to invest in capital expenditure is - outside of the US - considered a wise use of public funds. If the result is a more competitive industry, whether that's ship building (South Korea), steel production (recent UK nationalisation efforts), military hardware (United States), or medical research, physics, chemistry, computing (look at the history of all the G7 there), and so on, and so on... irrelevant.

China has decided to spend it on complex manufacturing that they've been the supply chain for to Western manufacturers for the last 30 years. That's not controversial - it's been obvious this is where they were heading for some time.

First off, I admit I have no idea what the EU and US car manufacturers are doing, their positions for the past decade don't make any sense to me in the electric market. Actually smells like hubris and inertia more than anything to be honest.

I'm not being super academic with citations, but the CCP investments in BYD, to the point it makes no sense to exist without aren't exactly hard to find secrets.

You're not comparing comparable things, in the UK, there is a great deal of expectations of what an employee has as rights for instance. There are extremely rigorous safety regulations that are very onerous. We can debate wether those are justified but it's a very complex topic you're brushing off. Their innovation seems mostly on small iterative gadgets, but look more closely into what they tolerate as self driving and the death it causes, and be sure you want that in the UK for profit margins.

I'm really not against neither subsidies nor artificially inflating one's strategic advantage at all to develop a market and corner the competition. I never said China is wrong to do what it's doing. What I am saying is that its dangerous for us outside of China to buy into it now. Beyond the security implications of chinese robots with sensors everywhere roaming about cities the CCP considers their ennemies, there's just the dependency risk, there's the "how much do you trust the people who fed paint to their babies to handle super dense explosives that cant be put out by water in dense cities", and the basic question, maybe its better to have the lightest car possible, not the most gadgetty with drones and ipads.

So the basic point above "China has more electric trucks therefore it makes economic sense" is helped by none of this

>They already very agressively hide car lithium fires

But you found out... how?

They regularly pop up on the usual guanxi, douyin/weibo etc. They stay up for a few hours usually.

> but they're very frequent.

Yet you state their frequency as some sort of statistical fact. Your anecdotal experience doesn't make it any more or less true.

and you are refuting with even less justification. I told you how to check for yourself if you actually cared about veracity. Best of luck trying to get funding to publish something academic anti-CCP though, but I'd love it if you did. Also this is just a conversation, not an academic debate

> I told you how to check for yourself if you actually cared about veracity.

Which means nothing. You still dont get my point.

> Also this is just a conversation, not an academic debate

It can be both.

Being dependent on (cheap) oil can make economic sense as well. Unless you get cut off all of a sudden. Depending on local energy might make more sense in the long term. also for factor other than the economy.

Due to Iran, they're cutting oil/fuel imports 30% YoY, and consumption by the transportation sector by 5~10%.

And opened about 80GW of coal last year alone. That's the only advantage to electric trucks, they can run on coal too, even though you can only carry half the capacity whilst moving the same total weight, it still can make sense, just not economic and certainly not ecological. They sure love people writing articles about it though, and how green and solar they are.

Running trucks on a 50% coal grid like in China makes both economic and environmental sense.

It makes more of both as the Chinese grid gets cleaner.

neither of those are true, if they were, remember when tesla wanted to sell trucks like 10 years ago ? if you use electric trucks, half the mass you pay to move around is useless. Also the grid isn't "half coal", the truck doesn't wait for the sun to come out to charge. Which is another cost to transporters: the hours of downtime to recharge. They only make very limited sense in very last mile scenarios in dense cities. Also coal is way worse to burn than petrol, and in China's case, it's mostly bituminous, one of the worst coals in terms of pollution.

Solar is only about 13% of China's power. They have hydro, wind, nuclear and gas too as well as coal.

Their off peak prices have generally been overnight, ideal for truck charging, though they have started having them around noon too like many other nations with growing solar share. Great for a mid shift top-up.

Coal is worse to burn than gasoline, but a car engine throws 80 percent of that away so you have to burn more compared with an efficient EV.

This has all been debated to death for over a decade, MIT has interactive tools to calculate figures, there's really no excuse for not knowing this about a subject you are so passionate about.

I never said anything about green. They don't have oil, they want to be less reliant on oil. Electricity allows them to adapt the mix in a way petrol doesn't.

There are a lot of trucks that never go very far in a day. Many of them are used for "last mile" delivery. They start at a warehouse, get loaded, then go make a few deliveries and head back for the next load. While fast charging is needed, they don't go very far and thus don't need extreme range.

It is a valid question though: how do we get more of the long distant freight onto trains. Followed closely by how to we get existing freight trains to move to all electric instead of diesel electric (I've been told railroads have studied this: if diesel gets to $8/gallon it is cost effective - but I can't find any references to cite and so you should take this "Fact" with some salt)

yes i conceded that use case a bit bellow, it mostly makes sense in dense urban areas, where access to the grid is easy, and not emitting polution is at a premium. But even then it's a very difficult case to make before eg: electrifying buses, or more generally, decarbonising your electricity supply. If this made sense, musk tried to sell it a decade ago, it just doesn't. A lot of the value is that the majority don't understand the tradeoffs and complication, and just think electric = more green, and it makes for great PR specially abroad.

There are for sure higher priorities than trucks used as trucks.

Fast charging probably isn't really necessary for last mile delivery trucks. They usually work about 8-10 hours a day then spend the majority of their time sitting in a lot or garage. Perfect time to charge them.