You can do small aircraft like this, no problem. The trouble is you can't scale it up, due to how quickly the power and energy demands go up. This thing is 560 kW and gets a range of 86 nmi; an A320 is around 40 000 kW and has a range of 3 500 nmi, while an A380 is around 80 000 kW and has a range of 8 500 nmi.
Going from this DHC-2 to the A380 requires an increase in energy storage by a factor of around 14 000x, while the max takeoff weight ratio between the two planes is only 250.
Airbus is developing a hybrid electric jet, the E-Fan X. They've done the math. When their CTO was asked about the possibility of an all-electric A320, the response was
"""
Assuming for a moment that we’d be able to rely on batteries 30 times as energy dense as that of today, an A320 would be able to fly with half of its payload for one-fifth of its current range, 500nm max. So, assuming a battery which today does not exist... It doesn’t work, purely electrical will not work.
We can accomplish the same by producing the jet fuel using electricity. Realistically this will likely involve methane (natural gas) extracted from the ground and water, but it could one day be carbon neutral using captured carbon. The trick is to use clean energy like nuclear of renewables. There was an article on HN just recently about doing that with portable nuclear generators like those used on ships, this could be done right in the airport.
We already have a fantastic dense energy battery called kerosene. All we need to do is make it carbon neutral and our existing aviation tech won't even need to change.
Methane can be created via carbon capture entirely. It is in the SpaceX TODO list to create a factory to literally create metholox (methane + liquid oxygen is what they use as fuel for the new Starship / Superheavy rockets they want to use to go to mars) via carbon capture. Elon has already discussed this before. The end goal that the rocket launch is carbon neutral when you are using carbon already captured from the atmosphere.
Elon has explicitly stated in interviews that one of the benefits of the design is that here on earth, it means they can be carbon neutral. I'm just relaying what he's publicly stated already. Yes, Mars ISRU is a HUGE benefit of this design, but it also means they can make their own fuel here on Earth with nothing more than some big machinery and solar panels.
I believe his exact quote was:
"""
Sometimes I get criticism for, ‘why are you using combustion in rockets and you have electric cars’. There isn’t some way to make an electric rocket. I wish there was. But in the long-term, you can use solar power to extract CO2 from the atmosphere, combine it with water, and produce fuel and oxygen for the rocket.
"""
> The whole "carbon neutral" think is a crock. Coal is, after all, just dead trees, so coal plants run on "biofuel" and are "carbon neutral".
The difference is in the timeframes for capture and replacement - with coal it is millions of years, and with wood it is years. That means burning coal releases carbon which was trapped millions of years ago, and it would take millions of years to trap equivalent amounts of carbon with the formation of new replacement coal deposits. Burning wood on the other hand releases carbon that has been trapped within our lifetime, and it is easy to replace with new trees grown in our lifetime. Bear in mind that if we reverse millions of years of carbon capture we would revert the atmosphere to what it was like millions of years ago, and time travellers visiting that era are likely to need breathing equipment.
That's not possible, our energy needs are too great for that now. But nobody would seriously suggest wood (or other biofuels) be our principal energy source anyway.
That's my point. Any scheme involving burning wood to create aviation fuel is an indicator that the wrong side of the energy usage balance is being addressed.
My point is calling something "carbon neutral" if it is burning wood is equally unhelpful. Nothing is gained by burning a tree you just chopped down instead of burning a tree buried for a million years - the same amount of CO2 is released.
But the tree you just chopped down got its carbon from the atmosphere just a few years ago. That's what makes it carbon neutral. The coal (/gas/oil/etc.) got its carbon from the atmosphere in the far distant past, so from our point of view it's new additional carbon that wasn't in the system before. It can only be considered carbon neutral over a time span of millions of years, which is pretty meaningless.
The CO2 emissions are not themselves the point, the CO2 concentrations are. The concentration is neutral in time scales we care about from wood/alge/bioethanol/etc., but goes up from fossil fuels.
It’s also fine to burn fossil fuels if you can make long-term carbon sinks from other processes, hence people caring about making carbon-rich rocks or whether dead plankton floats our sinks.
It’s a question of being responsible for the consequences of actions, not outright banning those actions before the alternatives have been deployed at scale.
"Unhelpful"? We have a specific problem we are trying to solve. That problem is: Too much CO2, right now. The term is obviously useful in solving that problem.
Nobody is worrying about CO2 on geological timescales. It is simply not relevant to any discussion anyone is having, or any problem anyone is trying to solve.
This isn't complicated? How are you managing to miss the point with such vigour?
> How are you managing to miss the point with such vigour?
I could ask the same of you - how are you helping matters at all by chopping down a tree and burning it over digging up a tree and burning it? You're emitting the same amount of CO2.
Want to reduce global warming?
1. plant a tree
2. burn less
If you're wondering what to do with the tree after it grows, you can:
The carbon neutral part is when you plant another tree in place of the tree you just cut down. The new tree then starts taking up the equivalent carbon from the tree you cut down and burned. That is what makes tree farms somewhat carbon neutral. You can’t do that with coal.
There's an implicit time window on the sum. Burning fossil fuels is evaporating all the carbon captured in the past billion years, over a few hundred years.
Nope, that's outright wrong (and from other replies you should have learned that by now, so why keep reiterating something false?). Anyways...
The total amount of carbon in circulation is what matters because that part can end up in the atmosphere as carbon dioxide where it shows its heat capturing effects.
Trees fix carbon while growing and emit it while decomposing but do not change the total amount of carbon in circulation in the long term.
Digging up carbon that has been locked away for aeons is what is so damaging. There would be nothing bad about burning oil IF that oil were produced by capturing carbon dioxide. We do not do that. We dig up loads of fossil resources and add them to the cycle.
If that explanation was too complicted, here is an easier one: fill a bucket to the brim with water, take a cup and start scooping and pouring back to the bucket. Everything is fine. Now get a second bucket full of water and start pouring into the first (material so far not in circulation is added to it). You see the problem?
If you still insist on your view with burning coal and trees being equivalent, then I challenge you to conduct the water-bucket experiment in the middle of your living room. I mean it wouldn't do no harm, right?
Both are the same. Calling (1) "green energy" is outright wrong. Want to be green? Burn less carbon. The source of the carbon you're burning is irrelevant.
Just stuff the tree into the furnace. It'll burn just fine.
(The only reason the industrial revolution switched to coal was because the landscape was denuded of trees. The Jamestown colony in America was tasked with making glass, glass needs lots of fuel, and England ran out of trees. "Connections" by James Burke)
I don't really know where else to ask, so I'll ask here.
Another topic of research is very rapid sub-orbital passenger flight. Are there any numbers on proposed fuel efficiency for that? I'd expect you gain a lot by removing hours and hours of wind resistance, but getting up to speed and out of the atmosphere probably (gut feel) uses more.
I also haven't seen numbers, but I imagine the energy usage even to reach sub-orbital altitude would be pretty huge compared to a jet plane takeoff -> cruising altitude. Sub-orbital means you also have to bring your own oxygen too (rocket vs jet engine), which can approximately double your fuel mass...
If the fuel is synthetic anyway, uh can be made better than kerosene.
Also, we have a huge amount of free nuclear energy, daily delivered from Sun, about 1 kW / m². It is nit stable enough for electric baseload, but, depending on the process, may be adequate for fuel synthesis.
North of Sahara may become a primary source of jet fuel, given its vast amounts of insolation, cheapness of the land, and access to seawater. Not exactly tomorrow, though.
Not exactly tomorrow, but we're facing a problem today. What are we supposed to do to reduce CO2 emissions between today and the mythical day we will have unlimited amounts of synthetic fuel available shipped by tankers from Morocco?
Ok; until then, we have to reduce CO2 emissions by 7% each year from now until we reach net zero in 2050. Even if we figured out fusion today (highly unlikely), it won't be deployed at scale by then (a modern fission reactor takes 10 years to build). So there are two choices really: progressively scale down the aviation industry, or ignore the climate crisis and let 100s of millions in poor countries die from climate-related causes.
We could actually do that using fission alone, since we have we enough fuel for 70,000 years or so, and nuclear waste is free of green house gases. It would just be very expensive up front, as nuclear plants tend to be.
Assuming we have infinite renewable energy supply to produce kerosene from electricity and therefore carbon neutral flights, it still doesn't quite solve the air quality issue.
A step in the right direction, but I hope this doesn't get used as an excuse to fly more.
This is not true. It's easier to scale up. You get more efficient.
Scaling up an electric motor is not particularly hard. Some of the largest machines in existence are electric.
Power is not a challenge for electric. In fact, this electrified seaplane has much more power (560kW) than the original radial piston engine one (336kW), and even more than the turboprop conversion (510kW).
A LOT of very confident people on the Internet post lots of very wrong and/or outdated misinformation about electric aircraft (and electric vehicles in general).
Energy is a challenge, but the answer there is to increase efficiency and increase the mass of the vehicle which is battery. Both of those together give you a usable range of about 1000km. The same motor provider, Magnix, is also providing the motors for the 1000km range Eviation Alice.
Just because a conventional aircraft maker thinks something isn't possible, doesn't mean someone can't make it work. It most certainly doesn't require 30 times the energy density. For the same exact reason why electric cars don't require batteries with 30 times the energy density to compete with gasoline cars.
I'm not saying it's impossible to make a 5, 10, 15 seater all-electric work. I'm saying a 100 passenger all-electric will never fly without a revolution in battery tech.
You say "just increase mass of the vehicle which is battery". If you read about this airplane you find that since they are using batteries with an appropriate safety rating for aviation, they've used all the space and mass already:
"this eBeaver isn’t carrying passengers — there isn’t room — and will only have a 15-minute endurance with a 25-minute reserve."
I tried finding concrete info about the Eviation Alice, but the best I could find was a photo of an unpowered full-scale model. They've been saying the first flight test is a couple of months away for more than one year it seems.
I’m curious if there is some monetary trade off for the sound level:
>> the plane’s four-bladed Hartzell composite propeller generated all of the remarkably quiet takeoff sound — a fraction of the thunder from the legacy Beaver’s radial piston
Maybe they’ll get a special class to be able to launch closer to cities without the noise complaints. Although I’d imagine it’s still pretty loud.
Also the bit after the paragraph about the batteries filling up the back mentions they didn’t use fully efficient batteries... they purposefully chose very safe but underpowered batteries previously used and flight tested by NASA for their own testing purposes instead of the higher end batteries used today in EV cars.
Though all battery aircraft whether micro drones or A380 size will have a limited time they can stay up. Electrics currently seem limited to an hour or so whereas jets can do 16 hours now.
There seems quite a lot of potential on short routes <300 miles though using present batteries. (eg. London Paris or LA San Diego).
There's a lot of mistruth in green technology. You need to get to first principles - the numbers. Look at the power requirements and weight budgets of large airliners, look at the best case energy density of lithium batteries and do the calculations yourself. That's what the parent comment did.
They're using an existing certified battery for the prototype, not for operations. It takes time to certify battery chemistries.
And small general aviation aircraft like these usually only have a small portion of their takeoff weight as fuel, maybe 20-25%. But passenger aircraft may have 50% of their takeoff weight be fuel (for instance, 777 on long haul flights). Electric aircraft like Eviation will need to go further (55%). This is something you can do with a cleansheet design like Alice, but can't with a mere conversion designed literally over 70 years with manufacturing and materials from 70 years ago.
And you can apply the same principle of increasing take-off weight fraction for kerosene-powered aircraft as well. The Virgin GlobalFlyer was 82% fuel on takeoff. It flew around the world and then some. Kerosene is much better than it needs to be to enable modern flight.
You're absolutely right about Alice being late, but the design concept is a good example of what is possible. You combine state of the art but existing lithium ion chemistry (which needs some work for aviation certification but IS used on the ground already) with state of the art lift to drag ratio (and perhaps additional innovations, like wingtip propulsion to reduce losses from wingtip vortices) with efficient enough structural mass to enable 55% of the takeoff weight (as well as landing weight, of course) to be battery.
These things multiply together to enable long range.
Cars are not airplanes. Electric cars are much heavier but weight isn't a big problem on the road. That's why they work, and they're still catching up to traditional range expectations.
With airplanes, you have to lift that weight using the same energy stored within. In that case, energy density is the absolute issue. Nothing else matters.
There's no magical solution, a high-school physics class will teach you how to calculate the potential energy requirement to lift up a certain amount of weight, and dividing by energy density and volume of current battery tech does not lead to a working jet any time soon.
> the potential energy requirement to lift up a certain amount of weight, and dividing by energy density and volume of current battery tech does not lead to a working jet any time soon.
E=mgh
E=(1kg * 9.81m/s^2 * 10.000m) / 3600s = 27.25Wh.
Tesla currently is at around 260Wh/kg thus roughly ten times the amount of potential energy needed to get to 10.000m altitude.
I'd assume that till 2030 we get to ~500Wh/kg by improving current technology. And maybe some quantum leap to 1500-2000Wh/kg within 20 years.
An A320 or A380 will likely always need a fuel cell but a 15 seater with 1000km range is only a question of time.
>Tesla currently is at around 260Wh/kg thus roughly ten times the amount of potential energy needed to get to 10.000m altitude.
That's the energy - assuming 100% efficient conversion of battery power to altitude - to lift _only_ the battery to altitude (and then immediately fall back down).
Actual engines are nowhere near that efficient and you'll presumably want to lift the rest of the airplane too. Then you have to keep using power to keep the plane aloft and land it safely.
Your hypothetical 2000Wh/kg future batteries still have a specific energy less than 1/5 that of aviation fuel (Jet A = 11950Wh / kg). A 15-seater electric with 1000km range based on those magic (7.5x better than state-of-the-art) batteries would instantly upgrade to a 5000km range if you tore out the batteries and replaced them with a gas tank of equal weight.
Batteries need a ~40x improvement in their specific energy density to make sense as an energy source for aircraft that depend on thrust for lift.
Tragically, physics doesn't care that battery powered planes would be cool.
> Batteries need a ~40x improvement in their specific energy density to make sense as an energy source for aircraft that depend on thrust for lift.
I don't know how I can say "no" strongly enough.
If you only need 500km of range, it does not matter a single bit that jet fuel would increase your range from 1000km to 5000km. (Or 100km/180km/5000km respectively, if you want to talk about more contemporary batteries.)
Two things matter. Is the range good enough? How much does it cost? Jet fuel should not even be considered when answering the first question.
A good way to think of this is as a venn diagram. If an electric plane has 1000km of range then it overlaps with jet aircraft. And probably also cars, buses, and trains. I think of friends that live in the middle of Nebraska. If you want to take a plane first you drive three hours to Omaha. If electric aircraft were cheap enough perhaps they would come out ahead flying to Denver instead.
Potential energy is only one component of the power required by aircraft. If you want to actually go somewhere, you need speed, which means drag.
Drag increases the square of the velocity. That means going at 500knots (as an airliner does) uses a lot more power than going at the 150knots this seaplane might fly at.
You can calculate an approximate power requirement for the aircraft based on its glide ratio [1] or look at the power based on engine thrust [2]. In all cases you get figures in the 14-80MW range (engines don't tend to be full throttle during cruise)
That means your 260Wh/kg battery would need to weigh somewhere between 54 and 308 tonnes to sustain an hour of flight. That doesn't include takeoff, which is only a few minutes but might reach towards 200MW.
For reference, the 737 (low end power calculation) max takeoff weight is 62 tons and the 747-400 max takeoff weight is 397 tons. So in both cases you're looking at basically 30 minutes of useful cruise with current battery tech.
The range loss is additionally confounded by the fact that current aircraft lose fuel, so lose weight, during the flight. This accounts for a not-insignificant portion of the range.
All depends on what you want. You can have “infinite” range with “no” battery — gliders are a thing, you can rise on thermals and turn the potential energy into kinetic to get wherever.
But if you want to go as fast as a chemical engine and sustain that for as long as a chemical engine, you either need at least the energy density of a chemical fuel or some way to refuel in-flight.
Fuel efficient often means “slow”. Great for cargo, not so much for passengers.
Edit:
Just to add, I’m looking forward to a future of short-range electric personal aircraft, I’m just not expecting pure electric intercontinental for anyone other than hobbyists — unless there’s a big breakthrough in density or wireless power transmission.
The longest range conventional chemical aircraft flew around the world without landing. It's not necessary to equal that range for any commercial application. Kerosene is better than it needs to be.
Fuel efficient for aircraft doesn't necessarily mean slow, however (unlike ships). What matters is cruise lift to drag ratio. As long as you can adjust cruise altitude for peak efficiency and as long as all the flow is fully subsonic, then lift to drag ratio is mostly independent of speed (as you can increase altitude where the air is thinner to compensate).
So yeah, electric aircraft might stay at Mach 0.5 or so, but they don't need to be slow. Mach 0.5 is still much faster than any passenger high speed rail service and MUCH faster than car or bus or boat.
Pure electric intercontinental may be feasible for near-term chemistries like lithium-sulfur if you continue to push efficiencies (both structural and aerodynamic). Very long haul, like LA to Tokyo, will need lithium-air technology which is a few decades off.
Electric motor gliders should be great! You only need the battery/prop for takeoff and occasional sustaining flight and the glide ratio is ~4x better than general aviation planes.
It's almost like you didn't read the comment you're replying to. It makes the absolutely valid point that the power requirements of a small jet airliner are many orders of magnitude greater than the power storage capabilities of any current battery technology. I don't really see how you refute that. Nobody's arguing you can't make a small electric plane work (clearly - the article is about one which works). Big ones are another thing altogether.
Not even that. I believe an 86 nmi range is what they are hoping to achieve by 2025. Current range is a fraction of that. The technology demonstrator has a theoretical flight time of 15 minutes and no ability to carry passengers because all the room/weight is taken up by batteries.
"Kelly was now so desperate to save weight that he upped the ante to one hundred and fifty bucks to anyone who could save him a measly ten pounds. I suggested we inflate the Blackbird's tires with helium and give each pilot a preflight enema. Kelly tried the helium idea, but helium bled right through the tires. The enema idea he left to me to try to promote among the pilots."
> What certainly hasn’t been done before is to fill a Beaver’s cabin with lithium-ion batteries, taking the plane to its gross weight. As a technology demonstrator, this eBeaver isn’t carrying passengers — there isn’t room — and will only have a 15-minute endurance with a 25-minute reserve.
Sorry, you seem to be quoting a bit selectively. From the same article:
> These are batteries that NASA is using, but they’re not batteries that we’d use if we were going to try and make it economical to fly today, because they’re very low in watt-hours per kilogram
On the other hand, it's not like NASA was trying to get the lowest energy density possible. They were trying to get a li-ion battery pack with acceptable safety margin. And for this I understand one of the biggest factors is to have sufficient space between cells that a thermal runaway in one cell cannot spread.
It's a seaplane, it lands on the water, not an airport. Additionally, the total flight time including reserve is 40 minutes in this prototype and will be at least 60 minutes on the operational one (with Tesla-like-energy-density batteries).
It seems to me that they have two somewhat separate engineering challenges. The electric motor and throttle control system, all the drive train stuff forward of the instrument panel in a Beaver. Plus however they retrofitted the cockpit engine control. Which might be quite a bit lighter than a pt6 turbine retrofit to turn an old Beaver into a turbo Beaver.
And then the other much harder problem which is achieving sufficient Wh per kg energy density in batteries, and Wh per litre of volume. For which they are dependent on global factors for r&d of batteries and improvement in density.
No, not for safe landing. If a jet couldn't land safely while fully tanked then they would not be able to land in emergencies happening early in the flight.
They rely on the plane being lighter from fuel burn and therefore more efficient to extend their possible flight time, but not for safety.
I guess it depends on what you call a safe landing. For large airplanes the maximum takeoff weight is typically greater than the maximum landing weight. If an airplane lands overweight it can no longer fly until it has been inspected and repaired. Most emergencies will involve flying around for long enough to get the aircraft within the acceptable weight limit. Some older aircraft have the ability to dump fuel, although I don't know of any new ones that have this capability.
Needing to land before getting under weight usually means a crash landing. In modern times, very few things like fire or an engine self-destructing will require immediately getting out of the air. It is usually better to fly in a straight line, figure out what is going on, figure out where to land, then land. This lets you get underweight, lets you communicate with air traffic control, lets emergency services prepare, etc.
It isn't an issue for smaller planes (A320, 737), but larger planes (such as 747, 777, A340, A380) usually have a lower maximum landing weight than their takeoff weight. If an emergency happens early in flight they usually have to dump fuel to reduce weight before they can land. https://en.wikipedia.org/wiki/Fuel_dumping
An emergency overweight/crash landing is the opposite of a safe landing.
Airliners will dump fuel or keep flying to get below maximum landing weight if possible. If they're still overweight and manage to land without issue, the plane will need to be inspected and repaired before it can fly again.
The strain the weight of the fuel places on the airframe during landing is the issue, not a risk of explosion. Furthermore fuel tank inerting systems can greatly reduce the likelihood of any problems.
Sure, but I'm not sure what you're asking in context. It's not about fuel vapor but overall weight on the airframe at landing. The bigger jets are not designed to touchdown at the fully loaded weight.
That's all undoubtedly true, but fortunately, most flights don't require the capabilities of an A380, and in fact, demand for that specific set of capabilities is apparently low enough to stop building them altogether. Even for A320 flights, most are not 3500 miles, even if the aircraft is capable of it.
If we could make progress targeting just short hops targeted by DASH-8s or CRJs or whatever, we could still make significant progress, even if it meant leaving the longer-haul flights alone, or targeting their emissions with different technologies (synthetic fuels from carbon capture, maybe).
All electric with this century's technology might work for 8-16 passenger short-haul aircraft, if that market can be created (think, many flights from various regional airports between the SF Bay Area and LA area). Nothing bigger is going to fly without a massive breakthrough in battery energy density.
It really just comes down to energy density and the fact that batteries weigh just as much when you land as when you takeoff, whereas you burn off most of your fuel over the course of a jet-powered flight. Those two things together mean that as you increase the size of your aircraft, batteries take up a bigger percentage of your available weight budget.
It's pretty much a smooth curve, with the breakeven point depending primarily on energy density of your batteries. Until very recently, the electric aircraft weren't possible at all. We're now at the point where two seat trainers with short (but long enough for a typical lesson) endurance are possible and in production. If you look at where battery tech is going, we can probably push that up to 8ish seats and a somewhat longer endurance within a few decades. When you look at the size of even a small regional jet, it doesn't seem likely that current battery tech is ever going to get us to the energy density necessary to make it work.
Pedantically, the batteries do weigh less when depleted. Not enough to make any sort of difference, but E=MC^2. We're talking micrograms for a battery the size used here. Doesn't invalidate the point that electric airplanes can't work effectively with current lithium-poly battery technology though.
I could see a non-rechargeable electric battery (but refillable, ala jet fuel) such as aluminum-air maybe working.
The round trip efficiency would be similar to diesel (since you are re-smelting rather than recharging), but the effective energy density on the plane could actually be much better than jet fuel.
> Going from this DHC-2 to the A380 requires an increase in energy storage by a factor of around 14 000x
First of all: citation needed.
Secondly: it's a disengenious argument to say "you can't scale it up", then give the largest passenger aircraft in operation as your first scale up target.
What about scaling up to the size of the propellor aircraft regularly carrying people between Amsterdam and many cities in the United Kingdom every day, or thousands of the other short haul routes? Indonesia is another example.
If we are looking at an energy-conscious (or energy-scarce) future, then we really have to consider what forms of transport are feasible at all. For these kind of short-hop journeys, flight is probably not efficient enough.
Power (kW) determines takeoff weight (ie plane size/passenger count), energy (kWh) determines range. This article doesn't have all the info needed to say how this would scale. For instance, if the energy storage of the batteries doubled but the power stayed the same, you couldn't make the plane capacity any bigger but you could extend the range to more than double.
Fuel cells are a possibility. There is some pretty high power densities (2.5kw/kg for SOFCs, 10kw/kg for less efficient PEMs). Electric motors are now reaching 15kw/kg. For comparison, a GE90 is about 10kw/kg, and older turbofans down to 2kw/kg. Running on liquid hydrogen presents some problems that are definitely solvable, but SOFCs can run on pretty much any hydrocarbon fuels at extremely high efficiencies (50-60%, 80% with combined cycles, compared to the ~45% that jet engines get).
I actually think the future may be a lot more simple than we're making it out to be. With some slight modifications to design, we could run existing turbofans on liquid hydrogen fuel. The biggest objection that most people have is the storage of hydrogen...but liquid hydrogen doesn't actually need to be stored in cryo tanks as long as the fuel is being used at faster rates than it evaporates. That's not a problem with jet engine consumption rates...low tech insulation may be sufficient.
There reportedly is an additional threat to the climate coming from inversion traces (modifies enough of Earth albedo?), so if we're delivering water to high altitudes, it's still not good.
Electrical motors would solve this; if we'd be able to avoid dispersing water from fuel cells up high, that could work.
LH2 has storage - and safety - issues still not solved. Toyota Mirai approaches it from a different angle, with some other shortcomings.
How about using battery powered aeroplanes for shorter trips, and solar powered airships for longer distances? Bear in mind that the first electricity powered flight was an airship: "In 1883 the first electric-powered flight was made by Gaston Tissandier, who fitted a 1.5 hp (1.1 kW) Siemens electric motor to an airship."[0] And we also have solar powered airships which can stay in the air for 6 months at time now[1].
Why would it matter how big the plane is? For a certain battery energy density and battery mass fraction, you should get a certain range, no matter what the size of the plane is. If anything, large planes should be a bit more efficient.
I think hybrid would be a great compromise. Short range jets spend a lot of kerosene just during taxi and takeoff. If you could just do launch and climb on batteries and then replenish the batteries from a jet powered generator during cruise, that would already be huge in terms of not just CO2 but also ops cost.
I think people aren't quite willing to face up to the consequence of this, though: This means that commercial air travel, as we know it, is going to go away. We can not afford to keep burning fuel at the rate we do for flights today, and we won't even have that fuel available at some point. And if we can not develop electric or renewable alternatives, which we very well may not, we will just have to stop doing it.
It takes a 747 quite a bit more than 2.5 minutes to reach cruising altitude. 30,000 ft at 5000 fpm is 6 minutes, and engine input is a lot higher than 90 MW because engines are not even close to 100% efficient (neither are electrical ones).
Also, the weight on landing is critical not on takeoff, and you can't exactly shed battery weight because empty batteries weigh roughly the same as full ones do, so you will need to take maximum landing weight into account.
Finally, you need to take reserve fuel into account, alternates and headwinds.
I think you should re-do these numbers with more realistic inputs.
There are more practical ways to reduce the population than cratering airplanes into runways.
Fuel is a major expense for commercial airlines, they don't burn it just for shits and giggles. Airplanes use fuel when landing because destroyed aircraft and piles of corpses will quickly cost more than any fuel they'd save by trying to glide every plane to the ground.
Big aircraft are a thing because small aircraft are very expensive to operate. In GA there's a thing called the 100$ hamburger which is basically pilots doing short flights to grab a burger and spending about 100$ on fuel to get some air time. These are short hops and the handful of companies operating flights commercially for this kind of distances charge similar amounts (or way more) for the privilege per passenger. The main reason that this market is so small is the fuel cost. If you drastically cut that cost, you create a new market.
What electrical flight will do initially is enable the 5$ hamburger flight and create that market. Same distance, same speed, fraction of the cost. GA is currently prohibitively expensive mainly because of fuel. Operating that kind of flights commercially offers similar advantages though you still have to account for the pilots.
And while pilot cost is a factor, their availability is a much bigger problem. There simply aren't enough of them to operate the tens of thousands of mass produced electrical planes that on paper could out compete commuter jets on cost, scale, noise, flexibility, ability to land just about anywhere, etc.
The solution to that is self flying planes, aka. drones. This will likely happen long before we train up hundreds of thousands of new pilots. Like self driving cars there are challenges for this and like self driving cars those challenges are increasingly of a legal rather than a technical nature. It's technically feasible but getting permission to actually start doing this will take time and is happening very slowly despite e.g. Waymo 'drivers' actually needing to touch their controls is now becoming a once every few tens of thousands of miles kind of thing.
The list price for the Eviation Alice (projected to hit the market in 3-5 years) is around 3M and flies 9 passengers. The list price for an A319 is around 90M and flies about up to 160 passengers. So, ballpark it's not unthinkable to fly similar amounts of people using 20-30 mass produced self flying electrical planes competing on most 1-2 hour hops that these jets are typically used for. That will take decades to happen but it is entirely feasible with today's level of technology.
Small planes are not fundamentally hard. Cessna nailed mass production decades ago and electrical planes are vastly simpler (way less moving or combustible parts) And as Tesla and other battery manufacturers are showing, there's nothing fundamentally hard about producing a few hundred kwh of battery at a reasonable weight. A small plane with 500-1000khwh of battery will have a very usable range. With increasing energy densities, that will eventually extend into longer ranges as well. The Eviation Alice manages close to 600 miles on 900 kwh of what is essentially similar to the current energy density of mass produced EVs i.e. hardly the state of the art in battery tech. They are holding back here to get this thing certified ASAP instead of opting for already existing newer battery tech.
The impressive thing about this particular announcement is that it is a cost effective conversion for planes that are 60+ years old with a very well understood mission, which is very short hops. The reason that is economical is because combustion engine economics for that are so spectacularly bad and always have been. Electric flight is going to kill that market first and very soon because it hardly was a market to begin with. Small electrical planes crossing the Atlantic is going to happen at some point in the next decade or so. From there to that becoming a routine thing will take more time. But once that happens, it's likely to challenge the economics of dong the same in a 747. There's no fundamental need to scale electrical planes to that size even though that will probably eventually actually happen as well; but that will indeed require decades of improvements in energy density in batteries.
The only questions around electrical flight is when, not if.
How would planes would look like if fuel prices increased a few fold? I would assume probably less jets and more turbine aircraft, at least on short trips. Straight wings and slower speeds. Boeing and Airbus might lose some market share. Boeing never had a turboprop, Airbus owns 50% of ATR.
Assuming you mean turbofan vs. turboprop here, since both of these are turbine-driven.
In either case, my understanding is that turboprops don't present a substantial gain in efficiency, as turbofans allow for higher and faster cruising altitude, which reduces drag on the airframe.
I’m sure you have your valid reasons for doubting the feasibility of such a plane, yet here we are in 2019 talking over a network which was completely inconceivable at one point in history.
I just read your message as,
“Can’t be done yet, will most likely be done somehow in the near future”.
the scaling problem might be real, but it's not really a problem for harbour air, whose primary routes are ~50km from vancouver to victoria or ~80km from vancouver to whistler on nothing bigger than a twin otter.
The scaling problem is real. There's no electric plane in the world that can do that route with passengers right now (including this one). The scaling problem is probably surmountable for this particular use case, but it's far from trivial.
Jets consume an unusual amount of energy and you don't run them at full throttle all the time. You'd probably use propellers and/or ducted fans for any electric airliner.
I've seen a lot of skeptics and nay-sayers talking about this project, but I feel like there is a fundamental mis-understanding of why this is significant.
No, it's not going to compete with jet airliners even in the remotely near future. High-bypass turbofan engines have enormous cost advantages over traditional piston engines. It's almost always more economical to use a turbofan engine to power aircraft in anything more than a short hop.
I see this being a classic case of something like Mainframes vs. PCs however. Most people don't equate flying with General Aviation because GA has traditionally been so cost prohibitive, much the same way that mainframes were so cost prohibitive in the 60's and 70's. There are a few airlines, like Harbour Air, and Mokulele, that currently offer a short haul flights (usually over water) where people are willing to pay a lot more money. There are benefits like frequency of flights, but the big ones for me are not having to queue up for security, and being able to bring liquids on board. My wife once brought a can of soup on board Mokulele. Try doing that on Hawaiian.
If this can bring down the cost of short haul flights, particularly those around 200-250 miles, it could be extremely appealing, especially when coupled with ride hailing. I would much rather take a 45 minute flight and get Lyft on the other side, than spend 3 hours sitting in a car stuck in traffic. GA can fly out of smaller terminals and smaller airports. San Carlos (SQL) to South Lake Tahoe is a 40ish minute flight in a GA aircraft, but can be 5+ hours in traffic on I-80.
Some perhaps useful context: Harbour air operates the worlds largest sea plane service, the majority of it between Vancouver (city) and Vancouver Island (mostly Victoria). They are a perfect test bed for this, as the in air time is about 15-20 min for most routes. (less 100km/60m ).
So while electric is a long way from long haul domestic routes, let alone international, I could see it taking over specific services like this fairly quickly, at least relatively speaking. I can see why they are experimenting with it.
Apparently they plan to have certification for this aircraft in the next 2 years, but early days yet.
I wouldn't count out international so quickly. Once they've got Victoria sorted, it would be great to see them extend down to Everett, Washington to link up Seattle.
It's 68 miles from Vancouver to Victoria, 98 Miles Vancouver to Everett. Theoretically, they could fly out of White Rock to reduce that distance as well.
I'm waiting to see if Eviations Alice actually fly's and meets spec's. They're claiming 600 miles of range at around $200/hr. If they can hit that then they are not only competitive in existing markets. But new ones.
Logan Air are also planning on "the the world's first electric–powered commercial passenger flights" in 2021[0] using a converted Britten-Norman Islander. It is similarly for an island hopping service, with the shortest flight just 1.7 miles (typically around 1 minute) which it sounds like this converted DHC-2 de Havilland Beaver should be able to manage.
> "It's a prototype for sure," said McDougall, "but in every way it's a high-tech piece of equipment, which is kind of ironic considering the airframe that it's attached to is actually one year younger than me — 62 years old."
> McDougall's flight is the first exercise in what is expected to be a two-year process to get the e-plane certified for commercial use.
For some context Harbour Air is a scheduled floatplane airline operating primarily between Vancouver and Victoria in BC. Since there is no bridge connecting the capital Victoria to the largest city Vancouver, they offer short flights on seaplanes that connect downtown to downtown as an alternative to ferries or larger airplanes that arrive at the airports further outside of the downtown core of either city.
In this constrained context it seems like an electric airplane could work really well and provide fuel savings and a quieter ride. They also seem to have some ambition with these electric aircraft to provide other short range flights.
> MagniX CEO Roei Ganzarski said Dec. 10, 2019, will go down in history as the start of the electric aviation age, and believes the e-plane will eventually revolutionize how people travel by making short- to mid-range flights more economical than driving. "It means you can stop driving for three, five, seven hours to get to a destination because there's no other way to get there," he said. "It means you can fly in a small aircraft from a small airport to a small airport.... It's faster, cheaper and more convenient than any other method of travel, including going with a standard airline."
It happens! Sorry. We do plan to do something eventually to share karma with earlier submissons. In the meantime it's a bit of a lottery, but it does even out in the long run if you keep submitting good stories.
Adding a little context: Harbour Air is a short-hop seaplane operator working out of downtown Vancouver. Most of their flights are ~ 100km across the Georgia Straight to Victoria and Nanaimo on Vancouver Island. Trips are ~ 30 minutes IIRC. There is no bridge to this island and the alternative is a fairly large commute involving a ferry. It's quite convenient to have a direct connection between downtown Vancouver and downtown Victoria.
Fuel is quite pricey here, they might end up saving a couple hundred dollars per hour in fuel and engine upkeep costs.
Tangential; I took a Kenmore Air seaplane flight from Seattle (South Lake Union) to Victoria this summer, and it was absolutely amazing. I loved every second of it, and can't recommend it highly enough. 45 minutes flying time, so quick and convenient. We walked to and from hotels on both end.
When I lived in the northwest, it was trivial to drive+ferry to Victoria, even though it was very slow. I always thought the Clipper hydrofoil, let alone flying, were unfathomably expensive luxuries.
But as a tourist without a car and on a limited schedule, suddenly the Clipper (hydrofoil passenger-only ferry from downtown) and flying seem like reasonable options versus having to rent a car, pay for fuel, take a car ferry, drive a bunch on both ends, pay for parking, etc.
In the end, I think Kenmore cost less than 2x what the Clipper would have cost us. Not cheap, but absolutely worth it for a novel one-time experience. One passenger even remarked that the seaplane flight was cheaper than flying from Sea-Tac to Victoria airport, before even factoring in the fact that neither airport is near the major city you're coming from or going to.
Carbon neutral biofuel or fuel made via excess solar/wind should probably be the goal.
Fuel cells might be viable too and the regulated commercial nature of planes probably means that hydrogen's storage and pumping headaches wouldn't suffer the consumer problems.
But biofuels are probably the way to go for now.
There are probably hybrid airship designs with solar panels that could do lower cost shipping. All that extra surface area from the blimp can be covered in solar panels or those fancy solar paints.
Oh, and another thing, while long haul flights won't be impacted, self-driving cars and trucks will obliterate overland short hop flights, and for trucking probably medium range (1000miles) as well. 12 hours of driving 7pm to 7am overnight at 50mph average is 600 miles, and at 70mph with some convergent infrastructure would be 840 miles.
I would get no work done in that office. When in Vancouver, I spend a good amount of my down time sitting at the Convention Centre watching the comings and goings in the harbour.
Yes, when you start digging into the details, it turns out that they filled the plane, a de Havilland Beaver, to the gills with batteries. The batteries physically consume all the interior space, leaving no room for passengers, and they bring the takeoff weight to the max that the (electric) engine can manage.
With all that, the range is 15 minutes, with a 25 minute reserve. That is not even enough to reach Nanaimo, which is the closest town the planes could potentially serve.
So, neat demonstrator but a long, long way off from viable commercial operation.
This isn't true. If you want to keep making these claims, you're going to have to provide a source. For instance, there's plenty of space behind the pilot that is empty. There's plenty of interior space as the batteries are placed below.
Additionally, they are using bulletproof flight-certified batteries which are much lower than the typical good lithium ion batteries used in, say, a Tesla. They're just for the prototype. "“These are batteries that NASA is using, but they’re not batteries that we’d use if we were going to try and make it economical to fly today, because they’re very low in watt-hours per kilogram,” explained McDougall."
The electric motor (not an engine) is 560kW, almost twice the original 336kW radial motor, so it's not in the least underpowered (as you imply).
I'm a big fan of renewable energy (solar, wind), electric cars and likely electric planes (not yet available, so hard to say). But my biggest concern is that all this will eventually lead to people decisions being affected by rather this hipe, than common sense (like with nuclear power, which is the greenest currently available peak/off-peak source of energy). Something similar can also happen, as with Saturn 5/Apollo, after some time we will lose the technology, because people retire, workshops are disassembled. We can loose technology of efficient piston and jet engines, nuclear reactors, ultrasonic flight, et al. This by itself is fine, batteries work fine obviously, though one can imagine conditions where it is not the case: Antarctica, Mars, Moon, space, etc. Just look at Juno space probe, which instead of small RTG uses huge solar arrays, which produce just few hundreds of watts on Jupiter orbit, while being capable or producing kilowatts on Earth one.
Off topic and stupid, but could an electric plane be outfitted with lightning rods and/or lightning rockets to attract lightning strikes in order to charge the batteries?
The internet says the energy of a cloud to earth lightning strike is 10^9 joules. A gallon of jet fuel contains about 10^8 joules of energy. A strike would provide the equivalent of 10 gallons of fuel.
A 737 would need to be struck at least once every 10 miles to keep going.
Sadly, that lightning power number is for cloud to earth, a cloud to airplane is going to be far less. If you try to extract too much power from the bolt it will just go around you.
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Meta comment: I like the breadth of this comment's peers. We have this one about the scale of energy, one commenting that it doesn't help range because you can't rely on it, one about the disparity of power between charging and discharging, and one about avoiding complexity and mass in airplanes. All good points. I hope in 12 months we hear back from the lunatic that ignores them and makes a functioning prototype.
Yes a single lightning strike contains roughly a similar order of magnitude of energy as an entire charged flight battery would but it is delivered in microseconds.
That comes out to hundreds of terawatts of power while in comparison the new Tesla supercharger charges at an incredibly high rate of hundreds of kW. That's 1 Million times lower than lightning! There is no substance on earth that can absorb and store energy at that power rating.
On top of all of that, even if you could get it to work it would be such an unreliable source of energy that it would never make any economical sense to deploy on plane if you could just capture it on the ground and charge the plane from there.
About a decade ago an astrophysicist friend of mine told me that you can store lightning energy into some kind of a supraconductor, the problem being that we don't know how to take the energy out.
They have static discharge wicks to let the lightning pass through. Newer carbon aircraft integrate copper mesh to conduct the current through the hull. The aircraft must be flyable following a strike, the ones I worked on were basically only able to protect the crew and land safely in that event. After that, it was expected the aircraft would be fully torn down, inspected, and rebuilt.
The idea that a lightning bolt could be used as a power up source has been thoroughly debunked by myself and others in this thread already, but I thought I’d take another angle in response, just using electricity in general.
A single GE90 aircraft jet engine used in the 777 is up to 111,000 horsepower[0]. So for the Boeing 777, that’s ~220,000HP. Converting horsepower to megawatts, that’s 164MW of power during takeoff (and approximately half that during flight). There’s approximately 500-1000 B777s (very rough, but educated guess) in the air at any given moment during the day. That’s 82.5 gigawatts of power just for the 777 flights alone, not counting all the other commercial aircraft in use.
So how much is 82.5GW?
> The Palo Verde nuclear power plant in Arizona is the largest nuclear power plant in the United states with three reactors and a total electricity generating capacity1 of about 3,937 MW.
So 40+ of the largest nuclear power plants in the US?
> average wind turbines produce 1.5MW of power at 100% efficiency
So 55,000 wind turbines at minimum? Better hope it’s windy!
Flipping it another way:
> an average LCD TV uses 200W of power
So in other words, turn off 400M TVs around the globe to offset the power needs of up to just 1,000 planes.
Now finally...
ignoring the electricity generation needs, let’s talk about just battery storage on the plane itself. A typical 18650 (the battery that is commonly used to make large cells, for example in your electric cars) is something like 9W of power. So you’d need something like almost 20,000,000 batteries just for a short flight. Each 18650 weighs about 45g (not including wiring harnesses and safety gear). That’s 200,000 pounds of batteries. The batteries alone for a short flight is multiples of the weight needed in fuel for an international flight.
A fully loaded commercial jet is usually at or close enough to max engine power at takeoff. During flight, estimates I’ve seen online are around 50% of the maximum jet engine HP.
Utilizing the energy in lightning is hard, the voltage involved are hard to contain without damaging equipment and you can't charge batteries directly from the strike so it must be buffered somewhere.
And if you have the ability to buffer tens of gigawatts of power, if even for a fraction of a second, in the air while flying, why bother with batteries?
People say it's already useless on solid ground. I suppose we can forget that on moving objects.
That said I wonder if helium filled balloons with extremely capacitors could absorb some of the voltage difference in the atmosphere and act as mini batteries.
Some people already tap into atmospheric voltage near ground with drones carrying long wires.
There’s 20M lightning strikes per year in the US according to a quick web search, with the vast majority of those happening in Florida and very few on the west coast.
Let’s assume west coast flights don’t apply, only ones in the SE United States. Even then, you could maybe be “lucky” enough to get one strike per day.
Doing some very rough napkin math, a lightning bolt can provide ten billion watts of power, but for something way less than a millisecond (most sources I’ve seen say closer to a nanosecond, but let’s be optimistic and go with 1/1000th). Assume we have the ability to buffer this (we don’t, to my knowledge), that gives us 10MW for one second assuming 100% efficiency. A 747 takes 90MW of power just to get airborne and it needs that for longer than a second even for that. So basically you’d need something like at least 100 lightning strikes just to get the 747 airborne (assuming that’s doable in 11ish seconds, I think it “might” in extreme circumstances).
I’m sure my math is grossly flawed in some way, so don’t expect scientific accuracy at all, but it should clearly show the absurdity of using lightning as a power source for jet flight.
While the title may have it right, later in the article they state that this is the first electric aircraft... well they've been flying in WA for some time now
I believe the real benefit of electric planes is the maintenance cost. Most small planes require that the engine be torn down and inspected / parts replaced on a regular (per flight hour) basis.
An electric motor may have a longer service life than an engine, and is almost certainly much less expensive to service.
Still seems a bit far from replacing jet engines? This article was going on about fuel emissions in the entire aviation industry, this is just an electric propeller. Anyone know how far we are from electric jets? Is such a thing even possible?
>"Anyone know how far we are from electric jets? Is such a thing even possible?"
Electric will never replace long haul jets barring a revolutionary breakthrough in battery technology. But that's not the point. Much of commercial aviation takes place on distances of around 100 to 500 miles. That is, too far to drive but not quite far enough to take advantage of the efficiency of jet engines at high speed, high altitude cruise. For those applications electric propellor and ducted fan aircraft will be absolutely game changing. It will make these flights cheaper and safer by a factor of 10 at least. The vast majority of cost in a flight is maintenance of the engine. That all goes away with electric power. It will make commuter flights an affordable daily reality for normal people.
Hybrids are interesting because you can reach higher bypass ratio's because you can power n number of ducted fans off m engines.
Currently increasing fan sizes are getting problematic. That is the problem with the 737 MAX. The fan diameter of the new engines is too large to fit between the bottom of the wing and the ground. So it had to be mounted forward and up which fucked up the aerodynamics.
Two other advantages are, potentially maintaining thrust in an engine out situation. When you lose an engine not only do you lose half your power but the thrust is unbalanced. And faster throttle response. Turbine lag is a big issue with jetliners.
Note: The reasoning behind high bypass turbofans is thrust is proportional to delta v times the mass flow rate. Where power input is proportional to delta v squared. Bigger the fan the more efficient you are and the less fuel you use.
Diesel is kinda interesting. Manufactures are developing diesel engines for light aviation. I suppose you could have a hybrid diesel/electric aircraft.
I think "Electric Jet" is like saying "Electric Internal Combustion Engine" - A Jet is a type of engine, so an electric aircraft wouldn't be a jet.
I know people call Jet-powered aircraft "jets" but, that's really an abbreviation.
I think what you're asking though, is whether there are any electric propulsion systems with the same characteristics as jets - i.e. more thrust relative to speed. AFAIK, there are not, because a characteristic of chemical fuels is that increased compression and airflow can increase the efficiency of the reaction. Electric motors have a (relatively) fixed efficiency due to the battery.
The jet in jet-engine refers to the fact it uses jet propulsion - i.e. producing movement in one direction by ejecting a fluid in the opposite direction. This means that lots of things are actually jet engines - rocket engines and water jets being two common ones.
The propulsion of a 'jet engine' is normally through a gas turbine, which is a type of internal combustion engine, so you wouldn't get an electric gas turbine.
Replacing the gas turbine with an electric motor would in this case produce an electric jet engine.
A modern jet engine is just a shrouded propeller that happens to be powered by a jet turbine. An electric ducted fan would be the battery-powered equivalent.
>A modern jet engine is just a shrouded propeller that happens to be powered by a jet turbine.
No, it's not. A propellor creates thrust by slicing the air and creating lift just like a wing, but in a forward direction. A jet engine's fan blades create no thrust in themselves. They provide the compression needed for combustion to occur within the engine, and thrust is created by the expelling of hot exhaust gasses.
That is a description of a turbojet - the earliest type of aero jet engines[0]. GP is referring to modern turbofans which are defined by having a bybass - i.e. air that is compressed and then expelled rearwards without passing through the main turbine body[1].
This is done to trade the high speed of the jet exhaust for a larger amount of air moving more slowly. Making the speed of the jet plume closer to the true airspeed of the aircraft makes it more efficient.
And to be more detailed, in any jet turbine, the compressor blades will create power as the energy spent compressing the air will be recovered when it's exhausted out of the tailpipe. So it's not quite correct to say they will produce no thrust.
Looking at design of turbines, a lot of air is needed above the amount for combustion to help keep the post combustion chamber turbine from melting (or just weakening to the point of failure). Some of this will be the unburnt (nitrogen, etc) components of the ingested air but a lot of design goes into moving air around components to move heat away from them.
The less air needs to be compressed for the engine then the more efficiently it will run. This is often achieved by designing one that can run hotter. This is also one of the other ideas behind having the bypass on a turbofan, reducing the amount of air that is compressed.
No, the exhaust is not the primary thrust generator, unless you're talking about military jets. The fans themselves are creating the majority of the propulsion. Modern high bypass designs have bypass ratios of ~10:1, meaning for every 1 lb thrust generated from the exhaust, 10 lbs comes from the fan.
Note that modern military jets have low bypass ratios, but not zero. They use low-bypass turbofan engines, not turbojets. Even cruise missiles use turbofans rather than turbojets. I think the only place you might see a turbojet flying today is in RC scale aircraft.
I wonder if the limitations of electric flight will impact the infrastructure - big, dense networks of airports to support short range flights across the world.
sounds kinda weird. IC engine planes get more efficient with lower fuel (lower weight)whereas with Electric ones, you still have to carry the weight around with lower power.
Going from this DHC-2 to the A380 requires an increase in energy storage by a factor of around 14 000x, while the max takeoff weight ratio between the two planes is only 250.
Airbus is developing a hybrid electric jet, the E-Fan X. They've done the math. When their CTO was asked about the possibility of an all-electric A320, the response was
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Assuming for a moment that we’d be able to rely on batteries 30 times as energy dense as that of today, an A320 would be able to fly with half of its payload for one-fifth of its current range, 500nm max. So, assuming a battery which today does not exist... It doesn’t work, purely electrical will not work.
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