Electric Aircraft, MEA and charging - Page 1
Forum section: electronics / general

author: k5njp_PE
author_rank: Newbie
timestamp: January 21, 2020, 11:44:02 am
content: Greetings Ya'll. There are some big initiatives to replace the jet engines on large aircraft with large electric motors. There are a lot of people working on these things. If we take a rough swag at it and say that perhaps a plane might need two electric motors as prime movers, perhaps 1MW each...on perhaps a 4 hour flight across the US we have 8MW*h required to run the machine, on the assumption that the efficiency of the inverter and motor is in the ideal. and with the second law of thermodynamics, we know that it's not ideal, it's less. So we need something more than 8MH*h of battery bank where the fuel tanks used to be. And then we need some headroom on that. could you imagine coming into an iced over runway or a sudden snowstorm and getting diverted? I believe that has happened once or twice. Energy reserve will be needed to accommodate that. Let's say perhaps the battery needs to be 16MW*h to make the trip with safety margin.so the plane operates like a giant cordless drill. maybe they up the size of the APU a bit and make it all work like a series hybrid, but the APU is space constrained. it's not going to make the full tractive effort. it might contribute 25% or so, at which time the batteries are the prime source.now let's go out a bit over the skis. Let's say that the turn time on the aircraft is to be one hour, just like when they ran on jet fuel. We then have a plane landing needing between 8MW*h of charge and 16MW*h of charge. But is that the only plane that landed that day? not likely. At a large airport, they might land 100 of these in an hour.if we take the high number of 16MW*h, and 100 aircraft charging in an hour, my paltry mortal pencil gets 1.6GW required to charge these things. I don't think photovoltaics on the roof can provide that much power. The airport would have to be surrounded with large wind turbines and perhaps some hope that it was always windy?? or perhaps the jet fuel storage tanks are removed and a BWR nuke installed. Ok, so powering 100 fast chargers is formidable........but let's dig in a bit. Let's say the GPU is capable of this power level. Ok, if it is to run at 480VAC three phase and deliver 16MW, we get 5.3MW per phase, 19.2kA per phase. The lineset to the portable charger is then comprised of 10 strands of 500MCM cable per phase. For a five wire charger (U, V, W, N, Ground) this would be on the order of 100 pounds per foot for the "portable" cord. In an SO jacket, it would be as thick as my waist. If we upgrade to 4160 service, the cable gets lighter, but the insulation system would stay about the same thickness and no one would be able to hook it up because of the hundreds of electricians on duty at the airport only perhaps one of them can touch 4160 switchgear.maybe I'm the only one seeing this, but when I put my paltry mortal pencil to my paltry mortal paper, this isn't making a whole lot of sense.Or, perhaps we are going to do wireless charging in the ISM bands? Ok, so the linesets are replaced with 16MW (likely much larger) RF transmitters? and we can pretend that RF doesn't cause interference....?Maybe the tooth fairy will charge the planes and all of my concerns are moot?Holla back, think with me please.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 22, 2020, 12:50:33 am
content: Most likely long distance electric aircraft will use a light gas like helium or hydrogen for lift, which is a lot more energy efficient.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 22, 2020, 07:26:57 am
content: Quote from: k5njp_PE on January 21, 2020, 11:44:02 amYour points are correct, but basing all your calculations on such a "perhaps" gut feeling number won't be sufficient. You'll need actual data. You can start by looking at the jet engine energy efficiency and amount of fuel stored, and compare that to the electric propulsion efficiency, then calculate for the actual energy storage required, and from maximum allowed weight, calculate required battery energy density.Also requiring 2x the energy storage for diversions / holding won't be justified. On long hauls, the amount of "extra" fuel currently is much less than +100%.

author: filssavi
author_rank: Frequent Contributor
timestamp: January 22, 2020, 09:16:23 am
content: The more electric aircraft movement aim is to first and foremost replace all pneumatic, mechanical and hydraulic power transfer in a modern airliner with electric distribution.Things like de-icing, environemental controls subsystems (A/C and pressurization) etc. first and foremost, secondary and primary flight surface actuation gear etc in the future.The motives are varied:-For pneumatic power (such as it is/was used in de-icing and pressurization) it needs to go as sapping pressurized air just before the combustors greatly impacts a turbofan fuel efficiency-For all hydraulic subsystem the overall goal is complexive system weight reduction (the motors by themselves might be a little bit heavier but if you take into account all the fluid, tubing, valves, pumps, etc it starts to make sense).overall there will also be an increase in reliability as (when properly designed of course) an electric actuator is much more reliable and mantainace free than other typesThe first product of the MEA efforts are the boing 787, and to a lesser extent the A350 whose great efficiency is well known.The second step in aircraft electrification will be hybrid propulsion with a"Jet" power plant inside the fuselage and propulsion units (electric fans basically) on the outside, with the following benefits:-Better aerodynamics (less drag) since there is not this massive thing hanging from the wing-better propulsion efficiency with a large number of what ammount to small propellers (distributed propulsion)-smaller, lighter prime movers (now the engines are massively oversized for what they do more than 90% of the time since take off/climb requires a disproportionately large ammount of thrust when compared to cruising. With the addition of a small amount of battery storage and motors designed to allow overload for brief periods the prime mover will be required to provide only the cruising power level

author: Siwastaja
author_rank: Super Contributor
timestamp: January 22, 2020, 06:19:53 pm
content: Excellent post by filssavi, and as the next step, full electrification of fleet that can be used for frequent, short flights (like <1000km), for example, over Central Europe.Though, thisreallyshould be a case for bullet trains, but for some reason, flying is cheaper, even if the end-to-end time, including check-ins, safety circus, getting on/off the airport, etc., may beworsethan by train. Inherently and physically, the train should be cheaper, especially for energy and maintenance costs, but clearly there is cultural difference in how these businesses are operated.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: January 22, 2020, 11:57:27 pm
content: Quote from: NiHaoMike on January 22, 2020, 12:50:33 amMaybe hot air.

author: djacobow
author_rank: Super Contributor
timestamp: January 23, 2020, 02:47:07 am
content: GA Aircraft flying IFR under part 91 in the US are required to carry enough fuel to get to their intended destination, proceed to their planned alternate, and fly for 45 minutes.Airliners follow an ICAO standard that is more complex including taxi fuel and other considerations, but is conceptually similar.For short flights, that is more than double the fuel to get to your destination, for long flights, much less.

author: AG6QR
author_rank: Frequent Contributor
timestamp: January 23, 2020, 02:59:01 am
content: Quote from: k5njp_PE on January 21, 2020, 11:44:02 amWhat kind of miniature jet engined plane could use 1MW engines?Jet engines aren't normally rated in units of power (neither horsepower nor kW), but in thrust, because that's the more natural units to use. The conversion between thrust and power is a bit cumbersome, and depends on speed. For details and examples, seehttp://www.aerospaceweb.org/question/propulsion/q0195.shtmlNote that in the example they give, a 747-200 cruising at Mach 0.9 at 40,000 ft altitude generates 65,100 kW. That's the output power, thrust multiplied by speed. The input power required would be higher, depending on the efficiency of the fan used to move air. Also note that the 65,100 kW number is the amount of power actually used during cruise. For takeoff and climb, significantly higher power would be needed, while for descent and landing, lower power would be used.Of course, the 747 is a very large, long-range plane, and probably not the starting point for electric flight.A C-130 is a military cargo plane, but roughly the size of small passenger airliner. Each of its four engines produce 3,340 kW (from the same link above), for a total of 13,360 kW.A Cessna 172 is a tiny single-engine plane with four seats, but realistically, it carries two people with full fuel, or four small people for a short flight with minimal fuel. It uses a single engine of 135 kW.The difficulty for long-range electric flight is the issue of of specific energy and energy density. Specific energy is defined as the amount of usable energy per unit weight of fuel or batteries, while energy density is defined as the amount of energy per unit of volume.Weight is hyper-important in aviation.Jet fuel has a specific energy of 43 MJ/kg. Lithium-ion batteries have a specific energy of around 0.8 MJ/kg. Thus, it would take over fifty kg of batteries to get the same amount of energy as is contained in a kg of jet fuel. That's not even close! Batteries would have to improve by a factor of fifty, and if you look at the energy in chemical bonds, and the weight of the atoms involved, the basic chemistry doesn't allow a fifty-fold improvement in battery technology. Combustion engines have the advantage of being able to take their oxidizer from the atmosphere, whereas batteries have to carry their oxidizer as part of the battery.A long-range airliner, at takeoff, has more than half its gross weight as fuel. A small increase in the amount of weight required for the fuel would cause a disproportionately huge decrease in available payload.It's worse than just comparing the total weight of fuel versus batteries, though. A jet engine consumes its fuel during flight, so the plane becomes lighter and more efficient as the fuel tanks are emptied during cruise. The airplane has its best power-to-weight ratio at landing time, when power may be needed for an emergency go-around. A battery powered plane would have to land with the same weight as it had when taking off, and the largely discharged batteries would have the lowest power available at landing.Very short-range and small aircraft could be battery powered, as demonstrated by quadcopters and radio controlled models. There have been demonstration aircraft capable of carrying a couple of people for a short distance. But for long-distance commercial passenger aviation, the difficulties of specific energy are enormous. Liquid hydrocarbons are an incredibly dense and lightweight medium for the storage and transport of energy.If we as a society want to continue to use long-range aviation for transport, then I believe that, rather than electrification of the fleet, we should put some research into creating hydrocarbon fuels in a way that does not involve mining petroleum and producing excess CO2. Biofuels sound attractive to me, though there may be other ways.

author: hendorog
author_rank: Super Contributor
timestamp: January 23, 2020, 05:15:47 am
content: Did a quick google and aluminium air batteries apparently have a theoretical specific energy of 28.8 MJ/kg. Replaceable batteries which are reprocessedare may be more practical for commercial aircraft too- recharging is likely to be too slow.Any battery chemists here?

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: January 23, 2020, 05:48:33 am
content: Quote from: hendorog on January 23, 2020, 05:15:47 amhttps://www.youtube.com/watch?v=OmHnKKuBdco&feature=youtu.be&t=1004

author: hendorog
author_rank: Super Contributor
timestamp: January 23, 2020, 05:59:27 am
content: Quote from: ChunkyPastaSauce on January 23, 2020, 05:48:33 amI did say theoretical - prev poster was talking theoretical energy available in bonds etc.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 23, 2020, 06:11:55 am
content: Quote from: AG6QR on January 23, 2020, 02:59:01 amNote that converting fuel into mechanical energy has piss-poor efficiency - don't have exact numbers at hand, but electric propulsion is likely a few times more efficient, bridging part of the gap.The gap still remains huge, of course, but not 50x.You are of course completely right, the only case for electric aircraft with current or foreseeable future battery technology is short, regional flights. Most of which, IMHO, would work better by train (as long as the track exists).

author: SiliconWizard
author_rank: Super Contributor
timestamp: February 02, 2020, 04:39:02 pm
content: Quote from: Siwastaja on January 23, 2020, 06:11:55 amKind of, but the energy density of fuel more than largely makes up for that.Some basic figures:https://en.wikipedia.org/wiki/Thrust-specific_fuel_consumption#Typical_values_of_SFC_for_thrust_enginesWith an average efficiency of 20% to 35%, it's actually on par with typical car engines. Sure it's not that great.With good electric prop, I guess that could be closer to 75-80% (taking both the engines and power electronics into account).Rather than energy density, specific energy (ratio to mass) would probably be a more relevant figure for aircrafts, as obviously mass is critical there.Jet fuel has a rated specific energy of ~43 MJ/kg (https://en.wikipedia.org/wiki/Energy_density)For a typical Li-ion battery, it's 0.36–0.875 MJ/kg.So, for a (generous IMO) figure of x2.5 more efficient for electric prop, you have a typical 50 times less specific energy (with the current trend of using Li-ion batteries for electric vehicles.)Let's divide that by 2.5. Basically means we'd need to embark 20 times more in mass for the same flight autonomy.Now of course, if we could embark nuclear generators in commercial planes, that would be a completely different story, and would make it immensely more effective. I don't see this coming any time soon though.

author: JohnG
author_rank: Frequent Contributor
timestamp: February 02, 2020, 06:38:33 pm
content: Expect to see hybrid-electric aircraft long before you see all-electric aircraft (unless a miracle fuel cell is invented, in which case most of the arguments about batteries are moot).The design of a turbofan engine is greatly determined by takeoff and landing, and this hurts the cruising performance a lot, both in terms of reduced cruising efficiency and added engine weight. Since large electric machines mechanically couple to the turbine shaft are already a long ways into development for MEA due to a system efficiency and cost benefit, much of the analytical tools are already in place to look at the impact of a larger electric machine or machines. A hybrid machine lets you do things like decoupling of the fan with the turbine, so you can optimize the turbine and the fan separately.You can also capture energy on descent as you slow the plane down.John

author: MagicSmoker
author_rank: Super Contributor
timestamp: February 02, 2020, 10:25:26 pm
content: Quote from: SiliconWizard on February 02, 2020, 04:39:02 pmThe overall efficiency of a battery-electric drivetrain (not including the prop itself) will be in the range of 90-95%, based on a 99% Coulombmetric efficiency for a lithium-ion battery, 99% for the inverter and 92-97% for the AC motor. And yes, these are realistic figures.That said, I don't see electric airplanes being practical anytime soon unless buying a Mr. Fusion finally becomes possible.

author: ejeffrey
author_rank: Super Contributor
timestamp: February 03, 2020, 03:00:21 am
content: Quote from: hendorog on January 23, 2020, 05:15:47 amNot a chemist but I have been hearing about aluminum air batteries for a long time...

author: hendorog
author_rank: Super Contributor
timestamp: February 03, 2020, 03:27:11 am
content: Quote from: ejeffrey on February 03, 2020, 03:00:21 amI guess we will just have to wait and see if it happens or not. Of course no planes at all is the low carbon option...

author: Siwastaja
author_rank: Super Contributor
timestamp: February 03, 2020, 10:52:29 am
content: Quote from: SiliconWizard on February 02, 2020, 04:39:02 pm0.36 MJ/kg might be true for some first li-ion cells in early 1990's. Or some "heavy" chemistries such as LFP, which are irrelevant for aviation.Today, state of the art you can actually buy is around 270 Wh/kg i.e. around 1 MJ/kg at cell level. Low-cost old generation cells are at around 200 Wh/kg or 0.7 MJ/kg, but that isn't very relevant. I would expect 300 Wh/kg has been already achieved in production even if not available to small players yet.Packaging into parallel/series packs and adding battery management reduces this a bit, but properly done, not much more than, say, 10%.When comparing, don't forget to include the weight of the jet engines and fuel system, which is much more than the electric engines with inverters. For long hauls, it's irrelevant and excessive battery weight dominates, but for short, regional flights, direct ratiometric comparison ("20x") stops working because of this offset.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: February 03, 2020, 11:00:33 am
content: Quote from: MagicSmoker on February 02, 2020, 10:25:26 pmCoulombmetric efficiency is not energy efficiency. You may get the same charge you put into a battery out but the voltage is not the same. 99% is optomestic

author: MagicSmoker
author_rank: Super Contributor
timestamp: February 03, 2020, 12:56:04 pm
content: Quote from: ahbushnell on February 03, 2020, 11:00:33 amTrue, but a lithium-ion battery in an airplane will likely be discharged at a relatively low C rate (1C or less) so there won't be much IR loss to speak of, hence dischargeenergyefficiency will still be quite high (though not quite the 99% of the Coulombmetric efficiency, I'll concede). Charging efficiency of a lithium-ion battery will definitely suffer if done at a >1C rate, but that has no effect on the range of the airplane itself (just as no one factors in the incredible amount of energy needed to extract crude oil and refine it into Jet-A, diesel, gasoline, etc. when calculating the energy stored in such fuels).

author: JohnG
author_rank: Frequent Contributor
timestamp: February 03, 2020, 03:03:02 pm
content: Quote from: SiliconWizard on February 02, 2020, 04:39:02 pmThe numbers numbers above seem to include also the fan efficiency, i.e. they are electrical to thrust equivalent. I have no idea about the mechanical rotation to thrust numbers. While 99% for the inverter might be a stretch, it is only a small stretch and upper 90s is straightforward to achieve, especially with the development of SiC MOSFETs.There is also a good amount of work going in high power density electric machines. These also tend to require higher fundamental frequency for operation, but wide-bandgap semiconductors are getting mature enough for some commercial applications already, and they will be mature by the time this plane gets off the ground.It is not unusual for aviation engineers to think on much longer time-scales than many engineers are used to. I have friends in the engine business, and just an engine design can easily take many years of development, after many years of design studies, etc. So the idea of a 10-20+ year development cycle for electrified aircraft is realistic, and quite a few engineers are working on it right now (and have already been for quite a few years).One more cost saving aspect of electric aircraft is that it is likely that engine maintenance costs may be greatly reduced compared to gas turbines. There would be a lot less rotating mass at a lot lower temperature. Commercial planes are in the air for decades, and maintenance costs are a significant part of operating cost.Cheers,John

author: Siwastaja
author_rank: Super Contributor
timestamp: February 04, 2020, 02:33:56 pm
content: Quote from: ahbushnell on February 03, 2020, 11:00:33 amCoulombic efficiency is around 99.95% or more, so 'Smoker probably meant energy efficiency to begin with. 99% is achievable with high-power cells at lower loads, but 97% is realistic for energy-optimized cells in such use case (at around 0.5C discharge rates). (Using low-resistance cells to improve the efficiency from 97% to 99% could mean 30% decrease in energy density, so approx. 28% lower available energy, not worth it.)For example, a state of the art 18650 cell, say approx. 4.0Ah 3.6V, 50mOhm, at 0.5C discharge rate, generates loss of I^2R = 2^2 *0.050 ohm = 0.2W, or in two hours, 0.4Wh, which means the efficiency is 14.0Wh/14.4Wh = 97.2%.

author: MagicSmoker
author_rank: Super Contributor
timestamp: February 04, 2020, 02:45:31 pm
content: Quote from: Siwastaja on February 04, 2020, 02:33:56 pmNo, I just wasn't quite as up-to-date with how things have progressed in lithium-ion technology- 99.95% Coulombmetric efficiency is damn near perfect.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: February 04, 2020, 04:01:33 pm
content: Quote from: AG6QR on January 23, 2020, 02:59:01 amQuote from: Siwastaja on February 04, 2020, 02:33:56 pmLet's see... To fly that 747 for 10 hours usingstate of the artcells you need:Flight Energy: 10*65100e3= 651e6 WhCell energy: 3.6*4= 14.4 Wh# of cells needed: 651e6/14.4= 45.2 million (LOL)Cell mass 50gWeight of the cells: 2260 tons.Max takeoff weight of a 747: between 333..439 tons (*).=> Sorry guys, but you won't see electric 747s anytime soon.Comparatively, the fuel tank is ~= 200m3, @35MJ/litre -> 1940e6 Wh, and weights 162.8 tons.(*)https://en.wikipedia.org/wiki/Boeing_747

author: Siwastaja
author_rank: Super Contributor
timestamp: February 04, 2020, 04:17:33 pm
content: Subtract the difference in weight between the jet engines and equivalent electric engines, then subtract the amount of fuel spent in taxiing. Either of these are not that important for long hauls where the piss poor battery energy density dominates, but becomes more interesting for short trips. Then do the math for a 2-hour flight. (1-hour flights are extremely common in Europe.)Clearly, we are nowhere near replacing most aircraft with electric due to the massive difference of energy density between fuel and batteries, but we are close enough for short trips becoming interesting to analyze.Though, it's not a fair comparison; jet engines might not be optimal for short trips, anyway. We should compare to thoroughly modernized, next generation propeller engines.

author: nctnico
author_rank: Super Contributor
timestamp: February 04, 2020, 06:12:23 pm
content: Quote from: AG6QR on January 23, 2020, 02:59:01 amThere are ongoing experiments with bio-fuels. Hydrogen is also a logical alternative. Electric is just the 'hype du jour'.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: February 04, 2020, 06:35:59 pm
content: Quote from: nctnico on February 04, 2020, 06:12:23 pmIIRC Don Lancaster had a few .pdfs (tinaja.com) explaining why H2is a disastrous alternative.

author: fcb
author_rank: Super Contributor
timestamp: February 04, 2020, 06:57:14 pm
content: Quote from: nctnico on February 04, 2020, 06:12:23 pmI ran the maths (for a 737 size electric passenger plane) a few years ago during an argument with a pilot, back then battery tech would make it feasible around 2040-2045. Hydrogen is much less dense than kerosene - storage would have to be huge; perhaps flying wing designs could be suitable for H2 - just not going to happen.All electric short-haul would be feasible in the near term, then increase the amount of renewable biofuels to 100% for existing long-haul, then fully electric in next 50 years.

author: nctnico
author_rank: Super Contributor
timestamp: February 04, 2020, 07:12:33 pm
content: Quote from: fcb on February 04, 2020, 06:57:14 pmEuhhh.... Hydrogen is being used to fly stuff into space. And the energy content of hydrogen dwarfs that of carbon based fuels. 5kg of liquid hydrogen gets a car over 500km. Long haul electric airplanes isn't going to happen because of the required logistics of getting the airplanes charged. Hydrogen is much easier and cheaper.

author: fcb
author_rank: Super Contributor
timestamp: February 04, 2020, 07:28:29 pm
content: Quote from: nctnico on February 04, 2020, 07:12:33 pmRockets use cryogenic hydrogen and are loaded just before launch, the skin of the rocket can be used to contain the H2 as it is a liquid. Chances of big accident are high!Planes would need COPV (composite/carbon overwrapped pressure vessel) style tanks much like a Toyate Mirai, and store the H2 safely at very high pressures - these are not lightweight.

author: nctnico
author_rank: Super Contributor
timestamp: February 04, 2020, 07:31:16 pm
content: But needing about 8 times less in volume & weight compared to regular fuel makes up for it.

author: hendorog
author_rank: Super Contributor
timestamp: February 04, 2020, 07:41:10 pm
content: Some alternatives to storing hydrogen in pressure vessels here:https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20020085127.pdf

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: February 04, 2020, 08:11:31 pm
content: Quote from: nctnico on February 04, 2020, 07:31:16 pmYou got that backwards I think:https://www.tinaja.com/glib/energfun.pdfhttps://www.tinaja.com/h2gas01.shtmlQuoteThe density of liquid H2 at 1000 bar and 20˚C is only 50 g/l:https://en.wikipedia.org/wiki/Hydrogen_storage

author: nctnico
author_rank: Super Contributor
timestamp: February 04, 2020, 08:49:39 pm
content: Way too complicated. If a car can get 500km on 5kg of hydrogen where a similar car would need 40 to 50 liters of fuel you get to a factor 7 to 8 in weight ratio for the fuel. I don't care how it is stored and what densities are needed. It is a ball-park figure anyway without going into the amount of fuel needed per distance travelled.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: February 05, 2020, 01:43:31 pm
content: Quote from: nctnico on February 04, 2020, 07:12:33 pmThe hydrogen is liquefied for rockets. It's cryogenic.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: February 05, 2020, 01:50:57 pm
content: Quote from: nctnico on February 04, 2020, 08:49:39 pmAt room temperature that's 166 liters of H2 for 5 kg. Plus the weight of the tank and safety systems.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: February 05, 2020, 02:10:21 pm
content: Quote from: ahbushnell on February 05, 2020, 01:50:57 pmAnd @500 bar no more no less ! (that's ~510 kg F per square cm!)

author: nctnico
author_rank: Super Contributor
timestamp: February 05, 2020, 05:08:59 pm
content: Quote from: ahbushnell on February 05, 2020, 01:50:57 pmWithout doing actual math on weight versus size and what would be needed for an airplane this statement is meaningless. First do the numbers. Needing 7 to 8 times less weight hints towards having a lot of room for extra weight of the tanks.

author: gmb42
author_rank: Frequent Contributor
timestamp: February 05, 2020, 06:17:39 pm
content: Noted some electric plane articles this week, usual pinch of salt required when discussing "future" developments:https://www.vice.com/en_uk/article/m7q7qn/electric-planes-future-aviation-environmenthttps://lbndaily.co.uk/electric-easyjet-186-seat-aircraft-set-test-flights-2023/and the manufacturers themselves:https://weflywright.com/https://www.eviation.co/

author: f4eru
author_rank: Super Contributor
timestamp: February 05, 2020, 09:46:47 pm
content: An Al-Ox battery for a plane ?Utopia, much like this :

author: ahbushnell
author_rank: Frequent Contributor
timestamp: February 05, 2020, 10:49:49 pm
content: Quote from: nctnico on February 05, 2020, 05:08:59 pmThe point is the 5 kg has more volume then the JP4.

author: vk6zgo
author_rank: Super Contributor
timestamp: February 06, 2020, 01:36:30 am
content: Quote from: ahbushnell on February 05, 2020, 01:50:57 pm166 litres isn't huge-- a standard 44 gal(Imp)/55 gal (US) drum is 200 litres.