The engineering challenge of electrifying airplanes
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- Опубликовано: 3 июл 2024
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Throughout the development of the DarkAero 1, we've often been asked, "Will you make an electric version of the aircraft?" In this video we explore the underlying physics that govern this problem and look at what it would take to go electric.
0:00 - Intro
0:34 - Gravimetric Energy Density
3:54 - Electric Motors
4:59 - Hydrogen?
5:38 - Where Electric Works
6:46 - Why Weight Matters
8:00 - Final Thoughts
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Sources used in this video:
Amprius 500 Wh/kg Battery: amprius.com/the-all-new-ampri...
Tesla 4680 Specs: insideevs.com/news/598656/tes...
Energy Density of Gasoline: energyeducation.ca/encycloped...
UL Power 520iS Specs: ulpower.com/en/engines/ul520/...
Weight of Gasoline: www.jdpower.com/cars/shopping....
H3X HPDM-250 Electric Motor: www.h3x.tech/#hdpm-250
Energy Density of Hydrogen: www.energy.gov/eere/fuelcells....
Eviation Alice: www.eviation.com/
Beta Technologies: www.beta.team/aircraft/
Tesla Investor Day 2023: ruclips.net/user/liveHl1zEzVU...
Video Sources:
"The Story of Solar Impulse: Exploration to Change to World": • The Story of Solar Imp...
"Pipistrel Velis Electro | the world's first type-certified electric aeroplane": • Pipistrel Velis Electr...
"eXenos Electric Motorglider": • eXenos Electric Motorg...
"ALIA Highlight Reel 2022": • ALIA Highlight Reel 2022
"First Flight of Eviation's All-Electric Alice Aircraft": • First Flight of Eviati... 
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As an aeronautical engineer I studied general aviation cutting-edge tech at CPSLO (grad. 1995) and admire your work but the modernized engine you are using is still based on very old tech.
Consider building an electric version for pilot skills training, as that might have more market than long range...
Store hydrogen inside of metal hydrides and extract it as needed.
Hydrogen for the win 5:45
Nice video. You forgot one important thing, though. Electric planes energized by fuel-burning onboard generators. Rolls Royce is producing them. "Turbogenerators" rated from 500 KW output to 3.5 MW output. Specifically for the eVTOL plane market. I've seen the 500 KW gen. It's ~5'(L) x 2'(axial diameter). Listed weight (dry) = 280 lb. Fuel consump = 16 gallons/hr (~100 lb/hr). Your 77 gallon fuel tank holds 4.8 hr of flight at that rate. Cruising at 300 mph = 1,400+ mile range.
Really well presented, I appreciate the focus on fact's and figures rather than opinions. Well done, and awesome to see such clean and professional engineering approach towards your aircraft design. It is very inspiring!
The biggest problem with the masses of people, they don't know the difference between what they believe, and what they know.
@@noahway13 FYI - there's a term for it even: Dunning-Kruger effect. On that topic - their website makes zero mention of the word "laminar", and their design goes half the speed of the Celera 500L while still managing to use more fuel. Why is anyone listening to anything these guys say? They're so addicted to their own image and ideas that they're turning a blind eye to everything we know about state-of-the-art in aerodynamics and efficiency. The enemy of range is NOT weight, it's drag, and they've got blunt stubs on the ends of their wings. ROFL!!!!
@@chrisdrake4692 First of all, I don't see how laminar flow is relevant. The Celera 500L is still a prototype, any figures about it are just claims. The enemy of flight in general is primarily weight. Decrease weight > decrease required lift > decrease drag (Cd = Cd0 + kCl^2) > decrease required thrust. Sure decreasing drag works but most planes are pretty optimised for it now. They have already explained why they have no wing tips; the wings are overszied for cruise to give better stall characteristics, and so adding wingtips would just make the problem worse and increase the parasitic drag.
There is also a general misunderstanding of the function of wingtips; wingtips decrease drag because they increase the effective wingspan of the wing giving it a higher AR. Higher AR = less drag. The reason passenger planes use wingtips is because there are limits on wingspan for different classes. If you want to increase the efficiency of a wing increasing the wingspan is better than adding wingtips of the same length.
Funny that whole Dunning-Kruger effect you brought up
Have a nice day :)
p.s. These guys have actually built a plane, probably know something about it
@@noahway13 You mean like there is no such thing as "fossil" fuels? Hydrocarbons are compress with heat and pressure, then burned for energy, the released in the atmosphere, which is then absorbed by trees underground, then the cycle repeats. Petroleum is the second most abundant liquid after earth, the most renewable energy on earth and the greenest. This religious worship of globalist propaganda about how carbon is bad must end. There was a time that the world believed the earth is flat. Well carbon is good, and the more we have the better.
Thank you so much for this! You cleared up several of my questions about advantages/disadvantages of electric-powered aircraft. We'll see where technology will take this.
I knew the basics on all this, but your breakdown is fantastic. You have a way of simplifying complex ideas.
Excellent presentation! I’m very pro-electric but totally recognize that it’s not a viable solution for every application. Very thorough and well-explained, thank you.
Name a single application where electric is viable or better yet actually “greener” than gasoline or diesel.
@@dozer1642 They get more viable the smaller you go. There is a reason 99.9% of rc planes are electric and nobody uses gas/nitro rc planes anymore.
@@dozer1642 There is a video I saw a while ago that electric bikes are more efficient than human powered bikes. It takes more carbon inputs to fuel a human than to charge a battery. It sounded plausible in the person's pitch.
ruclips.net/video/_-FgxTxBtU0/видео.html
I don't see a future with electric planes or bio Jet-A. The math is incredibly hard given the global scale.
While energy content per volume is certainly an issue with liquid hydrogen (especially in a tightly constrained airframe such as DarkAero's), that's not the only big problem. The weight of the cryogenic tanks required is far greater than the weight of the hydrogen itself, and greater than the weight of gasoline or jet fuel plus the much simpler tanks required for those fuels.
I'm glad you mentioned engine weight, because the weight savings of an electric motor is not insubstantial. For extreme short ranges, that difference can be more than the weight of batteries needed. For short to medium range, the battery + motor still weighs more than an engine + gas tank, but the extra weight might be worth it in some cases, for long range the energy density of the fuel just takes over any calculation. As batteries improve, we will see the number of applications where electric aircraft are viable increase, but there is such a long way to go we might see biofuels take over instead.
Beautifully explained! Thanks!
This felt like an Engineering Explained video. Love it!
Excellent breakdown of the problem of electrification of aeroplanes, pleased to see that you included the latest battery technology in your presentation. Good luck with your developments.
Great job on explaining it!!
Well balanced! Nicely done
Excellent presentation.
Awesome breakdown thanks!
Very informative and easy to follow. Well done
Nailed it. Electric isn't ready to match the goals for Dark Aero. It is a bummer, but your presented data supports your position well. Kudos on presenting the data clearly and fairly. Well done.
Diesel though
Great breakdown, love your videos
Explained very well! Thank you!😊
Great video!
Nice job explaining!👍🏽👍🏽
This is a great video!
Very clear thank you for this video
Great explanation and great math. Clear statement at the end
One option you might consider in the nearer term is Solid Oxide Fuel Cells. Due to their higher temperature of operation, they allow for the use of hydrocarbon fuels, and they can even harvest energy from the oxidation of carbon monoxide that results from the hydrocarbon fuels. They’re not likely to ever be used in cars due to their long warm up times and slower throttle response, but neither of those problems are present for long range aircraft. They can get pretty light weight too…NASA has a patent they’re trying to license out for a SOFC that has a power density of 2.5 kw/kg, which would mean maybe 100kg for the fuel cell. And with that you’d get closer to 60% efficiency and pretty cool fuel flexibility (you can use any low-sulfur fuel from diesel to natural gas to pure hydrogen).
Excellent
One other thing I think many people miss about electric powered aircraft is safety. There have been few incidents of aircraft failures due to fuel exploding or starting the aircraft on fire, while in flight. There have been a plethora of incidents of electrical fires bringing down a plane. Upping the electrical energy and current on board by a hundred fold would have to increase this danger even more. Being 5 to 10 minutes or more until your plane can land while on fire will almost always conclude with 100% fatalities.
Teslas cease in below 0 temps, imagine flight up there during winter?
😍😍😍That's what I was thinking, The Courses. Now I can learn
I haven't even heard of an esoteric lab experiment in battery tech that could compete with gasoline. Electrons are great on the ground, but that gravity is the end of the conversation when you attempt to put them in the sky.
Awesome!
One more advantage of gasoline is that the aircraft continues to get lighter as it flies. That means it gets more efficient as the fuel is burned. Electric motors depend on batteries … obviously, but your motor is still forced to carry the dead weight of the depleted batteries throughout the entire flight. Batteries also have a finite service life and cost a fortune to replace especially if they are integral to the airframe.
Bye Aerospace is delivering electric trainer aircraft that cost $20/hr to operate, vs a similar airframe which costs over $140/hr. Including the maintenance savings over the life of an aircraft, the overall costs for this use case is estimated to be 80% lower for electric. And given no electric aircraft designer is integrating batteries into their airframe (some are even doing flight-line hot-swap battery designs) the cost argument is well in favor of the electric system.
While this is true and accurate, it sounds a little nit-picky. You could also bring up the fact that the weight savings from burning off fuel is inversely proportional to the needs of most missions, where the plane is heaviest when it needs to climb and lightest when it needs to descend. That again would be nit-picking.
Batteries are indeed expensive, but nowhere near the price of the amount of 100LL used during equivalent flight hours, not to mention oil changes and regular maintenance on aviation grade internal combustion engines. Not only is it not in the same ball park, it’s not even playing the same sport. Batteries, if integrated structurally, could become difficult to swap out, but many planes already come with detachable wings which would be the ideal place to integrate the batteries to distribute weight along the lifting surface and reduce bending moment at the wing root.
This is all irrelevant tho, since the points of the video still stand. Just pointing out what seem to be somewhat frivolous arguments against batteries.
@@imabeapirate Hahaha, great joke!
@@xpeterson Show us your math please.
@@pistonburner6448 it’s not my math. The math has been done on electric cars with numerous reports on cost of ownership. The numbers do not favor ICE vehicles, and that’s assuming lower octane fuel and mass produced internal combustion engines. The numbers, as any airplane owner will attest to, skyrocket when you go to 100LL and say an entry level Rotax engine.
Again, there’s still numerous issues to be addressed, one more notable one not mentioned being that current batteries on BEVs suffer in cold climates. That’s actually something to have concerns over. Price? That’s just laughably brainwashed
Great job taking the complexity and simplifying for common understanding. However, I believe you missed an opportunity to explain the significant energy achievement you have designed into dark aero already. Explain the energy efficiencies of a typical mission between Dark Aero and common GA aircraft. You guys have done a tremendous job just with the aircraft and with the manufacturing efficiency, quality, consistency. So excited for your future.
You should apply some SEO for topics like "optimizing aviation fuel and engine options" - your simple explanation here was a master class in how to deliver engineering spark notes!
Good video.
insane startup 👍👍👍👍👍👍👍
Thank you, clarifying explanation! Another challenge for any wider adoption of commercial electric flight is charging at the airports. Not only will there be a need to provide enormous amounts of energy, you will also need to charge at insane power to keep the aircraft in the air as much as possible (where they make money). It’s all physics.
That subject is a deep rabbit hole, your 9 minutes here just hangs around the top. LOL I look forward to flight testing in the DA!! Congrats on your work!! 8) --gary
Excellent concise presentation on limitations of electric aviation. Wishing for breakthrough of battery tech to increase energy density by an order of magnitude, within a lifetime.
Well done. The integrated design of any system starts and ends with the mission. In buildings, my expertise, I pushed the concept of “use less, use it efficiently, then and only then consider making it on site”. Not a direct analogy, but the concept of the design process I see you use is similar.
How do you control a thermal runway battery in Flight?
So, with all those assumptions, what would be the effective mission range of an equally heavy electric DA1 or the equivalent gallons of gas in a gas DA1?
Great video! I'd love to see one similar with the TurboAero. Yes, I know it isn't complete yet, but it's just a matter of time before someone puts one in one of your kits!
Excellent présentation
Thanks for encapsulating many of the points about electric versus gas engines in airplanes. I don't know why you would through mentioning hydrogen into the mix which you missed a lot of the downsides for. The weight of an airplane hydrogen storage tank would be very prohibitive. One expense that has to be considered would be how often replacing parts that come into contact with hydrogen would have to occur. Special dense alloys have to be used to contain a gas of the smallest atom. And since no alloy is dense enough to completely prevent being permeated by hydrogen, they all become brittle over time.
Regarding electric versus gas, about the only improvement to gas engines that could be made is reducing weight. Which isn't going to amount to much. Batteries on the other have a lot of potential to reduce weight.
Removing the factors of flying regardless of cloud cover and speed, solar electric assisted planes would be promising.
Excellent job!
PS - Really like the way you cut out the "breaths".
Well done gents!
Thanks for this video. It's important that we all understand the engineering limitations and virtues of all power system choices. Will there be a place for electric in the future of flight? Definitely. Does anyone now know what that will look like? I doubt it. Engineering is a developmental process where the technology leads us to the solutions that work for human needs.
One thing that I don't think was mentioned is the decrease of weight throughout the flight for a gas powered aircraft. As a plane burns fuel, that weight is subtracted from the overall weight of the aircraft and subsequently requires a lower angle of attack to maintain level flight. A lower AoA produces less induced drag thus allowing the aircraft to either fly faster for a given power setting or maintain the same speed with a reduced power setting for a reduction of fuel burn. The degree this will affect this aircraft, I don't know. I am interested in seeing this gradually explored in flight testing.
I was surprised he didnt mention this aspect. With a fuel tank nearly empty our are much lighter than at start. With a battery nearly empty you just carry "dead" weight around.
for special cases it is certainly possible and useful. But for most applications it isn't. And the 500w/kg is very optimistic and I wouldn't put lipos in any plane, too dangerous.
They omit the danger of power drop when the battery goes off optimum temperature, and the huge weight and consumption of the massive heating and cooling systems for the battery, motors and other systems. Not to mention the huge consumption of heating the cabin with electricity.
Then there's the huge charging losses. Then there's the huge, absolutely astounding costs which in the real world alone are enough to make battery-electric not viable even if miracles would happen and they could compete against ICE.
Luckily lipid aren’t used in any large applications like cars, storage etc
No one puts LiPo (lithium-ion with polymer electrolyte) cells in any aircraft carrying people, but if they did they would not use cells from toys.
Great presentation and fact based argument. Beats the insane bias you get from either side of the technology. Electrification will become viable when battery technology improves. In the mean time, if we want to run a viable economy, then ICE has a place.
I personally believe that batteries will need up to an order of magnitude increase in specific energy to wholly displace combustion in Aviation. And to nitpick, you meant specific energy and not energy density in this video.
An often overlooked issue with electric airplanes is the time it takes to recharge the batteries. You can refuel a conventional plane in a few minutes, that's not an option for electric planes. As battery capacities grow, this problem gets worse.
To take that Pipistrel Velis as an example, it takes as long to charge as it can be use to fly. For a flight school this basically means they have to invest in two planes for each instructor. One flying, one charging. This is in fact what is happening today at my airfield EHTE where there's two in use.
Long story short, the economics simply do not add up.
you left out one option: you could have electric propulsion plus a generator. That would give many of the advantages of electric propulsion plus the energy dencity of combustion propulsion.
Plus the weight of both.
Weight matters in aircraft more than almost any other mode of transportation. Installing a hybrid system means you have the weight of the engine, generator, and fuel, plus the weight of the batteries, switchgear/controllers, and electric motor. Plus, you lose energy every time there's a conversion--engine losses, generator losses, transmission loss between generator and battery charger, loss between the battery charger and the battery, loss between the battery and motor controller, loss in the controller, loss between the controller and the motor, and loss in the motor.
What possible advantage do you think there would be of the electric components of this hybrid propulsion system?
@@olpaint71 you would be quite a bit lighter than a pure electric system, Because you only need a small battery, to account for power peaks like take of. The electric motors (plural, you would want to take advantage of multible controll vectors. ) have a pretty good power to weight ratio. on the generator, you gain a few design freedoms: you can put it pretty much anywhere helping with weight distribution. You don't need the same peek power output, so you can make it smaller. You don't need range at all, that allows for fuel optimisation. You also have a wider choice on types. you could use a free piston engine wich comes with its own perks. or you could use turbine since you don't need to worry about a gearbox and range.
@@brianb-p6586 less mechanical components, more reliability, a number of design freedoms and multible tight controlle vectors. The later is vital if f.e. you wonna do VTOL. Pretty much all the advantages that electric planes have. but without the weight penalty.
@@MusikCassette You're adding all of the electric components and yet keeping all of the engine, so you have increased the number of mechanical components and reduced reliability. This is not a VTOL design, so there is no design advantage (such as decoupling the propeller mechanically from the engine). If you're talking about a completely different type of aircraft, then of course there will be different design decisions.
Fits the mission.
good to see metric used. the future of aviation is probably in some sort of synthetic fuel.
Agree. The problem with synthetic fuel for cars is that it is super inefficient to produce and use leading to higher costs which don't outweigh the benefits. Extra weight doesn't matter so much for cars, but for planes it's a big enough deal to justify the additional cost to produce.
The accepted term for energy/mass is specific energy. As you noted, energy density is the term for energy/volume.
++. Showing the basic figures is a good thing. There's reasons for your design.
I can't wait for when batteries get up to 2.1-4x their current energy density, but even then, it'll only be scraping what's worthwhile on a platform like your aircraft.
Shouldn't be too long, but you'd certainly make a different aircraft for it than this one. This one looks good on size/ weight/ efficiency and aerodynamic performance, with the powerplant and fuel it's using.
It's entirely possible that battery technology will plateau and never reach that energy density. Technology doesn't get exponentially better forever. Eventually we'll just figure out how to make the ideal battery and they'll never get any better.
The sr71 was created 61 years after the wright brother's first flight... 59 years later we still haven't made a faster jet.
We went from exponential improvements in speed of aircraft for about 60 years, then we developed a plane that's about as fast as you can possibly make a plane move through the atmosphere without melting, and then we've had zero improvement in speed since.
Hey that's my Sonex Xenos you shared. You are spot on with your analysis. However I think your focus was primarily on range and performance. If you look at cost per hour electric is demonstrably better. I also think there will be significant safety and reliability benefits with electrics. Don't get me wrong, gas is for sure the performance winner, but that is not the only factor in many applications...
Hey thank you for checking out the video! Agreed that cost per hour and reliability are other important metrics to add to the discussion. How has flying your Xenos been?
@@DarkAeroInc over 200 trouble free hours and just had to do the first maintenance. Needed new tires... If you guys ever want to come fly it, build an electric (battery or H2), or just have look at real data, let me know...
@@DarkAeroInc also, efficiency come in many forms and I do lust after a DarkAero1 ;)
@@DarkAeroInc You should pin DeVault's comment. Thanks for another great video.
From an electrical engineer and physicist working in the EV industry, your explanation was beautifully spot on.
I always like to say that the problem with fossil fuels is that they are so damn good at energy storage!
@@GabrielDeVault Where is your base at? Is it far from Canada?
Giving a realistic assessment of the battery numbers that were kindly stretched, it appears the best current batteries need to be 15X more energy dense to meet an equivalent gasoline range.
That is not happening any time soon.
Another challenge is that altitude does not deplete the power however the lower associated temperatures do.
This wouldn't be a significant issue for direct altitude as you heat the battery up significantly while getting there. It would be an issue for cold locations where the battery would not be pre-heated and fully powered on the ground.
The battery power reduction at lower temperatures is because the battery starts cold limiting total storage. If charging and pre-heating the battery it becomes much less of an issue.
A lot to consider between the two power plants.
For an engineer, energy, weight, speed, altitude, and other features are key. In practice, money is the decisive feature.
For a given mission, efficiency is measured in cost per mission, all costs considered. The less expensive solution wins.
Then, consider relativity 😂: relative costs are always changing. Right now, electricity is becoming less expensive, and environmental damage more expensive.
Do you really think electricity is becoming less expensive? All "green-governed" nations elsewhere in the world have experienced skyrocketing electricity prices...
Do you really think that the US will be able to build new, very cheap electricity production at a faster rate than the *_massive_* energy content of all the gasoline and diesel is being removed? Including all the grid work? And charging infrastructure? I see the complete opposite happening, as has been experienced in countries like Germany when they did their "Energiewende" push which resulted in *_no_* reductions in CO2 emissions while simultaneously skyrocketing electricity prices. Germany has very many similar countries all around it so benchmarking is incredibly easy too, so we got very good and reliable data on how incredibly badly Germany really did fail. And this was clearly seen and proven well before the Ukraine war.
I also don't see how HVO biodiesel, biomethane, bioethanol and e-fuels would cost much nor create environmental damage. In fact since those are nowadays produced by big corporations they have all the necessary certificates and they've done additional environmental studies proving their green credentials.
It is clear that EVs do in fact do massive environmental damage and what's most indicative of how dishonest the dictation of EVs really is, how fraudulent it is: they have *_not even bothered to pre-plan or pre-pay for the produced EV batteries' recycling!_* None of those virtue-signaling fake 'environmentalists have taken *_any_* responsibility for the upcoming fate of of the tens of millions of tons of EV batteries with their expensive, difficult, specialist-equipment-requiring handling and recycling!
@@pistonburner6448 Relative prices. Electricity cost is going up, fossil fuel cost is going up faster. COST, not market price, which is influenced by radical ambiental activists. Fusion may disrupt relative prices. Lots of research for fusion, solar, bateries, engines and other related to electricity, not that much for fossils and combustion engines.
@@sysfx Why is fossil fuel cost going up though? In the USA it is because of Biden admin wanting to _destroy_ the petrochemical industry as they themselves have stated as their goal. Biden's political blunders have also caused Saudis with OPEC to also want to restrict supply and raise prices.
Then: did you know that ICE can be run on fuels other than fossil fuels? And even other fossil fuels than gasoline and diesel, for example natural gas?
Those are not rising in price nearly as much, and even they just like gasoline and diesel contain a lot of taxes and tariffs.
Some real engineering explained vibes going on here
River giving Professor Ryley a run for his money…really appreciate the work you guys are doing!
I have 0 interest in aviation. I don´t know why this channel was recommended, but what you guys are doing is awesome and interesting
Just look at the Pipistrel Velis electro! It’s an electric plane, but it has a really low range and an only okay speed. Batteries just aren’t ready yet.
The first analysis of electronic motors application with an honest assessment of the pros and cons! I fly RC planes, with electric, gasoline and methanol/nitromethane. In terms of flight time, both type of liquid fuel will give you about 10 to 15 min depending on your power management style and engine power excess! For electric model 5 min is considered standard 🙄🤦, for ducted fans (sort of turbine) 3 min is considered good!🤷🏻♂️🤌🏻
It'll get there, but aircraft aren't the low hanging fruit we should be going for first. Energy density will improve hugely over the coming decades, until then we should focus on the easy wins, stationary storage and ground transport with sodium ion and Lithium Iron Phosphate batteries.
You guys are such amazing engineers, I have no doubt that you could design a battery that meets the energy output of fossil fuels for long range high speed flight.
The problem I wish to be fixed with electric aviation is that typical long flights for flight training and testing are under 4 hours. So the day electric aircraft can fly 4.5 hours will be the day electric aircraft are a true option.
Normally you can not hold back pee for 4.5 hours unless you dehydrate your body which combined with low cabin pressure environment and low O2 will have some bad effect on your health...
@@electricaviationchannelvid7863 what are you even talking about, this is regarding minimum ‘fuel reserves’ just so you don’t lose power half way though a flight.
How dense would batteries have to get before they are without contest better in every way?
By a factor of 8? 4000 Wh/kg?
At the current 5-8% battery energy density growth, it would take 30-40 years to get to that density. Assuming growth continues like this, which is doubtful.
Wanted: new electricity storage physics. Giant reward awaits. And I can tell you, universities and private industry is hammering the problem.
I like how everything is discussed as a matter of choice now: should it _just be_ whatever we want. Next points to discuss: should fusion nuclear power be easy, should there be death, should there be gravity?
With growing technology there will be possibility to charge batterys while flying.
Uhh, the ul engine in your plane is now available with a turbo! Would that fit???
I keep seeing people using near perfect efficiency for electric motors, however, the system efficiency is always ignored in these "30% ICE vs. 99% Electric Motor efficiency" comparisons. In this type of application, what is the transmission loss between the battery, through the switchgear and controllers, to the motor?
It can be very low. 1 percent loss is definitely achievable. The losses in the motor will generally dominate, especially when operating at high torque. Because there is a weight tradeoff with motors. Making them extremely efficient generally makes them heavy also. So they will probably be optimized for cruise efficiency. At takeoff the efficiency of the motor will likely be poor. Lets say 80 percent.
@@mckenziekeith7434 Do you have references for that loss, since that's significantly lower than what I'm able to locate after a brief search? For example, Dana's TM4 line (ground vehicles) advertises 95% efficiency for the motor/controller combo in a similar kW range, but that doesn't include the battery-to-controller part of the equation. Typically, driving efficiency of a system up from 95% to 99% is a non-trivial engineering problem.
As stated in another reply, the aircraft use case doesn't typically have a large margin between takeoff and cruise power. Cruise is usually quoted at 75% with lower settings (often in the 60-65% range) for economic cruise, so the max power and cruise design points are much closer than in a car.
@@olpaint71 let's be clear what we are talking about. You asked "what is the transmission loss between the battery, through the switchgear and controllers, to the motor?" I interpreted that to specifically exclude losses in the motor. Maybe I misunderstood. What I am saying is that if the battery is supplying 1000 Watts, the controller and wiring will likely be consuming less than 10 Watts. That is not hard to achieve. I have done it. The balance is delivered to the motor. And of course the motor has losses too. I NEVER claimed that the motor losses would be as low as 1 percent. I am sure it is possible to design a motor like that, but I am equally sure that it will be heavy. What I did say is that typically the motor losses are going to be larger than the controller losses to the point that we can ignore the controller losses for back of envelope designs. That is based on my experience over the last 8 years or so designing small BLDC controllers for electric skateboards and bikes. To a first approximation, the motor losses are I squared x R, where I is the MOTOR current and R is the series resistance of the motor winding. There are other losses, too, but those are usually the largest. The small motors I have worked with have efficiencies of something like 80 percent. Larger motors are typically more efficient. ANY motor will be less efficient when operated at higher torque (torque is proportional to current, power loss is proportional to current squared). So when the efficiency of a motor is given, that is at one operating point. If we call takeoff power 100 percent power output, the motor will always be more efficient at cruise (60 to 75 percent power output) than it is at takeoff. This is for the simple reason that power loss scales as the square of torque. I presume that designers would try to achieve at least 90 percent efficiency for cruise. You yourself said that the Dana TM4 is 95 percent efficient. So the motor must be around 95 percent efficient (or slightly better). A full system analysis would be required to determine if higher efficiency can be achieved since higher efficiency motors tend to have more iron and copper in them and are thus heavier. Perhaps increasing the motor efficiency beyond a certain point will cause the motor to be too heavy or large and will actually decrease range.
@@mckenziekeith7434 Your interpretation is correct. Basically, if we grant the near 100% motor efficiency, what's the unknown efficiency factors that need to be added to give a truer comparison between electric drive and ICE? Alternatively, the same question could be raised by asking for the conversion of fuel/battery energy to delivered horsepower at the propeller flange. That's why I asked if you had some source documentation for assuming a loss factor of ~1% from battery terminal to motor terminal--so that I could learn more about the overall system at these power levels (100-300kW).
ICE efficiency in this application is very simple, since the typical energy cost of a fuel pump transporting fuel from tank to engine is so low as to be essentially negligible and the typical 500ci aircraft engine is direct drive, eliminating transmission loss as a factor. A controllable electric motor in this power range is reliant on external devices that have non-negligible losses. The TM4 data was handy in that it incorporates the motor controller, but it lacks whatever power conditioning equipment is required for the battery. I'm also assuming a high-efficiency motor is direct-drive, as well, but I'd note that the TM4 would require some sort of reduction drive to match to propeller RPM which would bring down the system efficiency in this application.
The point of my original comment is that the over-simplification of the analysis does an unintentional disservice to the intended audience because it reinforces an unrealistic view of electric drive systems.
@@olpaint71 yes, many considerations. It is also a fact that for a given power level, a low torque motor will be lighter (and faster) than a high torque motor. But then it may require a reduction gear, which adds weight and saps efficiency. So there are many, many tradeoffs. As far as sources, I don't really have any, but I do have the observation that grid-tie inverters, for example have efficiencies in the high 90s. Switching power supplies in general can be made over 90 percent efficient. And ultimately, the drive for a BLDC or synchronous permanent magnet AC motor is just a fancy switching power supply. That is why I am confident that losses can be kept very low in the drive electronics. But since I don't work in that field (I work with lower power systems) I can't say if the efficiency of the drive and wiring is 99 percent or 98 percent or whatever. High nineties is realistic though.
When will the Dark Arrow fly?
New battery chemistry will soon change the power to weight issue and provide a massive boost to performance. Looking forward to seeing Dark Aero go for volts. Beautiful piece of aircraft design.
And how do you know? You are replying to a fact based video presentation with 100% conjecture.
@@floydragan watch FullyCharged and their excellent sideshows. It’s all out there. Fact-based. Battery technology is accelerating rapidly and already they have batteries out in the field with three times the density. The motors are also getting better. Even major airlines are testing electric and hybrid-electric systems. If you want sales to really rocket, then you’ll need a compelling line of systems to suit every customer.
@@floydragan watch FullyCharged and their excellent sideshows. It’s all out there. Fact-based. Battery technology is accelerating rapidly and already they have batteries out in the field with three times the density. The motors are also getting better. Even major airlines are testing electric and hybrid-electric systems. If you want sales to really rocket, then you’ll need a compelling line of systems to suit every customer.
Cars can afford to make the weight to energy trade off. For instance a Tesla Model 3 is about 500lbs heavier than a comparable vehicle.. 500lbs. is not critical in a car however in a small plane it makes electric design unrealistic. I have no idea what the future holds, however we are not even close to replacing ICE in airplanes, IMHO.
You guys are great! Awesome explanation. But I do see electric aircraft when they have a L/D over 50 & 70%ish battery mass fraction.
I replied to the wrong comment... 😮 😂
@@NZobservatory No range extender. Plot it into breguet range equation
@@NZobservatory 😂
Published data projects that petroleum will be a major energy source for the rest of this century. In fact, the overall contribution of alternative "clean" energies will be virtually stagnant despite massive government funding programs. If petroleum continues to be used, then I can't think of a better application than aviation. If a reduced footprint is the goal, then builders would be just as virtuous to source reclaimed lumber and concrete made from biofuel ash. Sure. It's heavier...but so are batteries.
After calculating a little bit with your Data i found if you replace the ICE propulsion system 1:1 with an electric system you would reduce the range from 1700miles (2700km) to 270miles (430km). This is way less but for a guy from the little country germany it would be enough for my usecase. For the US i assume it wouldn't be enough to get from one city to the next.
Axial Flux motor 50lbs, 300hp, can be power by diesel genny, as a hybrid configuration, and likely be under the current weight of your current motor with 30% more power, and near instant torque, and while coasting power off can reclaim some energy as you climb and dive or play in thermals, further increasing loft time.
Some constructive criticism of a good video: A better way to compare apples with apples is to work out the mass of the ICE & fuel powertrain then assume the electric powertrain has the same mass. This allows you to work out battery mass for same MTOM hence the reduction in available energy as a fraction of range or endurance. There are some caveats like the fact that electric aircraft would ideally be repackaged to maximise battery mass and you might deliberately reduce best L/D speed by introducing wing tips (or similar).
I think series hybrid to trickle charge batts during extended cruise has been mentioned below (if ICE then doesn't help CO2 of course).
FYI, the food you eat relies on that CO2.
They went over the mass difference of the motors, which in an aircraft is like 95% of the weight for the system. Hybrid technology for flight isn't a viable option as the loads are static for the bulk of the operation. It will always take x amount of power to go y speed based on the weight and drag of the aircraft. One of the main advantages of hybrid electric drive is the linear torque output of electric motors. This is moot in aviation but exactly why a train uses electric motors with diesel generators.
@@lorendjones I don't think that's true. We are currently increasing the amount of CO2 used as developing countries match the developed world's GDP. The goal of CO2 reduction is to slow this growth in CO2 emissions and avoid temperature increases which would cause large scale flooding, human migration, and crop failure.
@@andyb2339 you don't think it's true that your food likes CO2?? You need to take some basic science classes. There's zero actual evidence that CO2 emissions have ANY of the effects you mentioned. In fact, the slight increase in CO2 has enhanced crop production by every metric. As far as temperature increases, the ability of CO2 to significantly impact temperature was maxed out at 280 ppm (the dawn of the industrial age.) We could double current CO2 and affect global temps by a tiny fraction of a degree. That's the actual science.
@@andyb2339 There is no scientific evidence that CO2 causes warming. You have plenty to the contrary however. CO2 global warming is the biggest fraud ever perpetuated on the human race.
It would have been worthwhile to take a couple more steps, calculating the energy content of a battery-electric system (just battery and motor+inverter, for simplicity) of the same total weight as the gasoline-fueled system (just fuel and engine, for simplicity). This would show how much shorter the range would be for the same airframe with the same payload.
I fly an ultralight single seat plane that has a MTOW of 240 kg with an empty weight of 120 kg.
Quite frequently some friendly passer-by suggest this plane would be a good candidate for electrification. Well, it isn't. It is, in fact, despite it's high aerodynamic efficiency, one of the worst candidates for electrification due to the fact that the engine package is just 35 kg, so assuming I keep my own weight of 90 kg there's no more than 65 kg left for the entire electric propulsion package. The motor and propeller may be around 15 kg, which leaves 50 kg for batteries. If I apply your equations to my own plane I'd need the power of at least 160 kg of batteries to have the endurance i have right now.
I mean, flying for maybe almost an hour with a 50 kg battery pack sounds kinda "not bad", but where would that take me other than a few times around the pattern?
Also, those "high energy density battery packs" are not blessed with the best safety track record, and I actually do mind crashing down in a fiery ball of flames....
Lmao imagine the checklist for an electric aircraft to be “ in the event of a battery fire, crash into the ground before the fire gets to you.”
Slight fact check, that Tesla graph is a bar chart not a timeline.
It's also INCREDIBLY difficult to contain hydrogen because the molecule is so small.
How close are you guys watching TurbAero and their 200hp turboprop project?
If they can really hit their 12.5 gph @ 150hp, it seems an interesting option. The 40 lb weight penalty could probably be more than offset with a more streamlined shape right behind the spinner.
Man, I wish our politicians and policy makers could explain problems and solutions as clearly as he has. I look forward to seeing what performance metrics this plane design and build can accomplish.
Expect very little from people who generally have a net zero of accountability.
@@kmg501 I wouldn’t even want more politicians getting involved into GA, it’s suffering enough already.
Two ways that can improve the electric engine:
- catapult the airplane early: take-off is the most energy-intensive moment; how much could be saved by throwing the airplane with an external power source?
- solar panels: you have beautiful shots of an airplane above the clouds; how much solar energy could be captured from having solar panels on the fuselage and the wings?
I watched this a few days ago and was thinking about it. Did you consider the range extender model? I don't remember you mentioning it. An electric motor at the prop, maybe some batteries, maybe not, but a ICE generator. The engine could perhaps be smaller, more efficient. The electric motor could be just big enough for your requirements. Some cars seem to be headed that direction with success. If you have thoughts or ran the numbers, I'd be interested to hear.
Good and fair video. Before the video even started, I knew the battery weight would be the biggest issue. I know it's sci-fi, but Tony Stark overcame this energy density issue by creating an energy cell that was very light weight but had massive stored energy. I'd love to see the day when there really is such a device. For now, it might be more possible to build a slow but long range electric plane.
Energy density is why lithium ion chemistry was developed. Only hydrogen is lighter in molecular weight. Hydrogen is far more difficult to store than lithium.
Tony Stark is fiction. Try reading chemistry and physics instead of comics.
With a fusion reactor it is possible...but not needed...Energy is everywhere all around us...
@@keithjurena9319 In my original post, I stated that "Tony Stark" is sci-fi(fictional). So I don't see the need to tell me that it is a fictional character. I watch the development of various energy sources. So I'm familiar with most the limitations. I brought up this fictional character because it portrayed a significant leap forward in technology. This happens from time to time. After looking over most of the available energy tech(batteries & storage), a leap forward is needed for fast electric planes(and other craft).
How about a hybrid airplane?
The Pipistrel aircraft only "works" if you ignore the economics associated with operating such an aircraft.
Another small? issue. As an aircraft consumes liquid fuel, it get lighter, increasing efficiency over the duration of the flight. With electric, the mass of the battery doesn't change as it's energy is consumed.
I would be more excited about a jet-a powered DarkAero than an electric.
I would be interested just to see this one fly
This is probably a difficult question to answer, but what sort of drag concequences would come from designing a plane around hydrogen fuel cells from the ground up and generally how would having a lighter, but significantly larger and less dense aircraft change its flight characteristics?
The biggest headache is storing the hydrogen, which requires high pressures and low temperatures. The latest carbon wound tanks can astonishingly handle 700 bar, but the volume is much larger than liquid hydrocarbons. So the issue is one of fuselage drag not dominating the wing drag. This is why Boeing and Airbus are still toying with the idea of flying wings to accommodate all that hydrogen...
I'm sure, when battery technology catches up, you'll be well positioned to design and manufacture an electric plane.
There is no prospect currently of battery technology catching up.
@@mckenziekeith7434 Yup, and it is certain that alternative fuels for ICE will reign supreme over electric solutions.
@@pistonburner6448 I think the only change that will happened is the switch from 100LL fuels to alternatives like gas or sumting.
How about the the small turbine FROM THE AUSTRALIAN TURBAERO
Turbines become less efficient the smaller they get and piston engines become less efficient the bigger they get. This is why you see lower HP engines all being piston engines.
@@AnonyMous-jf4lc it is a clean sheet design tubine with a recuperator.
@@tc6984 and it's been in prototyping phase FOREVER. There has been a long line of these that never ever see any production because they all fail to meet the goals they have laid out. We can revisit this if they ever release it to the public. It can then be verified against its claims.
@@tc6984 Yes, and even TurbAero's planned specs show it almost as heavy as the UL 520iS and with much higher fuel consumption.
Electric powered flight will remain a novelty until there is a quantum breakthrough in battery technology. I'm not holding my breath.