Electric Airplanes?

Discussion in 'Hangar Talk' started by Stephen Poole, Jul 19, 2019.

  1. Skip Miller

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    Well, some of it also beats on your eardrums - in a thoroughly enjoyable manner! -Skip
     
  2. Old97

    Old97 Pre-takeoff checklist

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    If the Chinese add a million electric cars, thats one for every thousand people. I think the US could handle that as well. Who said can’t?

    Proper planning and realistic engineering study is not the same as naysaying.
     
  3. Stephen Poole

    Stephen Poole Pre-takeoff checklist PoA Supporter

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    There's no "somehow" to it. No need to ask them, either. The stats are available online.

    They're building a bunch of new power plants to meet demand. The original plans a few years ago called for 1,100 GW new generation, they've already upped that to 1,300 GW (that's as of early 2019, and it'll probably go higher).

    They already get the bulk of their energy from coal-fired plants. Most of these new plants will be coal-fired as well. Lots of black smoke and radioactive C14 emission. But hey, they have electric cars ...

    (There's a reason why China is a very heavy polluter and carbon emitter.) (Edited for Giga, not Mega.)
     
    Last edited: Aug 13, 2019
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  4. Old97

    Old97 Pre-takeoff checklist

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    Do you mean 1300GW? 1300MW is one large powerplant.
     
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  5. Stephen Poole

    Stephen Poole Pre-takeoff checklist PoA Supporter

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    Yeah, gigas, not megas. Or, as Doc Brown called them in Back To The Future, "Jiggawatts." Fixed.
     
  6. tspear

    tspear Pattern Altitude PoA Supporter

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    A few details on that capacity coal capacity.
    https://www.americanprogress.org/is...32141/everything-think-know-coal-china-wrong/

    Tim
     
  7. Stephen Poole

    Stephen Poole Pre-takeoff checklist PoA Supporter

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    I'll bite my tongue and avoid saying anything about the source of the info in that link. Greenpeace, for one, has been complaining for years that the Chinese are notorious for playing the numbers and pretending that they're doing more than they actually are. (For example, during peak demand, the coal plants are prone to switch off all that shiny "scrubbing" equipment to get more juice. Greenpeace has documented this.)

    Instead, I'll just bang my head on the table, say, "OK, so the 'black smoke and C14 thing was a joke,'" and point out that they're having to build power plants. Ryanb said to ask the Chinese how they're doing it, so I answered. That's how.

    And that's what we'll have to do: build a bunch of new power plants.
     
  8. genna

    genna Cleared for Takeoff

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    Assuming that electric motor+generator is doable, you are removing the gas power plant as a critical component. Even having a small amount of battery there enough for 10 min of level flight(or something like that) will be enough to land with gas engine out without much of an emergency.
     
  9. Tantalum

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    And people complain that having a parachute adds costs, weight, and maintenance...

    undoubtedly we will see electric planes, I just can't see how the physics justify a hybrid
     
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  10. genna

    genna Cleared for Takeoff

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    It may or it may not. I don't know. The point that was being made that instead of having a $50K 1930s style certified engine, you can have $5K run of the mill modern generator, a pretty simple, cheap and reliable electric motor, and a small and also cheap battery pack. Whether this is a possible solution, i cannot say. But this(if possible) how it would be economical
     
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  11. jsstevens

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    Probably all three of those components will have to quadruple in price to get them certified. It would be an interesting experimental project of you can get the weight down.
     
  12. Flybuddy

    Flybuddy Pre-takeoff checklist

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  13. genna

    genna Cleared for Takeoff

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    Indeed, and I have no idea if the numbers ever work out.
     
  14. genna

    genna Cleared for Takeoff

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    @Tantalum . Here is a potential use case(i'm ignoring weight issues since it's a current hurdle):

    a plane has a 300HP engine. It needs that to take off and climb to an altitude. But at altitude(before oxygen is required), this big heavy engine can only produce about 60% of rated power.

    The theory is to have a small 300hp(hell, you can have a 400 as it costs nothing in electric motors) electric motor with 10 min battery pack at full power and a 200hp modern generator with a small turbo somewhere in the back providing cruise power and recharging the battery. The E motor has no altitude issues, so it will get you up there quicker. And smaller generator will be significantly more efficient than bigger engine, negating much of the loss in generating electricity. The whole thing will be more aerodynamic as well without that big engine in the front..

    It's similar to how locomotive works rather than a car.
     
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  15. tspear

    tspear Pattern Altitude PoA Supporter

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    No issue. My point was China is building capacity, and even replacing capacity that is just twenty years old.

    Tim
     
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  16. Sac Arrow

    Sac Arrow Touchdown! Greaser!

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    I understand your argument, but I think you reversed your analogy. You describe a hybrid car with an undersized gasoline engine. A diesel locomotive has no electrical storage, the motor/generator is just a transmission.
     
  17. Tantalum

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    thanks, I appreciate the effort in justifying it, but ignoring weight is a huge factor here. Planes are already tight on weight and especially the smaller aircraft all have frankly pitiful useful loads. But putting weight aside, I don't understand why putting a small turboed generator in an airplane and adding an additional powertrain makes more sense than just optimizing the existing engine and putting a turbo on that so it can continue to generate 75 or 85% of its rated power at altitude. This is why I like the rotax, you can run that thing at pretty much 90% power at altitude and it's light and small. Same thing with the diesels on the Disamond, that plane, DA62, has Cirrus performance with two engines and uses less gas, something like 14-16 gph at cruise

    Exactly, locomotives use diesel electric because the transmission and clutch required to pull those kinds of loads would be absurd, utilizing diesel-electric also lets you take advantage of dynamic braking
     
  18. genna

    genna Cleared for Takeoff

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    Because small Rotax can’t handle the takeoff power demands of a larger plane. Yet it’s perfect at altitude.
     
  19. Tantalum

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    Then you size up the engine and stick to one efficient power plant

    Hybrid technology is predicated on the efficiency and capacities of batteries to outweigh the losses of the current system. They work in cars because there's no reason to be running your gas engine when your idling in traffic and when you spend almost half your time braking you can regenerate that energy

    Adding a battery and electric motor to help get you to cruise faster only to rob energy from your main powerplant is dubious at best. I get the theory behind it, but it's kind of like arguing that putting a wind generator on a sailboat then having that drive a fan to blow into the sails is going to help you sell more efficiently
     
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  20. genna

    genna Cleared for Takeoff

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    Except scaling ICE exponentially scales losses in ICE. And most of the flight you are operating big ICE in suboptimal regime. Generating electricity is very efficient. It’s not currently feasible I don’t think, will it be in the future? Possibly. Really depends on battery tech. I wouldn’t dismiss put out of hand
     
  21. tspear

    tspear Pattern Altitude PoA Supporter

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    Actually I think the first Hybrids will really be "range extenders". They will not even have enough power for normal cruise; likely just enough power to bring a plane down safely. Therefore, the range extender will likely only produce 20-30% of the power needed for takeoff.

    Tim
     
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  22. Salty

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    The first hybrids, and all the ones that follow, will be money transfer engines. Transferring money from suckers to shysters.
     
  23. Stephen Poole

    Stephen Poole Pre-takeoff checklist PoA Supporter

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    I obviously misunderstood your point. Apologies.

    (Stephen hangs his head in shame.)
     
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  24. Stephen Poole

    Stephen Poole Pre-takeoff checklist PoA Supporter

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    WHEN is Rotax going to add 2 more cylinders to make a 180-200 HP game changer? :rockon:
     
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  25. 3393RP

    3393RP Pattern Altitude

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    The "can't do" is going to happen because New York and New England states have banned natural gas pipeline construction, and Berkeley is prohibiting natural gas connections to new buildings and homes. New York is also closing down the only operating nuclear plant in the state, which supplies NYC with 2 gigawatts of power, and nothing exists to replace it. California is shutting down its nuclear power plants. Acts like these are spreading nationwide, and it is an appalling display of collective stupidity.

    The electric revolution is going to be stillborn.

    An article in yesterday's Wall Street Journal about utility battery installations said that all of the utility connected battery systems brought on line worldwide in 2018 had enough capacity to power 50,000 homes for one day.

    The chimera of "renewable" and "carbon free" energy is going to be a rude awakening for states and municipalities that have passed laws dictating X percent of power at some point in the future will be produced by wind or solar. The politicians haven't done the math, nor have the so called visionaries.

    The proponents of electric cars, semis, airplane, air taxis, trains, motorcycles, and skateboards also actively seek to dismantle the power grid supported by natural gas. They have already killed coal. Wind and solar supported by batteries isn't going to replace them.

    Unless, of course, every ridgeline and prairie is covered in wind turbines, all of the Southwestern desert is turned into a giant PV array, and huge sections of the Earth are laid bare and stripped of their minerals to build batteries. That's going to be the reality of the Green New Deal.

    Unless the cognoscenti embrace nuclear power, the outlook for the electric future is, well, dark. There's every indication the fierce opposition to nukes will continue. If so, increased electricity prices due to the stunning lack of reality will cripple the worldwide economy in the not so distant future.
     
    Last edited: Aug 15, 2019
  26. Cap'n Jack

    Cap'n Jack Final Approach

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    Thanks for proving my point. A lot of the quote above is speculation by the poster, or speculation by fringe writers, yet it is being taken as fact. A lot is non-sequitur to electric aircraft.

    The USA has become "Can't do". I doubt we'll go to the moon again, much less to mars. The Chinese, maybe the Indians, will.
     
  27. bflynn

    bflynn Final Approach

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    Well, the 2 seat eflyer training is already well into type certification, so the battery for it is fixed. They would have to amend the type certificate in order to change out the battery and who wants to do another round of testing like that.

    Otherwise, the LiS battery could be up to 5 times more energy dense, but it's still experimental. I doubt we'll see a production airplane flying on it within 5 years just because of the amount of paperwork and testing to be performed. But it is nice to see that future candidates are coming.
     
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  28. Cap'n Jack

    Cap'n Jack Final Approach

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    What testing would need to be done? Assuming the battery has the same mass and fits in the same space, the flight characteristics will be unchanged. I agree "tip tank" batteries, at the end of the wings, would need spin testing if they cause a change in the moment of inertia.

    The LiS batteries with 5x the energy density are experimental (maybe not even at that point, yet), but the ones with 2x energy density are being produced now (Sion, the company referenced in the links).
     
  29. GeorgeC

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    Does anyone know what battery chemistry is used in the Flight Design F2e?
     
  30. bflynn

    bflynn Final Approach

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    Because the FAA is requiring them to specify the type of battery in the TC and given LioN batteries' history of combustion, I'm not surprised. An there's an assumption that the the LiS battery does weigh the same and isn't heavier or lighter.

    So the path isn't changing the TC but creating a STC. Either way, there's going to be testing and paperwork, just less of it.
     
  31. Tantalum

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    But you can't have something for free. If a plane requires 180kw to sustain level flight you have to get that from somewhere. I'm not seeing how a "small turbo'd generator" turning mechanical energy into stored energy and back into mechanical energy helps increase efficiency. Maybe I'm missing something. The range extender part I don't get either.. why am I going to carry 100 lbs (min) of batteries, etc., just to get an extra 10 minutes of flight / range?
     
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  32. genna

    genna Cleared for Takeoff

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    You're missing something. :) I know you don't see it possible or make sense. I'm not saying that it is currently possible or feasible. I'm simply giving you a scenario when and if technological/cost issues are resolved, it can make a lot of sense

    SR22 at 55% of power is a pretty common operating procedure at 11,000ft. That's 170hp. Big IO550 is operating very inefficiently at these power settings. Rotax 915 is not quite enough, but scale it just a little more and you have a modern light, economical engine operating at its most efficient power setting that makes enough power to sustain SR22 in level flight at altitude. Or, since it's not a critical engine, but more like an APU, you can adopt your average Honda automotive 1.5L. BUT, it won't have enough to get it up in the air with any urgency. An electric motor can produce 300, 400, 500hp very easily(something that cannot be done easily in aircraft ICE). You only need it for short period of time to get up to altitude. Then you dial back to 170hp with energy provided by that "Rotax" generator.

    You can do it as a true hybrid system with 2 motors in series(complicated, prone to failure) or you can do it more like original Volt or diesel-electric locomotive. Locomotives make it work without any regen, so there is obviously a case that is viable. What you have here is lots of performance on take off and good cruise. All without a need for some monster ICE.
     
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  33. GeorgeC

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  34. genna

    genna Cleared for Takeoff

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    @Tantalum

    Here are some real current numbers. IO550 makes 310hp at sea level and weighs 439lb dry. Which we all know is not realistic in summer in USA

    Honda's L15B7 1.5T makes 200hp.. let's say it's de-tuned and gives us 110KW or electricity. You then need 19KWh battery pack to make up to 300hp(223KW) for 10 minutes

    Honda's engine 220lb(I looked it up)
    Battery pack: 250lb
    Electric motor:50lb
    Electric generator: 30lb

    Total 550lb.... so yes, it's not good now, but it's not that far off... 110lb loss, but gains in efficiency and some performance(say what density altitude?). A little larger battery pack may even gain you GW increase with more ponies on take off
     
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  35. Stephen Poole

    Stephen Poole Pre-takeoff checklist PoA Supporter

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    Hmm. No, they're not saying. (That I could find, anyway.) It's a Siemens system, so maybe Siemens is doing the batteries?

    Edit: incidentally, the electrical system is only 55KW -- not quite 74 horsepower. Not exactly going to climb like a homesick angel ...
     
  36. Stephen Poole

    Stephen Poole Pre-takeoff checklist PoA Supporter

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  37. Stephen Poole

    Stephen Poole Pre-takeoff checklist PoA Supporter

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    If you read up on lithium-sulfur, there are still very big problems with it. The number of charge-discharge cycles is not good at present, so they're banking on a few engineering breakthroughs to get around these limitations.

    I don't know anything about the companies that are trying to put these into mass production, but my cynical side suspects that a lot of the hype is vapor to snag investors. I know the theoretical math works on using that topology to improve energy density, but thus far, no gold ring.
     
  38. flyingbrit

    flyingbrit Pre-takeoff checklist

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    You are asking us to believe that the Honda engine is significantly more efficient that the IO550. Do you have evidence of this, say bsfc data?
     
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  39. Tantalum

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    So basically a JATO type setup, but instead it's a battery and electric motor

    That's assuming a lack of turbo. That 55% power at 11K is not really by choice, it's just basically the best you are going to get without a turbo, even WOT. In the Cirrus (TN) I still cruise at around 80% power at 17K-19K with 30 inch manifold pressure and around 16-17 gph. The plane is still going to require that 80% power at 17K to maintain that 200 knot TAS. Sure I could pull the power way back, but now I'm sacrificing a ton of speed. I wouldn't trade my current setup for a plane that can't get me more than 55% power in cruise, and has availability of that extra 45% only for 10-20 minutes to get me to climb. A slower plane with limited full power takeoff reserves doesn't sound like a fun time

    Locomotives are turbo diesel to resolve transmission issues. Without a turbo diesel set up locomitives would need ridiculous clutch, torque converter, and gearing mechanisms.. that the electric part resolves

    I'm not saying it can't be done... it certainly could, I just don't really see the point. Mind you, hybrid cars (take the Prius for example) are typically no more efficient (in fact some less so) when on the highway. Compare two otherwise similar cars, say Prius and Corrola, and drive them at 75 mph cruise on the highway... the hybrid isn't getting better mileage, it may even be slightly worse. No free lunch.
     
  40. genna

    genna Cleared for Takeoff

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    Yep, kind of like JATO :)

    Turbo on bigger engine solves different problem(allows to go faster up top). It's also $$$$. This "JATO" setup does not increase your speed at altitude, but increases efficiency.

    I was using SR22 as an example. If you want TN speeds, you can have a 300hp Honda motor and bigger battery pack. This will give you your TN's speeds and something like a 400-500hp take off performance


    Ah, i have no idea where you are getting hybrid use more gas on highway part. They do not get as much benefit if largely driven on highway, but they still use smaller engines and less gas than their non-hybrid counterparts. A non-hybrid Corolla needs a bigger(or at least differently tuned) engine then otherwise similar Prius(or even a hybrid Corolla) because it doesn't have e assist from the stop. It would take too long to accelerate with a puny Prius' power plant. But at highway speeds steady go, you only need about 50-60hp, so a very small engine is enough. I'm pretty sure Prius does better mpg than Corolla at steady highway speed. I don't know how to find what they do at 75mph, but their highway ratings are as follows
    2020
    Prius 1.5L: 43mpg
    Corolla 2.0L: 40mpg
    Hybrid Corolla 1.8L: 52mpg

    https://www.fueleconomy.gov/feg/PowerSearch.do?action=noform&year=2020&make=Toyota
     
    Last edited: Aug 14, 2019