Electric Airplanes?

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

  1. Brad Smith

    Brad Smith Line Up and Wait

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    At one time electrics were seriously considered because we were running out of fuel (circa 1973?). Now the excuse is “saving the planet” since there has been no word of a fuel shortage for the last 45 years. Seems that petrol works great for the average GA mission and even better for the airlines doing trans-oceanic flights (duh!). So why are we trying to convince people that we need an electric solution to GA? GA as a whole contributes so little to climate change that it’s truly laughable.
    Adapting cars to battery power has proven doable with just a couple major drawbacks, and many find the compromise worth it. Trying to adapt aircraft to battery power will be a whole new ballgame if you expect to cruise at 200kts for 4 hrs as it takes 4X the HP(watts) to achieve that speed over a 100kt puddle jumper. Or how about feeding a light twin with two 300hp electric motors? Seems there are a lot of breakthroughs to be had before the next Baron leaves the runway for a 800nm trip on battery power alone.
     
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  2. Dan Thomas

    Dan Thomas Final Approach

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    It would work until your landlord found out why his electricity bill had jumped by $120/month or whatever.
     
  3. Dan Thomas

    Dan Thomas Final Approach

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    You think the general public will happily let you indulge your noisy, expensive, CO2-generating hobby after they've all been forced off fossil fuels? The amount of CO2 will be irrelevant; their perception will be that the elites are claiming privileges denied to the proletariat. That perception is already bad enough, and getting much worse, with wealthy hypocrites jetting all over the world and living in gazillion-dollar mansions while telling the rest of us that we need to reduce our carbon footprint.
     
  4. Tantalum

    Tantalum Final Approach

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    Because it's the current fad, and drawing up a futuristic looking airplane with paper thin wings with CGI can get you clicks and millions of dollars in seed money for your vaporware. The environmental aspect of it is a laughable reason because even if you reduce the carbon footprint through renewable energy sources you still have to mine those.. lithium mining and disposal are environmentally quite destructive

    There is no free lunch.
     
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  5. tspear

    tspear Pattern Altitude PoA Supporter

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    Actually a fair number of us are more interested in the economics of electric aircraft. Think about it; basically no engine work, ever. No worries about the fuel pumps, no overhauling one magneto a year (250 hours a year in a partnership), no spark plugs, no 2200 moving parts. You have one.
    Talk about simpler; much easier to inspect; a very high percentage of airplane owner effort is dealing with preventing and managing maintenance induced failure. With electrics, this is almost eliminated completely.

    For a hybrid model; a couple solutions were looking at using a standard genset from Honda. Think about it, with the batteries able to provide the reserve power; all critical components are largely insulated away from the failure of the genset. Theerfore a few believe the FAA may let the airplane manufacturers use mass produced generators. When the genset dies, no writing a $35-50K check to CMI, instead it is a $2K check to Honda or Homedepot....

    Tim
     
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  6. Tantalum

    Tantalum Final Approach

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    But why not have that Honda engine just power a propeller directly? There are always going to be efficiency losses when transforming energy from one to another. So you can take the Honda engine, power a generator, store that in batteries, then run through another set of motors, all with their own losses - OR - just bolt a propeller directly onto that Honda engine (instead of a generator) and skip the weight and associated losses of all that transformation

    If the logic is that you have some extra reserve juice for takeoff, etc., then it keeps topped off in flight I guess makes sense, and to extend your range, but it just seems like such a roundabout way of converting mechanical energy (ICE) into something else then back into mechanical energy while hauling around a set of extra components and parts that will get used for what, 10% of the flight (take off?). The LeFerrari is a hybrid, but they use that primarily as a way to get extra power into the car, not as an efficiency measure (per se).. it seems hybrid aircraft will be more LeFerrari-esq as opposed to Prius-esq

    **Now, as @tspear said if that can used in a way also to lower the high costs of GA, and yes, mean that a repair is only $5K for the genset and not $60K to rebuild a WW1 era engine, then I'm all for that.. economics will drive that decision. But from a straight physics perspective it inherently seems flawed to me to go from mechanical to stored and back to mechanical.
     
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  7. 3393RP

    3393RP En-Route

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    Many people believe that. Most of them have no idea how chemical batteries work.

    Is there any factual basis for your belief, or are you assuming someone will make a miracle discovery?
     
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  8. tspear

    tspear Pattern Altitude PoA Supporter

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    Regulations. That Honda will never pass FAA PMA and related rules.
    Hybrid battery gives you the potential buffer. Basically these guys are trying to apply IT concepts like RAID using commodity parts with higher failure rates one step removed which ends up giving you a better MBTF.

    Tim

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  9. Cap'n Jack

    Cap'n Jack Final Approach PoA Supporter

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    And many people with no idea how chemical batteries work just say "it can't be done" too.
     
  10. Tantalum

    Tantalum Final Approach

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    the problem with physics and chemistry are there actual laws that can't be broken. This isn't theoretical Star Wars stuff here, these are well known elements with lots of scientific journals out there to prove. There certainly are ways to make batteries have a higher capacity and energy density, but they will never get to the point where fossil fuels are at, that's a hard limitation. It's equivalent to us hoping for a breakthrough in anti-gravity technology or time travel

    they will incrementally get better and better, and there will be some limited market for electric and hybrid planes. But you will never see a777 equivalent flying long-haul flights
     
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  11. Cap'n Jack

    Cap'n Jack Final Approach PoA Supporter

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    Duh.
    No s****, Sherlock. I do read those journals. There's some actual advances being made.

    What do you consider that point? Certainly, for the driving I do most of the time, an electric car will do fine until the snow falls, at that point, the ones I see for sale now won't work for me.

    Agree with a 777 type plane, but electric and hybrid planes, I think, are a reasonable possibility for they type of C-150, C-172, LSA flying that a large number of us do.

    I've posted references in other threads (probably @flyingcheesehead 's Tesla thread) detailing some of the advances being made now in both energy density and charging speed.

    I'll give a slight apology for the snark above. I just got a manuscript accepted for a method that makes chromatography much easier. My management didn't believe it worked- when I asked if I could publish, they said "sure"- they felt certain it would be rejected. It wasn't rejected.... and the algorithm is in our software now. The acceptance by both the European Peptide Society and American Chemical Society changed their minds. I'm just a bit impatient with people simply saying "It can't be done"; "It won't work"; "It can't work", even when presented with evidence showing otherwise.
     
  12. bflynn

    bflynn Final Approach

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    Actually, power density in batteries has turned out to be a soft limit, because it keeps creeping upward. Yes, for a particular battery, there is a limit, but a year later there is going to be something better out there.
     
  13. Tantalum

    Tantalum Final Approach

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    no apology necessary, most people tell me to go F myself on POA after finding out I fly a cirrus anyway.. lol. Congrats on the publication. I trust engineers. For "as good as fossil fuels" I mean energy density. Like I said, there's a market for hybrid and electric planes, but there are limitations to it that many pretend don't exist
     
  14. flyingbrit

    flyingbrit Pre-takeoff checklist

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  15. 3393RP

    3393RP En-Route

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    Can you list the better batteries of the last five years you describe?
     
  16. bflynn

    bflynn Final Approach

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  17. JOhnH

    JOhnH Touchdown! Greaser!

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  18. mwagg737

    mwagg737 Pre-takeoff checklist

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    I subscribe to the theory of, "everything is impossible until somebody does it."
    To me, the nasayers are nothing but background noise.

    Sent from my Pixel 2 XL using Tapatalk
     
  19. Cap'n Jack

    Cap'n Jack Final Approach PoA Supporter

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    Argue for your limitations, and they are yours (Richard Bach).
    If everyone subscribed to that theory, we wouldn't have stone tools.
     
  20. Tantalum

    Tantalum Final Approach

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    All of this is true. My only point was that batteries have been around since 1800 as a voltaic pile.. they've continued to improve over the last 2+ centuries but I think many people are expecting big tech breakthroughs like we saw with nuclear power, the gas turbine engine, internal combustion engine, etc. Batteries have improved, and continue to do so, but we're a long ways off from the kind of energy density a fossil fuel gives us. There are physical and chemical limitations at the molecular level that will make it very difficult to approach fossil fuel energy density.. I just think people also have to be realistic about their expectations of battery miracles

    Trust me, I welcome any advancement we can get in GA.. especially ones that involve finally ditching us of our 1940s engine tech
     
  21. Captain

    Captain Final Approach

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    Easy fix, build a tin roof over the solar panels!
     
  22. tspear

    tspear Pattern Altitude PoA Supporter

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    The companies I used to follow in the field were looking at roughly 20kw gensets. With a slippery plane like a Mooney or Sunflyer the math has apparently supported roughly 65HP in cruise for 135 knots. The idea is the battery provides a little more than half the power.

    70-80kw would completely replace the power draw on the battery at a much higher speed or in a draggy frame.

    These guys were more in the realm of current battery tech gets you a nominal three hours. We need four at that speed to handle most regional city pairs. So, a genset which gives about 40% of the cruise power will allow a two and half hour battery to hit four hours.

    Tim

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  23. Cap'n Jack

    Cap'n Jack Final Approach PoA Supporter

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  24. tspear

    tspear Pattern Altitude PoA Supporter

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    If the battery is "real" it could be a game changer. This more than doubles the energy density of most of the stuff on the market currently. And the time horizon is not very long.
    What is also interesting is they second material. Sulfur, this is a rather low cost material and not exotic.

    Tim
     
  25. Cap'n Jack

    Cap'n Jack Final Approach PoA Supporter

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    It depends on how we define "real". The battery exists, been watching it evolve for some time. I posted about them in this thread: https://www.pilotsofamerica.com/community/threads/those-monsters.117731/
    Now- whether it actually becomes a commercial product is another question. It seems far along, but I also take press releases with a bit of salt. Another company, Sion, is also pretty far along the development curve and has been selling batteries. In theory, they could get 5x the energy density with this chemistry.
     
  26. tspear

    tspear Pattern Altitude PoA Supporter

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    By real I was referencing a commercial product with such density.

    Tim

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  27. Old97

    Old97 Pre-takeoff checklist

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    500Wh/kg. Thats 0.303 hp*hr/lb

    Compare to cherokee 150 at 75 percent power 112 hp x 5 hr / 300 lb gas = 1.875 hp*hr/lb

    Edit: you could add 100lb due to heavier engine so that gets you 1.41 in the cherokee
     
  28. Cap'n Jack

    Cap'n Jack Final Approach PoA Supporter

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    Keep in mind a lot of the power in gasoline is thrown away as heat.

    I can agree with that definition for our discussion here.
     
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  29. Old97

    Old97 Pre-takeoff checklist

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    I don’t understand your point. I am using hp at the prop vs. real fuel weight.
     
  30. Cap'n Jack

    Cap'n Jack Final Approach PoA Supporter

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    The number you mentioned- 300 lb gas. Roughly 2/3 of that doesn’t become hp at the prop. It is lost as heat.
     
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  31. Old97

    Old97 Pre-takeoff checklist

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    Im really not following. Are you saying my calculation is wrong? Or that the comparison isnt valid because one is more efficient than the other?
     
  32. SoCal RV Flyer

    SoCal RV Flyer En-Route

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    I LOVE electric airplanes!

    (just not 1:1 scale)

    IMG_6291.JPG

    Here's the real deal at OSH:

    IMG_4191.jpg
     
  33. sarangan

    sarangan Line Up and Wait

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    Calculation looks correct. The efficiency of combustion is not relevant here because it is already contained in the fuel weight to energy ratio.
     
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  34. Cap'n Jack

    Cap'n Jack Final Approach PoA Supporter

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    Internal combustion engines are 20-30% efficient at converting chemical energy into horsepower. so, being generous, only 100 lb of the 300 lb of gasoline is turning your propeller. The rest warms the air passing over the cooling fins. An electric motor/battery converts 85-90% of the chemical energy to turn your propeller.

    Even so, I also see what you are saying- even with the losses, you still have a higher power density now. _If_ they get the expected improvement in power density in the LiS battery, that gap will close considerably.

    I haven't seen the time that it takes to recharge LiS batteries mentioned, and that may limit their use. What use is 3 hours range if it take 9 hours to recharge?
     
  35. Stephen Poole

    Stephen Poole Pre-takeoff checklist

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    Interesting comments here; I enjoyed reading them. But to rephrase the question that I asked in the OP: suppose we DO come up with batteries that are light, have high energy density and are reasonably priced. Now suppose that electric airplanes become commonplace. How are you going to charge them?

    I still say that's the real killer. If you need 100KW hours worth of juice to make the trip, you will need 100KW hours (plus losses) to charge the battery pack. Dozens of shiny new electric planes, each drawing 40 amperes at 240V, are going to represent a huge increase in the load on the utility.

    That's what I think the e-air-taxi folks are missing. Those who dream of an all-electric car fleet miss this little point, too. We're going to need a bunch of new power plants. Wind and solar ain't gonna do it.
     
  36. 3393RP

    3393RP En-Route

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    OXIS is pushing vaporware with their claims. Again.
     
  37. Cap'n Jack

    Cap'n Jack Final Approach PoA Supporter

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    Ask the Chinese how. They will buy over a million electric cars this year. That’s in addition to the electric motorcycles and bicycles they buy, too.
     
  38. Old97

    Old97 Pre-takeoff checklist

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    The statistic i heard is that if the US suddenly converted all cars to electric we would have to triple our electricity generation.

    I have a strange feeling it wont be all be hydro, solar and wind making up the difference.
     
  39. Stephen Poole

    Stephen Poole Pre-takeoff checklist

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    Agreed. The basic theory is intriguing, but there's quite a ways to go before they're ready for real life.
     
  40. Cap'n Jack

    Cap'n Jack Final Approach PoA Supporter

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    Yet, somehow the Chinese are doing it. Granted, they are starting from a lower percentage of car ownership. Man, this country has turned into a bunch of "can't do".
     
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