Ranger electrically powered?!?

Discussion in 'Electric Propulsion' started by erkki67, Jul 26, 2019.

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  1. Aug 25, 2019 #81

    pictsidhe

    pictsidhe

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    A Ranger will not fly with that profile.

    OK, I'm out, this is a fantasy physics thread.
     
  2. Aug 25, 2019 #82

    GeneG

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    Not sure where the fantasy physics are.
    The battery performance is from a major company producing a real product in volume.
    Will it work for a Ranger ... no.
    Will it work for any USA part 103 ultralite ... no.
    Could it work using Austrailian rules and a different airframe ... yes.
    Could it work in Switzerland .. I haven't calculated that.
     
  3. Aug 25, 2019 #83

    litespeed

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    For us down in the wide brown land and scorching heat- Australia, at last some of our rules make sense.

    But it still requires a pilots certificate but not a PPL. Our sub 300kg rules would suit electric quite well as we have no speed restrictions, no fuel restrictions and only a simple wing loading and stall speed in landing config. Which is better than clean stall ie allows flaps etc.

    As long as it meets those rules and is signed off for its structure as not a death machine- you are generally good to go.

    In general the need to play with the part 103 rules in the USA artificially reduces the ability to innovate and be safe. I know people like the idea of no licence or flying permit but it is a big price to pay for marginal flight.

    Our rules do not restrict people building their own designs as long as it meets some basic criteria. Could the rules be better- sure. But its better than most.

    Any flying refugees are welcome to come down and enjoy life in Australia.

    Also our LSA rules do not have silly max speed restrictions either, just weight and stall.

    Or we can use our SAAA rules which are experimental GA and have none of those limitations.

    .......Aussie walks off to beach, punches White pointer shark in nose:mad:, wrestles a massive crocodile whilst downing a beer with a smug smile.....:D
     
  4. Aug 25, 2019 #84

    GeneG

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    In general the need to play with the part 103 rules in the USA artificially reduces the ability to innovate and be safe. I know people like the idea of no licence or flying permit but it is a big price to pay for marginal flight.

    I may be tempted to join you. In the mean time I will design an aluminum machine to be electric power and meets your rules.
    If the new LSA rules allow electric power, I believe that it would be possible to do worthwhile here.
    Meantime I could possibly supply kits via a distributor there.
     
    Last edited: Aug 25, 2019
  5. Aug 25, 2019 #85

    12notes

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    The actual energy density of the whole Nissan Leaf battery pack, is 81.4 Wh/kg, but that's with the steel boxes, frame, electronics and wires. The individual pouch cells are 3.8V, 33.1Ah, 799g each, giving an energy density of 157.4 Wh/kg.

    First link is a teardown of a battery pack from 2015, second is details on the pack including individual cells from 2018.
    https://qnovo.com/inside-the-battery-of-a-nissan-leaf/
    http://www.electricvehiclewiki.com/wiki/battery-specs/


    That gives about 8,000 Wh for 50kg, not 14,000. Assuming the rest of your numbers are correct, it gives a 54 minute maximum endurance with no reserve while reducing the life of the battery by discharging them all the way (I think. I've been reading a lot on batteries, I'm pretty sure this is for lithium ion, but could be mistaken). Realistically, 32 minute flight + 15 minute reserve + 7 minutes (10% charge remaining to extend battery life).

    Also, you're probably going to need to add some weight for the wires and electronics, possible cooling depending on charge/discharge rate (I've done no calculations on this, just mentioning the possibility). This will add weight to the system, so that density will go down.
     
    Last edited: Aug 25, 2019
  6. Aug 25, 2019 #86

    GeneG

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  7. Aug 25, 2019 #87

    BJC

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    While steel boxes may not be required, an effective restraint/containment system would be prudent.


    BJC
     
  8. Aug 25, 2019 #88

    GeneG

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  9. Aug 25, 2019 #89

    GeneG

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    If you look at the pack construction you will notice that the cells are bundled into modules. These are then assembled into the actual battery pack.

    This bundling into modules is attractive because it provides a protective case as well as easy assembly into the pack you require as well as cell protection.
     
  10. Aug 25, 2019 #90

    BJC

    BJC

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    I was referring to the airframe structure needed to protect the aircraft structure from inertial loads plus the need to protect the pilot from a break-away dense and heavy load in a crash.


    BJC
     
    Last edited: Aug 25, 2019
  11. Aug 25, 2019 #91

    GeneG

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    I totally agree!
     
  12. Aug 25, 2019 #92

    stanislavz

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    Go for tesla. it is better in power density terms - this is data is with box already (i would call it for 1 hours with reserve of10-15 minutes. )

    • dimensions: 685 x 300 (280) x 75 mm (l x w x h).
    • Weight: 25 kg
    • Voltage range: 24,9 vdc to 18,6 VDC
    • Capacity: 5,3 kwhr

     
  13. Aug 25, 2019 #93

    12notes

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    That link does not give a weight or specific energy density for the 62kWh battery.

    It states it uses 288 cells for the 62 kWh battery instead of 192 for their 40kWh battery. The 62kWh car weighs 140kg more than the 40kWh version. 40kWh/192 = 208kWh per cell, 62kWh/288 = 215kWh per cell, using the best number 215kWh/140kg = 153 Wh/kg. Some of that weight is wire/electronics/frame, lets estimate 25% of weight is structure, 215kwh/112kg = 192Wh/kg. Plugging those numbers in results in 9.6kWh. 8kWh for cruise, is 68 minutes total, or 45 minutes cruise + 15 minutes reserve + 8 minutes (10%battery life for longevity).

    This is assuming 1.6kW for climb and 7kW for cruise is correct, which I do not think are close to real. The Ranger is being designed for a 35hp 1/2 VW motor, and 1.6kw @100% power for 5 minutes equates to 19 hp full power, and 7kW is about 9hp, whereas the cruise power of a half VW is going to be around 20 hp, greater than the peak of your climb number.
     
  14. Aug 25, 2019 #94

    GeneG

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    If you look at the chinese description of the cell from the manufacture it gives the watt hour density.
     
  15. Aug 25, 2019 #95

    12notes

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    Yes, and unless your wing chord is greater than 1m, then you're claiming 16000W/14m^2, or 1100 W/m^2 power generation generation, when in reality even the best (and most expensive) solar cells available produce 230 W/m^2.

    1100 W/m^2 is solar irradiance, is only that much during peak hours, and you'd need a fictional 100% efficient solar cell to get that.
     
  16. Aug 25, 2019 #96

    12notes

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    Using realistic numbers for flight on the Ranger to calculate needed energy density of batteries for 1 hour flight on 50kg batteries. Please note that 50kg is 2kg less than the weight of a half VW and 5 gallons fuel (enough for climb, 2 hours cruise + reserve), and you still need to add the weight of the electric motor, electronics, wiring and support.

    Takeoff, full power (35hp, 26kW) 5 minutes = 2.1kWh
    Slow cruise, 60% power (15.6kW), 1 hour = 15.6kWh

    Energy density needed for 1 hour flight without 15 minute reserve or 10% charge remaining:
    2.1kWh + 15.6kWh = 17.7kWh/50kg = 354Wh/kg
    with 15 minute reserve
    2.1kWh + 15.6kWh + 3.9kWh = 21.6kWh / 50kg = 432Wh/kg
    with reserve and 10% charge remaining
    2.1kWh + 15.6kWh +3.9kWh + 2.4kWh = 24kWh / 50kg = 480Wh/kg

    Lets see what power level is needed for an hour cruise with the best currently available batteries, assuming we are using magic wiring, electronics, structure, and electric motor that combined weigh a total of 2 kg to keep empty weight the same.

    260Wh/kg*50kg = 13000kW-2.1kWh-3.2kWh -1.3kWh = 6.4kW or 8.6hp. I seriously doubt that's enough for the Ranger to cruise, it's probably marginal to get it moving from a dead stop on lumpy grass.

    These are optimistic, best case numbers for replacing a 1/2 VW engine with 50kg of batteries and an impossibly light (2kg) motor, electronics & wiring.
     
    Last edited: Aug 25, 2019
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  17. Aug 25, 2019 #97

    GeneG

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    I discounted Ranger already. Try the SD-1 Minisport.
     
  18. Aug 25, 2019 #98

    stanislavz

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  19. Aug 25, 2019 #99

    12notes

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    I posted this because the thread is titled "Ranger electrically powered". Also, the numbers are not plane specific, just specific to any 1/2 VW powered plane. You never mentioned the SD-1 before now, I can't do calculations for random planes in the hopes it might be the one you think of next.

    The SD-1 MiniSport uses a 50 hp Hirth F-23 engine, this will make the power requirements higher, not lower.

    http://www.skycraftairplanes.com/sd1-minisport
     
    Last edited: Aug 25, 2019
  20. Aug 25, 2019 #100

    GeneG

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    SD-1 Also uses 24HP Briggs engine.
    Briggs weight approx 70 pounds + FWF
    (Allowed engines up to 93 pounds).
    9 gallons fuel = 54 Pounds for total of 124 pounds + FWF
    Versus
    100 pounds batteries + 8 Pounds for 15KW motor + 2 pounds for controller =
    110 pounds total plus FWF.

    Thrust would be 150 pounds so enough for operations.
     

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