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Thread: Electric Motors for Aircraft

  1. #1

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    Exclamation Electric Motors for Aircraft

    Where can I pickup a kit to convert a J-3 with a C-65 to an electric powered aircraft?
    I've seen that there are a few new aircraft with them built-in and wanted to see if I can do it with a cub.. so where do I start?

  2. #2

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    Quote Originally Posted by rkirk77 View Post
    Where can I pickup a kit to convert a J-3 with a C-65 to an electric powered aircraft?
    I've seen that there are a few new aircraft with them built-in and wanted to see if I can do it with a cub.. so where do I start?
    Not aware of any such kit.

  3. #3

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    "
    so where do I start?"

    The glib answer would of course be - "With a dump-truck full of money."
    "Don't believe everything you see or read on the internet" - Abraham Lincoln

  4. #4

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    At this point, there are not many "kits" and no STCs. So if you are working with a certificated aircraft then you need to budget as much for FAA approval as for parts.

    But if you have an experimental, there is some information out there, and Pipistrel is even selling a kit:
    https://www.pipistrel-usa.com/electric-propulsion/
    Looking to buy my first airplane, message me if you have a nice trainer or experimental for sale.

  5. #5
    cub builder's Avatar
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    This is something that would be accomplished under Experimental Exhibition. FSDO can help you with the legalities of that. Not a difficult change to make.

    However, I am not aware of any existing kits. You would have to contact the manufacturer of one of the electric motors and controllers that are being experimented with and start designing with them. Not my cup of tea, so can't help much in that arena. But look at one of the light sport planes that is touting electric power and go from there.

    To me, it seems a criminal thing to do to a classic aircraft.

    -Cub Builder

  6. #6
    rwanttaja's Avatar
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    Quote Originally Posted by cub builder View Post
    This is something that would be accomplished under Experimental Exhibition. FSDO can help you with the legalities of that. Not a difficult change to make.
    OP is in Canada. Probably falls under their "Owner Maintenance" category.

    Ron Wanttaja

  7. #7
    DaleB's Avatar
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    It's not like there's a scarcity of old Cubs. The Pipistrel kit looks like it would roughly equivalent to 53 HP max takeoff power, 40 continuous. Experimental R&D might work too. It's an interesting thought, but I wonder if there are other possible solutions that might be more than just a novelty. I don't know exactly what kind of flight time you'd get with a 40 AH battery and that setup in a Cub, but I suspect it would be about enough for "proof of concept" flights, like maybe 15-20 minutes or so. A couple laps around the pattern, and back to the charger.

    Battery capacity (40 Ah) - 9.7 kWh
    Motor power 40 kW (1 min), 30 kW cont. Air cooled

    What's 9.7 divided by 30 or 40? Or even 20? I don't know how much power it would take to keep a Cub flying... but it looks to me like you'd be lucky to get a takeoff and 15-20 minutes of flying.
    Measure twice, cut once...
    scratch head, shrug, shim to fit.

    Flying an RV-12. Building a Fisher Celebrity.

  8. #8
    robert l's Avatar
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    Personaly, I like the sound of the engine up front, once you get atuned to it, you can hit almost any RPM just by the sound. I've never cared for gliders either, even though there is a glider field less than 15 miles from my house. When I'm flying, I don't want to have to depend on thermals and wind currents to stay aloft, heck, I may change my intended flight plan just because.
    Bob

  9. #9
    rwanttaja's Avatar
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    Quote Originally Posted by robert l View Post
    Personaly, I like the sound of the engine up front, once you get atuned to it, you can hit almost any RPM just by the sound.
    Anyone who has flown electric RC airplanes can tell you: It may sound different, but the noise varies significantly by motor speed. One could set the RPM by ear.

    The elephant in the electric-airplane closet is 14 CFR 91.151, Fuel Requirements for VFR Flight.

    (a) No person may begin a flight in an airplane under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed -

    (1) During the day, to fly after that for at least 30 minutes;
    (2) At night, to fly after that for at least 45 minutes.


    I'm sure this'll require a re-interpretation by the FAA, since battery power isn't a binary situation (e.g., having gas vs. not having gas). If I were to have absolute control over the regulatory process ("What, AGAIN?") I'd word this to require that the aircraft have enough juice to maintain altitude for 30 minutes after arriving at the first point of intended landing.

    Most electric-airplane articles I see mention about a 30-minute duration; in these cases, the plane shouldn't even be taking off. Even if your battery has a 1-hour life, you're still expected to land after 30 minutes to comply with 91.151.

    Ron Wanttaja

  10. #10

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    Just do it. The FAA will not move until they are forced to do so. Newton knew that years ago. "An object at rest will continue to stay at rest until a force is acted upon it." You're best off to start with something that is already up and operating and adapt it to your installation.

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