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  1. T

    Electric Powered - High Performance Design

    Two motors are fine, except... 1) It needs a way to reduce propeller speed 2) What if a motor seizes? Answer, with this design, they both freeze apparently
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    Electric Powered - High Performance Design

    Fire is a bigger enemy. Unlike a kerosine or oil fire, lithium batteries (and magnesium metal) can and will burn without oxygen. Those cells need to be in small enough arrangements so that a fire can be contained. The heat cannot get into the spar(s). I don’t want the weight of making the...
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    Electric Powered - High Performance Design

    Yes, that is outlined on the post linked below, with both overpressure and venting to atmosphere for pressure differential while climbing and descending. I suspect that the venting needs to go through an air filter, since air would be going in and out of the battery cells. The overpressure can...
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    Electric Powered - High Performance Design

    Much like gasoline or Jet-A, there is a lot of stored of energy that can burn amazingly well when things go bad. It’s super important to protect the airframe during a fire, especially with the fire in a wing. This picture is cylindrical 18650 cells (18mm diameter x 65.0mm) that caught on fire.
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    Electric Powered - High Performance Design

    This airframe is 2600 pounds with the turbine power plant and prop. Maybe about 2000-2200 without a motor? By the way, it hauls the bacon with 750-1000 hp.
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    Electric Powered - High Performance Design

    The inverter is only part of the noise issues with an inductive motor. There’s enough power in there to wipe out bearings and shafts.
  7. T

    Electric Powered - High Performance Design

    I believe the NASA design is: 1) High wing (so the prop blades don’t hit the ground) 2) Low power per motor 3) A dozen motors
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    Electric Powered - High Performance Design

    All the metrics that they proposed were all pie-in-the-sky... range, payload, etc. Snake oil salesmen. Hopefully, burning this one down might have saved a few lives.
  9. T

    Electric Powered - High Performance Design

    The 2170 cells fit in “sheets” between the spars, where the petroleum stuff normally goes.
  10. T

    Electric Powered - High Performance Design

    The lithium cells have instant power. There’s no advantage with capacitors. Capacitors are not “energy storage”. If there’s going to be a turbine “range extender”, you probably should just get rid of the batteries and power the plane with Jet-A. That’s a LOT of extra weight... engine, gearbox...
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    Electric Powered - High Performance Design

    Yes, I’ve explored known wings, like the Swiss P16 / LearJet 35/36 wing and now Piaggio wing. Since we know exactly how much fuel they hold, and how much that fuel weighs, it’s pretty straight forward to determine how many battery cells will fit (at 1kWh / 10 pounds up to about 1.25kWh / 12.5...
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    Electric Powered - High Performance Design

    I think EPPP will look bad ass with those 8.5 foot diameter 5 blade Hartzell composite props, spinning at 1800 RPM. .
  13. T

    Electric Powered - High Performance Design

    Propellers on the wing tips has got to be the dumbest idea, designed by people who don’t fly. They will likely attract lots of venture capital from equally dumb people.
  14. T

    Electric Powered - High Performance Design

    Well, you could use anything, but I’m going to use lithium cells of the 21mm x 70mm cylindrical size. They would fit in an arrangement like that quite well.
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