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Fuel Cell (Aeropak) Electric Motor Selection

Posted by Calvin Lee on January 14, 2011 at 11:14pm
Hi Dear Forum-ers,I am writing in to seek your kind advice on electric motor selection for fuel cell (in my caes, Aeropak).I presume that the RC motors are mostly designed for Lipo or NiCd batteries, which has relatively lower voltage and higher current ouput as compared to fuel cells.For my case, my fuel cell has a continuous output of 20V, 10A and output power of 200W.Some other parameters: The weight of the fuel cell is 2kg and the overall takeoff weight is estimated to be about 7kg. The wing span is about 2.5m.I am totally lost in the world of motors except that I should be choosing larger motors (40s and 50s series to carry the heavier weight and somehow with lower maximum current efficiency).I have purchased AXI-5325/16 motor for tests but it is only capable of producing 0.8kg of static thrust which is severely below my requirements.Which paramters of the motor are important and which I should focus on in choosing RC motors?Otherwise, I am also open to commercial grade or in fact any suggestions, if they are more optimised for "maximum thrust" with this power profile.Thank You and I seek your kindest advice with your experience!Yours Truly,Ying Qin

AEROPAK_Technical_Data_Sheet.pdf

AEROPAK.pdf

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Replies

  • Moderator
    Graham Dyer February 4, 2011 at 11:25am

    200W / 7kg is 28W a kilo, low powered efficient gliders can fly on as little as 60W per kilo, 28's going to be pushing it a bit. You'll need a highest quality competition motor with 6:1 (or higher) gearbox and massive propellor to get any results. Kontronik and Hacker brands come to mind.

     

    Something like the Kira 650-11 with 6.7:1 gearbox might produce some thrust at that wattage with a very large prop (Kontronik Kira 650-11)

  • bGatti February 4, 2011 at 9:44am

    motors are rated at RPM per Volt. as you have High voltage, you'll generally want a slower motor; I'd also consider a geared motor to help reduce speed and increase efficiency.

     

    Here is an interesting option:

    http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...

     

    it's a dual motor, but your problem is still high voltage - so you may need to rewind the motors.

     

     

  • Ground Loop February 4, 2011 at 9:21am
    With the heavy plane and 200W peak output, you might want to consider pairing the fuel cell with a LiPo battery.  The idea would be to use the LiPo to supply additional current during peak draws (climb) and then recharge off the fuel cell during lower demand.  I imagine some cell management electronics would be required, and then the weight added is also a concern, but it would widen your power envelope quite a bit.
  • jlcortex February 4, 2011 at 9:00am

    Hello Ying, you need good controller-motor-propeller efficiency to keep a plane in flight with 200w and 7kg, I think this motor is big, it get maximum efficiency with more than 15A.

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