REFLECTOR: electric Velocity

[Douglas Holub]

Just for fun, I crunched some numbers to see what could be done with today's off-the-shelf technology. With an electric constant speed prop, I think a Velocity could get by with a 100kW motor (135 hp).  For 3 hours of range it would need 16,000 farads of 250 VDC capacitance. The Mouser catalog has Nichicon 4000 farad, 2.5 volt capacitors for about $200 each, so it would need 400 of those, for a total cost of $80,000. The internal impedance would be about .05 ohms for the entire capacitor array. These capacitors would require a volume of 36 x 42 x 12 inches, and they would weigh about 700 lbs + another 200 lbs for motor and controller for a total of 900 lbs "fuel" and engine installation weight. 

20 years ago the biggest capacitor you could buy was 1 farad, and the internal impedance was a few ohms. I can't wait to see what the next 10 years brings.

Doug Holub
  ----- Original Message ----- 
  From: Douglas Holub 
  To: reflector at tvbf.org 
  Sent: Sunday, September 13, 2009 11:53 PM
  Subject: REFLECTOR: electric Velocity


  Scott's latest adventure reminds me how complicated the internal combustion engine is. I can't wait to put an electric motor in my V. Decades away? We'll see. It's hard to design an electric car that makes sense today because automotive engines are so cheap. $2000 buys you a great automotive engine. But airplane engines cost $25,000, and that buys a lot of hi-tech batteries (or fuel cells or capacitors.)

  Quiet, smooth, no loss of power at altitude, simple, virtually no maintenance-- it will revolutionize GA. You heard it here first.

  Doug Holub


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