Old 10-09-2011, 03:31 AM
  #80  
CT4
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Join Date: Aug 2006
Location: Sydney Australia
Posts: 14
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I have been flying for 40 years I am an instructor and I am authorized to issue permits to fly for oversize aircraft (anything over 12 Kg but under 25Kg in Australia). I am however a total newbi to electric flight with aircraft. I have been reading endless threads on line but I am having trouble understanding prop size to motor to amp draw. In order to try and understand this I have started using either the CC ICE data logger or the Eagle Tree logger.
The results I am getting are so far from those published by the manufacturer of the motor I am really confused and would appreciate some help.
Example
Scorpion SII-3020-1110Kv (V2) motor CC ICE 75 ESC 3 cell and 4 cell 25c battery

Scorpion says with a ACP 10x5E prop on 3s I should pull 29A and with 4s should be 48A
I get 37A and 56A respectively. If I change to a SP 10x3.7 prop the current draw jumps to 71A

I have tried similar other setups with different motors and in every case the current draw has been a lot more than the figures published.

If anything what am I doing to get such a different result to the manufactures published results. I have tried Motorcalc but could not get it to work due to the data base not having ICE ESC or any of the current Hyperion batteries in its data base. Any help would be appreciated.
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