Planes > Park Flyers / Foamies

Prop Size..

<< < (2/2)

Aidan:
Looking at the specs for those components, the ESC is fine up to 20A and the cells are rated for 30A or bursts of up to 45A. The motor however has a max current rating of 13A so it should be the first to go - by a long way.
There's some test data given for the motor on an 8x4 prop at various voltages. Unfortunately they don't say which 8x4 they're using. They should as all props have different characteristics.

Configuration:      Propeller:      Volts:      Amps:      Thrust:    
  Direct Drive      8040      7.4V      8.2A      12.0 oz / 342.86 grams    
  Direct Drive      8040      8.4V      8.6A      13.8 oz / 394.29 grams    
  Direct Drive      8040      9.6V      11.1A      17.0 oz / 485.71 grams    
  Direct Drive      8040      11.1V      13.1A      21.0 oz / 600 grams    


Assuming they used a non-slowfly 8x4 similar to say an APC-E prop there's probably not a huge difference between these figures and what you should expect with your folder.
For a 20C battery I usually estimate a supply voltage of 3.5V per cell under moderate load for the purposes of working out a power system. So your 3s pack should supply about 10.5V. From the data above you can see that should produce a current draw of somewhere around 12A.
If their test data is accurate and unless the 13A maximum current figure is very conservative you might well have problems if you go to a 9x5. If you had an instrument for measuring the current I'd say give it a quick try but otherwise you'll be taking a chance with the motor. Not the end of the world at that price but you might be without a plane until you get a replacement. I think if you want a significant improvement in performance the ESC and cells are fine but you'll need to change motors.

The larger prop sizes mentioned in the motor spec are presumably intended for 2s applications but the info is poor and that's not made clear.

Aidan

Happy Days:
“If forty volts and forty amps produced but half a watt,
I wonder,” asked the student, “would Ohms Law still work, or not?” :?:
“I doubt it,” said the tutor, “but it would get bloody hot!” :lol:

skyhawk newbie:
Cheers Aidan

Think I'll just stick with the 8x4 then...

Here's where I got the info for the
1750 kv motor/20a ESC / 8x4Prop Set up...
http://www.dmitrynizh.com/tw742.htm

Sean

Navigation

[0] Message Index

[*] Previous page