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Watt Meter question...

Old 09-08-2008, 10:22 PM
  #1  
JGMM_BC
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Question Watt Meter question...

So I took some advice found in the forum and bought an E-Flight Watt meter. I can now understand why it is such a "must have" tool... Great information. I am however baffled by some of the information it gave me.

My setup:

Motor: E-Flight brushless park 400 (4200 KV) with 6:1 gearbox
ESC: Phoenix 35
Battery: Thunder Power 3Cell Lipo 11.1V, 2000mah
Prop: 9X5

At full throttle it reports that I am only generating 5AMP draw. Can this be right?
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Old 09-08-2008, 10:32 PM
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firemanbill
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in-runner motor on a gearbox and a smallish prop? Sounds feasible.

If I had that combo I would double check the results for you.
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Old 09-09-2008, 12:28 AM
  #3  
Dr Kiwi
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Can't get Motocalc on the Library Computer, but I'd say 5A is not too far off for an effectively 700Kv motor on 3s with a 9x5.

That's close to what I got for a 740Kv Axi 2212/34:

10.9v




5.05A




55W




6870rpm




32.5mph




459g




16.16oz




8.35g/W





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Old 09-09-2008, 02:33 AM
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groundrushesup
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Originally Posted by Dr Kiwi View Post
Can't get Motocalc on the Library Computer, but I'd say 5A is not too far off for an effectively 700Kv motor on 3s with a 9x5.

That's close to what I got for a 740Kv Axi 2212/34:

10.9v




5.05A




55W




6870rpm




32.5mph




459g




16.16oz




8.35g/W





Well, I must say... that is the happiest set of statistics I have ever seen.

Actually it reminds me of what I see in my brain when I'm trying to read the Motocalc tables lol Stop Mocking me, computer!

gru
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Old 09-09-2008, 11:07 AM
  #5  
Sky Sharkster
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Default Pretty Close!

Hello JGMM BC,
Here's what I got on the FLY DMA calc;
http://brantuas.com/ezcalc/dma1.asp
Results:
Motor Amps:
Watts In :
Watts Out:
Efficiency:
%
V to motor:
Motor RPM:
Prop RPM:
Max
Efficiency:
%
Current
@ M.E.:
Watts In
@ M.E.:
Watts Out
@ M.E.:
V to motor
@ M.E.:
Prop
Pitchspeed:
mph
Prop Static
Thrust oz:
Pack Weight : oz Batteries + Motor + 10% =























In the ballpark!
Ron
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Old 09-09-2008, 03:16 PM
  #6  
Dr Kiwi
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Originally Posted by groundrushesup View Post
Well, I must say... that is the happiest set of statistics I have ever seen.

Actually it reminds me of what I see in my brain when I'm trying to read the Motocalc tables lol Stop Mocking me, computer!

gru

I have no idea why those "happy" symbols appeared - I hate computers which think they know what you need - even if you don't!
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Old 09-12-2008, 02:35 AM
  #7  
EpoweredRc
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well my himax 2015-4100 geared 6:1 only pulls 13 amps wide open throttle. with a 12x6 prop
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