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Help !!!!!!

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Chris Channon10/07/2008 17:30:00
57 forum posts
1 photos

I was bought an Alley Cat look a like for Fathers day, nice little aeroplane, it was just the bare airframe, ie, no motor, speed controller,nothing.

It is the prop version, prop's supplied. So i bought a 3200kv out runner, ( as per the instructions)

35 amp brushless speed controller,

1350 3s li-po pack.

All assembled, i get just about one minute's run time and the li-po is hot, the bec cuts in , i have charged the pack using a balance charger but still only get just over one minute run time !!!!

Help!!!!!

Chris.c 

birdy10/07/2008 19:06:00
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1423 forum posts
110 photos
If you have a watt meter check the amps pull. What prop is it, and what is the lipos C rating? If you are pulling something like 25 Amps from that lipo, your overdoing it abit!
Frank Skilbeck10/07/2008 23:10:00
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4450 forum posts
101 photos
A 3200 kv motor is a very high rpm motor for use with a prop unless used with a gearbox. What size prop was supplied.
winchweight11/07/2008 00:31:00
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2516 forum posts
67 photos
I'd say your lipo is a bit of a light weight too. It's quite a low capacity for such a demanding motor and esc setup.
Chris Channon15/07/2008 20:13:00
57 forum posts
1 photos

Hi all, looking at the prop, it looks like a 4 x3 if it was a glow prop.,

I have to re-think the setup as the esc blew out all of the magic smoke on the last run, getting expensive this electric flight lark !!!

Getting really confused now, i was told that the motor i have is ideal for D/F , not for direct drive, so surely if i use a fan then the motor will be pulling a lot more amps than a little prop?

Confused again

Chris

Frank Skilbeck16/07/2008 13:16:00
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4450 forum posts
101 photos

Not really it would depend on the diameter of the fan, if its only 50-60 mm then it will be a smaller diameter than the prop, I have a couple of small EDF's around 50mm using 4,000 kv motors and they pull around 20 amps.

a 1350 mah battery is very small for this application hence it's getting very hot and probably cutting out after a min due to the LVC cutting in.

Just for interest I ran a 3200 kv motor with a 4.5 x 3 GWS prop in the Drive Calc simulator and on a 3s set up it predicted it would pull 20 amps, so I would say that it's the battery which can't deliver the amps. Not sure why your ESC failed though. Note an APC 4.5 x 4.1 prop increases the current draw to 25 amps, so it would be good if you knew what the prop is as a small differnce in size can give a big difference in the amps drawn.

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