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Old Mar 31, 2013, 07:54 AM
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Malcolm H's Avatar
Nr Glasgow UK
Joined Feb 2004
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Problem with F3a Motors

Hi.Please help.My friend and I are both flying F3a using a Brenner Sharp Contradrive powered by a Neu F3A motor. Problem is one has much more power than the other.The models are both identical Oxai Asyulers. We have exactly the same speed controllers, Batteries etc etc but the difference in power is the same as the difference between a Hacker C50 13 wind and 14 wind. We have tried swapping controllers, batteries and connectors and they high power setup stsys with one motor. Is it possible that we each have different wind motor? The only difference we can detect is that the "powerful" motor cogs more than the other. My colleague has already asked you if cogging is an indicator of performance and you have answered no unless cogging changes from new which isnt the case here.

We are in the UK so difficult to return the motors for inspection and in any case the "good" setup is needed for competition which is just about to start here. Are there any measurements we could make between the motors to help diagnose the problem?

Look forward to your reply.


Steve Burgess
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Old Mar 31, 2013, 08:16 AM
For flying out loud!
planemad man's Avatar
United Kingdom, Maidstone
Joined Sep 2012
735 Posts
it is possible that they sent you the wrong one but not likely. chances are is they is one that has not been wound very well(wire to far from stator).

solutions:
1--put a bigger prop on the one that dose not go as well= more power and will not damage as still same amps(note do not put to much bigger prop on maybe 1 or 2 more inches in diameter)

2--if it is powerful enough for flying competive leave it. it wont damage anything

3--send back but i am also in uk and know how hard it is

hope you solve the prob
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Old Mar 31, 2013, 09:26 AM
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sneu's Avatar
United States, CA, San Diego
Joined Dec 1999
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Hello,

The Kvs can differ by as much as 5% depending on the batch of magnets used and the supplier. How much difference in current are you seeing?

Steve
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Old Mar 31, 2013, 11:36 AM
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Malcolm H's Avatar
Nr Glasgow UK
Joined Feb 2004
93 Posts
Steve,
Both motors are pulling around 85A static but there is a big difference in energy consumption for the same pattern schedule. The "good" motor is using around 3000mAHr and the bad motor 3800mAHr. The difference being you need to be on full throttle for a lot more of the pattern and don't have any power in reserve.
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Old Mar 31, 2013, 12:04 PM
For flying out loud!
planemad man's Avatar
United Kingdom, Maidstone
Joined Sep 2012
735 Posts
i dont know what would do that even if they sent you wrong one it would not be that much less efficent
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Old Mar 31, 2013, 06:17 PM
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United States, CA, San Diego
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Quote:
Originally Posted by Malcolm H View Post
Steve,
Both motors are pulling around 85A static but there is a big difference in energy consumption for the same pattern schedule. The "good" motor is using around 3000mAHr and the bad motor 3800mAHr. The difference being you need to be on full throttle for a lot more of the pattern and don't have any power in reserve.

If the current is the same then what is the static RPM? If they are both the same then something else is going on with the controller or setup. Make sure you have the controller set to the lowest advance setting.

Steve
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Old Apr 01, 2013, 01:29 AM
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Malcolm H's Avatar
Nr Glasgow UK
Joined Feb 2004
93 Posts
Steve,

Measuring rpm with the contra rotating drive isn't easy, but we have a tap on one of the motor/ESC connections to enable connection of an Eagletree rpm sensor so will try and get a figure. We have checked all ESC settings including setting the controller (Jeti Spin) to fixed end points and ensuring receiver is driving it to full on. Advance is set to 5 deg at present and as we said this is working really well on one motor. Are you suggesting that lowering the advance on the "poor" motor might improve its performance?

Malcolm
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Old Apr 01, 2013, 08:25 AM
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United States, CA, San Diego
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Quote:
Originally Posted by Malcolm H View Post
Steve,

Measuring rpm with the contra rotating drive isn't easy, but we have a tap on one of the motor/ESC connections to enable connection of an Eagletree rpm sensor so will try and get a figure. We have checked all ESC settings including setting the controller (Jeti Spin) to fixed end points and ensuring receiver is driving it to full on. Advance is set to 5 deg at present and as we said this is working really well on one motor. Are you suggesting that lowering the advance on the "poor" motor might improve its performance?

Malcolm
Timing should be set to low for all our motors.

Steve
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