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Author Topic: Foamy wot4 power  (Read 743 times)

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Offline propwash

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Foamy wot4 power
« on: November 20, 2018, 13:27:54 PM »
Any one know the wattage of thefoamy wot4  brushless motor?
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Offline PDR

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Re: Foamy wot4 power
« Reply #1 on: November 20, 2018, 13:54:58 PM »
Depends what size prop you put on it and how many cells you use. On 3s and using the stock ESC (which claims a 40A capacity) the maximum power available could be as much as 500watts, but I suspect they've de-rated the ESC so it's more likely to be around 250-300watts into the supplied 12-6 prop.

But electric motors do not have a "wattage limit" - they have a maximum current and a maximum RPM. for any given voltage (cell count) this will imply a maximum usable power, but it's the current which is the actual limit, not the power.

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Offline FlyinBrian

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Re: Foamy wot4 power
« Reply #2 on: November 22, 2018, 06:08:17 AM »
I have replaced the power train in my W4foam-E with a Hacker ESC and an Axi 28/20/10 - It is too much for the airframe as at full chat strange things happen which I think may be due to the airframe distorting due to the motor torque. I'd estimate that on 3 cells and a 12 x 7 there is well over 400 watts but I have not measured the current yet.
On the standard ESC and motor a 12 x 7 was drawing 34A but there is noticibly more revs with the 28/20/10. The ESC is rated at 50A and the motor ar 40A neither get esp warm.
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Offline PDR

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Re: Foamy wot4 power
« Reply #3 on: November 22, 2018, 08:54:20 AM »
A 12-7 is WAY too big for an axi 2820/10 on 3s unless it is one of the very first ones made. The original 2820/10 had a Kv of about 1000rpm/v, but after a year or so they used better magnets which increased the Kv to around 1200rpm/v as it has been ever since. On a 3s lipo this means that it suits a 10-6 graupner CAM prop or in APC's either a 10-7e or an 11-5.5e (because curiously APC don't make a 10-6 e-prop). These all draw around 42-44A on a fresh 3s battery, dropping to 40A after about 30 seconds (550watts dropping to 500watts), and that's the current the motor is rated for.

I would guess that a 1200Kv one on a 12-7 would pull about 50-55A at full chat - nearly 700watts, which may explain your "strange behaviour"!

PDR
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Offline FlyinBrian

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Re: Foamy wot4 power
« Reply #4 on: November 23, 2018, 14:50:14 PM »
PDR you may well be right, it is one of the 1200 KV motors. I'll check the current b4 flying again.

I have just finished double glazing my shed window  so now it has roof, floor,and wall insulation and an expelair fan for when it gets too hot, I have got a solar panel to charge the leisure battery and am thinking of building a small 12V wind turbine,  I'll be totally off grid soon (some say I have been for a long time  ;) )

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Offline FlyinBrian

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Re: Foamy wot4 power
« Reply #5 on: December 02, 2018, 23:29:45 PM »
At about 11:30 today the skies over east Lincs. started to clear and suddenly I decided to go flying.
 Of the local clubs that I have joined my first choice is a 40 min or so drive away and of course once I got there the grey murk was either back or had not left that area. After a coffee and a read of the paper things started to brighten so out came the Foam Wottie now with an I C style 11 x 6 prop pulling 38A max on the ground.

As well as the prop change I had done a bit of work to stiffen the model and the two changes seemed to have done the trick. Despite being v windy - I was able to progress backwards relative to the ground at times - the model was much better and flew really nicely, no odd behaviour except from me and three very enjoyable flights prior to my being too cold to carry on

It makes ones day!
Basic Research is what I do - when I don't know what I'm doing!.


 

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