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Author Topic: Brushless in an Arun??????  (Read 2342 times)

Stavros

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Brushless in an Arun??????
« on: December 28, 2008, 07:34:07 PM »

Right then I am restoring an Arun for a fellow Mayhemer and the following motors have been reccomended to him


TURNIGY AerodriveXp

Model: TR42-50A
Max efficiency :38A
Max Load : 43A
Kv : 700
Power: 720W
Weight : 195gr
Pull/Thrust : 900~2100gr
Prop size: 11x5.5 or 12x8
Voltage Range: 9~15v
No Load Current : 3.4A
Shaft: 5mm
Resistance: 0.0327ohms
Max Efficiency: 82%
Power equivalent :  .40 glow engine

Now apparently these motors will give 700 revs/volt which is fair enough BUT What really concerns me is that they are drawing 38A at max efficiency,this I think seems to scupper the old 12v/7amp route and possibly the 12v stick packs or have I got this brushless malarkey wrong,knowing me I have,but the maths of it don't seem right.Am I barking up the wrong tree HELP.
Am i right in thinking that you Lifeboat lads are using gel cells or have you gone LIpos,what do I use and what kind of run times should we get

Also what couplings should I use as I have my doubts that the red Dyco couplings wont take the power????



Stavros(as confused as FLJ with brushless)
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andyn

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Re: Brushless in an Arun??????
« Reply #1 on: December 28, 2008, 11:28:25 PM »

Righty then Stav, those motors are all well and good but will be very slow on 11.1v lipos = 7770rpm, and on 7.4v = 5180rpm, and at that speed you may as well be running it on a pair of servo motors.

Your 12v7a jellys wont last long in this before they decide theyve had enough, so it would probably be best to run it on Li-Po's, and youre probably looking for an Arun (im assuming 1:16th here) for 14.4 - 18.1v

Try having a look at the larger Feigao motors on the Astec Models site, theyre more what you need.

I do appreciate having type this that you won't pay any attention to my comments because you knwo full well I'm trying to make it faster...

Or failing this, a pair of Zen's would fit it nicely. Authentic scale sound too...
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Stavros

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Re: Brushless in an Arun??????
« Reply #2 on: December 28, 2008, 11:48:01 PM »

Quite the contrary Andrew These motors have been recommended by someone else but I admit that I am clueless to which motor to put into the Arun,having been reading Lifeboat Pauls build I am defo confused.Faster yes please!!!!!!!!!!!!!!!!




Stavros
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Sandy Calder

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Re: Brushless in an Arun??????
« Reply #3 on: December 29, 2008, 07:40:47 AM »

Hi Stavros.
I've no idea about that power thingy but I think you have nothing to worry about.
I'm totally clueless about 3-phase machines so I'm just guessing you were initially well advised for an Arun of 1/16 or 1/12 scale.
I don't know where I got the notion from but you might end up using a 6v 10Ah SLA and  you could even run twin screws with one motor if you wanted to .

Can you better Ģ19.68?
Regards
Sandy Calder

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gingyer

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Re: Brushless in an Arun??????
« Reply #5 on: December 29, 2008, 10:51:12 AM »

Stavros, I am sure I saw on the forum that Lawrie from modelslipway had fitted brushless motors
to his new tamar kit and the in video link it went like a rocket.
why not give him a shout and ask what he fitted to his and copy the arrangement for the Arun :-))
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gingyer

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Re: Brushless in an Arun??????
« Reply #6 on: December 29, 2008, 10:55:25 AM »

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Stavros

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Re: Brushless in an Arun??????
« Reply #7 on: December 29, 2008, 11:31:55 PM »

Now sorted will be using those motors,more power than Pauls :-)) and I will nto be using gell cells MINH at 12v yeah ah on paper this baby will be FAST .....OK ok I know I am a speed freak,watch this space
Andrew thanks for the telephone call I owe you one :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-))


Stavros
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Hannu

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Re: Brushless in an Arun??????
« Reply #8 on: December 31, 2008, 12:25:01 AM »


Hi,

What is the weight of Arun?
Do you have some ideas about itīs needed scale speed?

BR,
Hannu
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