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[Stavros]

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)

[andyn]

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...

[Stavros]

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

[Sandy Calder]

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

[andyn]

You want speed eh? well I'll look in to that one...

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5146&Product_Name=HXT_36-56_2700kv_Brushless_Inrunner_(WaterCooled)
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=4941&Product_Name=KB45-12L_1400kv_Brushless_Inrunner
http://www.astecmodels.co.uk/catalog/product_info.php?cPath=24_46_75&products_id=486
http://cgi.ebay.co.uk/DYNAMITE-RC-C4-BIG-STICK-BRUSHLESS-MOTOR-7700KV_W0QQitemZ220334060450QQcmdZViewItemQQptZUK_ToysGames_RadioControlled_JN?hash=item220334060450&_trksid=p3286.c0.m14&_trkparms=72%3A1301|66%3A2|65%3A12|39%3A1|240%3A1318

[gingyer]

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

[gingyer]

found the thread it was on
http://www.modelboatmayhem.co.uk/forum/index.php?topic=13465.0

[Stavros]

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

[Hannu]

Hi,

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

BR,
Hannu