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Author Topic: 36" Perkasa Motor and ESC help  (Read 785 times)

Korp1010

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36" Perkasa Motor and ESC help
« on: June 05, 2018, 09:43:13 PM »

Hi all,


I currently have a 36" PT boat running a MFA torpedo 850 motor that I want to replace with a brushless motor, the reason for replacement is that the 850 gets quite hot and doesn't sit in line with the prop shaft very well.


I'm a complete newbie to the brushless world so i'm looking for both the motor and esc recommendations and where to purchase them would be great.


I don't want to be full blast round the lake with the boat but would like planing speed as well as a steady cruise speed if that's possible.


Model specs are,


36" long
3.7kg Weight including the 850 motor.
35mm 3 blade plastic prop
Running off a 11.1 5000mah Lipo


Appreciate any help possible, Cheers







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canabus

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Re: 36" Perkasa Motor and ESC help
« Reply #1 on: June 06, 2018, 07:05:27 AM »

Hi Korp1010

The  MFA 850 is about 132 Watts on 12 volts with an unloaded RPM of 9778.
A good replacement is a Hobbyking 3639-1100kv on 3S unloaded RPM of 12210.
Use a car ESC 100Amp(part No. HK-100A) with program card (part No. HK PROG-CARD).

ESC Setup:-

1 Cutoff Voltage for 3S=10.2 and 4S=13.6
2 Start Power Percent=5%
3 Advance Timing=4
4 Run Mode=2
5 Brake Force=1
6 Drag Brake Force=1
7 Neutral Range=1
8 Initial Brake Force=1
9 Reverse Force=1

I used this set on my Sea Commander and Huntsman, both have no problem to get up an plane.

Prop to 3 blade will work OK, or a 2 blade CNC 40 to 45mm.

If you wish to up the speed later, a straight changeover to the sister motor 3648-1450kv.

Note these both have 5mm shafts, so a new coupling is required.

Hope this helps.
Any questions post or message me.

Canabus
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Korp1010

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Re: 36" Perkasa Motor and ESC help
« Reply #2 on: June 06, 2018, 09:35:01 PM »

Hi Canabus


Thanks for the very informative reply, i've sent you a PM with a few more questions.



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Hotglove

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Re: 36" Perkasa Motor and ESC help
« Reply #3 on: June 08, 2018, 07:28:09 PM »

I also have a 36" boat that had the MFA 850 fitted. Acting on advice from Canabus I bought the Turnigy 3648 1450kv from Hobbyking UK. I had heard that Hobbyking can be a bit slow to deliver but it was there two days later.  For an ESC I ended up with a Leopard Hobby (HobbyWing) 120a waterproof type that is designed for rock crawlers. 120a might be overkill but it is reassuringly solidly built and has a bigger fan than its (brushed) predecessor, I used Canabus' settings to programme the ESC with the program card, but mine has the option of forward/reverse without 2 taps on the stick. The ESC came from The Component Shop, ordered at 15.30, delivered next day at 14.00, pretty impressive.
Two couplings, one heavy duty rubber, one solid (used for setup) came from Model Boat Bits and Steve was kind enough to include a short length of 5mm shaft at no charge. 42mm 2 blade plastic prop from Cornwall Model Boats, but I will try a smaller prop and compare performance and, hopefully fit an alloy type once I am happy with the result.
I also chose to fit an aircraft type motor mount (Great Planes, medium) the medium size mount needed some filing and drilling to fit the motor but is a perfect fit in the engine room, the large size mount would fit the motor perfectly but take up more room than I have.
If all goes well the pudding will be proved on the lake on Sunday. 
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Hotglove

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Re: 36" Perkasa Motor and ESC help
« Reply #4 on: June 09, 2018, 09:24:41 AM »

Scale speed? This 1930 Chris Craft has 454 Mercruiser V8 bored out to 496 and tweaked giving 500bhp.
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Korp1010

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Re: 36" Perkasa Motor and ESC help
« Reply #5 on: June 09, 2018, 09:58:18 PM »

Hi Hotglove


Thanks a lot for your reply it's very helpful.
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Hotglove

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Re: 36" Perkasa Motor and ESC help
« Reply #6 on: June 10, 2018, 08:17:01 AM »

Perhaps I should add that motor mount, Lipos, battery charger, Tx, Rx and numerous small purchases were sourced from local shops including TJD at Dartford, Dockyard Models and Regal Models (Atlantic Mouldings) Chatham, MWM Warbirds and Rochester Games and Models in Rochester and RC Model Centre Sittingbourne.
All these shops have given great service, friendly advice, cups of coffee, etc. etc. etc. I always try local shops first and only buy online as a last resort.
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Hotglove

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Re: 36" Perkasa Motor and ESC help
« Reply #7 on: June 10, 2018, 03:55:51 PM »

In response to request from Korp1010, some pics of new installation, early days yet but performance on the lake today was superb, quick. quiet and very responsive
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Korp1010

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Re: 36" Perkasa Motor and ESC help
« Reply #8 on: June 10, 2018, 10:23:53 PM »

Hi Hotglove, really appreciate the pictures and info on where to buy the parts, thanks for all the help.
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