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Author Topic: Another Brushless perkasa... and some more brushless advice...  (Read 7149 times)

bikerdude999

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Another Brushless perkasa... and some more brushless advice...
« on: September 29, 2012, 03:06:25 PM »

First, sorry for starting yet another thread on a brushless perkasa, I have had a look through other threads here but I really don't understand the brushless stuff.

So 1st I have a Hooben Perkasa, about 38 inches long....



It's got twin prop shafts, and its never had motors fitted so I've got no idea how much power it takes to get it up on the plane. The boat weighs approx. 2.4KG. I have no idea what the difference or benefits are to inrunners and outrunners?

After a quick look I was wondering if this combination would work ok:

2 of these motors:
http://www.hobbyking.com/hobbyking/store/%5F%5F22847%5F%5FTurnigy%5FLD3730A%5F1000%5FBrushless%5FMotor%5F1000kv.html

2 of these ESC's:
http://www.hobbyking.com/hobbyking/store/%5F%5F18005%5F%5FHobbyKing%5FRed%5FBrick%5F50A%5FESC.html

and this battery:
http://www.hobbyking.com/hobbyking/store/%5F%5F15521%5F%5FTurnigy%5F5000mAh%5F4S1P%5F14%5F8v%5F20C%5Fhardcase%5Fpack.html

and this low voltage warning:
http://www.hobbyking.com/hobbyking/store/%5F%5F18987%5F%5FOn%5FBoard%5FLipoly%5FLow%5FVoltage%5FAlarm%5F2s%5F4s%5F.html


and 2nd, I want to fit a brushless set up in this boat:



It measures approx. 24 inches long and was wondering if the same motor and ESC as above would be ok? Either running on 7.2V 5000 mAh, or on a lipo pack. Any idea's as to whether these might work ok or not? And would I need to water cool any part of this set up?

Thanks
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Timo2

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #1 on: September 29, 2012, 03:43:05 PM »

Hi Bikerdude999

  1st your ESC are forward only type have a look at === http://www.hobbyking.com/hobbyking/store/__24568__HobbyKing_50A_Boat_ESC_3A_UBEC.html

  2nd look OK to me but have a look at ====   http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10010     ,  maybe easier to fit .

 Timo2

 P.S.   ( nick_75au a may help he has build a few brushless scale type boats )

 
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bikerdude999

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #2 on: September 29, 2012, 04:18:28 PM »

Thanks, how do you know whether its forward only? I spent ages reading everything and couldn't see anything about no reverse....

bookmarked those esc's cheers
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bikerdude999

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #3 on: September 29, 2012, 04:57:36 PM »

Having spent time looking at lipo's I've got another question, what is the difference between 30c, 40c etc? Do I want a higher number or what?
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Timo2

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #4 on: September 29, 2012, 05:42:38 PM »

Hi Bikerdude999

   The higher the   " C "    Number the faster you can discharge ( load ) the battery

    Timo2
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Mad_Mike

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #5 on: September 29, 2012, 05:54:52 PM »

Hi Bikerdude999

   The higher the   " C "    Number the faster you can discharge ( load ) the battery

    Timo2

yes to be more specfic on that you take the C rating and multiply it by the battery mah. For example

5000mah battery or in other words 5ah battery, mulitply by 30C gives you the constant discharge rate.

5 X 30 = 150amps constant
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bikerdude999

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #6 on: September 29, 2012, 06:49:56 PM »

yes to be more specfic on that you take the C rating and multiply it by the battery mah. For example

5000mah battery or in other words 5ah battery, mulitply by 30C gives you the constant discharge rate.

5 X 30 = 150amps constant

So using your figures above, you could have 2 motors drawing up to a maximum of 75amps each?

I assume working the other way doesn't matter ie if I was to use the above figures and a motor that only draws 30 amps, would that be a problem?
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Mad_Mike

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #7 on: September 29, 2012, 08:51:39 PM »

no that wouldnt be a problem. The motor will only pull what current it needs, the battery can deliver the amps if the motor requires it. Ideally when selecting a motor and battery that you leave some head room. While battery will delivery this current it is running at it limits and will run hot.
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Mad_Mike

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #8 on: September 29, 2012, 09:16:57 PM »

In my personal oppnion i think the motor and battery that you have selected is better than the one timo has selected. While yes the inrunner is easier to install the outrunner isnt much more complex, it has screw holes in the from which you then mount to a flat plate perpendicular to the propshaft. What Im not sure about is the propellers you are using? what size and pitch are they?

The esc no i wouldnt use that. When it comes to esc's Either spend a bit of money and get decent ones like seaking or if your cash wont go that far get a decent forward only esc.

For the 2 motors will need 2 60 amp esc's:

http://www.ebay.co.uk/itm/SEAKING-60A-Water-Cool-Ship-Brushless-Motor-ESC-SL175-/390249326975?pt=UK_ToysGames_RadioControlled_JN&hash=item5adcac297f

These hobby wing seaking esc's are the same as turnigy esc's, just a different sticker.

With these esc's you will not need 2 use a low voltage alarm as they have an lvc on the esc's. When the lipos are run down the boat will go into a slow running recovery mode. You will need to use a y lead to connect both esc's to the receiver. Both esc's have a bec too so you will have to also disconnect one of the red wires from one of the esc's to stop double supply to the receiver.

I also must add that the battery you have selected has a constant current of 20C with a spike current of 30C. That means then that the constant current is 100 amps. 2 motors with a max current of 45 is 90 amps giving you 10 amps of head room before you go into the spike current area.
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nick_75au

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #9 on: September 30, 2012, 02:01:32 AM »

Hi,
Chiming in here, The motor you use is going to depend a lot on the prop size, I haven't seen the info but I'm guessing a 35-40 mm prop, of which the motor at 1000 Kv would be OK, maybe a touch on the High end of what you would use on a 14.4 Li-Po, I don't use hard case packs, they are designed for off road cars to protect the battery from damage, not really necessary in a boat. Using them has no affect on the operation of the boat so its up to your choice.

I haven't used the 50 amp boat ESC linked yet but  :} I have just ordered one and will be testing it as soon as it arrives, I've been using the car ESCs in boats (they are the same as the square Seakings but not watercooled) that are dry but I have one that always takes on water (its an open skiboat), If you do want reverse, set the ESC to the minimum reverse power, the big trim tab on the back will pull the stern of the boat under if anything more than a small amount of reverse is used, seen it happen many times {:-{

The little boat I would use a lighter setup, maybe a 2 cell Li-Po with around a 1600 Kv motor 30 mm prop should be all you need and a motor and ESC with a peak rating of around 20-30 amps will have the poke to get her moving. I haven't water-cooled anything except the Skiboat due to its relatively high performance and then only the ESC.

Hope this helps,
Cheers
Nick
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bikerdude999

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #10 on: September 30, 2012, 11:20:30 AM »

Hi, thanks for all the help. The props on the Perkasa are 30mm 3 blade, they came with the kit, so I assume are the right sort of scale, and they're firmly attached to the shafts so can't change them without buying new prop shafts aswell. The battery was just the highest mAh I could find for the least money, as I want to try and get a decent run time out of it, I've seen some 2200mAh 11.1V packs that I'm more likely to use (1 pack per ESC/motor). Reverse would be handy, as it's actually for my dad, and he might need reverse as an emergency brake....

So I'll order the motors I linked in my 1st post, can't afford more expensive ESC's so I'll have to give those that timo linked to a try, unless you have any suggestions for forward only ESC's that are equal or cheaper, and you know work ok? Batteries... I'll probably get 2 of these packs, 1 per motor: http://www.hobbyking.com/hobbyking/store/%5F%5F9927%5F%5FZIPPY%5FFlightmax%5F2450mAh%5F3S1P%5F30C.html



The other boat is using a 35mm 2 blade prop, maybe running something like this:

battery:
http://www.hobbyking.com/hobbyking/store/__8935__Turnigy_2200mAh_2S_25C_Lipo_Pack.html

Maybe this as the motor?
http://www.hobbyking.com/hobbyking/store/__14735__Turnigy_L2206A_1650_Brushless_Motor_130w_.html

With either this:
http://www.hobbyking.com/hobbyking/store/__15205__Hobby_King_30A_ESC_3A_UBEC.html

or

http://www.hobbyking.com/hobbyking/store/__24567__HobbyKing_30A_Boat_ESC_3A_UBEC.html

It still amazes me that motors so small can power such large boats!
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Mad_Mike

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #11 on: September 30, 2012, 12:24:42 PM »

hmm lets have a think. For 30mm props for your perkasa the first motor is a little on the large side i feel and uneccesary to run those props. On the other hand though such large motors turning such tiny props the current draw will be miniscule thus a lower rating esc can be used.

for the perkasa i would try these:

http://www.hobbyking.com/hobbyking/store/__8495__Turnigy_2830_Brushless_Motor_1000kv.html

2 of these esc's

http://www.ebay.co.uk/itm/HOBBYWING-SEAKING-25A-Water-Cool-RC-Model-Ship-Brushless-Motor-ESC-SL182-/270965566878?pt=UK_ToysGames_RadioControlled_JN&hash=item3f16ce6d9e

if you cant afford them then use 2of these forward only AIRCRAFT esc's.

http://www.hobbyking.com/hobbyking/store/__2164__TURNIGY_Plush_30amp_Speed_Controller.html

drive off the 3s lipos you have selected. I trust you have a balance charger for lipos?

for the monhull use the first motor you selected:


http://www.hobbyking.com/hobbyking/store/__22847__Turnigy_LD3730A_1000_Brushless_Motor_1000kv.html

a 4s lipo:

http://www.hobbyking.com/hobbyking/store/__15521__Turnigy_5000mAh_4S1P_14_8v_20C_hardcase_pack.html

and this forwards only AIRCRAFT esc if you cant afford the boat one.

http://www.hobbyking.com/hobbyking/store/__2166__TURNIGY_Plush_60amp_Speed_Controller.html

If you go with the aircraft esc you will need to water proof them a bit. Its not hard to do either, all you do is fill up the ends with epoxy too stop water getting in.

If anyone feels different to my recommendations please say so :-))
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bikerdude999

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #12 on: September 30, 2012, 04:33:38 PM »

If that motor you suggest would be ok on a 25amp ESC, then I'll be able to afford the seaking 1 you linked as I've got 1 spare in the drawer. And yes I've got a balance charger, I intended on trying brushless before so bought the charger and a few bits but then never got round to it.
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Mad_Mike

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #13 on: September 30, 2012, 10:39:49 PM »

Those are the choices i would go with  :-))
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nick_75au

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #14 on: October 01, 2012, 08:52:30 AM »

Nothing wrong with what Mike has selected, as the props are smaller than I guessed I would actually up the Kv to 11-1200 Kv, or even up to 1400Kv if you go the 3 cell battery route. 28 mm diameter motor is big enough. Depends as well if your happy for a sedate model or one that has a really good burst of speed ok2

I think to waterproof the ESC you are better off using "non acid cure" silicone or a type of sikaflex, epoxy is not flexible so when the heatsrink flexes it could break the "seal"

Otherwise for $14.00 US the 30 amp boat ESC (with reverse) doesn't look too bad.

Cheers
Nick

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AlisterL

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #15 on: October 01, 2012, 09:48:52 AM »


http://www.hobbyking.com/hobbyking/store/__24567__HobbyKing_30A_Boat_ESC_3A_UBEC.html


I have a couple of these, but I've only bench tested them and not used them in anger at all yet. They seem to work ok (on the bench) - I also got the programming card just in case... Oh - I think they default to having the brake on, so the card helps remove that unnecessary function.
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bikerdude999

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #16 on: October 02, 2012, 09:07:01 AM »

Ok thanks for all the advice, I decided to go with the motors that mike suggested, prop shafts aren't great quality so will probably get cut out and new 1's fitted at some point, so if I need bigger props to get it going faster that won't be a problem. Thought I may understand brushless more if I can see things in action.

Will be using the seaking 25Amp ESC's, (1 question, how do you programme them? Do you need 1 of those cards?)

'Found' a brushless motor in another boat I've got, so taken that out and will be trying it in the small monohull I've got, hopefully be taking it for a test run on sunday.

HobbyKing have sent me some codes/links, for discounts off the items I purchased. You have to be logged in to use the link, if you want the discount's PM me and I'll give you the links. Discounts include:

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9927 $0.99 discount, making it $13.27 each

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8495 $1.14 discount, making it $15.32 each

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=22847 $0.90 discount, making it $12.10 each

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=18987 $0.13 discount, making it $1.79 each

every little helps!
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Mad_Mike

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #17 on: October 02, 2012, 01:57:35 PM »

no you dont need a programming card you can do it by the transmitter but you will need the destructions to do it.
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essex2visuvesi

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #18 on: October 02, 2012, 02:45:02 PM »

no you dont need a programming card you can do it by the transmitter but you will need the destructions to do it.

true but a programming card makes life hell of a lot easier
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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #19 on: October 02, 2012, 02:57:28 PM »

I always derate lipos, especially if they're a cheaper brand. For instance if I have a motor combiantion that draws say 5A under load, I will pick a battery that can supply a minimum continuous current of 10A.

This makes light work for the lipos and helps the cycle life.

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #20 on: October 02, 2012, 03:19:29 PM »

Please excuse me for butting in Bikerdude, but having never made a purchase from Hobbyking, could you advise what other costs are incurred when buying from the states / abroad e.g. postage, duty payable, or surcharges of any sort that could affect the total cost?  Am always a tad wary of the hidden bits  %) {-)

                        Regards, Tony.
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bikerdude999

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #21 on: October 02, 2012, 04:02:59 PM »

Well for 3 motors, 1 ESC, 2 lipos, and 2 low voltage alarms, the postage was $23 (around 14) total payable to HobbyKing, was approx. $115 (70-75), I think it said there was an extra charge for paying with credit or debit card, but I paid using Paypal, as for customs charges, I think it's luck of the draw. This is the 1st time I've ordered from HobbyKing (my order is from the HongKong warehouse), however I have ordered bike parts from USA in the past, was charged around 35 on a set of shock absorbers that cost 140, and then a 'ForceWinder' air filter kit cos nearly 200 and I paid no customs or anything.


As for programming cards etc has anyone got a link to a suitable card for the SeaKing 25amp ESC's? I don't seem to be able to set up my Mtroniks ESC's with my planet T5 gear, yet (until the receiver drowned) I could do it easily with my cheap GiantCod 2.4Ghz set...
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Netleyned

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #22 on: October 02, 2012, 04:38:56 PM »

A member of our association has just had a delivery from HobbyKing which totalled about 50 inc postage,
he has been hit by customs for 18.
I have had two deliveries from HK at about 30 inc post each time and escaped customs charges.
Talking to other members it seems that jiffy bags slip through but Parcels are a different matter.
All in all it seems to be a bit of a lottery.

Ned
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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #23 on: October 02, 2012, 06:04:59 PM »

Thanks for replies gents, seems a case of  "yer pays yer money yer takes yer chance"  pity like many other situations, clarity is too much to expect!
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bikerdude999

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Re: Another Brushless perkasa... and some more brushless advice...
« Reply #24 on: October 02, 2012, 06:43:58 PM »

Not sure if they do it by weight actually, the shocks were very heavy and got charged, air filter was expensive but weighed hardly anything and didn't get charged.
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