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[marksg]

Hi - I'd like to have a twin brushless motor set-up for a nautical marine motor torpedo boat (Perkasa 35") - I'd like it to be fast.  Could anyone recommend motors, speed controllers and lipo batteries to give good performance.

Thanks, gary

[red181]

HS93 has done a brushless motor set up , hopefully he will see this and advise accordingly, at least you are then getting advice from someone who has actually done it. I helped him set the speed controllers up, we had a very hard time doing this, they where both exactly the same, but just would not come in at the same time. I think the motors where mystery outrunners, I know the boat was smaller than yours, and it was WAY over powered!, extreemly quick

You might consider single screw, I have done this on a 42" Huntsman, Align brushless 600 motor, castle creations 120amp esc, 6 lipos cells, 5000mah, 3:1 gear ratio.I did a load of testing, 2:1 ratio was giving very fast acceleration, 3:1 is better top speed, 52.5mm "X" prop on  a small lake, 55mm on a big lake.

 I ran the boat tonight, its ballistic, and topped 99.9amps , If I hit 100amps is that a record for a scale boat   I also ran freshly charged 19.2v nims, 4600mah, the speed was noticeable slower, unfortunately I didnt have any means of recording it, but I guess it was 2/3rds the speed of the lipos

Hope that helps

 

[snowwolflair]

If you are going to use brushless you need to use oil bronze bearings as brass will seize and nylon/Teflon will melt.

On my Percasa I mounted the motors on the shafts with no need for a coupling, tricky but worthwhile.

She goes like a rocket and gives fast electrics a run for their money at ten times the weight!

[marksg]

Thanks for the feedback - would this combination work (2 of each):

Motors - EZ-RUN 12T 3300Kv Bushless Motor, 3,300 rpm/volt, max 35 amps
http://www.giantcod.co.uk/ezrun-3300kv-bushless-motor-p-403300.html

Speed Controller - Hobbywing Seaking Marine 35A w/ Reverse program Brushless ESC V2
http://www.giantcod.co.uk/hobbywing-seaking-marine-reverse-program-brushless-p-403646.html

Batteries - 5C Charge Loong Max Tipple 4500 3S1P 20C-30C Lipo Battery
http://www.giantcod.co.uk/charge-loong-tipple-4500-3s1p-20c30c-lipo-battery-p-405213.html

Propellers - 30mm 3 bladed props

Will this combination work OK together - any potential issues? (I'd like to keep to 2 props as that is how the nautical marine model is designed)

thanks, Gary

[nick_75au]

Hi Gary
I looked at your spec's and think the motors are to high in the Kv rating, at 11.1 volts your asking the motors to spin at 36000 RPM.
 Less than half that will give you very sprightly performance. I would look for 1000-1500 Kv motors

http://www.giantcod.co.uk/black-mantis-bm3560-1200kv-inrunner-brushless-motor-p-405229.html

looks fairly good for an inrunner 13000 Rpm

Nick

[HS93 (RIP)]

you seem to have picked car motors and as nick_75au says far to high, about 1700 is about right I have found for a scale type boat, you will need to experiment with props start small about 28-30 mm buy cheap plastic ones and check temp on a very reg basis when prop testing every lap of the lake, it does not take a lot to fry everything, your speed controllers need to be a lot bigger, if a motor draws 35 amp you need a 60 in my experience to account for over proping and problems, the different in price is not that great but it is if you have to buy  new speed controllers because you want a slightly bigger motor, also Chinese amps are about 2/3 of any other amp.

Peter

[marksg]

Thanks for the advice - I'm still learning how to understand the specs for this kit, so I appreciate you taking the time to post - I will take on board your comments - I think I know what I'm going for as a starting point now - should be fun!

Regards, Gary

[phillnjack2]

is there any chance that someone can tell me how to mount the motor on the shaft without a coupling ?
i can understand you dont use a universal joint type coupling, but there has to be something like a straight coupling surely

if not them im way behind the times


phill
confused as usual 

[HS93 (RIP)]

Ill give a brief description how it's done but it can be complicated. first it can only be done on out runner motors that can have the main shaft changed (which is most of them) you have to pick a motor to match the type of shaft you have  4mm or 5mm  a flange is fitted on the end of the shaft that the motor will bolt to  , as most shaft tubes are 8mm if you leave a space at the end of the shaft and the flange you should be able to fit a 8mm x5mm x 2.5mm bearing stainless steel with Teflon bearing shields ,if you make them similar to the way I make mine you can fit more than one bearing (much better) you then need a longer shaft (inner) by about 75mm you remove the shaft from the motor by undoing the grub screw at the rear and re assemble on the new shaft then bolt the motor to the flange on end of tube.
that is the simple version I put  a heat sink in between the motor and flange, I will be doing another one soon so ill take pictures if that helps

it is not my idea I saw it a few years ago on another site but by snowwolflair and put my own spin on it as i work in brass and ally normally and was not shore how he did it .


Peter

[HS93 (RIP)]

Just found a picture.

[phillnjack2]

WOW now that looks very good to me.

this way there can be no misalignment at all and that means less motor stress,less wear all round.

but what does it cost to do such a modification, or how much time etc.

you might find this easy to do, but to us normal people that is like witchcraft or wizzardry.

do you put any shaft guards under the boat or prop guards to make sure there is no damage to this system ?

i can see all the befits, just wonder about hitting anything with a prop, or do you use props that can break easy to
save the shafts etc ?

on full size boats its great to use stainless props, but the big problem is buy using stainless you risk the gearboxes getting
shattered is this the same with this type of set up ?

you should put this into production, loads of people would like this im sure.



phill....

[Guy Bagley]

philnjack are you aware that snowwolflair mentioned on this thread and he is on this forum is only 4 miles down the road from you ??? -i expect i will see him at black park this sunday at the annual regatta!!!- just a thought.....

[phillnjack2]

oh no dont say its this sunday

ive told her indoors im taking her to kent for a dog funday.

with a bit of luck it will rain very early then we wont go to kent,
then the sun can come out nice and bright when its too late for kent trip ,
but early enough for black park boat event  to be realy good ha ha .

ill be doing a naked rain dance round a dustbin saturday night, 
not a pretty sight by any means, but it just might work. 

ill be gutted if we go to kent now i know this is on.

what time does it start ?

[HS93 (RIP)]

the new shaft is high quality stainless steel and the props will be prop shop in the tests they where x type but will be fitting some of Simons we have a strut brace underneath at the prop end, the chances of hitting something is the same with all boats you may bend a shaft I bought 10 meters of shaft recently so will make new ones , the shafts are long so we fit a centre bearing 300mm plus the length of the motor and it's 5mm thick but I have done some 4mm as well as i sais i first saw it on snowflairs boat a few years ago and all I have done is beef it up a bit and use materials I use normally and am happy to work with as my health has changed over the last few years I have moved more to metals as it is less hand work.

peter

[Guy Bagley]

oh no dont say its this sunday

ive told her indoors im taking her to kent for a dog funday.

with a bit of luck it will rain very early then we wont go to kent,
then the sun can come out nice and bright when its too late for kent trip ,
but early enough for black park boat event  to be realy good ha ha .

ill be doing a naked rain dance round a dustbin saturday night,  
not a pretty sight by any means, but it just might work.  

ill be gutted if we go to kent now i know this is on.

what time does it start ?

10 am til about 5 pm

[phillnjack2]

mmm so i need rain from 6 am till about 9.15 
then scorching sunshine 


phill

[dave1985]

Hi I have a perkasa running one brushless motor and it very rapid this is what I'm running

[Big Ada]

Hi Dave, I have a 42" Perkasa, would your set up work in it, is that an inrunner, do you have prices and where did you buy from, did the ESC come with water jacket.
Any info would be welcome.

Regards.

Len.

[Big Ada]

It is 48" long.

Len.

[dave1985]

Hi Len I have had my boat in the water a couple of times since I. put this motor in to my boat I think it is way too fast on full speed over 3/4 of the boat is out of the water and it's a bit unstable think I will put this motor into my arrow that I'm im the middle of building.  The esc came with the water cooling already fitted , I bought it all from my local model shop can't remember how much I paid for them because I bought alot of things that day lol.
Dave

[mikethepipe]

In an earlier post 'snowwolflair' mentioned oil/bronze bearing prop shafts.  Does anyone know of a supplier of this type?

Thanks for any info,
Mike