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Old Mar 25, 2014, 04:15 AM
NeverAgainVolunteerYourse lf
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Something in the 36 mm diameter and 700 to 900 Kv should match the YM2776 motor quite well

You can set a Low voltage cutout (LVC) in 99% of the brush less ESCs, most offer either hard cutout, which stops the motor in most cases or soft, which slows the motor, a good proportion allow you to set the voltage to 0,1 volt per cell as well, best option is 3.3 -3.5 and soft cutout for boats, up to your discretion

If there is an option of a program card, get it, it saves lots of time, dont 100% need it as can be programmed by TX but you need to be R2 -D2 to decipher the beebs
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Old Mar 25, 2014, 04:28 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
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Quote:
Originally Posted by KiwiDavid View Post

I also have a large (47") wooden runabout with a Jaycar YM2776 motor. (700 type?) That runs beautifully on 11.1V with a 50 or 55mm prop but I'm prepared to swap that also for a brushless - any suggestions?
Hi David,

If you like a little speed, check out the brushless propulsion of my MAS:
http://www.rcgroups.com/forums/showt...ti+sommergibil

Running pics and a video on page three (turn it up real loud).

Regards, Jan.
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Old Mar 25, 2014, 04:51 AM
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Hi Nick,
Thanks for that. I'll study all the information you have kindly provided. This is a great start for me. E-beers all round.

Jan - nice video - that thing looks like it's on rails and sounds amazing. The hull is similar to my Vosper but bigger. The Vosper leans in to corners - something I didn't realiize until I fitted a camera on board.

Cheers,
David
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Old Mar 25, 2014, 12:37 PM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
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Hi David,

Thanks for the E-beer.

Actually, your 47" hull is larger (119.38 cm) than my 110 cm MAS.
Due to the very shallow V, the MAS only leans a little in turns.

I can make it spin 180 when I try to force the boat in a too tight right hand turn though.
Very frightning, as the side tend to dig in on such an occasion, so overturning is a real possibility...

I really did my best to drive as smooth as possible on the video, only on a few occasions you see (and hear) the boat starting to skip sideways when I turn too sharp at speed.

It took me some sticktime to get to grips with driving such a large model; from my fast electrics I'm used to drive and turn at full throttle, but the MAS hullshape requires a more delicate steering and throttle finger (which is much like the 'unseaworthy' behaviour of the original).

Regards, Jan.
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Old Mar 26, 2014, 04:33 AM
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Hi Jan,
It's people like you that have turned the hobby in to both an art form and a science.

I'll short list some motor options and place an order this weekend using the wife's Paypal account. I'm still acutely aware that Watts are Watts regardless of if they are brushed or brushless Watts. The only thing that may reduce heat build up is efficiency and I'm not sure if brushless motors are appreciably better as I haven't seen enough good data on them.
Nick - you mentioned the ESCs programming card - what exactly are they? I agree about all the beeps so a card sounds like the way to go.

Cheers,
David
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Old Mar 26, 2014, 06:37 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
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Quote:
Originally Posted by KiwiDavid View Post
Hi Jan,
It's people like you that have turned the hobby in to both an art form and a science.
Hi David,

I think that's too much praise, as I like to see myself as a tinkerer, empirically working out what works best for me.

You are right in stating Watts are Watts, but in my experience brushless multipole motors tend to be quite a bit more economical in what you get out of these Watts.
Specially outrunners are very efficient compared to similar wattage brushed motors.

On 2x 4800mAh 4S Lipo's wired in parallel, I can run my MAS for over two hours in mixed running style, mainly walking pace with the occasional 100m sprint up and down a canal section.
I've only managed to drain the lipo's to the point where the LVC of the ESC cut in and that took an 'excessive' amount of full throttle running (close to two hours).

I'm running the 100A version of this ESC in my MAS:
http://www.himodel.com/electric/HiMo...C_ICE-80A.html
The 100A ESC is a bit overkill, but I didn't know what to expect, as the 150A version got hot during the first testrun without watercooling.
With watercooling the 80A version is sufficient for the 4250-800KV outrunner in the MAS.

This is the programming card that you should order with a brushless ICE ESC:
http://www.himodel.com/electric/LED_...ires_ESCs.html
This card has a lot of options, compared to the four you have on the progbox for the Turnigy 120A from HK (for example).

I've tested both the T120 and the ICE100 ESC with the outrunner in the MAS and I didn't like the lack of low end response of the T120, hence the ICE 100A.

Others have good results with car ESC's but most of those only go up to 2-3S.

The ones that can handle 4S are more expensive, and unfortunately the one that I got, didn't work very well (very rough low end) and responded to my programming attempts with a puff of smoke...

Regards, Jan.
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Old Mar 27, 2014, 02:47 AM
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Hello Jan,
Many thanks for the further enlightenment on brushless motors and their ESCs.
I can also see how the cards work and as Nick said - it's got to be easier than being R2D2.

I liked the opposed water in/water out tubes in the base of your model. I haven't seen that before. If I don't see an efficiency benefit with the brushless I would consider going that way as it's all hidden in the bottom of the boat. I will also look at the micro fan idea.

Your comments on slow running with brushless motors is a concern. I currently enjoy excellent slow speed with the brush motors and would miss that if the brushless ESCs cut in abruptly. Hopefully reviews on the various parts will indicate what has been well accepted by the various modellers.

Cheers,
David
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Old Mar 27, 2014, 03:46 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
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Hi David,

I know there are brushless motor/ESC combo's around that have an excellent low end response, I'll do some digging and let you know what I find.
From the top of my head I believe it's a Robbe ESC series that has these charactaristics.
This is the type I mean:
http://www.robbe.de/roxxy-bl-control-930.html
Available in all sizes.

Regards, Jan.
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Old Mar 27, 2014, 06:14 AM
NeverAgainVolunteerYourse lf
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I've used the Hobby King Quick car ESCs The low speed response is fine on those
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Old Mar 28, 2014, 04:18 AM
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Thanks guys for the pointers there.

I've short listed the following motor for the 27" balsa/ply cabin cruiser-
http://www.hobbyking.com/hobbyking/s...Outrunner.html

and this for the 36" balsa/light fibreglass Vosper
http://www.hobbyking.com/hobbyking/s...ess_Motor.html

I'll run the Vosper at lower revs but with a slightly bigger diameter prop which should be a bit more efiicient.

I have a question about the current rating on the motors - is the figure quoted a stall current or a maximum safe operating current? I would think the stall current would be considerably higher - like when you get a plastic bag wrapped around the prop. How much margin should I allow over and above the motor rating?

Will sort out ESCs after understanding the motor ratings but at the end of the day we're not talking big money here so I can afford the odd goof-up.

Cheers,
David
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Old Mar 28, 2014, 05:43 AM
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Theres plenty of threads where overcurrent protection gets discussed. The accepted rule seems to be to fit a fuse between battery and ESC, higher value than normal running, lower than the ESC rating, obviously the ESC needs to handle normal running with a generous allowance.
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Old Mar 28, 2014, 06:04 AM
NeverAgainVolunteerYourse lf
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While that first one is a 28 mm it is a bit on the low end watts wise, as an example a 40 mm prop on 6 volts is 6 amps at 6000 RPM, I would look at this one

http://www.hobbyking.com/hobbyking/s...ess_Motor.html

Same price but better specs, it wont draw more but the headroom is beater making watercooling less likely to be needed,

Same opinion on the second, its a bit light
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Old Mar 28, 2014, 06:13 AM
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Hi,
That makes sense and is pretty much what I do with my home grown brushed ESCs. I use a soldered 15 amp fusewire link on the pcb but the difference is I use 150A FETs.
I'll opt for about 2:1 ESC to motor rating and keep my fingers crossed. What's the worst that can happen - burn to the water line?

Cheers,
David
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Old Mar 29, 2014, 08:15 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
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Hi David,

I'm with Nick regarding the headroom; a slightly bigger motor most likely eliminates the need for watercooling (unless you run really long, which builds up heat).
For the Vosper I'd go for something like this:
http://www.hobbyking.com/hobbyking/s...ner_Motor.html
On 3S you'll end up with 9000rpm under load, whic, in combination with the right prop is plenty fast (if required).

Regards, Jan.
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Old Mar 29, 2014, 03:01 PM
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Hi Jan,
Thanks for the reply. I would prefer a motor about that size but I would like to use a front mount if possible as I can probably use the existing motor mount in the boat.
The motors I selected are more than comparable in power to the 540 style can motors I'm currently using but they look rediculously small and any heat they produce has little mass to spread to.
I probably should embrace water cooling as I do have a flat foot so a water cooled in-runner would solve all my problems. I'll ponder this a bit more before deciding on motors but as I mentioned - it's not a lot of money to get some basic experience with brushless motors and besides it's this tinkering that keeps us out of the pubs.

Cheers,
David
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