Model Boat Mayhem

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: Brushless Motors  (Read 3194 times)

Hmshood

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 59
  • Model Boat Mayhem is Great!
  • Location: Buckingham
Brushless Motors
« on: December 09, 2013, 12:50:52 PM »

Has anyone experience of using Brushless Motors in model boats (around 150 - 200 cm length) as they would seem ideal from a space perspective but seem a bit powerful and draw more heavily on the battery power on first sight. I would be interested in configurations used and any complication, gearing etc, that may have been used.
Regards
Vic
Logged
I love warships bring back the big guns

Sandy

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 301
Re: Brushless Motors
« Reply #1 on: December 09, 2013, 01:07:57 PM »

I am putting one in a 48th scale Flower class corvette. Not run it yet though.
Logged

Hmshood

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 59
  • Model Boat Mayhem is Great!
  • Location: Buckingham
Re: Brushless Motors
« Reply #2 on: December 09, 2013, 01:21:18 PM »

Hi would you keep me updated on the results especially the performance etc as I am thinking of a 4 motor configuration for a battle cruiser and want to make sure it does not drain the power too quickly or require 4 gearboxes which would defeat the object of the exercise
 
Regards
 
Vic
Logged
I love warships bring back the big guns

Sandy

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 301
Re: Brushless Motors
« Reply #3 on: December 09, 2013, 01:33:55 PM »

I will do.
 
Off the top of my head I cannot remember the exact spec of the motor but it is an outrunner, of about 900 rpm per volt, which I will drive off a 6v SLA battery. It is directly connected to a single shaft. As was explained to me though, they should take less out of the battery as they are more efficient.
 
Sea/bath/pond trials in January .... hopefully.
 
Logged

Hmshood

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 59
  • Model Boat Mayhem is Great!
  • Location: Buckingham
Re: Brushless Motors
« Reply #4 on: December 09, 2013, 01:36:53 PM »

That's an impressive model, is it scratch built from a plan or a kit. Details would be appreciated and also your experience building it. Happy sailing
 
Vic
Logged
I love warships bring back the big guns

Sandy

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 301
Re: Brushless Motors
« Reply #5 on: December 09, 2013, 01:49:35 PM »

Hi,
 
It is a Fleetscale (maybe) HMS Bryony extra long fo'c'sle Flower hull cut down to a short fo'c'sle HMS Gloxinia.
 
It is rather scratch built as it is built from the only photo of Gloxinia available.
 
I used the Scalecraft book as well as it has a small set of drawings of HMS Camelia and the Harland and Wolff Flowers had their own peculiarities, no planked well deck for example.
 
All the best
Sandy
 
Logged

pompebled

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 586
  • Location: Sneek, Netherlands
Re: Brushless Motors
« Reply #6 on: December 15, 2013, 12:56:52 PM »

Hi Vic,

Not knowing how heavy the model is going to be and which props you'll be using, I'm guessing 3000 - 4000 rpm under load will be about right.
Running on 6V, a motor like this would be sufficient, if you take four of them:
http://www.hobbyking.com/hobbyking/store/__39037__Turnigy_Multistar_2216_800Kv_14Pole_Multi_Rotor_Outrunner.html
As it's a 14-pole motor; the low end response will be good, compared to lower pole motors which tend to burst into life at one third throttle, making crawling along an illusion.

If you're planning on running on a higher Voltage, say 12V SLA, finding a suitable motor that doesn't break the bank is harder, as low KV motors tend to be more expensive.

Robbe has a very good line of motors, suitable for boats, this one springs to mind on 12V SLA, or 3S Lipo:
http://www.ebay.at/itm/4990-Robbe-ROXXY-BL-Outr-C35-30-45-300kv-/141129036733?pt=RC_Modellbau&hash=item20dbf233bd

Running on 12V you'll have about 3240 rpm under load.
Depending on the prop selected you should be able to run this motor on an ESC like this:
http://www.robbe.de/roxxy-blcontrol-908.html

The ampdraw of a properly selected brushless setup is low; I can run my single outrunner powered MAS for over three hours on a 9600mAh Lipo, running 80% of the run time in a brisk walking pace with the occasional sprint.
Average ampdraw is 4,5A.
Build thread with video: http://www.modelboatmayhem.co.uk/forum/index.php/topic,34033.0.html

Regards, Jan.

Logged
Boaters are nice people

Hmshood

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 59
  • Model Boat Mayhem is Great!
  • Location: Buckingham
Re: Brushless Motors
« Reply #7 on: December 15, 2013, 08:36:58 PM »

Jan,

That's a lot of information I will need to digest first. I had not really got to this degree of detail, I have actually used four 350 style motors which I believe will do the job however I feel there must be a more scientific way of calculating the optimum motor configuration and voltage rating which I suspect is related to the weight of the boat amongst other things, I will ponder this unless someone has a magic method. The only reason for considering brushless was they on first inspection would seem to be better suited where one has limited room (which is not actually the case on my current model of HMS Hood as its some 5 feet long), I was thinking ahead to a smaller craft like a MTB which will need speed as well as being smaller.

By the way you mention Lipo batteries which I have always avoided with some of the problems with charging and fire risk, what is your experiences with these.
Regards
Vic
Logged
I love warships bring back the big guns

pompebled

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 586
  • Location: Sneek, Netherlands
Re: Brushless Motors
« Reply #8 on: December 15, 2013, 09:47:31 PM »

Hi Vic,

In my career as 'battery abuser' running my speed boats in competition, I must say that Lipo's are much user friendly than NiMH, which are really high maintenance and have a much shorter lifespan than my current lipo's.

It goes without saying that you'll have to treat the batteries right, something that applies to any type of battery chemistry.

Over the years I've switched all my models from NiMH to Lipo's without a hitch.
The trick is to use suitable chargers, an ESC suitable for lipo's (with a lipo cut-off to protect the battery from over discharging) and common sense running the model.

If you have seen the video of my MAS, the boat can run at this speed for close to an hour, due to the large capacity I installed.
In fact, I'm 'recycling' Lipo's in my scale models that I've ran in my competition boats for one season, after which the capacity tends to drop off and these lipo's are no longer fit enough to give me sufficient runtime for seven minutes full throttle.
In my scale applications these 'second hand' lipo's don't even get handwarm, even at full throttle, as the ampdraw is substantially lower.
When I reduce the amount of full speed running, the runtime of the MAS is over three hours, I don't last that long...

For a smaller MTB, brushless motors are ideal, either inrunner or outrunner, the latter having my preference due to the better low end response compared to inrunners.

Regards, Jan.
Logged
Boaters are nice people

Hmshood

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 59
  • Model Boat Mayhem is Great!
  • Location: Buckingham
Re: Brushless Motors
« Reply #9 on: December 15, 2013, 09:54:53 PM »

Jan,

That's really interesting I will look more into this option. I will stay with my current configuration until I run the test (as I have only just completed the HMS Hood hull planking and moving on to the fibre glass stage soon) this may be a while. I take your point onboard regarding the safety aspects and note that some manufacturers suggest charging inside a special bag that is fire proof (probably a wheeze to get more money from you). Thanks for the info will keep you posted if interested.

Regards Vic
Logged
I love warships bring back the big guns

pompebled

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 586
  • Location: Sneek, Netherlands
Re: Brushless Motors
« Reply #10 on: December 15, 2013, 10:07:41 PM »

Hi Vic,

I'll monitor your Hood build thread and I'm looking forward to hearing from you when the sea trials with the 350 motors have been absolved.
BTW; your pictures are really small, not much to see as far as details go...

Regards, Jan.
Logged
Boaters are nice people

Hmshood

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 59
  • Model Boat Mayhem is Great!
  • Location: Buckingham
Re: Brushless Motors
« Reply #11 on: December 15, 2013, 10:11:24 PM »

Jan,

I presume you are referring to those HMS Embling and HMS Hood that were posted a while back or are you referring to the pics of the HMS Hood hull?

Regards
Vic
Logged
I love warships bring back the big guns

nick_75au

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 257
  • Location: Brisbane, Australia
    • Logan City Marine Modellers
Re: Brushless Motors
« Reply #12 on: December 16, 2013, 05:01:25 AM »

http://www.rcgroups.com/forums/showatt.php?attachmentid=4261513&d=1315289844


Hope this helps in your selection of suitable motors


Any questions feel free to ask.


Nick
Logged

Leaky Bottom

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 119
Re: Brushless Motors
« Reply #13 on: December 16, 2013, 10:03:58 AM »

I take your point onboard regarding the safety aspects and note that some manufacturers suggest charging inside a special bag that is fire proof (probably a wheeze to get more money from you).


This charging in a lipo bag is definately not "a wheeze"
 
A fellow club member in my aeroplane club was charging a lipo in the back of his van on the way to the field, the lipo was in one of these bags underneath his petrol model when it caught fire and the bag contained the fire completly, as his van had a sealed front bulkhead he did not realise it was on fire untill he got to the field and opened the rear doors and the van was completly filled with smoke. In this instance a lipo bag saved not only his models but also his van.
 
The reason he believes the lipo caught fire was that he had left his model switched on over night and the lipo was flat so he was trying to recharge a completly flat battery at high amps
Logged
"Leave me alone I know what I'm doing"

Hmshood

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 59
  • Model Boat Mayhem is Great!
  • Location: Buckingham
Re: Brushless Motors
« Reply #14 on: December 16, 2013, 11:16:56 AM »

Hi,

I thought that there were some problems with using Lipo batteries and that's why I am a little reluctant to use them. Thanks for sharing that awful experience it makes me feel that staying with traditional is somewhat safer

Regards
Logged
I love warships bring back the big guns

Leaky Bottom

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 119
Re: Brushless Motors
« Reply #15 on: December 16, 2013, 12:25:49 PM »

Hello
 
There perfectly safe if used and charged correctly, that guy's problem arose from trying to charge a flat battery to quickly at to high a amperage so he could use it to fly his model, luckely he had the foresight to put the battery in a lipo bag.
Logged
"Leave me alone I know what I'm doing"

pompebled

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 586
  • Location: Sneek, Netherlands
Re: Brushless Motors
« Reply #16 on: December 16, 2013, 10:21:09 PM »

It goes without saying that you'll have to treat the batteries right, something that applies to any type of battery chemistry.
Charging a Lipo unattended falls in that category...
A flat Lipo is chemical waste in most cases, only with special care (and knowledge) you can try to get it to recharge again, it'll never regain it's original capacity or 'oompf' again though.

Regards, Jan.
Logged
Boaters are nice people

pompebled

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 586
  • Location: Sneek, Netherlands
Re: Brushless Motors
« Reply #17 on: December 16, 2013, 10:25:51 PM »

I presume you are referring to those HMS Embling and HMS Hood that were posted a while back or are you referring to the pics of the HMS Hood hull?
Hi Vic,

I meant this update on the hull:
http://www.modelboatmayhem.co.uk/forum/index.php/topic,45681.msg462299.html#msg462299

I don't know if it's wise to open a new topic on every item regarding the build of the Hood, things tend to get scattered and hard to find...
It's better to keep it in one topic.

Regards, Jan.
Logged
Boaters are nice people

Hmshood

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 59
  • Model Boat Mayhem is Great!
  • Location: Buckingham
Re: Brushless Motors
« Reply #18 on: December 17, 2013, 11:20:34 AM »

Jan,

OK that's a good point but I do not know how to link or continue with a topic for updates etc
s

Vic
Regard
Logged
I love warships bring back the big guns

Tug-Kenny

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 7,680
  • Location: Newport. S Wales
Re: Brushless Motors
« Reply #19 on: December 17, 2013, 07:50:46 PM »


Just click   REPLY  under the posting.      :}


Ken



Logged
Despite the high cost of living   .......... It remains popular

Hmshood

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 59
  • Model Boat Mayhem is Great!
  • Location: Buckingham
Re: Brushless Motors
« Reply #20 on: December 17, 2013, 08:36:36 PM »

Ken,

thanks much appreciated

regards

Vic %%
Logged
I love warships bring back the big guns
Pages: [1]   Go Up