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Author Topic: Brushless motor/ESC for Dumas 19" racing runabout.  (Read 8871 times)

Jeremy

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Brushless motor/ESC for Dumas 19" racing runabout.
« on: November 23, 2011, 11:38:12 AM »

I would appreciate advice on a brushless motor for my Dumas Chris Craft 19" racer (28" long).  I fitted a 2881KV water cooled in-runner with a Seaking 60 amp ESC and 8.4V NiMh battery to my Bluebird and it goes fine.  It looks as though I made a mistake in opting for the same set-up for the Chris Craft which has a submerged drive as against the surface drive of Bluebird which planes over the water.  The motor on the Chris Craft sometimes stops in mid lake  >:-o which I am told may be due to overheating.  The advice so far has been to reduce the prop size (current 35mm diameter, 30 degree pitch) and the battery to 7.2V.  However, I am told that a lower power motor would be the best solution, particularly as the Chris Craft is not normally run at full throttle.  Ideally I would like an in-runner motor, around 1800-2100kV for batteries of 7.2-8.4V to fit the same 380/400 motor mount and of apprximately the same dimensions (45mm long, 32mm diameter).  Does anyone know of a motor that would fit that spec?  The higher powered motor could then go in my Slo-mo-shun which I want to upgrade from its current Graupner Speed 600 Race 7.2V unit.
Jeremy
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #1 on: November 23, 2011, 04:51:01 PM »

i reckon this will fit the bill for ya:

http://www.hobbyking.com/hobbyking/store/__17725__XK2845_B_2000kv_Brushless_Inrunner.html

you can still use that other motor just put a 30 to 32mm diameter prop on it. where did you get the prop you have from?
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #2 on: November 23, 2011, 05:06:36 PM »

Motor looks the right size - thanks  :-).  But would it not need to be watercooled (as is the Seaking 60 amp ESC currently installed)?  My props are all Graupner plastic from Cornwall Model Boats.  I have 25mm and 32.5mm diameter examples on order from them and will try them with the existing motor first.  If that doesn't work, I'll go with the Turnigy.
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #3 on: November 23, 2011, 05:11:13 PM »

i dont think heat issues will be a problem especially on 7.2 and 8.4 nimh. ill see what else there is.

where did you get the motor from that you currently have??
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #4 on: November 23, 2011, 06:21:10 PM »

I got the combo BL5 from Prestwich model boats.
www.prestwich.ndirect.co.uk/brushless.htm
It works fine on Bluebird (would go even faster with Lipos) and I bought the same combo for the Chris Craft without maybe giving it sufficient thought.  As I have watercooling installed in the boat, I might try to find a water cooling jacket that fits the Turnigy.  If you come across an alternative motor that is water cooled, that would be even better.




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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #5 on: November 23, 2011, 06:56:36 PM »

the cooling jacket on the motor you have will fit on the new turnigy one. with the smaller 32.5mm prop though i very much doubt it will create enough heat to warrant a cooling jacket.
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #6 on: November 23, 2011, 07:24:43 PM »

Except that it is not removable..  :((!
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #7 on: November 23, 2011, 08:07:28 PM »

heres one btw its exactly the same. they are removable because there push fit and sometimes epoxied on:

http://www.ebay.co.uk/itm/RC-Boat-Aluminium-28mm-380-Motor-Water-Cooling-Jacket-/220778484560?pt=UK_ToysGames_RadioControlled_JN&hash=item33676c5350
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HS93 (RIP)

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #8 on: November 23, 2011, 08:39:22 PM »

There is nothing wrong with the prestwich set up you just need the correct prop and make shore you have water colling working correctly as the speed controller MUST have good water cooling as they reduce the heat sinks on them now and fit water cooling plates that are not very good without water passing through them, try contacting Prestwich and ask what prop they recommend as they are selling it as a combo, or just go a lot smaller and work your way up plastic props are so cheap these days,underproping will not hurt it it will just rev and go slower, you should always start small with props and work up.

Mike have you used the turnigy motor in a boat ? what prop did you use? have you any pictures of the set up?
Peter
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #9 on: November 23, 2011, 08:51:18 PM »

not that motor no i just found him one that suits the criteria he wanted. its essentially the same motor, just lower kv. Seaking, Turnigy, FlySky, hobbywing, eurgle, Imax and some others are all the same chinese company. I have a 2845 brushless motor though not the turnigy one a seaking one.
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HS93 (RIP)

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #10 on: November 23, 2011, 09:36:50 PM »

not that motor no i just found him one that suits the criteria he wanted. its essentially the same motor, just lower kv. Seaking, Turnigy, FlySky, hobbywing, eurgle, Imax and some others are all the same chinese company. I have a 2845 brushless motor though not the turnigy one a seaking one.

there all from the same factory? same spec ? not what I have seen of them

Peter
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #11 on: November 24, 2011, 07:59:59 AM »

OBVIOUSLY JEREMY THE TURNIGY WILL NOT SUFFICE SO DONT BUY IT

HS93 IF YOU FIND A BETTER CHOICE FOR THE KV  AND SIZE HES ASKED FOR THEM BY ALL MEANS PUT IT UP.
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HS93 (RIP)

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #12 on: November 24, 2011, 09:19:19 AM »

Calm down, Calm down, I only asked if you had tried it, no where did I say it would not be suitable.and I queried your statement that they are all the same, as I have had motors from most of the company's named by you and found the build quality varied.

Peter
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #13 on: November 24, 2011, 09:49:57 AM »

the build quality is varied but so is the price you pay for them. ive read somewhere that there all linked somehow, i cant remeber where though. its just funny how the hobbywing seaking 180 esc is the same as the turnigy 180 esc and its funny how all these escs can all be set up from the same programming card. From what i gather Turnigy is hobbyking's renamed range of hobbywing parts.

I will withdraw the statement then that their all the same chinese company, because i have no proof.



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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #14 on: November 25, 2011, 03:49:55 PM »

Hi Mad Mike

I've gone for the motor and cooling jacket you recommended and I'll transfer the BL5 combo to my Slo-mo-shun - an upgrade from the Graupner Speed Race 7.2V unit which does not really provide enough power whilst getting extremely hot.  Thanks for your advice. :-))

Jeremy

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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #15 on: November 25, 2011, 04:21:36 PM »

tell me how it goes when you done :-))
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #16 on: November 25, 2011, 09:33:51 PM »

Will do, Mike but it will be a few weeks before I get the parts, particularly the cooling jacket.  Hopefully, I will get a chance to check out the new set-up in January.
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Jeremy

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #17 on: December 06, 2011, 07:34:09 PM »

Hi Mike

The motor and cooling jacket have both arrived, earlier than expected  :-).  However, I cannot get the cooling jacket onto the motor  >:-o.  It obviously has to fit tightly because the motor casing forms the inner wall of the cooling jacket.  There are O rings at both ends and a spare set is included.  Advice on how to put this on would be much appreciated.  There must be a way!

Jeremy
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #18 on: December 06, 2011, 08:07:54 PM »

while ive been offline ive been thinking and heres what i would do. Put the o rings on the jacket then using get this BUTTER to slide the the cooling jacket onto the motor. When its on flush the water jacket threw with hot water and a little fairy liquid. :-))
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HS93 (RIP)

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #19 on: December 07, 2011, 01:54:13 AM »

dont use WD40 as it can ruin the rubber seals, just try a bit of fairly Liquid to get it on then it will wipe off and wash out of the jacket.

Peter
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Jerry C

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #20 on: December 07, 2011, 07:53:48 AM »

there is a product called rubber grease (no sniggering please) available down here in most engineering supplies places, designed for just that sort of thing.

MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #21 on: December 07, 2011, 07:55:29 AM »

theres a product called vaseline here does the same job :-))
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Nige52

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #22 on: December 07, 2011, 09:00:19 AM »

Except that Vaseline attacks rubber seals ........... %)

Use Silicone based grease  :-))
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MikeA

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #23 on: December 07, 2011, 09:10:12 AM »

lol seals bein attacked by tubs of vaseline %%

i still reckon butter will do it. Not much point buying a tub of grease for 1 small job. 

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Jerry C

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Re: Brushless motor/ESC for Dumas 19" racing runabout.
« Reply #24 on: December 07, 2011, 09:28:46 AM »

I too am a great fan of vaseline for many modelling jobs but I have used rubbergrease on the piston tanks of my sub and it works a treat and only seems to come in small tubes similar to superglue which is good because I tend to lose it inbetween uses.
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