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Author Topic: Motor for Caldercraft Cumbrae  (Read 1719 times)

SimonCornes

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Motor for Caldercraft Cumbrae
« on: February 24, 2022, 12:10:15 pm »

I have an RS-550 motor that I'm thinking of using to drive a 40mm 3 blade Prop Shop prop. Speaking to Simon at PS he recommended maybe a 555 or a 777 so I'm wondering if the 550 I have will do the job? It feels like a multipole motor and I can see a Robbe sticker on the can.
Many thanks for your opinion,
Simon
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Colin Bishop

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Re: Motor for Caldercraft Cumbrae
« Reply #1 on: February 24, 2022, 12:29:36 pm »

Simon, I think the 550 is the high speed, high current version. The 555 is the low drain version which would be appropriate for Cumbrae as Simon at Prop Shop suggests.

Colin
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SimonCornes

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Re: Motor for Caldercraft Cumbrae
« Reply #2 on: February 24, 2022, 01:07:10 pm »

Ah, right, typical! It was one of the motors in my recent Imara renovation so it’s a good job it’s not in that boat anymore! So a 555 it will have to be then. At least it will fit the same mount!


Just had a look - where do you get a Mabuchi 555 from then? I saw one this morning for £12 plus postage but when I tried to buy later it was out of stock- typical!!
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Colin Bishop

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Re: Motor for Caldercraft Cumbrae
« Reply #3 on: February 24, 2022, 02:23:54 pm »

Component Shop have them for £9.

https://www.componentshop.co.uk/mabuchi-555-dc-motor.html.html

Treat yourself...

But the 555 needs at least 12v according to the spec so I wonder if a 540 which runs on 4.5v to 15v might be better? You could run it off a 9.6v pack.

https://www.componentshop.co.uk/540-standard-dc-motor.html.html

Decisions!

Colin
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GG

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Re: Motor for Caldercraft Cumbrae
« Reply #4 on: February 24, 2022, 03:38:10 pm »

Ah, the trials of finding a 500/600/700 series motor to match a sedate scale model.  I've been caught out a few times with an advertisement or even the sellers personal assurance that a motor would be an ideal match this type of model.  Perhaps the worst example was a kit based on a canal boat, the ultimate in sedate scale models?, which included a motor that would have been at more at home in a screaming fast electric model.  When tackled about this, the kit manufacturer admitted he had never actually tested the motor the model, but had been assured by the motor supplier that it would be perfect for this model...!!!


For this reason I tend to use the "Rock Climber" types of motor, which have many more armature turns, hence lower RPM but lots of Torque, to directly drive surprisingly large propellers safely. I've even rewound stock 27 turn motors (which were well past their high performance days) with something like 100 turns to carry on sailing in scale models.


There is an alternative of using a lower voltage battery to tame the speed of a motor.  I've used a 2 Volt battery (usually used to start glo-motors) to power a scale model using a stock 540 motor.  If using an ESC you simply have to connect the 2 Volt battery to the ESC  but  keep the BEC switched OFF and power the Receiver with a separate battery.


Glynn Guest
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SimonCornes

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Re: Motor for Caldercraft Cumbrae
« Reply #5 on: February 24, 2022, 07:30:07 pm »

Component Shop have them for £9.

https://www.componentshop.co.uk/mabuchi-555-dc-motor.html.html

Treat yourself...

But the 555 needs at least 12v according to the spec so I wonder if a 540 which runs on 4.5v to 15v might be better? You could run it off a 9.6v pack.

https://www.componentshop.co.uk/540-standard-dc-motor.html.html

Decisions!

Colin


Thanks Colin,
I have a 'spare' 12v 3.7aH gel cell so I think I'll go for the 555 option simply because its is described as low drain and implied good torque so that should be okay with a 40mm prop. Simon at PS reckoned it was a slow mover - maybe 12 knots? (My thinking) so as long as I've got enough water moving over the rudder then I should be okay. But I am tempted by that 540 as well because Simon suggested 10,000 rpm which is probably nicely in the rev range for 12 volts at full chat. I suppose I'm so used to the 1980's idea that a 540 is no good in a slow scale boat!
Simon
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SimonCornes

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Re: Motor for Caldercraft Cumbrae
« Reply #6 on: February 24, 2022, 07:32:44 pm »

Ah, the trials of finding a 500/600/700 series motor to match a sedate scale model.  I've been caught out a few times with an advertisement or even the sellers personal assurance that a motor would be an ideal match this type of model.  Perhaps the worst example was a kit based on a canal boat, the ultimate in sedate scale models?, which included a motor that would have been at more at home in a screaming fast electric model.  When tackled about this, the kit manufacturer admitted he had never actually tested the motor the model, but had been assured by the motor supplier that it would be perfect for this model...!!!


For this reason I tend to use the "Rock Climber" types of motor, which have many more armature turns, hence lower RPM but lots of Torque, to directly drive surprisingly large propellers safely. I've even rewound stock 27 turn motors (which were well past their high performance days) with something like 100 turns to carry on sailing in scale models.


There is an alternative of using a lower voltage battery to tame the speed of a motor.  I've used a 2 Volt battery (usually used to start glo-motors) to power a scale model using a stock 540 motor.  If using an ESC you simply have to connect the 2 Volt battery to the ESC  but  keep the BEC switched OFF and power the Receiver with a separate battery.


Glynn Guest


Thanks Glynn
I think it will be the 555 for the torque potential with a 40mm prop. But I might experiment with that 540 as well as I already have a motor mount and they are the same shaft size. I doubt that I would need a long duration on the water as most social events involving a lot of standing around and not so much time actually driving around the lake! Hopefully I might get an hour out of a 12v 3.7Ah gel cell?
Simon
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Colin Bishop

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Re: Motor for Caldercraft Cumbrae
« Reply #7 on: February 24, 2022, 07:55:02 pm »

Yes, Cumbrae's speed was 11.5 knots.

Colin
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SimonCornes

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Re: Motor for Caldercraft Cumbrae
« Reply #8 on: February 24, 2022, 08:24:31 pm »

I think I’ll go with the 555 and be prepared to replace it with the 540 if I’m not happy. Sometimes it’s nice to have to see excess power and then to be throttled back for normal running.
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Circlip

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Re: Motor for Caldercraft Cumbrae
« Reply #9 on: February 25, 2022, 11:10:30 am »

0.75cc, 1cc, 1.5cc, 2.5cc, 3.5cc, 5cc.   NO problems.


  Regards   Ian.
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Shipmate60

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Re: Motor for Caldercraft Cumbrae
« Reply #10 on: February 26, 2022, 05:41:13 pm »

Originally the Cumbrae was advised to use a Monoterm Super motor.
This motor revs at about 5-6000 rpm on 6 volts.
This is about the rev range to aim for.
The 555 is a good motor but will require 12 volts.
The standard 540 is way too fast unless you can find a low drain 540 which spins about 5000 rpm.


Bob
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Colin Bishop

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Re: Motor for Caldercraft Cumbrae
« Reply #11 on: February 26, 2022, 05:49:58 pm »

Bob,

I did suggest the low drain 540 in an earlier post but Simon says he has a 12v GEL cell.

https://www.componentshop.co.uk/540-standard-dc-motor.html.html

My review Cumbrae was originally fitted with a Monoperm Super and reduction pulley drive. It did drive the boat OK but performance was a bit lethargic with nothing in hand if conditions demanded more power. It now has a low drain 540 but I kept the pulley drive and that combination runs very well. Initially I used a 6v GEL cell but I swapped it for a 7.2v NiMH pack.

Colin
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SimonCornes

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Re: Motor for Caldercraft Cumbrae
« Reply #12 on: February 27, 2022, 12:12:42 am »

I found another 500 series motor and this at least a 5 pole so I may have a go with several different motors to see which works best.’I suppose I’ll need to get some capacitors for suppression purposes!
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roycv

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Re: Motor for Caldercraft Cumbrae
« Reply #13 on: February 27, 2022, 01:23:13 am »

Go by GG's suggestions. 

ALL the large motors turn over on very low voltages or even 2 volts, ignore the 12v label it is a possible maximum.  I use Monoperm Supers and they are lovely motors 6 volts is enough remember it is the size of the propellor that decides the current.  The current times the voltage gives the watts used.

I have a 32 inch cargo ship beam 6 inches weight 4 kilos runs with a 555 on 6 volts (5 cells) with a 45mm prop.  I can run that very sedately just using the esc trim control on the Tx.  I can even watch the prop turn over on low speed.
At the other end an electric motor will run with a 50% increase in voltage providing the current is kept down and motor is cool.  I used to run a Graupner 600 9 volt variation at 12 volts 2 1/2 amps with a 1 : 2 gearbox 50 mm brass prop, on 12 volts never got hot ran at 30 watts and made my Streamlinia (old Bassett-lowke design) plane very nicely.

Once a boat has a single wave from bow to stern it will not go much faster without a waste of power and a dipping of the stern.  To look right you do not scale down the speed by saying 1 : 50 scale then boat speed should be 1 : 50 of prototype speed.

Simples is to use the single wave, or prove it using Froude  formula:-  speed to length ratio equals flow speed over square route of waterline length.  But no one is going to do that are they!!!!!

The main consideration is the max current of the esc.  I use tiny esc's cost about a fiver on fleabay no heatsink about the area of your thumb in size and 8mm thick with connections as like the old RC receiver battery connectors.  Handle 6 cells or 2S up to 4 amps (although advertised at 10 amps?) without getting hot, been using them for years from when they were just half the price.
Hope this helps
Roy

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