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[richardabeattie]

I am now building the Mountfleet Ben Ain - a 47" long heavy displacement steamer - and will in due course provide some feedback on the kit.  It has a 65mm diameter prop and I have been advised to use a 12v 800 size direct drive motor and a 20 Amp ESC.  But I already have a Graupner Speed 600 and an MFA RE 540 (and a Viper 15 Amp ESC).  Would either of these motors do instead or would they be struggling?

[shadysadie]

Have a look at Mobile Marine Models' T12 motor which is a high torque low revving unit. Not cheap but I have used them in similar sized models to Ben Ain and can thoroughly recommend them.

[Stan]

HI to answer your questions the motor recommended at this time by mountfleet is the MFA 800.I suspect the 540 range of motors will struggle to power  such a large and heavy model and may get warm during operation. I have provided this information on the motors you have mentioned  I have no wish to determine you final choice.

I have provided some specs for the motors you have mentioned.

M F A 800  STALL CURRENT AT 12 VOLTS 25.86 AMPS  so you would need a 30 amp speed controller  rpm at maximum efficiency his around 4800 rpm. These  figures may change depending on prop size.

Speed 600 these will not handle 12 volts you would have a  speed 600 turbo stall current 40 amps.

M F A 540/1  stall current at 12 volts 16.48 amps   M F A  540 /LN stall current 20 amps

[richardabeattie]

Thanks for the suggestion of a Mobile Marine Models' T12 motor butt he website does not give the voltage and says that the shaft diameter is 6mm which sounds wrong

[richardabeattie]

Stan


Thanks for your advice to go for an MFA 800, a 30 Amp ESC and a 12 V battery.

[Stan]

Hi Further to our conversation would recommend fitting a 20 amp fuse this will provide a reasonable buffer for the speedo. Finally contact M F A to verify my figures for the 800 motor.

Stan.

[coch y bonddu]

Type

Voltage (V)

At max efficiency

No load

Weight

800[/font][/color]

Min

Max

Voltage

Revs (r/min)

Current (A)

Power (W)

Torque (gf/cm)

Speed (r/min)

Current (A)

595g

12

12

4280

5,28

36,88

836.98

5167

1,058

[/color] [/size]Dimensions: 69 (mm long) x 51.8 (mm dia)[/color][/size]Weight: 595g[/color][/size]Shaft Length: 13.2mm[/color][/size]Shaft Dia: 6.35mm[/color][/size][/color][/size]Taken directly from the Component shop website [/color]

[shadysadie]

The T12 is a 12 volt motor (T24 is 24 volts) and what is the problem with a 6mm. shaft? The appropriate coupling will take care of motor shaft/prop. shaft discrepancies.

[Stan]

Hi guys the chart above may mean nothing to this member keep it simple surely is the golden rule.




Stan

[malcolmfrary]

For a motor designed to give high torque, or any kind of high power, a 6mm shaft is perfectly reasonable - everything inside the motor contributing to that torque is fixed to that same shaft and needs enough shaft to be mounted on and stay there while delivering that power.  That it is going to drive a 4mm or 5mm prop shaft is immaterial - that is why you get to specify the size of hole at each end of the coupler.

[tugboyben]

Morning richard
The CEM900 Motor sold by steve at model boats would be a good choice for your model

Link to the motor [size=78%]https://www.modelboatbits.com/CEM-900-MOTOR-1-1-1-1[/size]

Steve can all-so supply the coupling as that motor as a shaft that is 6.3mm


If you need more in for the motor Steve is all-ways happy to help


Jason

[Buccaneer]

I fitted my Ben Ain with a T12. Coupling Inserts are readily available for a 6mm shaft and running off of a 12V/7 A/Hr Battery I got over an hour running time. The large prop was no problem as the T12 has enough torque to shift a double decker bus.

John