Technical, Techniques, Hints, and Tips > DC Motors (Brushed) and Speed Controllers
Motor for Caldercraft Cumbrae
Shipmate60:
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
Colin Bishop:
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
SimonCornes:
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!
roycv:
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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