Electric motor suggestions

[Brian MorrisParticipant @brianmorris30448]

[Brian MorrisParticipant @brianmorris30448]

Ii have started the Vamoose commuter boat has per the Model Boat winter special ,however the suggested motor advertises has high revs and torque ,I believe I need low revs and high torque ,do I use geared motors if so what ratio , i would probably use 32mm brass props .

I was thinking perhaps in using one motor instead to reduce costs , what could be recommended motor and prop if I went down this avenue.

[shipwrightParticipant @shipwright]

I agree that if you want the same performance but at lower revs then you will need a motor that produces higher torque at lower revs and a larger prop. However, there aren't many readily available high torque/low revs motors and also they tend to be somewhat larger and heavier than 500/600 sized motors. Of course you can use the higher rev motor with gear or toothed belt reduction but there are drawbacks to that approach – loss of efficiency and noise/vibration – generally you are better off using a direct coupling between motor and prop. Another point to consider is how much space is there for a bigger prop ? I have no experience of brushless motors but you might find a suitable brushless motor (BLDC) and controller. You will need a low Kv (rpm/volt) motor – also make sure that the BLDC controller offers forward and astern (many don't as they are designed for model aircraft). Last, but not least, I am unclear why you wish to change from the proven/recommended design that is given in the Vamoose Model Boat article.

Ian

[Brian MorrisParticipant @brianmorris30448]

Thanks Ian for your reply , I was thinking that I would save cost using one motor , however I think I will use two has suggested .

i also have little experience of brushless motors , and would be more comfortable with the conventional brushed arrangement .

perhaps someone will suggest a motor reference of a readily available motor.

regards Brian

[ashley needhamParticipant @ashleyneedham69188]

Brian,

I use, for lower speed applications a cheap`n`cheerful MFA type 385 motor. On a gel 6v this will turn a 32mm or 35mm prop quite happily at low to medium speeds. A bit better with a 7.2v NiMh pack, and on a Gel 12v battery it becomes quite perky. It may be that this is overloading the poor thing a bit, but the current consumption is so meagre in the first place that a bit of overloading goes unnoticed. What voltage are you going to use?

For instance, my 48" Titanic has 3 x 385`s turning 2 x 35mm and one 30mm props, my "Devastation" , a portly Victorian sort of battleship has 2 x 385 driving 35mm props…

I am not sure I would go for a brushless, there are so many to choose from. As Colin has said, unless you want max speed or best endurance from a limited battery capacity, stick with a good old brushed motor.

Ashley.

[Brian MorrisParticipant @brianmorris30448]

Thanks Ashley . I will be using 2 x7.2v ( one per motor ) .

if its good enough for your models I am sure it will do my Vamoose .i will purchase 2 .

thanks again

Brian

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