Model Boat Mayhem
Mess Deck: General Section => Model Boating => Topic started by: Korp1010 on May 31, 2018, 10:00:06 pm
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Hi all,
I'm after a bit of advice please as i'm used to scale boats and not fast patrol boats with big motors.
I've recently picked up a lovely Perkasa PT boat which has a MFA Torpedo 850 motor fitted and a came with a 2 blade 40mm plastic prop fitted. I replaced this plastic prop for a 3 blade 35mm brass prop thinking it would suit the model better.
I've run the model today and kept bringing it in to check the motor and found that it was getting warm to the touch and had to spend 10-15mins letting it cool in between runs.
The boat is running off an 11.v Lipo and planes nicely but obviously something isn't right with either the prop or I possibly need cooling of some sort?
Any advice from people with these boats regarding the correct setup would be great. I'm aware going brushless is a good option would prefer for now to find away of running the 850 if possible?
Thanks
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Hi Korp1010
Try to the plastic one and if it works better replace it for a brass or CNC one.
The 3 blade is loading up the motor.
Canabus
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Electric motors do get warm that isn't a problem, its when they get hot to the touch they are working too hard.
Are you trying to fix a non existant problem?
Bob
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Hi thanks for the replies,
Sorry should of made it clearer, the motor is definitely getting too hot you can only put your hand on it for about 5 seconds.
Made a few alterations today and swapped the prop to a smaller plastic 3 blade one so will give that a try.
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Oh Dear me the dreaded Mfa 850 motor here lies your PROBLEM....get rid of it....simply because it is not only amp hungry but also it has the inherant problem of getting hot....if you still want to use it then you will need to water cool it without a doubt and get rid of the 3 bladed prop.I used to own a perkassa which ran a 900 series motors running on 24v and a 55mm 2 bladed prop and it used to plane with ease.
Personally I would go brushless with a KVA of around 950 running 12v and a 55mm 2 bladed prop this would be an ideal set up in my opinion as it would be a close match to the rpm of the 850
Dave
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Oh Dear me the dreaded Mfa 850 motor here lies your PROBLEM....get rid of it....simply because it is not only amp hungry but also it has the inherant problem of getting hot....if you still want to use it then you will need to water cool it without a doubt and get rid of the 3 bladed prop.I used to own a perkassa which ran a 900 series motors running on 24v and a 55mm 2 bladed prop and it used to plane with ease.
Personally I would go brushless with a KVA of around 950 running 12v and a 55mm 2 bladed prop this would be an ideal set up in my opinion as it would be a close match to the rpm of the 850
Dave
Thanks for the info, I had a multi meter on it today and out of the water it was pulling 1.6A.
I could go brushless but it's complete unknown territory to me.
Think I need to do some research.
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And I would hazard a guess in water well over 12A....I have seen one of theses pull in excess of 20 amps in water
Dave
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A short term answer is to put a little computer cooling fan near the motor, providing you can get some air moving in to the hull as well, It really does help. Longer term, definitly go brush less, I did recently for a couple of larger planing boats and I'm wondering why I waited so long.
Chas