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[Tug Fanatic]

Hi GG
The main problem is finding the specs on the motors at a voltage, but after a long crawl around the old interweb I found some answers !!!
Mainly for 540 rock crawler brush motors.
These are on 7.2 volts unloaded rpm:-
20 turn 18400
27 turn 15000
35 turn 12500
45 turn 9500
55 turn 7700
65 turn 7000
80 turn 5500

The 55 and 65 turn will happily turn a 3 or 4 blade 50 to 60mm prop in fishing and tug boats.

If you wish to go to brushless motor divide the rpm into the voltage to get the kv.
Brushless numbering is generally dia., length and kv.
eg changing a 80 turn brush motor, 5500 rpm divide by 7.2 equals about 750KV.
So a 3639-750Kv is the same bolt pattern as a 540, but shaft size is generally larger(5mm).

Running down the above motor to brushless will be about 2500, 2000, 1800,1250, 1000, 950 and 750KV.

Matching to you prop, I worked on the Raboesch prop chart maximum rpm.

It's a basic start.

Hope this helps someone on the forum.

Beers and Cheers
Canabus

This is not my experience of motors. Brushed motors seem much more willing to give up revs than brushless motors. It is quite common to see brushed motors loaded to around 50-60% of free running rpm whereas brushed motors will fight for more rpm and overheat wildly at anything like that load - 70-80% is much more acceptable for brushless. This means that whilst it appears from the above that a 20 turn brushed will give the same revs as 2500kv brushless in fact the brushless will turn the prop much faster. I am assuming an adequate power motor in both cases.

Just my opinion of course.

[john44]

Hi Chris, sorry about your hearing problem.
The pulleys and belts are on page 15.


Hope this helps


John

[frogman3]

HI GUYS many thanks for the motor an pulley info but the qeustion I asked was

HI RED181 do you know if MFA still sells the plastic cambelt drive motor mounting ?

shown in my linkpic below as this is the motor setup in my Nimitz carrier as you can see the motors are fitted in MFA cambelt drive  plastic motor mounts this is what I would like to get if I can for my tiger as its got 4 shafts
https://ibb.co/pKTgXJC

chris

ps

Hi Chris, sorry about your hearing problem.
The pulleys and belts are on page 15.


Hope this helps


John

 
An John cheers for the info i'll have a look at page 15 but there is no hurry as ive got to build the ship firstly but I like to think ahead in these matters an get things while I can    An thank you for your concern due to my hearing probs but in life you just have to keep on ploddin onwards an try an get through don't you 
all best chris

[RST]

I think the words you are looking for is "timing belt" usually, rather than "cam belt".  You can check MFA website easy-enough but I think you're possibly thinking of their "olympus" drives?, which on basic googling for ages haven't been generally available for quite some time now?  Never undestood that myself as plenty still look for them.  Perhaps brushless put that out of favour these days?  Interestingly in my many searches for 5 pole DC motors recently many places sell them -but they all seem to be MFA motors with a different sticker on top.  Hence I guess, why if one place is out of stock at the moment then just about everywhere is.  I had some searching to get hold of the really good noise surpressed 385's recently!  There used to be companies selling ex-equipment motors into the hobby market, but can't find any now.  Used to be able to get some very high quality multi-pole high torque motors back in the day without paying silly money.

[rcboater1]

When I went hunting for pulleys, O-rings, adapters, geared motors, etc for use in a paddlewheel project,  I found that robotics hobby suppliers have lots of great stuff!   
Servocity in the US and the RobotShop in the UK are two good examples....


-Bill

[canabus]

Hi RST
I use 540 rock crawler motors the 80 turn is 5500 rpm on 7.2 volts and turns a 3 blade 60mm prop in my fishing boat easily at 60% throttle.
Over that it's well over scale speed.

Banggood is a goog suppler from motors, belt and pulleys.

Canabus