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Author Topic: Motor/Prop query  (Read 2272 times)

big_bri

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Motor/Prop query
« on: January 16, 2015, 09:38:56 PM »

Could anyone please help?
I need some advice for a motor/prop combination for a 1/12 scale TID tug.
The prop I will use is a 130mm four blade, I have an MFA 800 belt drive power unit and a 12V Smiths type motor handy,  would any of these motors be suitable to turn this size prop?
Any advice would be most grateful.
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Brian

jarvo

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Re: Motor/Prop query
« Reply #1 on: January 16, 2015, 09:55:05 PM »

Hi Bri


Both motors would be ok, The MFA 800 is the high tourqe version but lower reving, about 5000 without the gearbox, if it is 2 : 1 reduction you are down to 2500 then the lost with the prop in the water, posibly down to 1800 - 2000 revs, might not be enough.


The Smiths motor, is it a heater motor or radiator motor????.


If its the radiator motor it has a large current drain, but high power. If its the heater blower motor, they have a lot lower power requirement and on direct drive to the prop shaft are very sutible for tugs, excelent throttle responce good reversing, enormouse torque, so swinging a 130 prop is simple without breaking the bank for an ESC.


Hope this helps


Mark
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Tugs are for pulling

big_bri

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Re: Motor/Prop query
« Reply #2 on: January 16, 2015, 10:23:48 PM »

Many thanks for the reply Mark. most helpful indeed :-))
The smith type motor was from Models by Design, so really don't know what it was originally used for, but think I may give it a try
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jarvo

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Re: Motor/Prop query
« Reply #3 on: January 16, 2015, 10:52:14 PM »

Bri


If you could post a picture maybe we can identify or at least confirm the type of motor


Mark
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big_bri

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Re: Motor/Prop query
« Reply #4 on: January 16, 2015, 11:10:40 PM »

Hi Mark.
This is the motor, took this pic off the internet as there`s two feet of snow outside. too cold to go out to the workshop, brrrrr!

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Brian

Stavros

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Re: Motor/Prop query
« Reply #5 on: January 16, 2015, 11:49:06 PM »

Is this for the models by design huge tid.......if it is ill have a word with Alan debsnall on the forum for you
Or go to my face book freinds and ask Alan Noble direct as he had the big girl at Wikki...tell him i told you

Dave
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big_bri

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Re: Motor/Prop query
« Reply #6 on: January 17, 2015, 12:06:06 AM »

No Dave, not Andy`s, building this one myself from scratch :-))
I`ve seen Alan`s TID on his website, a very nice model indeed, we hade two 1/12 scale models in our club, but now, sadly, they`ve gone, so I`ve decided to give one a go.
I`ve always like the TID tugs, they`ve loads of character.
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jarvo

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Re: Motor/Prop query
« Reply #7 on: January 17, 2015, 11:06:11 AM »

That motor looks like the one i have, plenty of power and good on battery life, should have a small hole drilled in the end of the shaft, this is for a locking pin on the fan, good for locking the drive coupling against the massive torque of the motor.


Just remember a strong motor mount is essential. Mine is 3/8 ply. Glassed into the hull


Mark
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big_bri

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Re: Motor/Prop query
« Reply #8 on: January 17, 2015, 11:21:38 AM »

This one has the same hole  :-))
Very many thanks for your help Mark, its most warmly appreciated.
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Brian

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Re: Motor/Prop query
« Reply #9 on: January 17, 2015, 11:37:49 AM »

Not sure if it adds anything to what has already been said, but I have the same Models by Design motor driving a 110mm prop on a 49" Northsider and it all works very well.

As has been said elsewhere plenty of torque and low drain on the battery.

Fastfaz

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Re: Motor/Prop query
« Reply #10 on: January 17, 2015, 12:46:19 PM »

  Hi Brian,
       That's one serious sized prop! I'm not familiar with 1/12th scale (very limited space so I usually go 1/32ish) so what are the dimensions, with a prop that big I imagine large and heavy. Post some photos of the build.
      Cheers,
             Peter. :-))
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big_bri

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Re: Motor/Prop query
« Reply #11 on: January 17, 2015, 01:29:27 PM »

Definitely go with the motor recommended by you gentlemen, once again many thanks :-))

The TID will be just shy of 6ft long  and 18 inches beam, so plenty of space for batteries etc.
I just got the drawing enlarged yesterday and will be making a start some time this week, I am planning to use 3mm marine ply for the hull, decks etc. with grp tape reinforced seams.
I built some sailing dinghies many moons ago using this method and it worked very well.
I`ll post some pics up when I start the build proper.
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Fastfaz

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Re: Motor/Prop query
« Reply #12 on: January 17, 2015, 06:10:52 PM »

   Hi again Brian,
         Wow! at that size you could make yourself the ballast. can't wait to see some pic's of the build and the finished article. I take it you are going on a body building course prior to launching.
            Cheers,
                  Peter. :-))
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