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Author Topic: Motor selection for 'High Hopes'...  (Read 4623 times)

U-33

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Motor selection for 'High Hopes'...
« on: April 15, 2014, 03:01:47 pm »

Right, you brainy lot...thinking caps on.

I'll shortly be looking for a motor for ''High Hopes'', my pulling tractor. Preferably brushless due to the fact that they are smaller and easier to hide.


Main criteria : it needs to have plenty of pulling power to be able to drag the sled, and plenty of revs to get the rear wheels spinning up prior to taking off.


It needs to be able to run from a small 11.1volt lipo battery, but only for a few seconds at a time, so the battery can be a small pack..easier to tuck away inside the turbine case.


Your ideas/comments/links will be much appreciated, chaps.




Rich
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Shipmate60

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Re: Motor selection...
« Reply #1 on: April 15, 2014, 03:06:05 pm »

Rich,
A g/box on a "hot" motor should do you well.


Bob
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U-33

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Re: Motor selection...
« Reply #2 on: April 15, 2014, 03:10:51 pm »

Gearboxes are a non starter, Bob..no room. The motor will be tucked away under the space between the end of the turbine case and transfer box, and drive the rear axle by a modified/shortened Tamiya drive shaft.


Rich
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Subculture

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Re: Motor selection...
« Reply #3 on: April 15, 2014, 03:15:54 pm »

You need lots of torque, which means having a large diameter motor or gearbox. Brushless motors are torquier than their brushed counterparts, but they can't work miracles.
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essex2visuvesi

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Re: Motor selection for 'High Hopes'...
« Reply #4 on: April 15, 2014, 03:40:57 pm »

If you can squeeze one in then a brushless out runner from a 450-500 sized helicopter should give you all the torque you need
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U-33

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Re: Motor selection for 'High Hopes'...
« Reply #5 on: April 15, 2014, 04:12:23 pm »

Thanks gents...I can possibly increase the size of the transfer box a touch, which would allow a slightly larger motor. It may be easier to get a working turbine!


Rich
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McGherkin

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Re: Motor selection for 'High Hopes'...
« Reply #6 on: April 15, 2014, 05:22:47 pm »

Ideally you will want an Outrunner for better torque. The motors in my lifeboat are Overlander Thumper V2 3548/5's, and are very torquey. Enough to propel a 1/16th Tamar VERY quickly. I don't know how that relates to tractor pulling but I'm guessing it'll go!
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Re: Motor selection for 'High Hopes'...
« Reply #7 on: April 15, 2014, 05:44:12 pm »

A rear axle was mentioned, so I would think that will have some form of reduction maybe 2 or 3:1. You don't specify the speed you want or wheel diameters, that can help with motor selection. If you're only using a smallish pack, that will limit the current you can pull. for best efficiency a motor should operate at about 75% of it's unloaded RPM.

I run 1/10th scale off road cars and generally the RPM range of those is between 2-3000RPM,  with motors running through gear reductions of about 7-8:1.
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essex2visuvesi

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Re: Motor selection for 'High Hopes'...
« Reply #8 on: April 15, 2014, 06:13:36 pm »

A rear axle was mentioned, so I would think that will have some form of reduction maybe 2 or 3:1. You don't specify the speed you want or wheel diameters, that can help with motor selection. If you're only using a smallish pack, that will limit the current you can pull. for best efficiency a motor should operate at about 75% of it's unloaded RPM.

I run 1/10th scale off road cars and generally the RPM range of those is between 2-3000RPM,  with motors running through gear reductions of about 7-8:1.


I know it's a bit of a thread hijack but what offroad car are you running?.... I'm running a Yokomo B-MAX4 III with 10.5T Brushless
Maybe we start another topic
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Re: Motor selection for 'High Hopes'...
« Reply #9 on: April 15, 2014, 06:35:39 pm »

They're old Tamiya cars mostly. Grasshopper/Hornet converted to brushless helicopter motor.
Monster Beetle and Frog, fairly standard but fully ball raced. Also have an AYK Buffalo and a Trial 12 (actually that's 1/12th scale). Don't run those two much as you can't get spares.

The modern kit is heaps better, but it's a bit like modern cars, well engineered and virtually viceless, hence a bit dull.
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nick_75au

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Re: Motor selection for 'High Hopes'...
« Reply #10 on: April 16, 2014, 05:32:46 am »

https://www.youtube.com/watch?v=FLQhvruimfs


Ones 650 HP, the other is 16 Hp LOL
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U-33

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Re: Motor selection for 'High Hopes'...
« Reply #11 on: April 16, 2014, 09:15:46 am »

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Netleyned

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Re: Motor selection for 'High Hopes'...
« Reply #12 on: April 16, 2014, 09:24:06 am »

Now Now Rich


Calm Down  {-) {-) {-)




Ned
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U-33

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Re: Motor selection for 'High Hopes'...
« Reply #13 on: April 16, 2014, 09:28:13 am »

I've gone all a'quivery...three of those in my tractor, it's enough to make any man go pale with excitement.   :o


Rich
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essex2visuvesi

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Re: Motor selection for 'High Hopes'...
« Reply #14 on: April 16, 2014, 09:47:11 am »

I've gone all a'quivery...three of those in my tractor, it's enough to make any man go pale with excitement.   :o


Rich


And I think your Bank manager will feel the same when he sees the cost  ;D
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U-33

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Re: Motor selection for 'High Hopes'...
« Reply #15 on: April 16, 2014, 09:53:48 am »

Hmm...well, I have just won my damages claim. What the bank manager doesn't see, he doesn't know about...  ;D




Rich
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MotorFlote build log : http://www.modelboatmayhem.co.uk/forum/index.php/topic,15222.0.html

IanPal

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Re: Motor selection for 'High Hopes'...
« Reply #16 on: April 24, 2014, 06:40:08 pm »

Go on Rich, you know you want to order them.
Although you do know if you do you will have me knocking on your door for a good look/watch  {-)




Hang on a second, each time I come to your place I seem to come away with another sub, your be trying to flog me that  one on the top of the wardrobe next to help pay for those turbines  :}


Just Had a look at your pic of the chassis, looking good mate, I bet you cant wait to get your hands on it.
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U-33

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Re: Motor selection for 'High Hopes'...
« Reply #17 on: April 24, 2014, 07:18:04 pm »

Hi Ian,

I'd love to fit a proper turbine in the tractor (three might be slightly overkill) but I'm not sure what the neighbours would think of me firing that up in the bedroom!

The chassis shouldn't be long now, wheels and tyres are sorted, I'm about to make a start on the bodywork. I've built yet another turbine, wasn't happy with the first two attempts...I'll show you next time you're over.

The sub on the wardrobe...you after that as well? It's big...

Rich






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~~~~~~~  "Motorflotes need love too...."  ~~~~~~~

MotorFlote build log : http://www.modelboatmayhem.co.uk/forum/index.php/topic,15222.0.html

IanPal

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Re: Motor selection for 'High Hopes'...
« Reply #18 on: April 24, 2014, 10:30:35 pm »

I wouldn't worry about the neighbours, just think what your lady friend would say, I guess you could always ask if she felt the earth move too  {-)


I know that sub's big, but you don't want to let that one go, you have plans for it don't you?


But if you ever did decide you would have to let me know how much first, then second I'd have to work out how to get it by the other half  :-X


By the way I've just ordered two books, simply submarines and submarine technology from amazon, so should have a good read soon.
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U-33

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Re: Motor selection for 'High Hopes'...
« Reply #19 on: April 25, 2014, 08:45:18 am »

Lordy lordy, she would go barmy if I ran up a turbine in the bedroom...might be safer to take it outside, methinks.


Pop over next Wednesday evening for a coffee and a natter about the big sub if you like...or any evening.




Rich
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IanPal

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Re: Motor selection for 'High Hopes'...
« Reply #20 on: April 25, 2014, 09:01:03 am »

 Next Wednesday is fine. You make me laugh, a month or so ago you had never seen or touched one of those Tamiya trucks, now look,  you have them coming out of your ears, a Volvo, Scania and another chassis being built up for the tractor puller  {-)
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U-33

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Re: Motor selection for 'High Hopes'...
« Reply #21 on: April 25, 2014, 09:29:55 am »

I like to keep my mind and my fingers occupied Ian...the more I work the fingers, the longer they will be useable...I do a bit on one, then put that down and do a bit on another...and so on.


The tractor...ah yes, the tractor. That's been a long time obsession of mine for years...you'd think it would be a simple job to build a realistic looking model turbine, wouldn't you? After all, it's only a tube with a few bits of pipework here and there...wrong. I'm on number three so far, and still not happy with it.


Oh well...onwards and upwards in a cylindrical manner.  %)




Rich
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MotorFlote build log : http://www.modelboatmayhem.co.uk/forum/index.php/topic,15222.0.html
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