fan motors?

[fooman2008]

hey all,
On this and several other board and web sites I have read about people using radiator fan motor (from cars) for propulsion (especially tugs) are they any good? I can get parts from a local autoparts graveyard and was wondering if this would be worth pursuing.
My current plan is to use trolling motors, but if the radiator motors will work and be less expensive then maybe that's how I'll go.
Foo

[patmat2350]

Pros: Cheap, runs on 12v, robust
Cons: TBD... questions: does it run at a usable speed for YOUR prop; if not, gears may be needed. How does it mount? Many automotive motors are bespoke designs that are built into the surrounding hardware.

These fan motors tend to be in the 50-70 watt range... on 12v, that suggests 4-6 amp draw in their loaded condition. That's a good range for a large tug prop.

For determing free-running speed, see my previous posts on determining Kv value with a drill press.

[PatricMichigan]

Will require some trial and error and time investigating the motors- as Pat said, mounting is going to be a problem. Would probably end up with a 'universal' type motor. (universal means it doesn't really fit any car lol)
I would be afraid of the current draw though- maybe the radiator fan motors would work but the inside blower motors that I see recommended are going to be very high current draw motors so I never understood how those were going to work very well.

Patric

[mfr02]

I have yet to find a fan motor with excessive current draw. If you look at your car fuses, fan circuits are very rarely rated over 10 amps, indicating a normal running current below 5 amps. Heater fan and radiator fan motors have both been used by members of my club without problems. Window winder motors work well. Provided the motor does not have too many custom lugs poking out in unexpected directions, mounting should not be a problem.
Some older motors might be field wound rather than permanent magnet types - these are best avoided as reversing them is a problem quite apart from the bulk.
Most are a tube that fits into a plastic mounting in the car - for boats all that is needed is a bed to sit it in with a metal strap over tensioned down with a bolt each end.

[Umi_Ryuzuki]

I know of modelers that have used heater
fan motors, but not radiator fan motors.

[pompebled]

My modified car radiator fan motor.

I had the shaft milled down from 8 to 5 mm to be able to use commercial available couplers.

The cooling is a bit excessive for a tug, a simple coil and maybe brushcooling will do on 12V.
Mine is intended to run on 24V in a MTB, hence the more elaborate cooling.

Regards, Jan.

[pompebled]

Fooman,

I saw the large scale project you're working on, if the motors are for that hull, don't bother with the (tiny) motor I show one post up, two of those will not perform sufficiently. (My MTB hull is only 43,3" long)
I've seen an article on a 4m Bismarck build that used two Bosch starter motors, paired on each shaft using toothed belts, which allowed for high scale speed.
The hull had at least two pairs of these, I'd have to look up the article to be sure...

The builder had his ESC's custom build, nowadays the ESC's used in battlebots would be a good choice.

Regards, Jan.

[BigDutch]

hey all,
On this and several other board and web sites I have read about people using radiator fan motor (from cars) for propulsion (especially tugs) are they any good? I can get parts from a local autoparts graveyard and was wondering if this would be worth pursuing.
My current plan is to use trolling motors, but if the radiator motors will work and be less expensive then maybe that's how I'll go.
Foo

Try surpluscenter.com. They had a ton of very reasonable priced new radiator fan motors of many different manufactorers as of last year.

[nick_75au]

Hi Fooman,
Here,s another option, less pricey than the trolling motors but no guess work with second hand blower motors, They would be roughly $70 US each.

http://static.rcgroups.com/forums/attachments/1/4/2/9/4/2/a1995093-111-Picture%20010.jpg

Post 136 in the Tygum Lagoon thread, Its Johns 11 foot USS Washington, powered with 700's through a 12:1 planetary gearbox. He runs a blower motor in his tanker Amanda Miller as well but is converting to a single motor setup as in his Washington.

One of those motors John Darke reckons will power the rescue Tinny we have with ease. A 16 :1 gearbox and 130 mm Raboesch props.

Regards
Nick

[fooman2008]

Tank you all, the auto salvage wanted $35 a piece for "some motors from busted radiator fans" didn't exactly inspire huge confidence.... The surplus store is definitely on the schedule for the next few days and I'll see what they have. I live within 40 miles (close for rural Idaho) of the largest surplus store in Idaho so it's not so bad.
As for starter motors that would be just the motor itself without the bendix? detech it from the bendix and just use the motor?
Other good news is that Eastern Idaho has about 25 potato processors within 10 miles of my place and their attendant suppliers for belt drives, gear boxes, motors, clutches, tensioners, so at leat gearing it and driving a shaft(s) won't be a problem.
A further question is it worth it for the complexity of using all four drives? It seems to be twice as many holes in the boat and electrical problems waiting to happen.

[P_J_Glor]

So, would you say that a motor like this 12 volt dc 3900 rpm would be suitable for a 40 - 60" hull? http://www.surpluscenter.com/item.asp?UID=2009021318331827&item=10-PM3609&catname=electric

It would go in a 42" tugboat or 60" Laker.

Pete G.

[Shaun Hendricks]

This puppy is 2.77" in diameter. If you removed the gearhead, it would probably run perfect for a high torque direct drive application:

http://www.allelectronics.com/make-a-store/item/DCM-331/24VDC-GEARHEAD-MOTOR/1.html

[nick_75au]

Hi fooman,

Me personally, yes its worth it, I guess you will have to answer that yourself. Trolling motors are most likely the simplest solution, in the long run, cheapest as well, Ill take back my comment "less pricey than the trolling motors" , once you take into account they already have speed control and steering built in. I think they will take away some of the "scale appeal" though.

A problem with the starter motors is if you want reverse there is a fair bit of work in modifying them. the negative has to be isolated from the case, field and armature windings have to be isolated from each other plus removing bendix etc Fighting Robot building forums have lots of information on how to do it if you search around.

Thats handy with the surplus store, I reckon you will be making more than one trip :D

Regards
Nick

[nick_75au]

Hi Pete,

I think the RPM is a little high for direct drive, depends on what size prop though.
My Nexus Tide is 63 inches long with a 100mm prop, the 2400 rpm motor is fine.
If you were running around 60-70 mm prop it would be about right I think.
Nick

[P_J_Glor]

Well, then, they have a 1900 rpm 12 v motor that is 3" in diameter, .9 amp at no load.

Here: http://www.surpluscenter.com/item.asp?UID=2009021318331827&item=10-1564&catname=electric

Pete G.

[mxz70017]

Hello fooman
I saw what Nick posted hes correct. Robotics stores offer a great deal of motors. An gearing As well as electric speed controls too.It just so happens, Ive had this site In my Favorites for some time!!!I hope It helps you...
http://www.robotmarketplace.com/store.html

[pompebled]

A further question is it worth it for the complexity of using all four drives? It seems to be twice as many holes in the boat and electrical problems waiting to happen.

How close to scale you want to stay is your decision, I don't see any electrical problems with an increased number of shafts/propshafts/motors, it's the increasing number/size of ESC needed that would be a (financial) concern.
Have you checked the prices on the battlebot ESC's?

Regards, Jan.

[pompebled]

So, would you say that a motor like this 12 volt dc 3900 rpm would be suitable for a 40 - 60" hull? http://www.surpluscenter.com/item.asp?UID=2009021318331827&item=10-PM3609&catname=electric
It would go in a 42" tugboat or 60" Laker.
Pete G.

Yes, it would.
Most likely even without having to add watercooling, if the load is within the parameters.
If the motor has to work hard in a tug, modifying the can by adding cooling slots and adding watercooling is advisable, to keep the motortemperature down.
Cooling the ESC is a good thing too, if the motor has to work hard.

Regards, Jan.