Fans on motors and esc

[ghostdogg]

Hi all,
Daft question but what way round do you mount the fan?
Blow air onto the motor or esc or take hot air away from the motor or esc!!!!

Cheers

[mattr]

In theory it makes little to no difference, in practice, blowing on to the item will work best.

(As long as you have somewhere for cool air to get into your shell and through the fan!!)

[simoncrabb]

Yes, agreed, blowing tends to work better than sucking.

I think the reason for this is sucking pulls air from areas other than the heat source, as it's not a 'sealed' air source.

But by blowing the air kinda can't miss the hot bits.

[Cardnim]

Damn good question though Ghostdog - I had never thought about that before.
Interesting.

Good to know that ive got the fan on correctly though so it blows (even though I 'suck' at racing)

[Gunter]

During the national events this year in touring cars (sorry buggy boys) we found that sucking the air reduced the heat by between 5 and 10 deg more than blowing.

This dose depend on the position of everything of course, fan infront of the motor in the direction of travel needs to be blowing, fan behind the motor needs to be sucking.

Basically you want to move the air faster in the direction its already traveling, not try blow air back againt the direction of travel and stalling the hot air around the motor heating it up and making things worse.

[Cardnim]

a "touring" car?
Nope, thats a new one on me.

[kayce]

Originally Posted by Gunter

During the national events this year in touring cars (sorry buggy boys) we found that sucking the air reduced the heat by between 5 and 10 deg more than blowing.

This dose depend on the position of everything of course, fan infront of the motor in the direction of travel needs to be blowing, fan behind the motor needs to be sucking.

I'd like to see pics on how that was accomplished, but (like many such temp lowering propositions) it seems be a rather drastic change that seems rather unobtainable. 10 degrees just seems like a huge variation.
But, being as most rc company's fans are designed to blow on items, it makes sense they'd know what they're doing (maybe not ).

Yet it also seems that a lot of people use fans as a fix to address overheating, despite them being more of a bandage, as I was always taught to get your temps to an acceptable level before adding a fan.

[Gunter]

Originally Posted by kayce

I'd like to see pics on how that was accomplished, but (like many such temp lowering propositions) it seems be a rather drastic change that seems rather unobtainable. 10 degrees just seems like a huge variation.
But, being as most rc company's fans are designed to blow on items, it makes sense they'd know what they're doing (maybe not ).

Yet it also seems that a lot of people use fans as a fix to address overheating, despite them being more of a bandage, as I was always taught to get your temps to an acceptable level before adding a fan.

At the end the day I'm offering my opinion from my experiences, what are you offering other than abuse? There Neva seems to be anything other than abuse that comes from the posts and some knowledge and advice would be more useful.

If I'm wrong I'm wrong but inless you have tryed it and found that blowing works better then fine but in my application pulling the hot air away from the motor works better.

[kayce]

Originally Posted by Gunter

At the end the day I'm offering my opinion from my experiences, what are you offering other than abuse? There Neva seems to be anything other than abuse that comes from the posts and some knowledge and advice would be more useful.

If I'm wrong I'm wrong but inless you have tryed it and found that blowing works better then fine but in my application pulling the hot air away from the motor works better.

If you're talking about something you're just making up, then it's just random jabbering about something you don't know what you're talking about. It's not abuse when somebody calls you out on your inaccuracies, or stuff you just make up on the fly - it's throwing the BS-Flag.

This is just like the thread(s) yesterday where you started with your "don't get a SP motor, I heard they melt" BS posts.

Stick to the things you know as fact or has some chance of being somewhat viable, or things you can support with some kind of evidence, but don't make up stuff and expect not to get called on it. It doesn't make it a (viable) opinion if you pull it out of your arse.

[Gunter]

But as I said last night I have blown up a SP motor so I am talking from experience so why u still going on about that.

And the entire associated team run fans blowing air away from the motor so it's not just jabber it's what we have found.

Shame u not offering any advice from your experiences, possibly due to the lack of them.

[kayce]

Saying "I heard they melt" is a far reach from "I have burned up a few myself" which would allude to some experience, and meanwhile all you keep showing is a lack there of and/or inexperience... as thus far, it seems you're the only one.

And, as I said yesterday, just having a motor go bad is not proof of much - being as I'm guessing that list would logically included EVERY brand out there.


(p.s. NO, the guy that overgeared and/or overtimed his motor does not count)

[stumpiey]

I personally dont run a fan on my motors in either touring sheds or buggys, i feel it gives a false reading when you temp it after a run.
I have seen it quite a few times people temping thier motors with huge fans and saying "great, its only 50c" then up the timing or boost and then it goes pop.
Although a fan will help get rid of some heat, the internal temp will be a lot higher.

stumpy

[OneKiwi]

If you build a little box with slots at the ends of the cooling fins and have a fan on top that could work well, as long as there was enuff cool air coming in and a place to remove the warm air.... too complicated, blow on that sucker

[Chris Green]

I believe in a touring car, drawing air across the motor will be more effective than blowing. A touring car has a constant supply of fresh air entering the car, through the gaps around the shell, and through the chassis. sucking air across the motor will encourage the cool air through the car. Blowing air onto the motor, will have a negative effect, as it will have the natural airstream entering the car to fight against.

In a buggy, where the chassis is sealed close to the bodyshell, the I'd expect blowing to be more effective. inside a buggy shell, it is almost a sealed air space. With a fan inside the sealed space you are relying on the velocity of air to cool the motor down.
Just like putting a fan inside a sealed room at home. It wont cool the air in the room effectively at all, but the air temperature leaving the fan blade will be considerably cooler than the ambient temperature.



Just my ramblings. Not based on "fact" as such.

[kayce]

Originally Posted by Chris Green

I believe in a touring car, drawing air across the motor will be more effective than blowing. A touring car has a constant supply of fresh air entering the car, through the gaps around the shell, and through the chassis. sucking air across the motor will encourage the cool air through the car. Blowing air onto the motor, will have a negative effect, as it will have the natural airstream entering the car to fight against.

Just my ramblings. Not based on "fact" as such.

Unfortunately, that's about like saying if you stuck small desk fan in the middle of a large room that had it's windows open, it would have any direct effect on lowering the overall ambient temperature in the room. Maybe vaguely, at best, but probably not.

[mattr]

Originally Posted by Gunter

During the national events this year in touring cars (sorry buggy boys) we found that sucking the air reduced the heat by between 5 and 10 deg more than blowing.

this is where theory and practise differs.

Best place for a fan, for maximum efficiency is in "clean air" so putting it in a position where it needs to suck (behind the motor) instantly puts it at a disadvantage due to the lack of clean air.

On the flip side, how "clean" is the air in front of the motor (in a blowing location)?
No-one knows, not without a wind tunnel anyway. And it will differ depending on car type, motor/ESC location, holes in the body shell (either sealing, cut holes, ducts, whatever). Then you have to consider packaging it all in as well, where do you have room for the fan, above, behind, in front (underneath!)? The difference between getting it wrong and getting it right could make 5-10 degrees performance difference depending on what temps you have in the first place (ambient, motor and/or ESC).

My specific example is on my buggy, with an ESC fan, where sucking thro all those fins on the heatsink really doesn't do it any favours, whereas blowing on to the heatsink fins, and consequently sucking the air from the intake above the ESC gives cleaner air flow (there is that damn theory again.......!) into the fan (and a more efficient fan, and more cooling)

Who knew that work would come in useful for RC cars

[Gunter]

Originally Posted by kayce

Unfortunately, that's about like saying if you stuck small desk fan in the middle of a large room that had it's windows open, it would have any direct effect on lowering the overall ambient temperature in the room. Maybe vaguely, at best, but probably not.

Just try it before 'bashing it' which u seem so against.

And thanks Matt for a decent reply, we just found in the AE touring team that pulling the air over the motor and away for it worked best, if we had space to put a motor infront of the motor aswell we would of and I think this would of been a huge help but there just is not that mch room.

And I agree sucking air off a speedo heatsink fins would do next to nothig

[jmke]

blowing air onto a heatsink will be more effective unless you can guide the airflow correctly over the motor/esc when sucking air away. Inside PCs you can create a nice tunnel and thus sucking air from front to back is easy peasy. Inside a car which has a lot more holes it's less straightforward to create such a tunnel effect. Thus blowing air onto your heatsink will be most beneficial.

of course it only takes 5 minutes to swap the fan around; so you can test it easily just be sure to measure ambient temp also at each reading, otherwise the value is worthless. Saying that you motor is 50°C without mentioning ambient temp doesn't give people a value they can use to compare

[kayce]

Originally Posted by Gunter

Just try it before 'bashing it' which u seem so against.

And thanks Matt for a decent reply, we just found in the AE touring team that pulling the air over the motor and away for it worked best, if we had space to put a motor infront of the motor aswell we would of and I think this would of been a huge help but there just is not that mch room.

Originally Posted by mattr

this is where theory and practise differs.

Best place for a fan, for maximum efficiency is in "clean air" so putting it in a position where it needs to suck (behind the motor) instantly puts it at a disadvantage due to the lack of clean air.

On the flip side, how "clean" is the air in front of the motor (in a blowing location)?
No-one knows, not without a wind tunnel anyway. And it will differ depending on car type, motor/ESC location, holes in the body shell (either sealing, cut holes, ducts, whatever). Then you have to consider packaging it all in as well, where do you have room for the fan, above, behind, in front (underneath!)? The difference between getting it wrong and getting it right could make 5-10 degrees performance difference depending on what temps you have in the first place (ambient, motor and/or ESC).

My specific example is on my buggy, with an ESC fan, where sucking thro all those fins on the heatsink really doesn't do it any favours, whereas blowing on to the heatsink fins, and consequently sucking the air from the intake above the ESC gives cleaner air flow (there is that damn theory again.......!) into the fan (and a more efficient fan, and more cooling)

Who knew that work would come in useful for RC cars

Originally Posted by jmke

blowing air onto a heatsink will be more effective unless you can guide the airflow correctly over the motor/esc when sucking air away. Inside PCs you can create a nice tunnel and thus sucking air from front to back is easy peasy. Inside a car which has a lot more holes it's less straightforward to create such a tunnel effect. Thus blowing air onto your heatsink will be most beneficial.

Exactly, these so-called "other theories" were first explored years and years ago when we first started using fans (or even before that when we had boxes we placed our cars on after races, designed to suck the heat away from a hot motor/that didn't work) - only to discover that like so many wild ideas the best cooling was given when the fan was directed right onto the motor/esc itself (in the same manner that a fan blowing right on your face feels better than it does if it's placed behind you pulling away) and thus why every company's fanmounts were assimilated direct cooling instead of offering random mounting.