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Old 07-28-2019, 10:13 PM
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Default Cooling fan location

Just wondering if anyone has mounted their motor cooling fan in front of the motor rather than behind? Did it cool more efficiently ? I would imagine that it's better in this spot if you can fit it rather than blowing hot air back at the esc and receiver against the direction of the air as the car travels forward.
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Old 07-28-2019, 10:28 PM
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The body acts like a bubble. Air swirls around inside it. There is no preferred direction of airflow inside the body. (EDIT: "preferred" by the laws of physics, that is. obviously humans would prefer that the air flow smoothly front-to-rear, but there's nothing we can do about that unless we want to cut a bunch of holes in the body and ruin its aerodynamics in the process.)
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Old 07-29-2019, 08:08 AM
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The best place in my tc is 2cms behind the motor. Any closer and it slows or eventually stops.
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Old 07-29-2019, 08:36 AM
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The best place for a fan, is on the other side of a duct from the motor. The interior of a car is confused and turbulant. "where" the fan is, has no real bearing in there. Being confused and busy air, any stream of air from a fan, is going to be disapated quickly. so you want it close to the motor. A duct keeps the airflow attached to the motor as much as you can, giving you the best cooling you can get.
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Old 07-29-2019, 11:47 PM
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Having the fan in front of the motor (as on mid-motor cars) rather than behind may help marginally but not much. Today's fans are very powerful so they will suck in air from any direction. It's more important to use some kind of ducting, especially on the underside of the gap between motor & fan. This is where the airflow is cleanest and going in the wrong direction as it's air trapped under the chassis rather than swirling around in the shell. A bit of tape or plastic joining the base of the fan to the base of the motor helps cooling a fair bit.
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Old 07-30-2019, 12:37 AM
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Using the data log my motor was 10 degrees cooler with the fan in the front on my mid motor A800.
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Old 07-30-2019, 01:32 AM
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Originally Posted by c-lyon View Post
The best place in my tc is 2cms behind the motor. Any closer and it slows or eventually stops.
If you can't get your fan any closer than 2cm without it stopping, you need a better fan.
You want it closer than that, seem to recall around 8mm was best.
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Old 07-30-2019, 01:40 AM
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Originally Posted by Marcos.J View Post
Using the data log my motor was 10 degrees cooler with the fan in the front on my mid motor A800.
Cool! Data is good. That said, any sort of duct would likely blow that out of the water. :-)
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Old 07-30-2019, 03:52 AM
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Originally Posted by Nerobro View Post
Cool! Data is good. That said, any sort of duct would likely blow that out of the water. :-)
yes lol I say mount it where ever you like too and let the data log tell you where the motor run the coolest
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Old 07-30-2019, 03:06 PM
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With heavy-ventilated motor cages, I suppose we should get better results if we pull the air out of the motor, the air entering by the different ways available. Two problems about that:
- First the duct you used has to be properly sealed to the motor
- Second the available fans are not designed to create depressions like that. They can only push some air in the correct direction.
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Old 07-30-2019, 03:48 PM
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Originally Posted by Airwave View Post
With heavy-ventilated motor cages, I suppose we should get better results if we pull the air out of the motor, the air entering by the different ways available. Two problems about that:
- First the duct you used has to be properly sealed to the motor
- Second the available fans are not designed to create depressions like that. They can only push some air in the correct direction.
all good points thatís why I chose the location by using the data log on the esc . Unless someone has a better method of checking the hottest reading of the motor Iím all ears
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Old 07-30-2019, 07:11 PM
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Thanks Skiddins. Today I ran with/without the fan. The difference was between 35 and 40f. It's a Reedy fan, and motor.
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Old 07-30-2019, 07:27 PM
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heat conducts through the mounting flange to the bulkhead allot faster than it can be dissipated by convection. Fan placement that helps convect the heat that is conducted would help. the more heat storage the bulkhead has the higher peak torques you can use and still have a low enough temperature that a fan can conduct it away.

overheating occurs when there is not enough time for air to convect the heat away. its an average of peak torques (current) and continuous current. if you store enough of it in the metal around it and it has enough surface area to be cooled while its stored you can dissipate more heat over a shorter time.

and in some cases minimize the need for a fan.

I dig science if you cant tell. There is a massive amount of heat storage in materials that change state. For example a solid to a liquid like wax, alcohol or ice or water (as in boiled). Too bad heat pipes are illegal.
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Old 07-31-2019, 12:20 PM
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We recently had a discussion trackside about whether it was better to have a fan in a duct pushing air into the motor (blowing) or pulling air through the motor (sucking). We didn't come up with a solid answer. Ideas?
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Old 07-31-2019, 12:24 PM
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You can't direct air going "into" a fan. You can direct air using pressure. Where you care about doing cooling, you're doing blowing, not sucking.
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