Heat dissipation - airflow direction?

[rhenbelz]

Hey guys, quick question.

I'm putting a fan on my ESC. Which way to I want it to go? I need to know if it's better for the airflow to go down onto the heatsink or up away from it.

The ESC is the Castle Creations Mamba Max ESC. I'm planning to run the fan off the 5V BEC.

[Tamiya Learner]

Away from the heatsink as the surrounding air is hot and you need to draw cooler air over the heatsink for it to be more efficient , like the expensive much-more motor cooler fan.

[necronomicon]

The heatsinks you have on computer processors often blow cool air down ONTO the heatsink, rather than try to suck the hot air away from them, so I would say the opposite to tamiya learner as an ESC heatsink is basically trying to do the same thing!