<p>Look at your fan: it spins in one direction, and the blades push the air from one air to the other side. In fact, the fan is nothing but a propeller! There are ways <a href="https://medium.com/@SimScale/how-to-optimize-a-propeller-design-c724329f97e" rel="nofollow noreferrer">to optimize them</a>. The Rotation goes for example clockwise, the leading edge <em>grabs</em> the air and the trailing edge <em>releases</em> it on the other side, and if the leading edge is towards you, then the air is pushed away. In the simplest way, it would suffice to physically flip the fan around.</p>
<p>A 3D printed new fan would need to have the whole geometry of the fan blades &quot;flipped&quot; (mirrored around a non-rotational axis). Now the leading edge of the fan is away from you, the trailing edge on your side, the airstream is again from the leading to the trailing edge, and the air comes out on your side.</p>
<h1>cave!</h1>
<p>Not all fans can be made to reverse the airflow by flipping the fan geometry: Radial fans just because less efficient.</p>
<p>Other fans can be made spinning backwards by swapping the polarity, but others use a simple diode setup and always spin their way. Also note that fans spinning backwards often suffer from reduced efficiency, as the blade geometry is optimized for one direction of spinning.</p>

CC BY-SA 4.0
2021-04-18T17:18:14.410Z
@DaVinziBoi for what? designing parts or making them printable? Many slicers allow to mirror items designed one way to create a mirror image - if the item has its "rotational" axis up, mirroring over either X or Y will create a "reverse".
Trish
CC BY-SA 4.0
2021-04-19T04:43:52.260Z
Just making designs which are printable.
DaVinziBoi
CC BY-SA 4.0
2021-04-19T10:18:12.017Z
Any CAD suite works. I like Autodesk Fusion 360,;others like different software
Trish
CC BY-SA 4.0
2021-04-18T11:51:51.783Z
2021-04-19T10:17:04.497Z
2021-04-19T10:17:04.497Z
Trish
<p>I am new to 3D Printing and I have taken up a summer project. The project requires a fan 3D Printed, If I use a normal fan the airflow will make my project (i.e. a air-propelled car) go backward. Can we modify a fan so that when the fans spin my car goes forward? If yes, how?</p>

<3d-design>
How can we control the airflow in a fan which can be 3D printed?
DaVinziBoi
# How can we control the airflow in a fan which can be 3D printed?

(Asked by: username_0 on 2021-04-18)

I am new to 3D Printing and I have taken up a summer project. The project requires a fan 3D Printed, If I use a normal fan the airflow will make my project (i.e. a air-propelled car) go backward. Can we modify a fan so that when the fans spin my car goes forward? If yes, how?

**Tags:** 3d-design

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## 1 answers

### Answer by username_1 on 2021-04-18. Score: 0 | Accepted answer

Look at your fan: it spins in one direction, and the blades push the air from one air to the other side. In fact, the fan is nothing but a propeller! There are ways [to optimize them](https://medium.com/@SimScale/how-to-optimize-a-propeller-design-c724329f97e). The Rotation goes for example clockwise, the leading edge *grabs* the air and the trailing edge *releases* it on the other side, and if the leading edge is towards you, then the air is pushed away. In the simplest way, it would suffice to physically flip the fan around.

A 3D printed new fan would need to have the whole geometry of the fan blades "flipped" (mirrored around a non-rotational axis). Now the leading edge of the fan is away from you, the trailing edge on your side, the airstream is again from the leading to the trailing edge, and the air comes out on your side.

# cave!

Not all fans can be made to reverse the airflow by flipping the fan geometry: Radial fans just because less efficient.

Other fans can be made spinning backwards by swapping the polarity, but others use a simple diode setup and always spin their way. Also note that fans spinning backwards often suffer from reduced efficiency, as the blade geometry is optimized for one direction of spinning.

> **Comments:**
> **username_1**: @DaVinziBoi for what? designing parts or making them printable? Many slicers allow to mirror items designed one way to create a mirror image - if the item has its "rotational" axis up, mirroring over either X or Y will create a "reverse".  
> **username_0**: Just making designs which are printable.  
> **username_1**: Any CAD suite works. I like Autodesk Fusion 360,;others like different software  

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