Hello guys, I’m new in Blender,
I was trying to model this, the cylinder (1) was quite easy to model, but those “propellers” (2) it’s been very difficult. The other type (3) of those propellers I think I can model with a cube and position it later. The holes (4) I can just use a boolean modifier, right? Or another cylinder, I don’t know.
I have a image inside too, but I can’t upload two medias.
A big thanks in advance.
This is a really crude example that I whipped up in 5 minutes, but it shows off how I’d go about designing those shapes.
For the circular divots, I’d block out the shape with simple geometry, subdivide, then add the constraint loops. Notice how I spread the constraint loop out, so that it tightens the corner of that keyhole shape without defining a sharp ridge along the rest of the shape. You want to constrain what needs to be constrained, and for the rest, you just loosen things up, and scale it so that it keeps the curve.
For the fins, just grab your faces, inset, then take the top set of quads, and flatten them so they’re even with the rest of the surface. That’ll give you that blend you’re wanting. From there, you just add more constraint loops to sharpen out the bits and bobs.
Keep in mind that constraint loops can be moved around. They don’t have to be uniform. It requires a bit of work to adjust, but it’s key to making weird shapes like this in SubD modeling.
And the file, if you want to study it more up close.
CylinderThing.blend (1015.8 KB)
You don’t need to create the whole of that modeling.
It’s marked in quarters, but it’s possible with smaller pieces.
Modelling with Bevel and Boolean can’t expect good results.
However, modeling with Bevel and Boolean is easy and fast to produce basic guides for understanding shapes.
Topology modeling seems necessary for modeling of the end goal, please refer to the video below.
This video is not a solution.
Look at it as a reference to how to model 
That’s great, big thanks, brother. I’ll try this way. The file that you create will help me a lot 
Really awesome. You didn’t catch the fish for me, but you’re teaching me how to fish. Thanks a lot, if I improve my topology modelling skills I will certainly make it soon . A big thanks for your time, brother
Attached is the modeling using Bevel and Boolean.
gsdgsd.blend (1.4 MB)
The shape is not correct.
But it’s a good way to quickly figure out the shape.
Because most modifiers are retained, modifications take effect when you make them.
I hope it helped you. 
