Windmill tutorial

In this tutorial, we will create a simple three-blade horizontal shaft windmill. Although not indicated, you move around in the 3D universe by pressing the Middle Mouse Button or (MMB) to do a rotation. If you want to pan inside the window, press Shift and use the MMB. You can zoom in or out of the object by turning the MMB in either direction. You make a selection with the Right Mouse Button, (RMB). The Left Mouse Button, (LMB) is used for the placement of the cursor in the 3D window. If you made a mistake, press the Ctrl key with Z to go back to your previous state. You can go from Top, Front and Side view by pressing Num 7, 1, 3 (the numbers on the right hand side of the keyboard) respectively. If your view looks a little odd, you may, by accident, have gone into perspective view. That happens quite easily. Press Num 5 to go back to orthographic view.

Blender is a powerful tool. It takes time to master, but once proficient you will be able to create fantastic things with it.

Happy Blending!

Mast

Start Blender and delete the default cube: X Erase selected Object(s) -> yes. While still in Object mode, create what will be the mast. The unit of measurement in Blender is the Blender Unit or BU. This unit can be anything in the real world: a BU can be a mm, a cm, a dm or a metre. For the following example, we can decide that a BU represents a metre.

We go in the middle of the 3D view and press the spacebar. We go to Add->Mesh->Cylinder

A box will appear, asking for the parameters of the cylinder. You can decrease the numbers of vertices down to 20, a radius of .5 and a depth of 10. You can use the left and right arrows to select the parameters of the properties or click on the boxes and manually add the numbers. Press OK when done.

We now see a circle from the top view. If we move around by pressing the middle mouse button (MMB), we see that the circle is actually a cylinder.

All our vertices, the yellow points, are selected. Good. We will now use the front view by pressing 1 on the numeric keypad on the right hand side of the keyboard or Num 1. N.B.: The numbers on top of the keyboard have another function.

We will move the cylinder from the middle to the top of the X axis. While all the vertices are selected, press G, for the grab function, followed by Z; a white vertical line will appear as an indication that the object can move up or down. Move the mouse; you will see that the cylinder follows the movement along the Z axis. Press the Ctrl key with your left hand and move the mouse with your right; the cylinder will move in incremental steps. When it reaches the top of the X axis, release the mouse button. The cylinder now sits on top of the X axis. If you make any mistakes, you can always retrace your steps by pressing Ctrl-Z.

Our cursor is still at the origin (0,0,0). We will create a plane that represent the field for our windmill. Go to the top view using Num 7, press the spacebar and Add -> Plane.

The plane is selected. Press S for scale and without touching the mouse, press 10 on the keyboard for the scale factor. We now have a field of 10 by 10 BU. If we press Tab and go into object mode, we should have something like the following.

Nacelle

The nacelle contains all the necessary elements to transform the wind movement into electricity. For this exercise, we will add another cylinder that will represent the nacelle. Go back into edit mode by pressing Tab. Now select the Front view by pressing Num 1 on the keypad. (Always remember that the top view is Num 7, the Front view is Num 1 and the side view is Num 3)

The next step is to de-select everything by pressing the A key. We will select the top end of the cylinder by pressing B (for Box selection). Our cursor is now a cross-hair that will draw a box: go to the top left of the cylinder, press the left mouse button (LMB), and hold it down. Go down to the bottom right hand side of the upper end of the cylinder. While doing this, you will see the vertices changes to yellow inside the box.

We will now move the pointer from the origin to the top of the cylinder without touching the left mouse button (LMB). Press the combination key Shift-S, a menu will appear. Choose Cursor -> Selection.

We now create another cylinder like the first time; Spacebar -> Add -> Cylinder The image shows a depth of 5, but change yours to 3 instead.

Our nacelle has been created.

But the nacelle is right in the middle of the top cylinder, like a T. Normally, the heavy equipment used to generate electricity acts also as a counterweight to the rotor. So to simulate this, we will move the nacelle a little bit. Switch to the side view with Num 3.

We're going to make a simple displacement. Press G followed by Y to force movement along the Y axis. While you move the nacelle press the Ctrl key to force incremental movement and place the cylinder off-axis to the right.

Congratulations, your windmill has been completed! Now would be a good time to give your project a name and save it by pressing Ctrl-W. Remember that in Blender, you use Ctrl-write to save a project and not Ctrl-save! By default, Blender saves files under the .blend extension, so choose an appropriate name like MyWindmill.blend.

Bulb

We will create a bulb that goes in front of the nacelle and hides away the hub that holds the airfoils. After we save our project, we create a new file by pressing Ctrl-X. Remember, if you haven't saved your project, Blender never ask you Are you sure?; Blender takes for granted that you know what you are doing. So if you do a Ctrl-X, you will have a laconic message OK? Erase All; if you say yes and haven't saved your project, you'll have to start again!

Click on the dialog box and a new project starts with the default cube. Erase the default cube, X, and go to the Front view with Num 1. Press Spacebar, Add -> Mesh -> UVSphere and add the following parameters.

We now have a sphere that we will cut in half. Go to the Top View with Num 7. De select everything with A. Select B the upper half of the sphere.

and erase that half sphere with X -> Vertices

We now have half a sphere that will cover the hub. Select B all the vertices on the X axis.

We will create a small space for our airfoils. Extrude E -> Only Edges along the Y axis by typing a distance of .3. The bulb should look like this.

Optional

We can have a more finished look by smoothing out the faces. It's a two step operation where the most difficult part is locating the correct buttons. First select all the vertices A. Press F9 and locate the panel Modifiers at the bottom of the screen. (You can pan inside this panel by pressing MMB). Click the Add Modifier button and select Subsurf.

Once selected, you will notice that the edges have a softer look. Go ahead and increase the smoothness of the bulb by increasing the level to 2.

Click on Set Smooth on the Links and Materials panel.

You now have an aerodynamic bulb that will go in front of the nacelle! Save your project under *.blend extension!

Airfoils

Figure 1: Naca airfoil profile

Now comes the most difficult part of this tutorial: creating an airfoil profile for our windmill. If you followed along, it should not be too difficult. To create the shape, we will use a background image, create a spline profile that will be transformed into a shape that will then be extruded and duplicated. Ok. Now create a new file Ctrl-X, and erase the cube X -> Erase selected Object(s). Download and save the image on your desktop. This is an airfoil profile and is used in the creation of windmill blades.

The next step is to put the profile image in the background of the 3D window and copy the shape. Click on the View menu on the lower left corner of the 3D window and select Background image menu item.

A small Background Panel will appear in the 3D desktop. Click on the Use Background Image button. Select Load and select the NACA profile file that you saved.

Keep the default values: it is much easier to create a large profile and scale it back than to work on a small picture at the right size. Press Spacebar -> Add -> Curve -> Bezier Curve. This will be our basic curve out of which we will create this complex curved shape.

We now see a black curved line connected by two straight lines. Those lines are the handles that manipulates the curvature of the Bezier curve that is the black line. The two extremities are handles that control curvature and orientation. The middle point is a pivot point. Although we have two extremities, we really have six points controlling the shape of our curve. We select each extremity with the Right Mouse Button (RMB). If you have done so, the whole handle is selected; we can move G around and place the end of the curve. If we go near any extremity and use the RMB we will select only one half of the handle; the pivot point will be where the extremity of the curve is located. Now click on the 3D view with the RMB to grab the handle and you will be able to control only the curvature and orientation of our curve. Press the LMB for placement of the handle.

Go ahead and practice until it becomes second nature. Once this is done, grab G the spline and place it near the leading edge of the airfoil.

The leading edge is done! To complete the shape, select one extremity of the curve and with the combination of the Ctrl and the LMB, create another curve, connected to the first one. Since practice makes perfect, place the new curve exactly over the profile of our airfoil. At the end of the trailing edge, our curve will go berserk: try as you might, you will never be able to create an acute angle!

To fix this problem, select the pivot point at the trailing edge of the airfoil and press V.

The handles are now green and you can place them independently. Complete the shape of the profile until you are near the first extremity.

Complete the shape by typing C; The airfoil profile is now a gray shape curve. Now that everything is fine with our profile, we need to convert the curve into a mesh for later modification. To do so, press Alt-C and answer Yes at the prompt Convert Curve to Mesh

Congratulations! Your airfoil has been completed. Now save your project under Airfoil.blend before something bad happens to your complete airfoil profile. The essential work has been done. What's left is a few manipulations that will be applied to the shape to create a solid out of it.

Our profile is in the wrong direction; we need to change that. We will use the center of the profile as a pivot point. Press F9 if you haven't done so and press Tab to go into Object Mode. Locate the Mesh panel and press Center New to relocate the center of the profile.

You now have a new center. The following steps are mainly keyboard manipulations. Press R to rotate, then Y for the axis (as we want the profile to go from left to right). You will see the white vertical line that restrains the movement along the y axis. Now type 180 to reverse the shape. Our airfoil should look like this:

Our airfoil is now in the right direction but is in neutral position. Our windmill would stay almost standstill under windy condition and do no useful work. To create a rotating movement, we need to have an angle of attack. For this exercise, we decide on a 10^o angle of attack. For more information about this complex problem, read this document!. We again press the R key for rotation, the Z key for the Z axis that passes through the monitor, and put 10 for the angle.

The airfoil is almost done! We now need to scale back the profile. Press S and type .1 so that it is 10 times smaller than the actual size, and place the blade at the center of origin in the Blender 3D window. To do so, place the cursor at the intersection of the X and Y axis and press Shift-S, select Cursor -> Grid. Verify that the cursor is at the origin by going from one view to the next with the Num 1, Num 3 and Num 7 keys and correct any mistakes. Once this is done, select Shift-S again, but this time choose the Selection -> Cursor option from the menu: the airfoil is now centered.

We will now add depth to our profile. That's right, our shape will go 3D! We extrude E the profile on the Z axis for 5 Blender Units. Go to the edit mode with Tab. Select all A the vertices and extrude E the Region along the Z axis for 5 Blender Units. Move around the 3D universe with the middle mouse button (MMB). We have a nice airfoil shape now. Pay attention not to touch the placement of the black cursor-cross-hair! It must stay on the point of origin!

Rotor blades

We will now duplicate our air wing and create a three blade rotor. Switch to the front view Num 1, press Tab to go into Edit mode, and do a select all with A. The cursor should sit on the X-Y-Z axis.

Locate the Mesh Tools panel. Locate the spin duplicate or Spin Dup button. Just underneath, change the Degr to 360 and Steps to 3. We have our rotor now.

To finish the last operation, press A twice to de-select and reselect everything and press the Rem Double button to eliminate all double vertices.

The rotor is now complete! Go into Object Mode to admire your handiwork and save Ctrl-W under Rotor.blend!

Assembling the parts

We now have all the elements to complete our windmill. We will start with our last file, the rotor, add the bulb and integrate this first assembly into the windmill. We go into Object Mode, Front view Num 1 of the rotor assembly.

Next step: we add the bulb. Press Shift-F1. The main window is now a file directory. Go up the hierarchy (use the P, for parent, button in the upper left corner) until you see the Bulb.blend file. Select Bulb.blend -> Object -> Sphere and click. You now see the rotor AND the bulb!

Switch to the Top view Num 7 and adjust the bulb using G and Y so the assembly looks nice.

...and we finally add the windmill proper with Shift-F1, Windmill.blend -> Object -> Cylinder.

We have to move the rotor assembly, just like in the real world, from our field to the top of the nacelle. As it is, you can only move the bulb, but we want to move both the bulb and the rotor. Hold the Shift key and select the rotor with the RMB. Move them up with G, along the Z axis until you are in alignment with the nacelle. Go to the Top View Num 7 and move along the Y axis until the rotor assembly is flush with the nacelle.

The windmill is now complete!

Explore different views of your model with the MMB. Save your work under WindmillComplete.blend and you're done!

Move inside the 3D window and explore the assembly and edit the model to apply a personal touch!