CATIA Tutorial 1 – Parametric Design, Wings and Empennage Units and Parameter setup •
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Units o Go to Tools -> Options -> Parameters and Measure (Under General section of tree) o Go to the units Tab and for length, change it to Feet o For Area change to Square foot Parameters o Go to Tools -> Options -> Parameters and Measure (Under General section of tree) o Go to the Knowledge tab and click checkboxes for With Value and With Formula under Parameter Tree View o Go to and expand the Infrastructure part of the left hand side tree and click on Part Infrastructure o Go to the Display tab and click checkboxes for Constraints, Parameters, and Relations
Getting started • • •
Create a new part (File -> New -> Part) Name it whatever you want. Go into Generative Shape Design (Start->Shape-> Generative Shape Design)
Parametric Design Parameters let us define a value, whether it’s a length, angle, constant, etc. This allows us to build a part or product in such a way that when we need to make an adjustment to a known dimension, we can simply change said parameter and everything will update automatically. For designing our wings and empennage, we’ll need the following parameters •
Wings o o o o o o o o
Wing X Location Wing Y Location Wing Z Location Wing Chord Root Wing Taper Ratio Wing Half Span Wing Root Incidence Wing Tip Incidence (effectively the washout angle)
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o Wing Dihedral o Wing Sweep Horizontal Tail o HT X Location o HT Y Location o HT Z Location o HT Chord Root o HT Taper Ratio o HT Half Span o HT Root Incidence o HT Tip Incidence o HT Dihedral o HT Sweep Vertical Tail o VT X Location o VT Y Location o VT Z Location o VT Chord Root o VT Taper Ratio o VT Span o VT Root Incidence o VT Tip Incidence o VT Dihedral o VT Sweep
To create a new parameter, click on the ݂ሺݔሻ button at the bottom
Then do the following in the window that pops up
1. Make this “Length”
2. Click this button
You’ll get your new parameter, you’ll need to rename it. Simply click on the parameter, and in the “Edit name….” text box, rename it “Wing X Location”
Rename this
Click Ok, and you’ll see the “Parameters” section pop up in your specification tree. Expanding it will show your new parameter.
Repeat this process twice, making an angle parameter and a real parameter. What changes for creating each is: • When you create the angle, the type becomes angle o Name this one “Wing Root Incidence” • When you create the real, the type becomes real o Name this one “Wing Taper Ratio” o Set the value to 1 You should now have 3 parameters that look something like this:
To create the remaining parameters, we can simply copy and paste them by doing the following.
Right click on the parameter and copy it. Then right click on the parameters part of the tree and click paste.
You’ll get that parameter copied, with the same type of value (see below). This can be renamed simply by right clicking on the new parameter and clicking properties
Repeat this for all the parameters we have for the Wing, make sure you copy based on the type of parameter • Wings o Wing X Location (Length) o Wing Y Location (Length) o Wing Z Location (Length) o Wing Chord Root (Length) o Wing Taper Ratio (Real) o Wing Half Span (Length) o Wing Root Incidence (Angle) o Wing Tip Incidence (Angle) o Wing Dihedral (Angle) o Wing Sweep (Angle) Once you get all your parameters, copy and paste the entire parameters section into itself as shown below
Rename the new parameters section “Wing” (Right Click on The new parameters-> Properties). Your parameters specifically for the win will look like this:
Go ahead and delete the original parameters you made, and then copy the wing section into parameters 2 times and rename each one HT and VT respectively. Additionally you can rename each parameter to match each section. Your results should look something like this:
We now have the necessary parameters to model our basic geometry for the wings and empennage
Wing Design Importing airfoils into CATIA On the S:\ Drive there is a file called “Airfoil Macro.xls”, save it to your P:\ (Or whatever storage you want) and open it. Once open, click the “Enable Content” button on the yellow bar that shows up (if it does). You should get the following:
Columns H and I have the airfoil coordinates (in this case a NACA 64-008A). Column A is just arbitrary point names, and BCD is the xyz coordinate space in CATIA, scaled for the airfoil size. (NOTE: this outputs into a chord length of 100 millimeters, so the file has been modified to output to 1 foot) Simply click on the “Exportar a CATIA” button, the program will prompt you to name your set of points, name it “Wing Airfoil Points”. Then it will run through all the points and create a new part with all your points in it. Your points are stored in a geometrical set called “Wing Airfoil Points”.
Copy “Wing Airfoil Points” set (Select it in the tree, and right click -> copy) and paste it into your aircraft part. You should see your points and parameters all in your part:
Delete these points
For the sake of this tutorial, delete the trailing edge points. (See above)
Making the Wing Wireframe To create the airfoil, right click on Partbody in the specification tree, and click “Define in Work Object”
Using the spline tool connect each of the points. Once those are connected, right click on the Wing Points and click “Hide/Show”. You should see the following
Use the point tool and place a point at the origin (0,0,0). Right click on this point in your specification tree, go to properties, and under feature properties, rename it Origin Point. Do not hide this point. In your wing parameters, set your Chord Root to 5 feet by double clicking on the parameter and setting the value to 5
Click on the arrow under the Translate tool
and click on the scaling tool
.
For Element, click on the spline. For reference, click on the origin point. In the Ratio box, press = , then click on your parameter tree. Then Click your Chord root parameter. The scaling box should now look like this:
Click on the ݂ሺݔሻ button and you’ll get the formula editor. In that window, simply divide the Chord Root Parameter by 1 foot as shown below. (This makes the value in the scaling command actually see a real as opposed to a length)
Click ok, and ok once more on the scaling window. Your airfoil will now be as long as your specified chord root.
Make a new point, this time press = in each coord box and select the respective x, y, and z location parameter. Click ok. Adjust the parameters and move the wing to (5,0,0). To move the scaled wing airfoil, use the translate function (You may need to click the arrow under the scaling tool if you can’t find it), select Point to point, then click on the airfoil, start point is the origin point, and end point is the translated wing location point.
Hide the original airfoil and the scaled up airfoil. Don’t hide the translated one. We now need to create lines that will represent the root incidence axis and the dihedral axis. Set the following values for Half Span, Dihedral and Root Incidence: • Half Span: 13 ft. • Dihedral: 1 degree • Root Incidence: -1 degree Use the line command respective line:
and do the following settings (endpoint can be any length) for each
Dihedral Axis
Root Incidence axis
Use the rotate command following:
(click arrow under translate/scaling tool if not there), and do the
Dihedral – For the angle, use the dihedral parameter. Hide the original when rotated.
Incidence – For the angle, use the Incidence parameter. Hide the dihedral one when rotated.
For the Span, create a plane
with the following settings
Then rotate the plane to the same dihedral angle, hide the original (if it’s hard to see, increase the dihedral angle to differentiate) To get the appropriate length of the actual wing, with respect to span and dihedral, some trig is involved.
Dihedral Γ Half span (b/2) The actual wing length is (b/2)/cos(Γ)
Use the line command again, this time with the type being “Normal to Surface”, start point is the point for the wing and press = in the end point. Select the wing half span parameter and click the function box (݂ሺݔሻbutton).
Like the above diagram, the equation becomes the following:
Click ok on all windows and you’ll get your length of the wing.
Use the translate function from point to point, select the wing root airfoil and the endpoints of the new wing length line.
Set the taper ratio parameter to 0.5 and your sweep angle to 5 degrees. Using the scale function, select the wing tip airfoil, reference the length line endpoint, and use your taper ratio parameter as the ratio.
To put sweep on the wing, we simply translate the wingtip back or forwards. Like the wing length, trig has to be applied here as shown below
Distance back Sweep (ΛLE)
Half span (b/2) The distance is (b/2)*tan(ΛLE)
Use the translate tool, select coordinates, and in the X component, press = and select the wing half span parameter.
Once the function button shows up, click on it and modify the formula to match the above diagram. Once translated you should have something like this:
Hide the previous tip airfoils and the wing length line. To add the washout to the wing, create a line from the top trailing edge of the root airfoil to the same point on the tip airfoil. (NOTE: normally, there aren’t 2 points for the TE, but we have this since we cut off the cusp for this tutorial)
Using the rotate command, select the tip airfoil, using the line just created as the axis, and select the wing tip incidence parameter.
Connect the bottom part of the TE with a line as well. Additionally, create a line between the top and bottom TE on each airfoil. The result will look like this (root chord shown here, but similar with tip)
To make the LE, put an extremum (click on arrow under point tool) on the tip chord airfoil. In the function, click on the tip chord, right click on the direction and select X Component, and then click the Min radio button
Make one last line between the LE of both the tip and root of the wing airfoils to complete the wireframe.
Making the Wing Surface To make the surfaces with Multi-Sections Surface in GSD, we need 2 profiles and guide curves. To create the root profile, click on the join command , and click on the wing root airfoil, and the line for the trailing edge and click ok. They will now be one profile.
Repeat this for the tip. Hide any remaining reference lines (i.e. lines used as axes or lengths, except the TE and LE of the wing) Click on Multi Sections Surface
. Then click on the root and tip profiles
Click in the guides box and select all the remaining lines.
Click preview to see if it will be generated properly, if you get and error, or the geometry looks messed up, we’ll have to change the closing points. To replace a closing point, simply right click on a closing point, and click replace. You can then move it to another position on the profile.
If there are no errors after previewing, click ok and you’ll have your main surface of your wing.
To fill in the tip, use the fill command and select the open tip of the wing. (The function must show the Closed Contour message to work)
Use the join command to join the filled surface with the main wing surface (This will help a lot with mirroring) Finally, to mirror the wing to the opposite side, select the symmetry tool wing, and click on the global ZX plane.
, click on the
Note the following: • If you want to create other surfaces, efficiency devices, etc. (flaps, ailerons, winglets, lights, etc.) make them before the symmetry function, then all of them will transfer over. Now you have your basic geometry of your wing. You can now adjust all the parameters to make different geometric changes.
Empennage Creating empennage is actually very easy; it’s exactly the same as making the wings. As practice, model the HT and VT yourself, you can select your own airfoil, or use the one provided in the airfoil macro (hint, almost all aircraft use symmetric airfoils for the HT and VT). Just put each one in the specified coordinates listed below. Horizontal Tail For the HT, put the HT location at the following coordinates: (22, 0, 0.5). Use any other value you want for the other parameters. (Protip: look at other aircraft in the GA category and see what they use) Vertical Tail For the VT, put the VT location at the following coordinates: (22, 0, 0.5, no this is not a typo.). Use any other value you want for the other parameters. (Protip: look at other aircraft in the GA category and see what they use) Also, you won’t be mirroring the VT, so there’s an added plus there. Additionally, given there’s actually no dihedral on the VT, simply modify the dihedral angle to 90 degrees and use that when rotating about the dihedral axis. (Or you could just modify the parameter name)
