Colin Alexander Sledge
Step St ep 1: Get an Airf Air foil Dat File An airfoil dat file can be found on the internet, such as airfoiltools.com Must have a file format that begins at the trailing edge and ends at the trailing edge!
Step 1: Get an Airfoil Dat File (Airfoiltools.com)
Once an airfoil is chosen, select the Selig format
Open notepad or an appropriate text editor
Step 1: Get an Airfoil Dat File (Airfoiltools.com)
Copy and past the data into notepad Delete the title information and line up the numerical data Save the file as a .txt format with the airfoil name
Copy and Paste
Step 2: Open Airfoil File in Excel
Open Excel or similar program
Open file -> All File Types -> airfoil_name.txt
A pop-up menu will appeared titled “Text Import Wizard”
Step 2: Open Airfoil File in Excel
Make sure “Delimited” is selected A preview of your .txt file should show Click the “Next” button
Step 2: Open Airfoil File in Excel Selected “Space” as the Delimiter A preview of your .txt file should show with black lines separating the columns Click the “Next” button
Step 2: Open Airfoil File in Excel
Select “General” for the “Column data format” (default selection)
Confirm the data format looks appropriate
Click the “Finish” button
Step 3: Modify Airfoil File in Excel Delete
Once in Excel, delete blank columns so data starts in first column
Check the data for repeated data points next to each other; such as multiple 0.00 | 0.00
Step 3: Modify Airfoil File in Excel
To open an airfoil in Solidworks, the data must contain X,Y, and Z columns A column of zeros must be added depending on which plane the airfoil should be in Front Plane – add zeros to 3rd column Top Plane – add zeros to 2nd column Right Plane – add zeros to 1st column
Added zeros (Front Plane)
Step 3: Modify Airfoil File in Excel
Save the airfoil File -> Save as
The same airfoil name may be used
Ensure the Save as type is “Text (Tab delimited)(*.txt)”
Click the “Save” button
Step 3: Modify Airfoil File in Excel If saving as the same airfoil name, confirm Save as replacing file A pop-up will warn that some features are not compatible with Text (Tab delimited) Confirm the warning by clicking “Yes” Make sure to close Excel
Step 4: Open Airfoil File in Solidworks
In Solidwork, open a new part document In the “Features” tab, select the “Curves” feature drop-down menu In the “Curves” feature, select “Curve Through XYZ Points”
Step 4: Open Airfoil File in Solidworks
In the Curve File menu, select the “Browse” button
In the file menu, select “Text File (*.txt)” as the file type
Browse for the desired airfoil file
Step 4: Open Airfoil File in Solidworks Find the airfoil_name.txt file and select open In Solidworks, the Curve File menu will populate with the airfoil data A yellow preview will show in the appropriate plane Click “OK” button
Step 5: Create Airfoil Sketch in Solidworks
A Curve1 feature will show in the feature tree as well as the airfoil curve in the workspace Right click on “Curve1” -> Select Feature Properties > Change name to airfoil name
Step 5: Create Airfoil Sketch in Solidworks
Select the appropriate plane and insert a new sketch
The airfoil curve will be shown in blue; DO NOT hide at this time
Step 5: Create Airfoil Sketch in Solidworks
Select the airfoil curve an then select “Convert Entities” in the Sketch Tool Bar This is create a sketch driven by the airfoil curve A black sketch will now be overlaying the blue airfoil curve Confirm the sketch by selecting the green arrow in the Convert Entities feature menu
Step 5: Create Airfoil Sketch in Solidworks Zoom in to the trailing edge of the airfoil and confirm that the curve is closed and connected If the trailing edge is open/broken, please see Appendix A for fixing the trailing edge sketch
Note: This airfoil imported with closed/connected trailing edge
Step 5: Create Airfoil Sketch in Solidworks Zoom to fit the airfoil in the screen Add a centerline from the leading edge to the trailing edge Provide a reference dimension for the length of this line
Step 5: Create Airfoil Sketch in Solidworks
Many airfoil .dat files import scaled to 1 unit chord length Select the entire sketch and select ‘Scale Entities’ in the sketch toolbar
Step 5: Create Airfoil Sketch in 2 Solidworks
In the scaling feature property menu, select the leading edge as the point to scale about Scale the entities by the desired length over the reference chord dimension Do not select copy (unless you need to keep the small airfoil in the sketch)
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Step 5: Create Airfoil Sketch in Solidworks
A preview will appear with the large airfoil If satisfied with the preview, click the green arrow to accept the transformation
Preview of airfoil scaled by a factor of 8
Step 5: Create Airfoil Sketch in Solidworks
Zoom to fit; if satisfied with the sketch, exit the sketch editor The airfoil curve may be hidden to make the sketch easier to view
Step 6: Create Airfoil Feature in Solidworks
If a straight wing is desired, extrude the sketch for design wingspan Make sure to extrude the wing Mid Plane to maintain centerline reference To create wings with taper, sweep, dihedral, and washout, please see Appendices B-E
Finished Wing!
: Fixing the trailing edge of an imported airfoil .dat file
When the imported airfoil .dat file is missing the trailing edge, this will prevent the profile from generating a solid body feature
This appendix will provide a method to fixing the missing trailing edge while maintaining the imported airfoil shape
Step 1: Repair Airfoil Trailing Edge
Import the airfoil curve and convert entities as usual Zoom in to the trailing edge of the airfoil and confirm that the curve is open and disconnected Note: This airfoil imported with open/disconnected trailing edge
Step 1: Repair Airfoil Trailing Edge
In the sketch tools, use the line tool Draw two lines, starting at each end point on the trailing edge, to some arbitrary location Do not apply any sketch relations at this time
Step 1: Repair Airfoil Trailing Edge
Choose one of the lines, select the airfoil sketch and the line while holding the CTRL key, and apply the tangent sketch relation Apply the same process for the second line Note: if the lines move on the airfoil when the tangent relation is applied, use a fix relation to fix the line endpoint on the airfoil spline.
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Note: 1 depicts the tangent sketch relation already applied to the airfoil spline and the first line sketch
Step 1: Repair Airfoil Trailing Edge After applying the tangent sketch relations to both lines, the trailing edge should be connected Use the sketch trim tool to remove the excess lines The repaired trailing edge should be closed and connect
Step 1: Repair Airfoil Trailing Edge After applying the tangent sketch relations to both lines, the trailing edge should be connected Use the sketch trim tool to remove the excess lines The repaired trailing edge should be closed and connect
Step 2: (Optional) Form 1 spline sketch feature
This optional step produced a single closed spline sketch as opposed to 3 sketch features Select the 3 sketch components Tools -> Spline Tools -> Fit Spline
Step 2: (Optional) Form 1 spline sketch feature
In the Fit Spline feature menu, the tolerance box shows how closely the spline is matching the sketch features Turn the dial to the lowest tolerance possible without losing the pink preview
Step 2: (Optional) Form 1 spline sketch feature
The finished spline will be one continuous sketch features
Scale and extrude the wing as usual
: Creating a wing with Sweep, Taper, Dihedral, and Washout (Twist)
Sweep, Taper, Dihedral, and Washout are all integral aspects of an aircraft wing. Most aircraft wings utilize at lease one of these aspects for better performance.
This appendix will provide a method to create a wing that has sweep, taper, dihedral, and washout. This will specifically resemble a commercial aircraft wing but can be applied to other aircraft and even propellers.
Step 1: Create Wing Root Chord
Designate your BL 0.0 Plane or Front Plane as the Root Plane Insert the airfoil as normal and scale the airfoil to the root chord length. Draw a chord line; a line that is horizontal from the leading edge to the trailing edge. Insert a point and define it so it is at the quarter chord, .25*Chord, starting at the leading edge Exit the sketch when complete
Step 2: Create Wing Tip Plane
Using Reference Geometry, create a plane for the tip chord of the wing The tip chord plane should be ½ of the total wing span from the root chord plane The direction of the plane will not matter due to symmetry
Step 2: Create Wing Tip Plane
Rename the plane Wing Tip Plane or Tip Plane
Right click on “Plane1” -> Select Properties -> Change name to Tip Plane
Step 3: Create Wing Sweep
The wing sweep is defined at the sweep angle of the quarter chord line; from the quarter chord of the root chord to the quarter chord of the tip plane To start, insert a sketch on the top plane or WL 0.0 plane Insert a construction line sketch from the quarter chord point of the root airfoil and set it coincident to the wing tip plane
Step 3: Create Wing Sweep
Insert another construction line sketch from the quarter chord point of the root airfoil, ensuring it had a vertical constraint This vertical line will be used to define the sweep angle Using smart dimension, define the angle between the vertical line and sweep line Exit the sketch when complete
Step 4: Create Wing Dihedral
The wing dihedral is the angle the wing makes with a horizontal datum The usual convention is for dihedral to be the wing angled upward with anhedral is when the wing is angled downward To start, insert a sketch on the right plane or STA 0.0 plane* and create a construction line from the quarter chord point of the root wing section coincident to the tip section plane *Note that the front plane and subsequent parallel planes are the true wing stations, as opposed to the convention shown
Step 4: Create Wing Dihedral
Insert a horizontal construction line or use the sweep line as a reference for the dihedral angle Using the smart dimension tool, set the dihedral angle
Step 5: Locate Wing Tip Section
The sweep line and dihedral line are used to locate the quarter chord of the wing tip section Insert a sketch on the wing tip plane Draw a horizontal line starting from the dihedral point, backward for an arbitrary distance* Draw a vertical line starting from the sweep point, upward for an arbitrary distance* *Note that you may need to use the pierce sketch relation to locate the line starting point correctly
Step 5: Locate Wing Tip Section
The intersection of the two lines is the location of the wing tip section quarter chord Place a point at the intersection of the two lines or trim the lines to create the intersection point Exit the sketch and rename the sketch “Wing Tip Quarter Chord Point”
Step 6: Insert the tip section and the wing taper
Insert a sketch on the wing tip plane
Select the root chord select ‘Convert Entities’ in the sketch toolbar
Step 6: Insert the tip section and the wing taper
Move the converted airfoil section near the tip quarter chord point using the ‘Move Entities’ in the sketch toolbar Select the airfoil sketch then select the leading edge as the point to move from move the cursor to the new location and left click then right click to confirm
Step 6: Insert the tip section and the wing taper
With the airfoil section in this arbitrary location, select ‘Scale Entities’ in the sketch toolbar Select the airfoil sketch and click on the leading edge as the point to scale about For the scaling factor, input the taper ratio desired* *Note that if using an airfoil section other than the root section, tip scaling factor will not be the precise taper ratio as this is defined as the ratio of the tip chord to the root chord
Step 6: Insert the tip section and the wing taper
Zoom to the wing tip airfoil section Draw a horizontal chord line starting at the leading edge, terminating at the trailing edge Place a point on the chord line and dimension appropriately so this point is precisely at the quarter chord position of this section
Step 6: Insert the tip section and the wing taper
Once again, select the ‘Move Entities’ sketch feature Select the airfoil section as well as the chord line and quarter chord point to move Click the quarter chord point as the point to start entity move Click the wing tip quarter chord location, found earlier, as the terminating point for the move entities feature
Step 7: Add wing tip washout as necessary
Wing washout is defined as a difference in the incidence angle of the wing tip with respect to the wing root Wing wash-out is the tip having a lower angle of incidence with respect to the root while wash-in is the tip having a greater angle of incidence with respect to the root Generally, only wash-out is utilized When generating a propeller model, this step will be used to provide the blade
Step 7: Add wing tip washout as necessary
To apply washout or wash-in, select the ‘Rotate Entities’ from the sketch tool bar Select the airfoil section, the quarter chord point, and the chord line as the entities to rotate Select the quarter chord point as the point to rotate about
Step 7: Add wing tip washout as necessary
Select an angle to rotate the sketch Visually confirm the airfoil section rotates in the correct direction Once satisfied, confirm the rotation, exit and rename the sketch ‘Wing Tip Section’
Step 8: Generate wing loft
Select and Isometric view and confirm that the root and tip chords are visually in the correct locations Select the ‘Loft Boss/Base’ tool from the features tool bar Select the root chord first, then the tip chord as the Loft Profiles If the loft does not immediately show a preview, drag the main connector to the trailing edge on each airfoil section The loft should generate a preview; if correct confirm the loft
Note: Connector shown having been ‘Dragged’ to the trailing edge on each section for loft to generate
Step 9: Mirror Wing
To complete the wing, select the ‘Mirror’ tool from the features toolbar Select the front plane or BL 0.0 as the mirror plane Choose the wing loft as the body to mirror* *Note: use the Bodies to Mirror selection as opposed to the Features to Mirror selection
Step 10: Finish Build the Aircraft!
The steps taken to create the wing can largely be used for the remain aerodynamic surfaces such as the tail sections, pylons, and engine components The nose section and afterbody of the aircraft require many surfacing tools for best appearance
: Creating a Propeller
Propellers are similar to wings but utilize large amounts of washout and various blade taper. For more information, please reference one of the many publications for propeller theory.
This appendix will provide a method to create a propeller using varying airfoils, chords, and blade section angles. Although this method is for a common aircraft propeller, it can be used for other applications.
Step 1: Create Blade Station Planes
Designate your BSTA 0.0 Plane or Right Plane as the Root Plane Insert the necessary blade station planes according to your propeller design. Label each plane based on it’s distance from the root plane More blade stations will give the user greater control over the design, but too many planes can make the blade
Step 2: Import Airfoil Curves
As discussed previously, import the airfoil curves. Make sure to change the name of each curve to represent each airfoil section as this will be hard to distinguish after many section have been imported. If this airfoil sections import in the wrong orientation, this can be rotated later; unless this section are imported on the incorrect plane. For ease, hide each curve after importing to clean up the work space.
Step 3: Setting Blade Station Twist and Chord
According to your propeller design, you will have a predetermined airfoil, chord length, and section angle. Insert a sketch on the given blade station plane. Unhide the appropriate airfoil curve for the blade station and convert entities to start the sketch. Fix the trailing edge where necessary.
Step 3: Setting Blade Station Twist and Chord
Scale the airfoil sketch to the design chord length at the blade station. As discussed previously, insert a point at the quarter chord* of the section as a reference for rotating the section. Select the rotation tool and rotate the airfoil section about the rotation point to the desired angle. Use the move tool to relocate the airfoil section so the points of rotation are coincident**. For ease of finishing the propeller, make the root section rotation point coincident with the origin.
*The rotation point can be a different chord position based on the propeller design ** The points of rotation can be a different locations based on the propeller design, but may impact loft.
Step 3: Setting Blade Station Twist and Chord
Step 4: Lofting the First Blade
Once all of the blade station airfoil sections have been set in terms of the airfoil, twist, and chord length, the blade is ready to be lofted. Starting with the root, select each section sequentially, and adjusting the main connector as appropriate. The main connector should not cross across the loft as this may introduce kinks if the loft will even generate. Dragging the main connector to either the leading edge or trailing edge should produce a smooth, continuous loft. Guide curves can be used to force the loft to follow a path between defined section if there is a low number of sections to generate the loft.
Step 4: Lofting the First Blade
Once the loft is generated, the Curvature tool can be used to identify kinks and irregularities in the loft. Select the Evaluate tab, then Curvature to activate the tool. The Curvature tool will color the loft according to the radius of curvature making it easy to see shape areas and potential problems. This also allows you to see if the loft generated as expected with smooth transitions.
Step 5: Finishing the Blade Tip
Often times on a blade or wing tip, it is desirable to finish the section with a smooth curve as opposed to a straight cutoff. To begin the process, add a blade tip plane that is perpendicular to the cutoff face and using the tip section chord line as a planar reference. *If a more complicated shape is desired with sections out of this plane, more reference geometry and guide curves are needed and will be a similar process to lofting the blade body.
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Step 5: Finishing the Blade Tip 1
Insert a sketch on the Blade Tip Plane and begin by adding a terminal point at the desired distance from the current blade tip. Exit the sketch for the terminal point and insert a NEW sketch for the guide curve. Begin by drawing a guide curve from the trailing or leading edge to the terminal point. Make sure that the curve is coincident to the terminal point and the edge of the blade*. Exit the sketch and insert a NEW sketch for the second guide curve. As before, make sure this is coincident to the blade edge and the terminal point. It is essential that the guide curve is broken into multiple parts for control and to ensure the loft generates.
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*Often times the sketch will need to use the “Pierce” relationship to ensure it is coincident to the blade surface. 1: Blade tip terminal point. 2: Leading edge guide curve. 3: Trailing edge guide curve.
Step 5: Finishing the Blade Tip
Enter the loft tool and begin by selecting the blade tip section sketch as the first loft section. For the next section, select the tip terminal point. The loft should show a preview of something that looks similar to a cone. The idea is that the loft will generate a conical section and then it will be stretch to the desired shape by the guide curves. Click the “Guide Curve Selection Box” and select the leading edge and trailing edge guide curves. If the loft does not produce a desired result, the guide curves may be over constraining or the start and end constraints may need to be adjusted*.
*The start and end constraints can help smooth the loft and blend the current loft to the adjacent loft, however, it can also prevent the loft from generating so use with caution.
Step 6: Finishing the propeller
To add the remain blades, create an axis of rotation using reference geometry perpendicular to the plane of rotation. Use the circular pattern to produce the desired number of blades. Even for 2-bladed propellers, use the circular pattern tool as opposed to the mirror tool to ensure the blades are in the proper orientation.
Step 6: Finishing the propeller
Use the extrusion or revolve tools to create the appropriate propeller hubs and spinner caps. To add tip markings or spinner cap markings, use the split line tool in the Features tab Curves menu. This will create a split face that can be colored at desired, but will not affect the part.
Step 7: Propeller References
Aircraft Propellers
Marine Propellers
http://www.pilotfriend. com/training/flight_trai ning/fxd_wing/props.h tm
http://www.propline.co m/Propeller-GeneralInformation/Propeller _Terminology.htm
http://www.aboutflight. com/handbook-ofaeronauticalknowledge/ch-4aerodynamics-offlight/basic-propellerprinciples
http://www.propellerp ages.com/downloads/ Technology_guideline s_for_efficient_design _and_operation_of_s hip_propulsors.pdf
