# Aerobody # Car 4 Aerobody Manufacturing Documentation ## Overview This article serves to document our manufacturing processes and decision making behind the aerobody for Flare. ## Materials A significant array of materials were required for the manufacturing of Flare's aerobody. Important materials are listed below with notes about their sourcing and purpose. If looking to order any of these products, please do due diligence to see if they are available cheaper elsewhere. **Foam** The selected foam for this project was XPS foam. Specifically, we obtained 46 sheets of 4 inch thick, 4x8 feet XPS foam manufactured by Dupont. This foam was ordered from FBM Global. Originally, we had inquired for Owen's Corning FOAMULAR XPS foam, however received the Dupont foam, which worked well for our purposes. These foam slices were CNC'd to develop a positive pattern of the aerobody shell. **Primer** The primer used for this project was Duratec Styroshield Primer. This primer is optimal for using on foam products. Primer is required for making any foam plugs as it protects the plug from being damaged by polyester compounds. This creates the surface which is captured by the gelcoat mold. **Loctite Glue** The glue used for adhering the mold slices together was Loctite PL Premium Polyurethane ([https://www.homedepot.com/p/Loctite-PL-Premium-10-oz-Polyurethane-Construction-Adhesive-Tan-Cartridge-each-1390595/202020473)](https://www.homedepot.com/p/Loctite-PL-Premium-10-oz-Polyurethane-Construction-Adhesive-Tan-Cartridge-each-1390595/202020473)). This glue is water activated, meaning that each slice had to be lightly misted with water before being stuck together with this glue. **Fairing Compound** To make patch repairs to the surface of the plug, we used TotalBoat Epoxy Fairing Compound ([https://www.amazon.com/TotalBoat-TotalFair-Compound-Fiberglass-Aluminum/dp/B00LLL9FXU?th=1](https://www.amazon.com/TotalBoat-TotalFair-Compound-Fiberglass-Aluminum/dp/B00LLL9FXU?th=1)). This is a 2 part, 1:1 epoxy-based filler used to fill voids or cracks on the plug surface. Fairing compound is typically left overnight to cure and is also susceptible to exotherm. **Sandpaper** The surface of the plugs were sanded up to 1000 grit. Thus, we used 60, 120, 220, 320, 400, 600, 800, and 1000 grit sandpaper throughout the manufacturing process. **PVC Piping** Several sections of 3/4" PVC piping were used as a method of aligning slices. Holes were made in the slices for each plug to allow the PVC pipe to fit between layers. ## Canopy ## Nose ## Bottom Body ## Top Body ## Integration ## Takeaways 1. Don't spend time trying to achieve absolute perfection. You can always post-process. This will save you a LOT of time. 2. No need for using another paint to go beyond 1000 grid on the plug, primer is fine. 3. Don't separate the nose from the bottom-body. 4. There's no need to overbuild your mold, 3-4 plies of fiberglass is sufficient. 5. # Composite Layup Tutorial #### Purpose This page acts as a tutorial for performing high quality composite hand layups with vacuum bag use. Many factors are to be considered in the setup and performance of a composite hand layup. Due to the timely nature of epoxy resin working/curing times in composite layups, these factors must be considered before performing the layup and a clear and concise plan should be should be created prior to beginning. #### Setup Setting up for a composite layup involves gathering materials, prepping layup surfaces, and prepping vacuum pumps. ##### Gathering materials [![IMG_3544.jpeg](https://wiki.ufsolargators.org/uploads/images/gallery/2025-03/img-3544.jpeg)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-03/img-3544.jpeg) The materials for a composite layup include - Composite fiber (Carbon fiber, Fiberglass, Kevlar, etc.) - Resin (Epoxy, Polyester, etc.) - Peel ply - Breather - Vacuum bag - Tacky Tape - Vacuum Pump - Vacuum Puck (Frog) - Paint Brushes/Squeegees - Scissors - Core (Foam, Nomex, etc.) \[Optional\] Ensuring materials are properly cut and sized before performing a layup will save time and allow for a smoother procedure. The amount of composite fibers, resin, and core depend on the design of the part to be made. Consider the desired weight, strength, cost, and stiffness of a composite part to determine this. Peel ply and breather must be cut out to fully cover any portion of the layup that will be wetted out with epoxy resin. The purpose of the peel ply and breather is to remove excess resin from the layup, creating a higher fiber ratio and a lighter part. ##### Prepping Layup Surfaces The surface on which a layup is to be performed must be prepped prior to a layup, which includes cleaning and waxing. [![IMG_3543.jpg](https://wiki.ufsolargators.org/uploads/images/gallery/2025-03/img-3543.jpg)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-03/img-3543.jpg) Any contaminants on the surface should be cleaned with isopropyl alcohol. Once the surface is cleaned, it should be waxed with #2 partall paste, PVA mold release, or covered in a mold release film. This ensures the finish part will detach cleanly from the layup surface. Consult wax instructions for prep times. ##### Preparing Vacuum Pumps The amount of vacuum bag and tacky tape depends on the type of vacuum seal to be made. An envelope vacuum completely encapsulates a part and is generally used for smaller geometries. Envelope vacuum bags can be thought of like a ziploc bag, putting a part inside and sealing with tacky tape. More traditional vacuum bags outline an area for layups to be performed, and vacuum bags seal against the layup surface. This type of vacuum bag uses less material and can be easier to perform, especially for large parts. Once the vacuum area is determined for a traditional vacuum, tacky tape can be layed on the perimeter before the layup has begun to save time. This tacky tape will need to be covered in painters tape to ensure resin does not contact the tacky tape. Resin in contact with tacky tape will compromise the tapes ability to seal the layup from the surrounding atmosphere. [![IMG_3551.jpeg](https://wiki.ufsolargators.org/uploads/images/gallery/2025-03/img-3551.jpeg)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-03/img-3551.jpeg) The amount of vacuum pumps depends on the size of the layup and the amount of potential leaks. Layups with large tacky tape perimeters have a higher chance of air leaks, and so more vacuum pumps may be desired. Most small parts will be sufficient to layup with just one vacuum pump. #### Performing the layup Once the setup is complete, the composite layup is ready to be performed. One last thing to consider before performing a layup is the manpower required to perform the layup. The vacuum bag of the layup needs to be working before the end of the working time of the resin used. Consider the size of the layup and the working time of the resin to determine how many people should be present for a layup. ##### Applying Resin Once resin has been mixed with hardener, the layup has begun. The layup surface should first be coated in a layer of resin before any composite fibers are used. This will help ensure the fibers are completed coated in resin, since dry spots in the fibers can compromise the integrity of a part. Be careful not to remove any PVA on the surface of the mold or wrinkle any release film when performing this step. In general, a blotting motion with paint brushes is encouraged as opposed to a brushing motion. ##### Applying Composite Fibers Once the layup surface has been sufficiently covered in resin, the composite fibers can be placed onto the layup surface. Ensure fibers remain woven tight while placing and applying resin to the fiber. Again, a blotting motion with paint brushed is encouraged. Squeegees are fantastic at evenly applying resin across the whole area of the fibers but must also be used with caution as too much pressure can compromise a fiber weave as well. [![IMG_3545.jpg](https://wiki.ufsolargators.org/uploads/images/gallery/2025-03/scaled-1680-/img-3545.jpg)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-03/img-3545.jpg) ##### Applying Core Materials Composite layups with core need to be very careful with resin use. Any resin that becomes soaked into a core material adds unnecessary weight to part, defeating the purpose of the core. When using core in a layup, no resin should be directly applied to the core. Instead, a layer of fibers should be placed over the core and resin shall be applied to that layer of fibers. Ensuring this subsequent layer of fibers is properly wetted out with carbon is crucial, since it will be placed onto a dry core surface. ##### Peel Ply and Breather Once the sufficient amount of fibers and core have been laid onto the layup surface and wetted out with resin, the layup will not be covered with peel ply and breather. The peel ply acts as a barrier between the resin and the breather, since peel ply is porous and does not stick to resin. The breather soaks up the excess resin that has passed through the peel ply. Important to note: the peel ply should be slightly larger than the breather and completely cover any parts of the layup that contain resin. Since breather will stick to the layup, any breather that is in direct contact with the resin will stick to it and cannot be removed later. It is common practice to cut breather about an inch in from the edge of the peel ply during a layup. Extra breather should be placed in spots where vacuum pucks are going to be used to ensure no resin gets sucked into the vacuum line. ##### Vacuum Bag Once the all the parts of the layup are in place, the vacuum bag can be attached and hooked up to the vacuum pumps. Ensure vacuum pucks have been placed on the layup before sealing the vacuum bag. The masking tape covering the tacky tape should be removed carefully as to not accidentally move the tacky tape or come into contact with resin. The vacuum bag should be completely sealed using tacky tape. A pleat may be needed to ensure a vacuum bag conforms to the shape of the layup. ##### Attaching the Vacuum Pump(s) A small hole should be cut into the vacuum bag in the center of where the vacuum puck has been placed. The vacuum line can now be sealed onto the vacuum puck to start to removal of air. Monitor the pressure of the vacuum and fix any potential leaks in the vacuum bag. A proper vacuum should a pressure >25 inHg to maximize removal of resin. Add pumps/fix leaks until a sufficient pressure has been reached. Post Processing After a Layup is done, the vacuum pump should continue pulling for 4-6 hours, or until resin is set. After turning off the vacuum, leave the part in place until resin is fully cured, generally 24 to 48 hours. The remove the layup from the layup surface and remove the peel ply. Trim the part to final size if needed. Congrats! You have completed a composite layup. # Fairing Templates Fairing templates allow for positioning of the fairing layup before the rest of the bottom body is manufactured. There are multiple ways to approach this The following is how it was performed on car 4 The car 4 bottom body mold does not include the nose. This is advantageous for positioning within the body, as it gives a datum to measure off of. We used this to find the position of the front and rear "axles" of the vehicle, and positioned midpoint of the fairings with the axles on the sides of the mold. To make the templates, you can use flatten surface feature in solidworks. This requires selecting a group of faces and then a line to base the flatten off of. Think of this process the same way the world map is made, where the equator is the line chosen. The consequence of this is that the further from the line your faces are, with greater curves comes greater distortion (just like Greenland on the world map). You will have an especially hard time fitting flat paper back along those curves when you position them in the mold. For car 4 a split line was added across the middle face of the fairing, and then flattened along that line. See figures 1 and 2 for examples. [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/scaled-1680-/EXQimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/EXQimage.png)**Fig 1.** Front fairing with a split line added in the middle (yellow) of the face to give the most accurate flatten geometry [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/scaled-1680-/K6qimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/K6qimage.png) **Fig 2.** Front fairing when flattened. There is minor distortion on the bottom fillet area It is beneficial to also have alignment lines on the fairing for knowing roughly where the fillet is, where the midpoint is, and where the wheel will roughly be. These can be achieved through using sketches and then split line features on the face of the flattened geometry. While it is all one face, the line segments are still separate on the sides. We use coincident relations with straight lines to get a rough approximation. One thing to note is that the midpoint line is not necessarily a vertical line here, it is typically at a slight angle. You should look at the CAD of the entire aeroshell to decide how to define it. [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/scaled-1680-/cHaimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/cHaimage.png) **Fig 3.** Front fairing split line sketch. Note where the horizonal lines have coincident relations with the line segments on the bottom left and right side of the sketch There are a couple options for printing. If poster paper is available, you can turn the part into a drawing and save it as a PDF. **Do not take a screenshot and have it printed to scale.** It will come out super low resolution, you must save it as some sort of scalable vector file type (pdf, svg, etc). Otherwise, you can do it on a regular printer, sewing template style. Just add a sketch in as the following images show, then use linear pattern it across the part. Make sure to unhide the sketch in both the part and the drawing in order to get it to appear when you save it as a PDF. [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/scaled-1680-/JrDimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/JrDimage.png) **Fig 4.** Initial sketch. The big rectangle is the size of a piece of regular paper. The circle/crosshair pieces are for alignment, and the diagonal line in the corners gets cut off on every sheet so that you can align the corners from piece to piece [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/scaled-1680-/WXGimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/WXGimage.png) **Fig 5.** Pattern it across the part at 1 inch less per instance than the size of paper (for copy paper, 10" in x and 7.5" in y) [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/scaled-1680-/Xrvimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/Xrvimage.png) **Fig 6.** Make sure you can see the sketch in the drawing and save the drawing file as a PDF [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/scaled-1680-/OWAimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/OWAimage.png) **Fig 7.** Open the PDF and zoom in on each section one by one and take a screenshot of each, and position each on into a word document with the edges of the rectangle sketch taking up the entire page [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/scaled-1680-/Hp8image.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/Hp8image.png) **Fig 8.** Save this as a PDF now, print, and assemble by cutting off the corners, aligning, and taping together [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/scaled-1680-/tMdimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-02/tMdimage.png) # Properly Fastened Fairings *Jacalyn Dean, Luke Penafiel* Fairing fasteners refer to the modes in which fairings are fastened to the aerobody of the solar car. While simple in design, the results of different designs can prove crucial during the extreme environment of competition. During competition, the team went through several emergency iterations of fairing fasteners, including: - Quarter turn fasteners - Magnets - Nuts & bolts Quarter turn fasteners proved a good idea, but the thin carbon fiber body interfaced with tended to break upon usage. Furthermore, the quarter turns had issues because they had been previously used for car 3.5 and were bent to fit the car’s aerobody geometry— this caused interference upon interfacing with car 4’s body. Magnets were easily embedded into the thin aerobody, but their fastening force was deemed too weak to stay connected to the car during race as a complete solution, so they were used alongside other attachment methods. Screw and bolts proved a strong emergency option after the quarter turns failed, but took far too long to remove in the need of maintenance, with a team member needing to uncomfortably hold onto the nut from underneath the car. ![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/scaled-1680-/image.png)***Fig. 1.** Picture of previous attachment problems* Basing our design on the comments from competition team members, we chose to adjust the nut-and-bolt design to create our new fairing fasteners. To solve the problem of requiring a team member to reach underneath the car, we designed a nut holder to screw onto the body of the car, which would allow us to thread into a bolt holding the fairing panels onto the car.
[![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/scaled-1680-/8eVimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/8eVimage.png) [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/scaled-1680-/hrOimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/hrOimage.png)
***Fig. 2 & 3.*** *First iteration of fairing attachment solution* The competition team members loved this design, but we realized screwing our design onto the body of the car would make the outer body less aerodynamic. Instead we decided to change the design and remove the holes for screws to instead attach the design to the car with epoxy. We reduced the nut holder’s size to be 10-24, based on the nominal screw size the team uses in competition. Finally, we included a taper on the nut holder to distribute shear loads, as we realized angles orthogonal to the z-axis of 3D prints cause low resistances to shear loads, with reaction only coming from layer adhesion.
[![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/scaled-1680-/ob1image.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/ob1image.png) [![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/scaled-1680-/oINimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/oINimage.png)
***Fig. 4 & 5.** Second iteration of fairing attachment solution* We got this iteration of the fairing attachment printed, and went out to the Solar Park to visually test them on the aerobody. The design worked well, but needed some sanding to better fit the sides of the fairing openings that they would need to sit alongside without having any overhanging material.
[![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/scaled-1680-/bLlimage.png)](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/bLlimage.png) ![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/scaled-1680-/oEFimage.png)
**![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/scaled-1680-/hloimage.png)*****Fig. 6, 7, & 8.** Third iteration of fairing attachment solution.* The general design got changed for the final time, decreasing the width to eliminate the need for sanding down the printed design as shown above. Additionally, a single iteration of a fairing attachment was needed in order to fit a lip in one section of the aerobody. Dimensions were taken and a specific fairing attachment was made to fit this spot on the car, with the geometry shown below, to ensure the nut would still be held correctly and be effective as an attachment method.
![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/scaled-1680-/ygGimage.png) ![image.png](https://wiki.ufsolargators.org/uploads/images/gallery/2025-11/scaled-1680-/cRZimage.png)
***Fig. 9 & 10.** Specific iteration of fairing attachment for one spot of the car.*