Greetings from Austin, Texas!

Wen Rui // // No Comments

All smiles as Zephyr rolls into our FSGP garage

After a 4 day journey from California to Texas, Zephyr has arrived at the Circuit of the Americas; primed and ready for the Formula Sun Grand Prix (FSGP) 2017. Throughout the next week, Zephyr will undergo 3 days of intense scrutineering by race officials before hitting the track and racing other teams.

Registration was extremely smooth for the entire competition, where all teams were registered and loaded by 10am – the start of the team briefings.

Doing final checks on Zephyr the night before FSGP

The teams were briefed on logistics of the race, including trivia that teams will be spending more time on the COTA track than F1 drivers. As such, solar car drivers will technically “know the track better”.

Afterwards, teams were informed about the importance of safety measures. This included the risk of battery fires and heat exhaustion with the high temperatures in Austin, Texas.

A quick team meeting before breaking out into work groups

As we await scrutineering, the team will be doing final checks to ensure that Zephyr will pass the scrutineering checks with flying colors.

Lastly, we will like to thank the numerous sponsors for making this race possible and we hope to do everyone proud!



And We’re Off!!

Tanwei Chen // // No Comments

Our intrepid truck and trailer crew.


Zephyr is ready to ship after a year of hard work, and departed for Texas this afternoon! She will arrive at Circuit of the Americas in Texas on Sunday July 2nd. While Zephyr still needs a few final adjustments after her multi-day journey, we are confident she will be ready for Scrutineering on Monday.


The past few weeks have been a flurry of preparation and testing, and many teammates have been putting in long hours at our workshop at the Richmond Field Station. We had time to hold dynamics tests this week to gauge our preparedness for scrutineering, and took careful care to replicate conditions at the race.

Wetting down the pavement for Zephyr’s brake test


Testing Zephyr’s maneuverability. This is the only color we want to see on our Scrutineering sheets.


Finally, we would like to make a shout-out to everyone who worked so diligently on making Zephyr Rayce-ready this year! Thank you as well to all of our loyal sponsors: without your help none of this would be possible. We are excited to see the fruit of our labors at Formula Sun Grand Prix 2017, and hope to make this Zephyr’s best Rayce yet!

Thank You Mun Manufacturing!

Tanwei Chen // // No Comments

We are excited to announce Mun Manufacturing Co.’s sponsorship for Tachyon! Mun Manufacturing is a machine shop in Oakland, California, and is run by dedicated owners Dennis and Jeanne Lee. They machined the tooling foam plug for our practice mold this summer, and we look forward to a very rewarding and productive partnership with Mun Manufacturing Co.

Practice mold plug, ready for trimming and sanding

Dennis Lee is also a Principal Lab Mechnician at UC Berkeley’s Mechanical Engineering Student Machine Shop, and is always ready to help us and other students with machining and advice. He has been essential for the success of many student projects and teams. We have benefited greatly from Mun and Dennis’s generosity, and can’t thank them enough for their help!

Mun Manufacturing Co.’s logo is proudly displayed our website, and will race with Tachyon in American Solar Challenge 2018, World Solar Challenge 2019, and beyond. We encourage you to contact them at for more information on their services.

Thank You DUNA-USA!

Tanwei Chen // // No Comments

We are very happy to announce DUNA-USA Inc.’s sponsorship for Tachyon! DUNA-USA Inc. manufactures a large range of low and high density foams, as well as chemicals and equipment for utilizing these foams. They have sponsored CalSol with high-density tooling foam and specialty adhesives for joining the foam into larger blanks for milling, and we look forward to continuing our productive partnership through Tachyon and beyond.


DUNA-USA Inc.’s high-density tooling foam is dense enough to hold fine details when machined, and is also nonreactive with a wide range of primers and chemicals. These qualities are essential for making high-quality “positive” or “male” mold patterns, which can then be used to create “negative” or “female” molds for part fabrication.


Large pieces of high-density tooling foam can be very heavy, and a single piece of foam large enough for Tachyon’s molds would be prohibitively difficult to transport and store for long periods. We plan to use DUNA-USA Inc.’s specialty foam adhesive to join together pieces of tooling foam into the required shape and size for our machining blank. We had a chance to practice with their foam adhesive and were very happy with the result: the adhesive expands as it cures to fill any gaps or unevenness between the foam pieces. Not only does this result in a very strong bond, this will also allow us to create our mold patterns without having to fill-in the glue lines after machining.


Our positive patterns for Zephyr were machined from Styrofoam. While we were create successful molds from these plugs, the low density and chemical vulnerability of Styrofoam necessitated much additional sanding and extra protective layers. DUNA-USA Inc.’s generous sponsorship will help us avoid these issues for Tachyon and aid us in making our best molds yet!


DUNA-USA Inc.’s logo is proudly displayed our website, and will be carried on Tachyon as she races in American Solar Challenge 2018, World Solar Challenge 2019, and beyond. We encourage you to visit their website at for more information on their wide range of foams, chemicals, and equipment.


Keep posted for more blog posts and pictures as we begin our mold-making journey with the help of DUNA and other generous sponsors!

Thank You Airtech!

Tanwei Chen // // No Comments

In addition to all of our generous sponsors for Zephyr, we would like to thank some of our new and returning sponsors for our upcoming 9th generation vehicle, Tachyon. We are proud to present Airtech Advanced Materials Group’s sponsorship for Tachyon.

Airtech Advanced Materials Group is the largest manufacturer of vacuum bagging and composites tooling materials, and has facilities all around the world. They have sponsored CalSol with vacuum bagging supplies since Goldrush, and we are glad to continue our partnership for next vehicle.


Airtech’s materials sponsorship with some members of the composites team.


CalSol uses vacuum bagging to ensure proper lamination in the finished part. In essence, we seal our composite layups inside an airtight bag and pump out all the air. This applies atmospheric pressure evenly to the composite part as it cures, making sure the layers stick together. While a large variety of bagging materials exist, we primarily use release ply, breather, and bagging film in our layups.

Example of Peel-ply. Photo Credit: Airtech International Online Store

Release ply (or “peel ply”) is the first layer we apply on top of the carbon fiber. This slick woven fabric prevents the epoxy in the carbon fiber from sticking to the other layup fabrics while allowing air to pass through. Furthermore, release ply leaves behind a textured surface on the finished part, making it easier for us to bond additional parts afterwards.

Example of breather. Photo Credit: Airtech International Online Store

Next, breather is a thick and “fluffy” layer which allows air to move laterally through the piece. This stops the formation of air pockets in the vacuum bag and cushions the bagging film from sharp protrusions in the part. Breather can also help to soak up excess resin in a layup, though this is less of a concern for our prepregnated carbon fiber layups.

Vacuum bagging film over a layup before vacuum is applied. Photo Credit: Airtech Global.

Finally, bagging film is an airtight sheet that holds the vacuum seal. This film has to be pleated so that no “bridging” occurs over concavities in the part. Airtech sponsored us with bagging film that allows up to 550% elongation, which makes it much easier for the film to reach and apply pressure to all parts of the layup.

Airtech’s generous support is crucial for Tachyon’s success, and we hope to create our best composites work yet with their help! Airtech’s logo graces our website, and will be displayed on Tachyon as she races in American Solar Challenge 2018, World Solar Challenge 2019, and beyond. We encourage you to visit their website at for more information on their wide product selection.

Thank You Sunpower!

Evan Lewis // // No Comments

authorised dealer

Sunpower, a commercial solar company based in nearby Richmond, CA, has been designing and manufacturing state-of-the-art solar cells and modules since 1985.  Thanks to a generous discount, we were able to use their high-quality E-60 cells for Zephyr, which, in addition to some valuable advice from their engineers, allowed us to create our most efficient solar array yet.  As a gold-level sponsor, Sunpower’s logo is proudly displayed on our website, shirts, and vehicle. Sunpower’s reliability and performance was instrumental to the success of Zephyr, and we are planning to continue working with them in the development of our new vehicle, Tachyon.

If you would like to know more about Sunpower, we encourage you to visit their website at

Thank You, Bay Area Circuits!

Hersh Sanghvi // // No Comments

Bay Area Circuits, a printed circuit board manufacturing company based in Fremont, CA, has been a dedicated sponsor of ours for 4 years. We custom-design almost all of the PCBs on our car, and Bay Area Circuits’ sponsorship has been critical to our development cycle. We know we can count on their rigorous testing process (which, having witnessed their flying probe test in person, is very impressive) and precise manufacturing to ensure the best possible implementation of our designs. In addition to their material support, BAC’s engineers have readily helped us with any unorthodox PCB design techniques that we were unfamiliar with. We will be proudly displaying BAC’s logo on Zephyr during the race this summer! If you have any PCB manufacturing needs of your own, we highly recommend you consider BAC! Visit their website:

Preparing for Formula Sun Grand Prix, Part 1

Tanwei Chen // // No Comments

Summer is drawing near. Tender green buds and new spring grass are giving way to lush spring growth, while the summer sun shines ever brightly in the cloudless sky. Well, this being Berkeley, the weather is like this most of the time. Still, you get my point…


The coming of summer also reminds us that we are creeping closer to Formula Sun Grand Prix 2017. This summer’s race will be taking place in Austin, Texas, on the Circuit of the Americas, and CalSol is enthusiastically preparing both our vehicle and our team for the competition. This past weekend, we focused on practicing pit operations and communications. Both are essential for success at the race: faster pit operations permit us to spend more time driving laps, while smooth communication skills help us facilitate personnel switches and reduce stress.


Ennzhi Chew, our Mechanical Coordinator, gave a detailed lesson on the intricacies of wheel and tire changing. We rely heavily on No-Mar’s tire changer to slip the rubber tires on and off the rim. Changing tires can be tricky, so several members took turns practicing.


Ennzhi teaches how to change tires.

Ennzhi (left) teaches how to change tires using our No-Mar tire changer


Meanwhile, Harrison Zheng (Engineering Director) and Hersh Sanghvi (Electrical Coordinator) led a quick lesson on the use of amateur (ham) radios. CalSol uses ham radio to communicate during the American Solar Challenge, when cell service can be spotty or nonexistent. We continue to use ham radio during Formula Sun Grand Prix as well, in part to maintain our proficiency for the next road race. New team members learned to use handheld radios and vehicle-mounted sets, while veteran members received a valuable refresher. Harrison and Hersh finished off the lesson with a radio relay, where a pair had to assemble and configure a pair of radios to transmit a code word. Geoffry Ding and Avinash Jois won the race along with Harrison’s reward of boba tea.

April 2017 FSGP Prep radio relay

Radio relay: assembling “vehicle mounted” radios. Their partners are far away configuring the handheld sets.

Finally, we tested Zephyr’s onboard radio range by driving in laps around our work space at the Richmond Field Station. It was great to see the vehicle driving again, and we look forward to continuing out preparation this weekend!

Elizabeth Li driving Zephyr near Building 460, our main workspace at the Richmond Field Station.

Elizabeth Li driving Zephyr near Building 460, our primary work space at the Richmond Field Station.

Thank You Rockwell Collins!

Tanwei Chen // // No Comments

Rockwell Collins-Teklam manufactures aero-space grade honeycomb sandwich panels for aerospace interiors, spacecraft, marine, rail, and automotive applications. They were a major sponsor of Zephyr, and we are very grateful for their generosity. We used their phenolic-resin and honeycomb core panels in the majority of Zephyr’s interior stiffening bulkheads and ribs. These high-quality and machineable panels were also used to attach Zephyr’s carbon fiber shell to her aluminum chassis. Thank you Rockwell Collins for your invaluable support!

As discussed in our previous blog post, honeycomb sandwich panels offer great weight savings over solid panels of comparable flexural strength and stiffness. However, the strength of a sandwich panel, like that of most composites parts, depends on a solid bond between the different component layers. Rockwell Collins’ sandwich panels are bonded under high pressure to achieve superior and consistent lamination. In turn, this translates to stronger and more consistent bulkheads on Zephyr. Furthermore, Rockwell Collins is able to manufacture panels in very large sheets, allowing us to cut long ribs in a single continuous piece. These factors combine to make Rockwell Collins, Inc. a great choice for our honeycomb panels, and Zephyr benefited greatly from their sponsorship.

Rockwell Collins’ logo is featured on our website, and will be displayed on Zephyr as she races in this summer’s Formula Sun Grand Prix. We encourage you to visit their website at for more information on their wide range of products and capabilities.



Blog post updated on June 5th to reflect B/E Aerospace-Teklam’s acquisition by Rockwell Collins.

Thank You Hexcel!

Tanwei Chen // // No Comments


Hexcel is an industry-leading manufacturer of composites materials, with products ranging from carbon fiber prepreg to honeycomb core and adhesives. We are very grateful for their sponsorship during Zephyr’s construction, and used their lightweight honeycomb core in both the exterior shell and interior stiffening panels. The aerospace-grade Nomex honeycomb was manufactured at Hexcel’s Casa Grande facility, and allowed us to strengthen our parts without adding unnecessary weight. In addition, Hexcel’s core was easy to work with in manufacturing, aiding our fabrication process. Thank you Hexcel for all your help!

The value of Hexcel’s sponsorship can be further demonstrated through a quick overview of composites sandwich panels. Sandwich panels comprise of a “core” material (Hexcel’s honeycomb core) sandwiched between two “facings” (carbon fiber in our case). While the facings provide tensile and compressive strength along the plane of the panel, the crush-resistant core stiffens the sandwich structure against out-of-plane bending. Since the honeycomb core is mostly hollow, very little weight is added. In this way, it acts much like an I-beam: the webbing in the middle adds stiffness and strength with very little increase in weight. The advantages can be substantial, as this table from Hexcel’s Sandwich Panel Fabrication Technology Datasheet demonstrates:

Demonstrates strength/stiffness benefits of using honeycomb core.

For this reason, we tried to incorporate Hexcel’s honeycomb core into the majority of our carbon fiber shell. Their core materials can be engineered to facilitate bending along a chosen axis, helping us lay core along the complex curves of the outer shell.

We proudly display Hexcel’s logo on our website, and look forward to racing with their logo at this summer’s Formula Grand Prix. We encourage you to visit their website at for more information on their cutting-edge products and facilities.