Day 4 of FSGP – Raycing!

Wen Rui // // No Comments

Rayce Day.

Preparing the car before the race start

Day 4 of FSGP is the first day of circuit racing at the Circuit of the Americas (COTA). The race format is as follows: over the span of 3 days, the team with the most number of laps completed is deemed to be the winner of the race.

Zephyr passing corner 15 in the COTA

Teams are given a full charge on Day 1 and have to rely purely on solar energy for subsequent charging of the packs over the next 3 days. At the end of Day 1 after 8 hours of racing(10am to 6pm), Zephyr completed 72 laps with a total distance of 244.8 miles traveled. This stellar result places us at 2nd position, only 1 lap behind the race leader at the end of Day 1.

Throughout the day, there were certain strategic decisions to be made. These decisions included when to speed up/slow down and the timing of the pit stops. Rotating all 3 drivers, CalSol did a total of 3 smooth pit stops. Here is a POV of one of the pit crew members during a pit stop:

Pit Stop FSGP 2017

Ever wonder what it's like to be part of the pit crew for Zephyr at #FSGP2017? Here's a video of a tire change and driver swap we did this afternoon. Race hours for today are done, and Zephyr held at first place for most of the day. Check live race updates here:…/formula-sun-grand-prix-2017-2017-circ…. Go Bears! (Make sure to hit the HD button)
#gopro #berkeleyPOV

Posted by CalSol – UC Berkeley Solar Vehicle Team on Thursday, July 6, 2017

Before entering the circuit again for another day of racing, the teams are given 4 precious hours for statically charging the solar array: 6pm – 8pm on the day itself and 8am – 10am the next morning. These crucial hours act as valuable time to maintain a good battery charge for the next segment of the race.

Going into Day 5, the team is definitely pressured to keep up these results but we’re hoping to perform as well if not better!

Day 3 of FSGP 2017

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Team photo right after passing all our scrutineering tests

And we are all GREEN!

CalSol ended Day 2 with a high, successfully passing all scrutineering tests with greens. This included passing the dynamics test like the slalom test below:

Passing these tests makes us track eligible for the circuit segment of FSGP on Thursday.

Free of any tests on Day 3 (Wednesday), we seized the opportunity to prepare ourselves for the next 3 days of grueling circuit racing.

At the crack of dawn, the early crew set up and tested the solar array. Potentially spending up to 24 hours on the track over the next 3 days, having a reliable and efficient solar array is crucial for success at the race.

The early crew testing out the solar array

After the daily team meeting, the team went for a road test at the COTA facility, further simulating race conditions in the scorching heat.

The team discussing race strategy

With all these preparations, the team is hyped up for the the first day of circuit racing tomorrow. GO BEARS!

Day 2 of FSGP 2017

Wen Rui // // No Comments

Zephyr waiting for a scrutineering station

The first few stages of FSGP went really well for CalSol, passing all static scruntineering stations with greens. This includes the daunting Electrical, Battery Protection System and Mechanical scrutineering tests. Making minor adjustments on-the-fly, the team managed to convert all yellows to greens within a short period of time.

The team preparing Zephyr for mechanical testing

The next challenge for the team will be the dynamics test. This includes braking and handling tests – tests which often make-or-break teams (literally). Zephyr will be required to maneuver around tight boundaries and a demanding braking test.

Zephyr proceeding for dynamic testing

We wish everyone the best of luck with this phase!

Greetings from Austin, Texas!

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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!!

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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!

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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!

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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!

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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!

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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: