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.

Thank You Patz Materials and Technologies!

Tanwei Chen // // No Comments


Patz Materials and Technologies manufactures cutting-edge composite materials for a wide range of applications, and has been a generous sponsor of CalSol throughout Zephyr’s build cycle. Their carbon fiber prepreg was an essential part of Zephyr’s success and forms the structure of our lightweight aerodynamic shell. Their high-performance materials were a great improvement over our previous composite processes in both performance and ease of use, and we can’t thank them enough for their help! We look forward to continuing our partnership through Tachyon’s build cycle and beyond.

In addition to material support, Patz Materials and Technologies also gives us valuable advice in material selection and layup practices, and has offered to validate our layup samples with their ASTM-standard testing equipment. Finally, Patz Materials and Technologies led us on a tour of their manufacturing facilities in January. They showed us their impressive core and prepreg-manufacturing facilities, and taught us a lot about the manufacture and processing of these cutting-edge materials.

Patz_01_Uni_Spools     Patz_04_Uni_Done

Spools of carbon fiber being made into unidirectional prepreg



Patz_06_Weave_Done   Patz_08_Joseph

Finished roll of woven carbon fiber prepreg and Joseph Talosig, our wonderful guide


The Patz Materials and Technologies logo is proudly blazoned on Zephyr and our website, and we look forward to representing them on Tachyon as well. We encourage you to visit their website at for more information on the amazing work that they do.

…And We’re Back!

Andre He // // No Comments


It’s been a while since we’ve posted on this blog, but let’s get things started again. A lot has happened in the past year: we’ve competed in the Formula Sun Grand Prix (FSGP) and American Solar Challenge (ASC) 2016 with a 9th-place finish, and have also begun development of our 9th generation solar vehicle, Tachyon! We’d like to extend a huge thanks to our team members, sponsors, and supporters for making all of the progress in the past year possible.

Looking forward, we are now preparing to compete in FSGP 2017, which will be held from July 3-7 at the Circuit of the Americas in Austin, Texas! We will be bringing our 8th generation vehicle, Zephyr, to compete in its final race.

See what we’re up to on Instagram, Facebook, and Twitter!

Thank You and Happy Holidays

Ryan Park // // No Comments

It’s that time of year again. There is a distinct lack of holiday decorations, not nearly enough presents, and no one appears to be caroling. Yet, everyone seems to be bubbling with glee and excitement.

It’s a different type of festivity — it’s Thanksgiving!

Thanksgiving weekend is quickly approaching, and the team is looking forward to spending quality time with family and friends, away from exams and assignments.

The entire CalSol team would like to wish you a happy Thanksgiving, one hopefully with endless servings of turkey, laughter, and a re-instilled sense of gratitude.


FSGP Scrutineering Success

Aly Scheske // // 2 Comments

Part of the FSGP Rayce Crew around Zephyr

All the green stickers have aligned- CalSol has completed each section of scrutineering and will be excitedly moving onto the Circuit of the Americas (CotA) track tomorrow! The three days of Scrutineering progressed smoothly with minor fixes to Zephyr, including some items such as re-securing our emergency stop button and adjusting the angle on our front headlights.

CalSol is represented by a team of 22 members. They have been diligently working through the heat in Austin, Texas to get us through scrutineering. We have had a Formula 1 garage bay to work in as we prepare for the track.  Along the way, we’ve made improvements to Zephyr, increased our knowledge of different aspects of the solar car, and most importantly- had fun along the way.

Members share some of their favorite parts about the scrutineering process:

  • “I have loved the opportunity to learn about details on different aspects of vehicles from the organizers during inspections. During Mechanical Scrutineering, our inspector explained how different qualities of stitching on a seat belt correlates to different G forces drivers experience. We will definitely take small details like these to guide the design of our next car!” -Alyssa Scheske, Operations Director
  • “It’s been awesome sharing this world class facility with professionals. Nissan has been using the track the past few days and it’s been really cool to watch their vehicle wiz by in the hot lanes from the garage!” – Chris Berthelet, Driver Interface
  • “I think that the sharing culture between the teams has been amazing. Every team is willing to lend materials and thoughts to get their compeitiors through scruintneering. Everyone is really genuine- the solar car community is a small niche of some of the smartest and kindest people around.” – Neeka Mashouf, Driver and Battery Engineer
  • “Team bonding!!! Meals have been so tasty, they are a great way to relax with the team.” – Nour Eldifrawy, Safety Officer

#FSGP2015 starts tomorrow and CalSol could not be more excited or more ready. Keep posted on our social media pages for updates as FSGP goes on!

Zephyr Fairing Doors

Aly Scheske // // No Comments
“The last 5% of the work takes 95% of the time.”
These words ring true to CalSol as we approach FSGP. We have nine days until competition starts with the time flying by. Zephyr has been in great shape since early 2015, but going through extensive road testing, debugging sessions, and minor hardware upgrades these past few months. This testing time has proved to be incredibly fruitful for CalSol.
Zephyr’s Fairing Doors has been one project absorbing a lot of attention. The design for Zephyr included fairings around each wheel to improve our drag; however, aerodynamics and maneuverability must be optimized for functionality. Fairing door structures are covers for gaps and spaces between parts of the exterior to reduce form drag and interference drag, in addition to improving appearance. Our design allows for the doors to be “shut” completely over the wheel-well while driving straight, but swing “open” as the driver turns the steering wheel and the wheels and tires turn. We trust that this design and hardware content will greatly improve performance. We are excited to unveil full functionality at FSGP.
Check out the pictures below of Zephyr’s fairing doors!
Rear view of fairing door

Rear view of fairing door

Top-down view of the fairing door wheel-well

Top-down view of the fairing door wheel-well

CalSol members Stephen Lu, Ian Fisher, James McCay, and Danial Gay have put countless hours into this project- the whole team would like to commend them for their hard work!


No-Mar Tire Changer Sponsorship

Aly Scheske // // No Comments

Tire-Changer jpgWith 2 weeks until Formula Sun Grand Prix, CalSol members have been excitedly pushing the pace of work in anticipation. This work has been happening full force in multiple disciplines of CalSol- engineering work, logistics work, and industry interaction. CalSol has just gained the partnership of No-Mar.

Not only has No-Mar Tire Changer donated a tire-changer to CalSol, they have also shared valuable industry insight. Via the phone and over e-mail, No-Mar’s knowledgable employees’s has opened crucial discussion points for materials CalSol uses. Their advise has opened CalSol to new ideas and opportunities never thought possible before due to higher quality tools and materials.

No-Mar has meet our needs and anticipated even more. They will be providing us with a Classic Tire Changer kit and a Balancer kit. It would take members of CalSol hours upon hours to physically change a full set of tires on Zephyr. Tires would be extremely tight on the wheel and take brute strengths. With No-Mar’s sponsored Tire Changer Kit, they will allow CalSol members to focus more on improving our engineering aspects of the car, improving efficiency for our team and even Zephyr.

CalSol would like to thank No-Mar Tire Changer for their assistance and contributions – we are looking forward to continually working together!

Their generous support will be returned by a sticker on our car and their company link on our website. We encourage you to please visit No-Mar’s website for more information at


Mid-Summer Update – Powering Up and Strapping In for FSGP 2015!

Viswanath Chatterjee // // No Comments

It’s just three weeks until the Formula Sun Gran Prix at the Circuit of the Americas race track in Austin, Texas, and the CalSol team is looking forward to driving with and competing against the rest of the solar car community! We haven’t posted in a while, and there haven’t been core design changes lately, but the excellent state of this car and this team has us feeling optimistic for FSGP. Addressing potential bugs (mechanical, electrical, and code), implementing optimizations to squeeze out every watt we can, and testing the systems has kept us plenty busy lately, so check out some photos of the work!


Tidying up the wires and securing connections in the all-important battery box

Tidying up the wires and securing connections in the all-important battery box

Reinstalling sturdy enclosures to hold up and protect the various boards on the underside of the top shell

Reinstalling sturdy enclosures to hold up and protect the various boards on the underside of the top shell

Revising boards to include additional safeties (gotta love capacitors) and power routing optimizations

Revising boards to include additional safeties (gotta love capacitors) and power routing optimizations. Shout out to Bay Area Circuits for all their help with the PCB’s!

Building the solar array for an off-site "electrical test bed": a scaled-down version of the electrical system!

Building the solar array for an off-site “electrical test bed”: a scaled-down version of the electrical system!

And with a mini solar array comes an equally adorable mini battery box

And with a mini solar array comes an equally adorable mini battery box

Mechanical folks contemplating life. CalSol is life.

Mechanical folks contemplating life. CalSol is life.

Installing an improved hinged fairing door mechanism

Installing an improved hinged fairing door mechanism with a carbon-fiber axle

Road-testing Zephyr, which now has a few hundred miles on it, brings us admirers of all ages

Road-testing Zephyr, which now has a few hundred miles on it, brings us admirers of all ages


We’ll be sending out updates during the race, or post another photo gallery at the very least. See you all then!