MIT Solar Car Team Blog

Composite Layup 2016

First we are pleased to announce the name for our newest solar car, which we will be taking to the 2017 Bridgestone World Solar Challenge, will be named Flux! On that note we are happy to say as well that our team is now officially registered for the 2017 Bridgestone World Solar Challenge.

It is now well into the fall semester, people are studying for finals, the leaves have fallen, and the team has been busy building Flux. The biggest part of this has been the composite layup (see below if you aren’t familiar with this) for Flux’s body. The molds for the upper and lower body were made by Custom Composite Technologies in Maine. We traveled to Maine on the weekends in order to complete all the layups that needed to be done. In total the team has been in Maine five weekends this semester from September through November. There were many late nights, but also some great times as well, such as the team trying to devour three 28-inch pizzas. Sadly the pizzas won. Between all of the weekends we manufactured: the canopy, the top body, and the lower body. We finished off by assembling the chassis and bonding it to the lower body. We have made amazing progress for one semester, and most of the composites work is almost done. Check out some of the pictures from the layup below.

What is a Composite Layup?

In order to make the car as light as possible we use composite materials, such as carbon fiber and Kevlar, as much as possible. Basically we use sheets of woven carbon fiber or kevlar that we then glue together to make a sheet with a high strength to weight ratio. However a single sheet is very thin and flexible. So we make a sandwich-panel where a sheet of honey-comb is sandwiched between two composite sheets. This increases the thickness of the panel making it stiffer.

Laying-up is the actual process of manufacturing a composite material. There are two main layup processes that the team uses: a wet layup, and a prepreg layup. In a wet layup the fibers start out dry. They need to be covered in epoxy before they can be placed on the mold. On the other hand a prepreg layup starts with fibers that are pre-impregnated (or prepreg) with epoxy. With wet layups the epoxy will cure in about a day, and you only have a few hours before it becomes semi-solid. So with wet layups the team has to move fast. Whereas with prepreg the epoxy will take about a month to cure at room temperature, so the work can go much slower. However to get prepreg to properly cure it needs to be heated up with a car-sized oven.

Summer Wrap Up

This summer was a really exciting time for MIT’s Solar Electric Vehicle Team. After coming back from the road trip, we got to work on constructing the latest vehicle for the 2017 World Solar Challenge. The release of the regulations gave us fun design challenges to think about.

We had several people working full time on solar car over the summer. They acted as owners of specific projects from designing the steering system to the turning fairings. Many of these students working full time were freshman, so they had the opportunity to conduct independent research and become experts in specific fields. Shop started at 11 AM and sometimes went late into the night, but thankfully there was breaks for Mexican food and other fun activities!

Now that the semester is underway, there are classes as well as solar car activities, so we are not in shop everyday! Currently, we have many new members and they are doing exciting new projects!

The future looks bright!

Posted on behalf of Priya Kikani

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Road Trip 2016: Ohio

The week following finals is usually a relaxing time to unwind, relax, and try to put those nasty tests in perspective. However, this is not true for solar car. Finals had barely finished, and the team was already abuzz with activity. The team was getting ready to leave on a road trip that Sunday for Ohio. Road trips are a strong tradition on the team, and for good reason; they offer a great chance to extensively test the solar car on public roads, get the team ready to perform in the upcoming solar challenges, and help train the next generation of drivers.

Photo Credit: Chris Pentacoff '06

Photo Credit: Chris Pentacoff ’06

This year’s road trip was during the last week of May in Columbus, Ohio. The main purpose of this road trip was to get more strategy data on Arcturus, and use Arcturus as a test bed for ideas for the next car. This included testing Arcturus with an off center center of mass to see how stable an asymmetric car would be. This road trip helped train new team members on how to work together during a solar challenge. From this road trip we now have two new solar car drivers who are both comfortable with driving at highway speeds. The data that we collected on our electrical system, brakes, balance, and stability will help improve the design for our 2017 car. The road trip helped with weeding out more issues that team can now address and prevent in future designs.

If you want to see more from the roadtrip check out our flickr

2016 Ohio Road Trip

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Sierra Circuits Sponsorship

Building a solar Car is a difficult task that mandates innovation and ingenuity. Almost every part on Arcturus was custom designed and built by the team. This includes all the electronics that run the car. The team makes custom designs for the many printed circuit boards (PCB) on Arcturus, and our other solar cars. Sierra Circuit’s sponsorship has been a great help on this front. They helped the team immensely by manufacturing our custom PCB’s. These Boards were manufactured quickly and with a high standard of quality. The team is very thankful to Sierra Circuits for its sponsorship, and helping make our solar cars run.

Sierra Circuits

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Regulations Released for 2017 Bridgestone World Solar Challenge

Just today the regulations for the 2017 Bridgestone World Solar Challenge were released. Since then the team has been meticulously reading the regulations. The team mailing list has been ablaze with emails looking at the impact of the regulations of the design.

From the regulations’ introduction here are the biggest changes that have been made for 2017:

  • The maximum allowable size for cars has been increased to allow greater diversity of design, and provisions made to find synergy with other international events.
  • Challenger solar collector area has been reduced to 4 m2 (for silicon PV) half of what was allowed in the first World Solar Challenge in 1987.
  • Cruiser solar collector area is reduced to 5 m2 for silicon PV cells, to make it easier to fit a solar collector on a practical car.
  • The apertures of solar reflectors and concentrators will be restricted.
  • Refinements have been made to the requirements for occupant protection and vehicle dynamics. In addition there is a new requirement for mechanical braking on all road wheels.
  • Energy storage limits have been removed for Cruiser Class, which will be run as a single stage regularity trial’, Success in Cruiser Class will be based on energy efficiency practicality and adherence to time targets.
  • Adventure Class will be non-competitive.

This marks many large changes for all of the classes. For challenger class, which we hope to compete in, this greatly reduces the solar collector area. The regulations also limit solar concentrators and other devices which will ultimately reduce the power output of the car’s solar array. More than ever efficiency will be the name of the game as teams work to further optimize how the precious Watts the solar array produce are used. Car will be lighter, and more aerodynamic, and will continue to push the boundary of efficiency. our team is excited to take this challenge head on, and hopes to see everyone at the start line on Saturday October 8,2017.

Bridgestone World Solar Challenge PRIMARY LOGO

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Aerodynamic Design with ANSYS

ANSYS is one of the team’s newest platinum sponsors. They have generously provided the team with several simulation packages, including Fluent which the aerodynamics team uses extensively in our analysis of the solar car.

Ansys Simulation

Aerodynamic drag makes up the majority of the power loss during the normal running of a solar car, thus it is of upmost importance that the car’s shape is optimized to minimize this loss. ANSYS Computational Fluid Dynamics (CFD) products enable us to perform detailed analysis to help us iterate on our designs. By looking at pressure distributions, identifying vortices, and looking out for flow separation, the aerodynamics team have a myriad of tools with which we can improve our design.

We are delighted to use ANSYS Fluent for its fast, accurate and reliable results. If you would like to try your hand at some simulations, check out ANSYS Student, which is available free to all students worldwide. It includes several solid as well as fluid solvers, and is ideal for those who want to explore engineering design.

Ansys simulation2

Posted on behalf of: Tommy Li

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Battle of the cakes 2016

It is that time of year again: time for battle of the cakes. On our team we have a tradition that every year during a team potluck there is a cake baking competition between the freshmen/new members and the upperclassmen. The rules are simple as a team bake a cake based on our solar car and then a panel of third party judges will decide the winner based on taste and appearance. Last year the freshmen won in a land slide, as you can see below. So who won this year? The judges have their opinions, but before we tell you we want to know your opinion. Check out the two cakes (in no particular order), and then vote below.

Cake 1

Cake 1

Cake 2

Cake 2

2015-cakes.

Last year’s cake entries. The freshman cake is back.

All photos were taken by the author

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Post WSC Adventures

After crossing the finish line in Adelaide, the adventure continued. Myself and 4 other team members made an extended layover in New Zealand on our way back to the U.S. We spent five days driving around the south island of New Zealand. We started and ended in Christchurch and stopped every so often to take in the spectacular views we saw around every bend. We saw the unusually spherical Moeraki boulders on the Otago coast, played with frolicking alpacas, found the most southern point of the island, explored the busy city of Queenstown, enjoyed a flying lesson to Milford Sound, witnessed the wonders of a cave full of glowworms and took in breathtaking views of the Southern Alps. The last day of our trip, Nov 1 also happened to be when the final Rugby World Cup match between New Zealand and Australia was being played. This meant we were able to watch the game in Christchurch with the locals. It was an exciting and  unforgettable experience.

After landing at the airstrip in Milford Sound from left to right: Christopher P. ’06 , Kelly R. ’12, Michelle C. ’17, Trang D. ’15 and Micah G. ’18

a typical road side view

We went on a short tramp and were rewarded with a spectacular view of Mt. Cook

check out the early morning view from our hotel in Queenstown

Photo Credit: Michelle C. and Christopher P.

 

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Spring Semester and Tilted Solar Cells

This week is the first week of classes for the spring semester. This is rather late for a college to be starting classes, but as I mentioned in our last blog MIT has the Individual Activities Period (IAP) for most of January. This is the fun week of figuring out classes, and bugging your Adviser every other day. I have managed to submit two add/drop forms by the second day of the semester. Let’s hope this trend doesn’t continue. So what does a nuclear Engineering student take? This semester I am taking thermal-fluids engineering, programming in MATLAB, Applied Nuclear Physics, and Soviet and Post-Soviet Politics.

Besides classes I have also been working on an interesting project for the solar car. Right now I am working on modeling the power output from possible array designs for our next car. I am working with the aerodynamics team to give them feedback so we can balance the aerodynamics with solar array output. In my research for this I came across this programming library called PVLIB which was developed by the PV Performance Modeling Collaborative at Sandia National Labs. This library is making my life so much easier by predicting the solar irradiance, calculating the “effective irradiance” for a single cell, and just doing all the complex (real numbers only) math I didn’t want to code. Now just to model a few hundred solar cells that move!

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New Year, New Members, and New Projects

Happy very belated New Year! It’s now January and here at MIT that means only one thing: IAP, or Independent Activities Period. IAP is most of January and is a time for students to relax and focus of fun activities, projects, and classes. Some IAP favorites include: mystery hunt, Charm School, and Battlecode. But I’m not here to explain everything there is know about IAP, I’m actually here to talk about the most exciting thing about January: SNNNNNOOOOOOWWWWWWW!!!!!! Oh right also I’m talking about the second most exciting thing about January: Arcturus is back in shop!

Arcturus in Shop

Arcturus is back! She got back to port in late December. Our team Captain, Priya, and a few other team members who got back right at the beginning of IAP made the fun five hour drive to Newark port at 02:00 in the morning to pick our trailer up and bring it back to shop. So now Arcturus is back in shop. The electrical team was able to power her back up after a few days of unpacking and rewiring. This is because many of the connections were disconnected in order to make the battery safe for shipping. Now you may be wondering what our plans are for Arcturus. First of all the electrical team is right now working on debugging the electrical issues Arcturus was having at the end of the 2015 Bridgestone World Solar Challenge. We then plan to in the spring and summer drive Arcturus a lot to gather more data on her performance so we can better optimize a four-wheeled car. In the mean time there are many small projects to be done. Such as my “fake motor” project. We are planning to send our motors back to manufacturer for some maintenance and to prolong their lives. The problem is that our car uses hub motors which removes the need for gears or belts connect the motor and the wheel. However this means that right now without a motor there is no way to attach the rear wheels to the car. So my project is to design a system to attach the spindle and hub that we use on the front of the car to the rear suspension, so the rear wheels can still spin. Many of our members doing these projects are participating in the Undergraduate Research Opportunity Program (UROP) and are receiving credit right now for working on the team. For example one Freshman, Helen, is working on reducing the weight of our braking system and preventing brake rub.

Finally I promised to talk about snow. Snow is fantastic! Ok my northwestern love of snow is showing. This last weekend winter storm Jonas gave us three inches of snow; I was hoping for more but any snow is still snow. It was wonderful. I spent many hours in the snow, and my friend and I tried to make a snowman. However the snow was too powdery so instead we tried making snow sculptures. Sadly though Tuesday was above freezing so now there is no more snow. :(

Snow at MIT! :D

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