Everyday Life of Our Mechanical Engineers

These are the guys doing the heavy lifting and investing so much effort, sweat (and maybe some tears) to make sure our solar-powered car actually looks like a car. Our mechanics design and build a frame to which all the rest will be attached to like the brakes, steering, interior etc. Our mechanics team consists of five main categories: suspension; frame; battery; interior, and aerodynamics - this team of incredibles is led by Aleks Tammela.

Aleks, our mechanics team lead is a TalTech alumni, he majored in product development and and manufacturing.

Photo: Simm Paap

• Suspension team makes sure the ride is as smooth as possible and that the car stays on its wheels. They also take care of its brakes and steering system. This team is made up of Ardo Tiits, Nikita Chornyi and Kevin Telliskivi.

• Making the bones of the car, namely the frame, happens under the supervision of Ülo Pajutee whose biggest responsibility is to ensure the safety of the drivers and design the platform that brings it all together. The frame of the car is the spine of the whole project - without it we wouldn’t be able to build a car at all.

• The battery gives power to our car, hopefully moving it from A to B in the most effective way. To make sure this actually happens, we decided to design and build our own battery. Our head engineer for the battery team is Peter Kipp, assisted by Danylo Bezruchenko.

• Our interior design team is led by one of our newest members, Triinu Lusmägi, who faces the challenge of creating an interior that enables our drivers to operate the car swiftly and to make sure they won’t overheat in hot climates.

• Aerodynamics direct the airflow in a way that helps the car move forward with ease and without using too much energy. Kristo Kanik and Sten Marcus Malva are our aerodynamics champions.

They are our superheroes and together they’ve already achieved a lot. Here are some of them.

We have a test-frame

This is a big one as it plays a huge role in our prep for the big race in Australia. The team focused on using low costing materials and methods for this test frame, leaving themselves room for revisions before manufacturing the final parts. Our partner QTH and mentor Tanel Haak were a great help in this process.

The frame will have to support suspension, braking and steering systems, engine, batteries, seats - you name it. All in the name for getting the car to actually drive. Peter Kipp, who is responsible for the battery says the test frame building process has gone relatively smoothly: “Our previous frame took about two months to build - welding this one for about four days was like child’s play.”

Can you believe our mechanics took this pile of pipes and build this whole frame!?

Photos: Joosep Ress & Mart Erik Kermes

Once the important pieces get attached to the frame, the team is ready to test it out. Testing will reveal what’s working as well as any revisions still needed. If all goes well, the parts will be sent for final production. For final production, higher quality materials will replace the cheaper test ones. Last season, our testing period was cut a little short and it ended up hurting us bad at the race. Other teams were able to take short tuning breaks lasting for just a few minutes, while we had to pause for hours.

Test frame in its full glory, waiting for the rest of the parts to be added.

Photo: Peter Kipp

Aiming for the lowest drag possible

There are many things that determine the effectiveness of a solar car. One of them is making sure the car experiences as little wind resistance and drag as possible. Our engineers are performing several tests to find the most aerodynamic body shape for the car. For a solar car, this means making sure the air can pass it by without much resistance. Air has many qualities that increase drag like turbulence, direction, and backflow to name just a few. They force us to use more energy to get the car moving. Kristo Kannik, our aerodynamics team lead, is says the current form is now in the optimization phase:
“The unfortunate thing is that each change has demanded a lot of resources from us for getting our aerodynamics analytics back on track and that slows us down.”

The good news is that the new body is already 26% more aerodynamic than the previous model:

“Soon, we’ll be able to enter our fine-tuning phase, where we can focus on smaller changes and finish our final body design.”

The drag equation states that drag is equal to the drag coefficient times the density times half of the velocity squared times the area of the car. Our goal is to get all the numbers we are able to influence to the smallest digits possible. The less drag it has, the faster our sunny pony will ride!

Our previous car model’s drag coefficient was 0.2, whereas our current one sports a 0.15. We are stoked to see what the number our final design will be! To calculate the coefficients, we use a simulation software called Ansys Fluent, which uses computational fluid dynamics. Our engineers have to insert the body shape into the software and create a virtual wind tunnel, which will let the program calculate and understand how the wind moves around our car, and which zones it creates on its surface.

Why does it matter? We need to design a car that encourages a neutral airflow with as little turbulence as possible. In order not to leak our new design quite yet, we are going to include here one of our earlier reports from the previous season. As you can see, the very front of the car is bright red, meaning the drag in that area is high. It makes sense, as the very tip of the car will be directly crashing into the wind without there being many opportunities for it to pass by. On the chart you’ll also be able to see the back side of the car, which means the drag is a lot less in that area than anywhere else. Finally, there’s a big difference between the top and the bottom side of the car. In the ideal world, there would be little to no difference in the colors that pop up on the analysis, meaning the airflow is smooth and even.

The airflow shouldn’t be too slow nor too fast. To direct it, we could use different methods. The easiest being changing the shape of the front and the back of the car. This way we can control how much air passes underneath or topside of the car as well as how they meet again behind the vehicle. The key to an aerodynamic car is breaking up the airflow and bringing it back together as quickly as possible behind the car. Kannik says they are working on several solutions to increasing the efficiency of the airflow.

The durability of the frame

In addition to the aerodynamics testing, the team also runs several tests on the durability of the frame, which seeks to understand how the frame will last in different situations, including crashes, rolling over the hood, and while hitting potholes. We want the car to endure weights, but also to avoid bending out of shape in other directions. Ansys Mechanical software uses the finite element method to understand how different areas of the car can handle impact and weights. For example, one of the tests uses a scenario of turning left with the car after which the weight of the car shifts to the right and its front wheel power moves up, while unexpectedly hitting a pothole, moving its force down, which will put pressure on the frame.

Drag isn’t the only challenge the mechanics have to wrestle with. The car needs to also not roll away or in the wrong direction. This part needs high attention to suspension and tires. Tires are easy - more pressure means a better moving car. However, suspension is a little trickier. Today, we’ve reached a model that helps us keep our wheels as straight as possible, keeping us away from leaning to either side. The model also helps us steer the car at varying speeds, making sure the wheel isn’t too light or heavy and keeping the wheels in the right position with ease.

Peter, the leader of battery team has graduated from high school this year.

Photo: Simm Paap

We already know how to do some things more efficiently, and as a result our new suspension will not be made out of aluminum, but out of tubular a-arms. It makes the production simple and quick, reducing the time it takes to make any revisions as well. For the race it means we’ll be able to take the whole suspension apart with ease and replace it entirely. This way, we can spend a lot less time on fixing the car and more time on focusing on reaching the finish line.

Each team is working hard, including working on designing our own battery:
“We had to keep testing an assembly of 50 parts to ensure it adheres to all the rules and standards. Finally, after dozens and dozens (if not hundreds) of tests, we finally completed one!”

To test whether each analysis and calculation is actually feasible in real life, we need that great test frame of ours! By attaching different components, we’ll be able to put theory into practice. To find out how that’s going and what else the engineers are up to, you have to come back next time!

This story was written by Solaride’s marketing team member Laura Korjus and translated by Jette Stammer