HAN Eco Marathon

The HAN Eco marathon is a student event organized by the HAN University of Applied Sciences. The objective of the event is to design and produce a car that can travel the furthest distance for each gram of CO2 produced. The powertrains allowed were combustion engines and electric drivelines. The car is supposed to be designed under certain rules which exist for the safety of the drivers, spectators and the engineers making the vehicles. The teams have a limited budget of 1000 euros and all the teams are allowed one testing day at the circuit and the main event took place at the Lelystad circuit in the Netherlands.

Maximizing efficiency was the objective of our team we had to have the largest distance travelled per gram of CO2 expelled. The team made the choice to use an electric driveline due to the higher efficiency of the electric motors as compared to combustion engines. The CO2 use for electric vehicles was calculated by seeing the energy consumed and then calculating the CO2 that is produced to make the energy.

My role in the team included leading a small team which made up the chassis and body department. Our job was to design a lightweight chassis and an aerodynamic body with least amount of aerodynamic drag. We worked by looking at ways reduce losses like air drag and rolling resistance. The basic concept we came up with was a 3 wheeled vehicle with 2 wheels in the front and 1 in the back with the electric driveline. We chose a driver and decided to make the vehicle around him to make the vehicle as compact as possible.

We initially decided on making a lightweight spaceframe for the vehicle with steel tubes.  After making our design on Solidworks and doing analyses we realized that the steel tube chassis was too heavy. We discussed the option to use aluminum instead of steel, however, that idea was scrapped as aluminium tubes would be too costly and since no one within the team knew how to weld aluminum it would add to costs if the chassis welding had to be outsourced. With a limited budget it was not possible to make this happen.

We decided to consult teachers who could help us reduce the chassis weight of the vehicle, some teachers suggested simplifying the construction or using wood in the vehicle. One of our teachers suggested that we could save a lot of weight by using a sandwich panel. We agreed this was a great idea and decided to make the base of the chassis with a sandwich panel. This meant we did not need a floor piece for the body. We used the partial spaceframe along with the sandwich panel to mount the rear and front wheels and steering system. We used a sandwich panel of wood skins and a foam core.

The steering system we used for the vehicle was one like the one used in go karts. The front wheels were 20-inch bicycle wheels and the rear 28-inch bicycle wheel. We used disc brakes for the front wheels and on the rear, we used bicycle v brakes.

The chassis and powertrain department worked hand in hand and while the chassis department was busy the powertrain department designed the driveline for the vehicle, we had chosen to go with a wheel motor like the ones that are present in electric road bikes. Along with a 36V battery system.

One of the mandated parts were the batteries, they were provided by the university and they were lead acid batteries of 12V. Therefore we had to use 3 batteries. Once the chassis and powertrain were finished the body was designed. It was decided the body would be streamlined to reduce air drag with separate wheel covers on the front wheels to reduce the drag around them as well.

The production process of the vehicle was the most challenging part of the entire project. It was here we realized that the design we made was not too simple and would challenge us. One of the biggest changes came from the choice of drivers. We had decided to switch drivers and go for a lighter driver; the said driver however was taller which would lead to changes in the design.

Immediately the packaging of the entire vehicle was changed. The sandwich panel had to be made longer and the steering interfered with the drivers legs. This was not allowed and was stated in the rules therefore changes had to be made. Several design changes were made during the production process and that was costing us a lot of time. We were behind several teams in production and in the end that became too much.

Testing day arrived and the vehicle we had made was heavier than expected and therefore failed the braking scrutineering, the steering radius of the produced vehicle was too much. Since the vehicle was not fit for the track the team decided to not to go for testing. This was a big blow for the team and the morale. The main race was only 2 weeks away, all other teams had a day of testing and our team had a vehicle that was yet not fit for the track.

 It was a tough time for the team but we had a meeting to discuss our options. And the only choice was to tackle our issues from the bottom up and work hard. The team went full steam working from 6am to 12 midnight for the 2 weeks.

We decided to change the vehicle dimensions, the height of the vehicle, the drivers seating position steering positioning and even the amount of batteries to use. The amount of batteries to use was changed because using 36V the vehicle was not reaching required speed after a certain amount of time, that wasn’t enough for the vehicle to do the 3 runs required by the competition. All these changes added weight and made the vehicle less compact but we were running the risk of not making the vehicle in time for the race so we agreed to allow these compromises.

 We put 2 V brakes in the rear wheel to make sure the vehicle can brake because of its added weight. After working for more than 1 week for around 16 hours a day our chassis was ready for the scrutineering. We were all very nervous but our hardwork paid off, we passed the scrutineering. The chassis was ready to hit the track and the driveline was ready too. However, the by-product of the changes was that since the dimensions had changed significantly due to that the body had to be redesigned. The body was redesigned and and then some members of the team produced the mold with wood and gave the mold to a company that specializes in fiberglass bathtub production.

After all this work the body was ready only 2 days before the race and everything was mated together only 1 day before the race. We put our sponsor stickers on the vehicle and tested it one last time on the night before the race and let the batteries charge till morning.

Raceday arrived and it was a completely different story, we arrived at the circuit in Lelystad and it was pouring down. This was a problem for he teams taking part in the event because the sun had been shining the entire week and the forecast was for a sunny day. None of the teams had done water proofing to their vehicles. So when the teams arrived to the paddock everyone got to work on waterproofing their vehicles. Thankfully our car was waterproof and all our electronics were safe from the rain and puddles on track. Raceday was very hectic and the first few teams went out on track to put the heats in, immediately we realized what a big problem the rain was going to be. Two of the first four teams that went out had problems with their electric systems.

We went out to set our first run and everything was going well, unfortunately 3 laps before the end of our heat we got a tire puncture and had to retire before the end of the run. We got back to the pits and replaced the tires. We also made a few holes around the windshield of the vehicle since visibility was poor due to the rain. After making these changes we went to make our second run. The second run went much better than the first and we were able to finish our heat. However, once we got to know out result, we weren’t too pleased we had a score of 165 km/l from the second run which put us in 5^th place overall. This was much less than what we had predicted for our vehicle. Since there wasn’t much we could change within the limited time frame between the runs we decided to make small changes.

We decided to swap our batteries for ones that were fully charged, we did that by swapping the batteries with one of the teams that was unable to take part in the event any further because their electronics were short due to the rain. With the fully charged batteries we went for the third run with a different driving strategy. This run we carried more speeds into the corners and accelerated slowly to maintain the required average speed. The third run was much better and when we finished and saw the result we were quite pleased that our efforts had come to fruition. We had a score of 285km/l. This moved us right up to 3^rd place.

We decided to keep working on the vehicle, improving the alignment and the driver strategy for the final run. We went for the final run and decided to carry even more speed through the corners so that the acceleration required on the straights is even less. 2 laps before the end of our run disaster struck the left wheel had a big wobble and while going through one of the corners the spokes of the wheel broke and bent and the rim lost shape. This meant that we had to retire and the we couldn’t finish our last run. This was a shame for us as this run would’ve brought our average score much higher. Our average score was now taken from the second and third runs. This meant that we finished 4^th of the 7 teams.

At the end of the day, the team was quite disappointed with the result and personally so was I. Most of the other teams had the goal to just pass the project and the teachers and fellow colleagues watered down everyone’s ambition. I personally wanted to win the event and that was my goal. That didn’t happen so naturally I was very disappointed.

As time passed, I realized what a great learning experience this was for me. Success and failure can both be great teachers and I learnt a lot through these few months than the previous few years. I plan to take what I learnt from this experience and be a successful engineer and learn from the mistakes made here so that I don’t make the in the future and consequently achieve the goals I have for myself and the goals of the team or company I am a part of.