Tag Archives: engineering

Why do race cars have aerodynamic shape?

This might be my very first post about engineering, which is a little bit weird considering that I am studying engineering (this is where the emoji with the hand on his chin wondering something goes). Anyway, let’s talk about something that I really like and hopefully someone will like it as well: cars, specifically racing cars!

Motorsports is where engineers test the limits of new technologies, where engineers break their head thinking on how they can defeat the other teams on the race track by building the best car. As you might know, I’ve been working on Chalmers Formula Student, where basically I’m part of a 32 team building a formula-like car.



Aerodynamics

As part of the Aerodynamics subgroup within Chalmers Formula Student, my job is to increase the overall performance of the car by adding wings to the car. This might sound non-sense, “adding wings into a car?”, for now just trust me when I say that wings on race cars or sport cars are good.

It might be a little bit complex to explain but I will do my best, let’s start by defining what aerodynamics is:

Aerodynamics

noun, plural in form but singular or plural in construction aero·dy·nam·ics \ˌer-ō-dī-ˈna-miks\
1. The branch of mechanics that deals with the motion of air and other gases and with the effects of such motion on bodies in the medium.

We all have extended our hand out of a car’s side window and felt the air pushing our hand, this is basically a straight forward way for understanding aerodynamics. If an object moves through a fluid, air in this case, then the object will experience forces acting on it. One of them it’s the resistance of motion, and this one is called aerodynamic drag. The second force might be not so obvious, mostly unnoticed by the everyday driver, this force is the one “pushing” the car more to the ground, known as aerodynamic downforce.

Now for racecars aerodynamic downforce is of a greater importance than drag, this does not mean that drag can be left aside, simply it comes secondary. So far, I have explained briefly what aerodynamics is and which forces are generated due to the airflow, and everyone has experienced firsthand the aerodynamic drag so it is easier to understand that one, but how does downforce is produced?


Downforce

To understand aerodynamic forces, specifically downforce, a typical cross section of a wing is of use. Now, let us assume that it moves from left to right. Because of the shape and angle of this airfoil section, the air will move faster on the lower surface than on the upper one. This speed difference creates a low pressure (suction) on the lower surface and a higher pressure on the upper one. The result of this pressure difference is the force that pushes the car more to the ground a.k.a aerodynamic downforce.

In a car, the forces to push it forward are created at the contact patch between the ground and the tire, these friction-like forces are strongly affected by the vertical force applied. Now, if we could increase the vertical tire force (and maximum friction) by pushing the tire more against the road, then the cornering force could increase dramatically, without the risk of sliding!

Long story short, if we push the tires against the ground we can take the corners at a higher speed without going off road, or without sliding, hence we can go faster around the track and reduce the lap times!

This is one of the main reasons why race cars look completely different to passenger cars!


#AndresInGöteborg

Chalmers Formula Student 2017

Over the past 9 months I’ve experienced a lot of new adventures (I’ve written about a few of them in here), and I’ve faced a lot of new challenges. But no challenge is as big as Chalmers Formula Student; designing, building and testing a car in only 11 months is very ambitious and demanding. A few months ago I wrote about Formula Student, the project and the outline of the competition; what is it about? why is it so big? and a little bit about Chalmers Formula Student 2017 (CFS17).

Now it is time to write about Chalmers Formula Student 2017.


Chalmers Formula Student 2017

Let’s start from the beginning. One of the cornerstones of CFS is not only to build a highly competitive car, but also to form skilled engineers. This is why at the beginning of every academic year a completely new team is assembled.

During the first weeks, the idea is to define a common goal and assign responsibilities as well as start planning for the months to come.

This year our goal is:

“By working as a team, CFS17 will design and build a high performance 2WD electric car with key components that are compatible with a 4WD concept. The car should run latest May 1st, 2017, weight less than 180kg and have tested and verified subsystems. As a result, the team will finish top 10 in all events and top 5 overall in FSN and FSG 2017.”

Once the goal was defined it was time to move on into investigating new solutions, this stage of the project is about reading reports from previous years and considering new technologies that can be implemented into the new model to improve upon last year’s model.

Sounds pretty much straight forward, but trust me, there are thousands of things and small details to consider, even the simplest change can have a huge impact.


Designing a car

After a couple of weeks of investigating new solutions and, developing together as a team a concept, we move on into the actual design, where we use CAD (Computer Aided Design, specifically CATIA; fun fact about CATIA…it hates me) to design and model the parts and assemblies that at the end come together to build a car.

This part of the project was a little bit hectic, probably everyone in the team pulled an all-nighter at least once by now, but for me the design part was very hectic and stressful. Specially because I was taking 2 courses (Vehicle Dynamics and Vehicle and Traffic Safety) at the same time while doing CFS.

The winter break was close but we had to lock down our design before taking a small time off, this means that everyone needed to be done with the parts they were designing to have a complete car assembly.


Building a car

Building a car in sounds much easier that it is. Manufacturing every single part in the way they are designed is quite challenging, and at the end this is the stage of the project when you realize that there are parts that look rather simple in the computer but they are a pain to manufacture.

At the end, no matter all the small issues during the process, we built a very beautiful car (still needs to be tested in the track but probably it will perform very good), and the important part is that everyone in the team worked so hard to achieve this. So, I want to raise my imaginary beer right now and just say, cheers to everyone in CFS!

*drumroll to create suspense* and this is how our car looks like! Hope you guys like it!


 


We will be now preparing and tuning our car until the very last day before the competition, which is taking place in the TT Circuit Assen in the Netherlands (FSN), from the 17th – 20th of July and in the Hockenheimring in Germany (FSG) from the 8th – 13th of August.

I’m really looking forward for the competitions and I hope that CFS wins both in FSN and FSG!


#AndresInGöteborg

CFS16 during endurance test in FSG 2016

THE ultimate engineering competition.

A few months ago, it never crossed my mind to be involved in a project as big as Formula Student, and if we go even further it never crossed my mind being in Sweden, and you know what, that is exactly what I like about decision making, ultimately every single decision will take you one step closer to a new adventure.

First things first, what is Formula Student? And why is it so big? If I had to explain Formula Student (Formula SAE) as simple as possible the only thing that comes to my mind is: THE most challenging engineering competition in the student environment.

CFS16 during Formula Student Germany ©


Formula Student

In my dictionary, engineering means developing and pushing an idea to the limit defined by science (the fun part is when you go over the limit). Now, let’s move on to the question what is Formula Student? Well, Formula Student is the world largest engineering competition at student level, just to give you an example; 249 teams from all over the world participated in registration to take a place in the event held in Germany!

Basically, each university team designs, builds, tests and present their concept of a single seat, open wheel formula racecar. The competition is not won by the team with the fastest car, but rather by the team with the best overall package of construction, performance, and financial and sales planning. The car is assessed through different events, both static and dynamic.To test the performance of the car, dynamic events like acceleration, skidpad and endurance take place during competition. Car is also judge in design, cost and in business planning.

I mentioned that the competition is in Germany previously, but the competition is not exclusively held in Germany. There are 10 different competitions around the world: Michigan, 2 events in Nebraska, Australia, Brazil, Italy, United Kingdom, Austria, Germany, and finally Japan. Germany being the most challenging and competitive one.

Formula Student involves a tremendous amount of effort from everyone in the team, it’s a project that extends for over a year, since the formation of the team until the last day of competition. Moreover, Formula Student it’s not just building a car, it is one of the best ways of getting experience.

 

CFS16 during Formula Student Germany ©

CFS16 during Formula Student Germany ©


Chalmers Formula Student

This year I have the fortune of being part of the Chalmers Formula Student (CFS17) Team, one of the top teams in the world (the best team in the world according to me but this is just me not being objective). Chalmers has performed quite good over the past years, just last year CFS16 ended up in the 6th place in UK; 2012, CFS12 won the competition in the UK; in 2014, CFS14 got the 3rd place in Germany, but this are only some of the results that Chalmers has achieved over the years.

I joined CFS without knowing what I was about to do, without knowing the amount of time that I would put into a single project, without knowing the number of things that I would learn just by looking at what previous years have done. So far, it’s been quite challenging.

I am part of the Aerodynamics and Exterior Design subgroup, where I work with 2 more team mates adding wings into the car…I know it sounds crazy but trust me, wings are good for race cars. You can expect a post later regarding aerodynamics, right now I don’t want to bore you with engineering facts.

To give you some context, the team consists of about 30 engineers, from different nationalities, everyone with a different background and from different academic programs. This is, in my opinion, one of our best advantages.


Right now we are building the car, every single component from the new complety re-design motors to the carbon fiber rims. CFS latest model will be running 1st of May (or at least that is the plan)

Stay tuned for the upcoming updates on Formula Student, I’m sure I will write again about it!


#AndresInGöteborg

 

 

Vehicle Dynamics Test Track day @ AstaZERO

Long live SAAB! The fate of SAAB is an oscillating. It is a story frequently brought up by people in the automotive engineering/applied mechanics department. The company is flip-flopping between speculations of bankruptcy and restructuring. Many people around the world and in Sweden specially are sentimental towards the car that is “born from jets”. They are great cars!

The Automotive Engineering vehicle dynamics class had the joy of spending the day at the AstaZERO (Active Safety Test Area – Zero traffic accident) test track. It is a brand new testing facility opened in September 2014, and it is owned by TU Chalmers and SP (Technical Research Institute of Sweden). The track overview is shown above (sorry it is in Swedish).

testbana_2000[ref: http://www.nyteknik.se/tidningen/article3841629.ece]

The purpose of our visit was to conduct a vehicle dynamics lab in collaboration with NEV (National Electric Vehicle, the company that owns the SAAB cars brand). Yes, we got to drive SAAB test vehicles.

The goal of the lab is to help us develop a feel for complex vehicle behavior under motion. There were three tests: steady state cornering, frequency response, and accident avoidance maneuver.

DSC08127-001Steady state cornering: driving around a circle while increasing speed until the tires is starting to lose grip. The tarmac is wet and slippery. I think we got up to 65 km/h around a 14 m radius track before plowing wide.

Frequency response: practically doing slalom in a car to determine how responsive it is. Accident avoidance: at 60 km/h & try to avoid a “moose”. We had the chance to experience the difference ESP – Electronic Stability Control made in a car.

Screen-Shot-2012-10-23-at-14.06.18

(Photo: Moose avoidance test, source: http://www.crankandpiston.com)

 

There was no real moose fortunately, just a row of pylons.

IMG_5056

Video about AstaZero: