[KVRC] DynaRace LMPC 2015

[MadMatt]

So here we go, finally my model, basically it is the same as it was at Christmas, only now legal with the latest regulations!

I called it the DynaRace LMPC 2015 for LeMans Prototype C! C for group C of course, as a wink to History!





More pictures on my blog HERE

I hope you like it, do not hesitate to post your comments on it! I did not have time to work on it as much as I could, but from the tests I have done, I believe I should not be too far behind!

[CAEdevice]

Very rational and clean!

[wesley123]

Looks like a modern McLaren M8F

Love the diffuser exit!

[variante]

Nice!

I'm sorry you couldn't develop it as you wished... Still, it looks rational and clean, as CAEdevice said. You know what you are doing, obviously.

I'm curious about the interaction between your front wing and the suspension cover.

Also, i used a similar raised nosecone on my first iteration, but it didn't seem to work as i wished... However yours looks much more refined than mine...curious to see how that works as well!

[MadMatt]

Thanks guys!

Yes I've tried to keep it simple although there was quite a bit of work done at the beginning to get things to work with Star-CCM+, only to find that with OCCFD some solutions that I thought were not working were in fact working (different solver and parameters), so I had to sort of start from nearly the beginning again.

The raised nosecone works well but it was not easy to find the sweet-spot I must admit.

I must also add that eventho someone might say the rear view mirror mount looks simple and could be designed better (which is true, I admit), they have a huge role in the aero performance of my car!

It is hard to quantify the improvement of my model since it went through different phases to cope with the changing regulations (at the beginning), but the very first model that I simulated had a CD of about 0.8 and a CL of 2.4. These values are long gone, but the efficiency remained pretty constant, which is an improvement in itself since the downforce level has increased!

[MadMatt]

Just a last thing that I am now checking with Chris but the geometry has been submitted!

[MadMatt]

Unfortunately I am retiring from the competition.

I just realized that due to an update in OCCFD the floor had moved, but I never saw that written anywhere so I kept doing my simulations and optimization with the small Z-axis offset. Last night after Chris made me realize that mistake, I ran a simulation with my latest car now on the floor and the performance is not where I want it to be. I cannot put more time into this project unfortunately so I will just retire the car and watch you guys.

Shame but I have wasted quite some time into this project, I cannot put more into it.

[machin]

Are you not tempted just to submit the car, get the results and then develop it? Don't worry about the championship and just go for race wins? Entering the car will also allow you to get some "official" aero coefficients which will be useful to calibrate your own CFD results... (plus, I suspect you will do quite well even if your current CFD results aren't where you want them)

...go on... Submit the car and show us how good you are at recovering the situation and developing it into a race winning car... A bit like McLaren are having to do...

The championship won't be the same without you..

[MadMatt]

Sorry machin I have a job and little spare time. I had plan to submit my car and not develop it, then submit a mid downforce setup and that's it. So even if my car had the correct Z axis setup I would not have improved it (I did this part before Christmas).

I wasted too much free time on this also due to the rule changes, I am not getting any pleasure in this project anymore and have plenty on my plate already.

Shame but maybe next year.

[machin]

That is a real shame... If you really aren't going to enter would you consider releasing your aero coefficients before and after you found the mistake so that other people can learn how much difference this sort of error can make?

You'd be helping the community out and therefore it wouldn't seem like such a waste of time, which I can see is how you're feeling right now....??? Think of yourself as a technical consultant helping people to avoid the same pitfall...???

[MadMatt]

Yes I will release the numbers and help people with advices no problem.

[CAEdevice]

Unfortunately I am retiring from the competition.

I just realized that due to an update in OCCFD the floor had moved, but I never saw that written anywhere so I kept doing my simulations and optimization with the small Z-axis offset. Last night after Chris made me realize that mistake, I ran a simulation with my latest car now on the floor and the performance is not where I want it to be. I cannot put more time into this project unfortunately so I will just retire the car and watch you guys.

Shame but I have wasted quite some time into this project, I cannot put more into it.

The McLaren example by Machin is perfect... You don't have to take the race too seriously!
To test the car in the actual race condition is useful: consider that I used the whole 2014 KVRC to compare the official solver to my tools!

Also consider that half of the teams had no CFD development, so you could gain points that can be important at the end ... and maybe you are not the only one the have used a wrong value

After my submission I had to change some small details and I also added a new idea that has never been tested (it is possibile untill 2nd of april) ... so I'm going completely blind too!

[MadMatt]

Thanks Matteo. You all seem more worried than me. It was a fun exercise I will probably come back next year. Again I didn't plan to develop the car throughout the competition (I would have no time for this, being on 2 different real racing vehicles projects already). I know the performance I achieved with my car (I used Star-CCM+ in which I know the performance of the car are quite accurate), so I will be able to see where I would have been without that issue because as I wrote, I found strange the trends were not the same between OCCFD and Star-CCM+. I therefore developed the car with OCCFD but I now understand where the problem was.

However, I don't understand the "test the car in actual race condition". I could already do that with OCCFD and virtual stopwatch, isn't it? What is different from submitting the files and have Julien to run them (unless again there is something I am missing)?

I had reached similar values than the official KVRC (11'000N of downforce and 2300N of drag) car with perfect balance (1.63m), but obviously wheels in the air, so not relevant at all. I was under these values with Star-CCM+ but without the development afterward so I am confident I would have reached at some point these values. When I put the car on the ground, downforce was reduced by half basically.

Oh well, I will follow the competition from outside, that will be fun to watch anyway, cannot wait to see the development you are going to put in this guys!

[variante]

I agree with the previous consideration!

And i agree, you should do what McLaren is doing: put the car on track anyway and try to score points while gaining data! Also, the difference between you and McLaren is that you actually have the chance to score good points...

About the data discrepancy, consider that i never tested my car with OCCFD...so my claims could be totally disillusioned; i've been testing it even at a different ride height too, so...

[MadMatt]

I know but the point in this competition is to develop the car, something I thought I would have time to do, but since I started my new job, this just flew out of the window so my plan was to bring a good car to start with, and hope it would allow me to score points without having to change its design. The latest car with wheels on the ground (shame I didn't find a way to make the car fly haha) are:

- CD*A: 1.5
- CL*A: 3.7 (!)
- CoP: 1.3 KVRC corrected (!)

Most of what I lost is in the rear diffuser which brings the CoP towards the front, oh well. I have so much on my plate I cannot spend more time in this project.