(KVRC) Variante

[variante]

Hi guys,
just an update afted the second race.

I'm happy for the victory, but i have to acknowledge the superiority of CSR car, especially considering its efficiency.
However the gap between us could have been smaller without a mesh problem i had to face... Have a look:

This is an automatic correction made by the programs involved in the CFD simulation to correct a very small error made by me while working in Sketchup.

Without it the performances of my car would have been much better: about 6% lower drag, 5% more downforce, 5% better CoP, with an efficiency of 1.96 instead of 1.74
Thus, the laptime would have been half a second faster.

Anyway, CSR's efficiency is still greater, so i need to work quite a lot to win at Monza...

[CAEdevice]

Hi Variante, I encountered a similar iussue (and in the same area), caused by the STEP2SketchUp translator I use to convert my geoemtry (I use Creo/SolidWorks/SpeceClaim and I can't draw a line with SketchUp).

I solved the problem dividing the "body" component into 4 or 5 sub components: it seems that the divisions help the faceting process.

About the last race: CSR at the moment has the most "refined" geometry and big modeling skills, but I like your approach that is simple but at the same time original.

I think that we will see new strategies in Monza, I really need to complete my MP001B chassis

[astracrazy]

Variante's problem was caused by gaps in the geometry. You have to be careful when using these plug ins so its worth going over zoomed in to check there are no gaps. Basically what happened here was the mesh program covered over those gaps.

[cdsavage]

I'm happy for the victory, but i have to acknowledge the superiority of CSR car, especially considering its efficiency.

I dont think our efficiency numbers from round 2 are directly comparable since my car was in a higher downforce configuration than yours. When moving towards a minimum drag configuration I find the efficiency drops as the drag from the body, wheels etc make up a higher proportion of the total drag.

[variante]

Last development update for the 2014 car, the Ira.

The main bodywork is the old one. Development concerned airfoils, wings/diffuser geometry and vortices management at the rear. As you can see i've also modeled part of the main bodywork as a wing.

Performance output of the original car at 44.7 m/s were: 1,29 (drag), 2,44 (downforce), 1,89 (efficiency) and 1,83m (balance)
New outputs: 1,4 (drag), 3,16 (downforce), 2,26 (efficiency) and 1,93m (balance)

The front axle is lacking DF, and drag is still too high...things that i expected to solve with the new bodywork, which will never be made, since KVRC rules have drifted away from F1 formula.

Some CFD visualisation. In case you are interested in seeing some other detail or you have any question, just ask.

[CAEdevice]

Hi Variante. The body/wing is impressive, and so is the total downforce... But what about the R75 rule?

I think that the body/wing is a brilliant solution to the problems caused by the absence of the beam wing.

Since the F1 rulebook will be abandoned, I'm going to post some final numbers too in my thread.

[variante]

R75 would be totally respected with the new bodywork (without significant DF losses, if any)

[wesley123]

Wow that looks really great and well thought out!

However, doesn't the large upward negatively affect airflow over the floor as well as to the rear wing?

[CAEdevice]

I't's a shame not to be able to compete against the last release of your car

[variante]

yep, but I'm confident that next season is going to be interesting anyway

However, doesn't the large upward negatively affect airflow over the floor as well as to the rear wing?

Those are the exact issues i had thought of before testing it, but that part of the bodywork actually generates 7% of the total downforce, with a mininum drag increase. Basically, it makes less damages than the gains it produces.

[CAEdevice]

I think that it makes the diffuser work better too

[MadMatt]

Out of interest, and if you want to share, what airfoil profile did you use for your wings?

[variante]

The airfoils i used were designed by me, so i can't really give you an airfoil name or code...what i can do is show them!
Notice that FW airfoils haven't been fully optimized yet, while the RW airfoils i'm showing here are designed for downforce without compromises, meaning that they are very draggy.

[MadMatt]

Very nice variante! That's something I've never done, designing my own profile. I think Katz mention bits about designing your own airfoil but what was your methodology for designing yours?

[variante]

Many factors are involved. I'll focus on the most important one: overlaps.

The main problem is that we are designing wings with multiple elements, therefore coupling each element in the best possible way is the main difficulty. Using the same profile for each element happens to be a wrong move for many reasons.

Now, let's remember why we want multiple elements overlapped: overlap funcion is to re-energize the boundary layer on the underside of the wing. The result is achieved accelerating air through the overlaps, just like it would happen in a Venturi tube, and heading that airfow to the right direction.

A greater (and well thought) overlap means better airflow acceleration (as long as the boundary layer inside the overlap itself is acceptable), which is the principle i followed on the Rear Wing.

The reason why i used small overlaps on the Front Wing is the amount of overlapped elements: the usable volume is limited and many huge overlaps take out a lot of it, decreasing the effective AoA of the each element; as a consequence the top side of the wing will suffer from lower pressure.

Tuning the leading edge geometry, taper and upper and lower side AoA (compared to the incoming airflow to each element) is the reason why you can't simply use any "good" airfoil.