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variante wrote: ↑

02 Mar 2019, 17:16

@LVDH will we see the results tomorrow?

I think not; I haven’t seen the CFD data yet, and I don’t have time to do the presentation this weekend...

As cool as those videos are (except for people with heart issues), i'd prefer to have the results as soon as possible rather than having to wait another week or so.

I have the possible results in my mind, mental CFD is becoming more and more accurate after 6 KVRC/MVRC editions. I only miss JJR car.

Yes, we need the official entry photos first... then we’ll see what JJR has produced...

Hi, this is my car for Pikes Peak. As usually I ´m not sure about ballance. I think my car has too much rear downforce and too dragy rear wing. I could go for more agressive front wing but haven ´t time to do it. My CLA should be at around 10 (I hope). This time I have too much cooling but again have no time to optimise it.

https://drive.google.com/file/d/1Z6W-ef ... sp=sharing

https://drive.google.com/file/d/1fddmb_ ... sp=sharing

JJR wrote: ↑

03 Mar 2019, 14:01

https://drive.google.com/file/d/1Z6W-ef ... sp=sharing

Thanks! Stunning car as usual.
This time it also looks a cleaner design.

JJR wrote: ↑

03 Mar 2019, 14:01

https://drive.google.com/file/d/1Z6W-ef ... sp=sharing

https://drive.google.com/file/d/1fddmb_ ... sp=sharing

Really Nice looking...

Nice car, JJR. Very aggressive. Cl.A of around 10 should mean a fairly close race, which is nice.
This means that the game will be won by the car with the best efficiency.

Hi guys,
sorry I am a bit slow this time. I had technical issues, a conference and now it is Karneval where I live.
Here are the images of the cars:

Better quality here:
https://mantiumchallenge.com/cars-mvrc-pikes-peak-2018
I think we should be able to see the full results next Sunday. Probably I will start releasing CFD images throughout the week.

hehe these frontwings Good job guys. Unfortunately I was not able to continue development the last months.

variante wrote: ↑

01 Mar 2019, 17:25

etsmc wrote: ↑

01 Mar 2019, 07:11

My diffuser first kick was only 21°

I did not mean the chord angle, but the angle of tangent to the first point of your ramp (fillet excluded). I've measured yours, and it is something like 28° or 30°. Mine is 25°. The chord angle is a different and less controllable parameter, from my point of view.

etsmc wrote: ↑

01 Mar 2019, 07:11

Anything else people would like to see?? wings, wing profiles suspension covers?

Velocity map of the undertray (view from below/behind, possibly).

Here is a comparison of the last diffuser and the less aggressive one i think this is what you meant me to change

cd: 1.453
cl: 6.050
cl/cd: 4.165
cop: 1.604

so it seems it actually lost performance compared to the original diffuser.

I also believe this is the velocity maps from under the car you asked for


I have also included the wing profiles in this image for Alonso Fan
top is the front wing which I think is 2 Eppler E385 profiles but the size and angle of attack does change along the length of the wing.
the bottom is the rear wing profiles I have run for the last 2 years I do believe I haven't even changed the angle on them more than .5 of a degree over that time.


I am about to go back to the original diffuser and drop the rear wing and see what that does.

Interesting... As Variante said in one of his previous posts, maybe you need to keep your original diffuser design but play with the diffuser strakes...

There was an interesting article about diffuser design by William Toet where he said;

If you add an additional fence or strake (a vortex generator of any design really) in each side of the floor it is possible to roll up two more vortices which take advantage of that airflow energy to create downforce.

The full diffuser design article is here;

https://www.racetechmag.com/2017/08/wil ... diffusers/

Judging from the undertray velocity field, it seems like there's a big wheel wake going straight to the middle of the diffuser.
I'm directing it towards the less sentitive gearbox area, altought i'm sure there are other options.

The Angle of Attack of the strakes seems off. I suggest less strakes for now to have more control on them; they need optimization.
I'm using just one strake and it works fine; more might ultimately be better, but they would require MUCH more optimization.

The aerofoils look good on the bottom pic, but messed up in the upper one, as the angles between first and second foil don't match.

I think you car has a good potential: a couple of right moves might improve performance a lot.

Obviously feel free to spend a word on mine, as i got so used to it that i might have missed some obvious flaws.

Thanks for taking the time to look at the images and tell me what you think.

The test of the lower rear wing has finished and the results are
Low rear wing cl/cd: 5.893
cd: 1.458
cl: 6.220
cl/cd: 4.267
cop: 1.596

High rear wing cl/cd: 5.729
cd: 1.484
cl: 6.373
cl/cd: 4.294
cop: 1.663

oddly enough with the rear wing lower my front wing produces a touch more downforce and less drag while the rear wing is more efficient, it produces less downforce and drag moving the cop forward.

The article by Toet is good I am sure I have read that on his linked in or something similar.

early in the design the diffuser was worse than what it is now when I added the strakes and aligned them with the flow coming into the diffuse it made a huge improvement so no doubt there are gains to be made there.

The upper airfoils are from my front wing which the top flap does change angle along the wing. this cross-section I think was taken near the middle of the front suspension cover if I gave the flap more angle it caused more drag as it pinched the air between it and the bottom of the suspension cover.

Thanks again it's all helping me understand my car a bit more.

@Alonso Fan if you want some pointers drop some pics everyone here is happy to help but as they say 'A Picture paints a thousand words"

....News from Colorado... the first cars are doing their practice runs and the times are looking tight...