[MVRC] Mantium Virtual Racecar Challenge 2019 (Grand Prix Cars)

[LVDH]

The gap helps to feed energy rich air to where the flow would like to separate. A larger overlap helps to direct the air to the correct direction. On the other hand the more overlap, the more friction the air experiences, loosing some of the energy it is supposed to deliver. In CFD, the flow is always pretty inclined to stick to surfaces anyway, which probably explains why in MVRC, a small or no overlap is enough. Having it would just waste energy.

[CAEdevice]

Here is the image I promised yesterday (from the car that I used in Singapore and Suzuka):



The section inside the gaps is reduced about 2 times (to increase speed, spending the pressure energy).

[machin]

Interesting; thanks for the slice... I was trying to find an old picture from one of Variante's previous cars, but I can't find one... and I don't suppose he would care to divulge one now?

...But actually it is interesting to note another difference between your wings: Varinate's flap elements all increase step by step in angle of attack (relative to the ground), whereas yours are much more similar to eachother (the upper element does have a higher angle of attack than the first flap, but Variante's upper element is almost vertical; I'll re-post the image before, which is just an extract from the official images, so he shouldn't complain too much )



In this respect Variante's wing is more like what I would expect to see, based on real F1 wings... Again, are you (Matteo) using flatter AoA mainly just for flow control purposes, rather than trying to extract the maximum from the wing?

[CAEdevice]

Interesting; thanks for the slice... I was trying to find an old picture from one of Variante's previous cars, but I can't find one... and I don't suppose he would care to divulge one now?

...But actually it is interesting to note another difference between your wings: Varinate's flap elements all increase step by step in angle of attack (relative to the ground), whereas yours are much more similar to eachother (the upper element does have a higher angle of attack than the first flap, but Variante's upper element is almost vertical; I'll re-post the image before, which is just an extract from the official images, so he shouldn't complain too much )

http://www.competition-car-engineering. ... arison.png

In this respect Variante's wing is more like what I would expect to see, based on real F1 wings... Again, are you (Matteo) using flatter AoA mainly just for flow control purposes, rather than trying to extract the maximum from the wing?

Yes, max downforce is not the only target. I had to accept compromises with cooling, rear wing feeding, mesh requirements and also the 10mm rule.

[CAEdevice]

Interesting; thanks for the slice... I was trying to find an old picture from one of Variante's previous cars, but I can't find one... and I don't suppose he would care to divulge one now?

...But actually it is interesting to note another difference between your wings: Varinate's flap elements all increase step by step in angle of attack (relative to the ground), whereas yours are much more similar to eachother (the upper element does have a higher angle of attack than the first flap, but Variante's upper element is almost vertical; I'll re-post the image before, which is just an extract from the official images, so he shouldn't complain too much )

http://www.competition-car-engineering. ... arison.png

In this respect Variante's wing is more like what I would expect to see, based on real F1 wings... Again, are you (Matteo) using flatter AoA mainly just for flow control purposes, rather than trying to extract the maximum from the wing?

Yes, max downforce is not the only target. I had to accept compromises with cooling, rear wing feeding, mesh requirements, 10mm rule and also an easy and consistent computational convergence, avoiding critical flow conditions.

I (roughly) estimate that I could obtain 50% more downforce from the front wing if I did not have to think about all the other parameters.

About the exit angle of each element: it is not visible in the picture, but each airfoil gains about 2° compared to the previuos lower one.

Well, now everybody knows everything about my airfoils... will it be enough to throw me out of the podium ?

[jjn9128]

I (roughly) estimate that I could obtain 50% more downforce from the front wing if I did not have to think about all the other parameters.

Out of interest what DF & L/D are you getting?

[CAEdevice]

I (roughly) estimate that I could obtain 50% more downforce from the front wing if I did not have to think about all the other parameters.

Out of interest what DF & L/D are you getting?

Please Variante, don't look at the numbers below

Code: Select all

Force Coefficients averaged wing_front - Cd: 0.1631827136, Cl: -1.0791803803, Cl/Cd: -6.6133253722, Cl(f): -3.3408536839, Cl(r): 2.2616733034, CoP: -

[jjn9128]

Wow that's honest. Like when Ron Dennis phoned Nick Fry in 2009 to ask for Brawn GP's wind tunnel numbers

For transparency my FW is between CzS = -1.2 and -1.27, CxS = 0.22 to 0.24 depending on configuration. I think it's where all my cooling issues stem from.

[CAEdevice]

Wow that's honest. Like when Ron Dennis phoned Nick Fry in 2009 to ask for Brawn GP's wind tunnel numbers

For transparency my FW is between CzS = -1.2 and -1.27, CxS = 0.22 to 0.24 depending on configuration. I think it's where all my cooling issues stem from.

Consider that I renounced to a bit of downforce (gaining a bit of drag too) from the front wing to have a significant outwash that helps my with downforce provided by the central part of the floor (much more useful because it does not affect cooling and balance).

PS: I think Variante could phone me too, but he does not need to know my numbers.

[jjn9128]

Again to even the score.




The wings are about the only thing I think I'm doing well on

[CAEdevice]

Again to even the score.
https://pz1vqw.by.files.1drv.com/y4m9Oq ... pmode=none

https://pz1mqw.by.files.1drv.com/y4mLYM ... pmode=none

The wings are about the only thing I think I'm doing well on

Congratulations for the excellent quality of the modeling. I also used three sections only at first, in order to have less paramter to be optimized. 4 o 5 section give advantages but not significant. On the contrary I only use a small strake under the front wing, just because I need a small vortex running near the wheels (internally).

[variante]

Hell, i'm already lagging behind CAEdevice, so i'm not giving away the schematics of my FW

But i can show you how a professional does it:

(taken from a SimScale webinar).

The way i make my wings is not too different. I find it important to decide a guide line for the low pressure side. It's an arc of circumference in the image here, which i also use for lower DF (and lower upwash) applications; for high DF, i use an arc of ellipse (as Machin essentially noticed).

The aerofoils arrangement, thickness and style from jjn9128 are extremely similar to mine.
CAEdevice's wing shape reminds me of a diffuser!

[wb92]

Wow that's honest. Like when Ron Dennis phoned Nick Fry in 2009 to ask for Brawn GP's wind tunnel numbers

For transparency my FW is between CzS = -1.2 and -1.27, CxS = 0.22 to 0.24 depending on configuration. I think it's where all my cooling issues stem from.

Interesting that with smaller FW I got similar numbers after Singapore but unfortunately I've got bit of separation on the endplate which is drag...

CAEdevice's wing shape reminds me of a diffuser!

That's what I wanted also to mention that general idea behind multi-element wing is that combined chord line is more cambered compared to less elements wing, but in CAEdevice's one it looks indeed like diffuser, and upper part of the leading edge of 3rd profile looks bit weird for me.

In my case I don't use one long profile as a base, rather 2 as a 'slat' and 'profile' and then two more for controlling upwash, everything with nicely working outwash, which still can be improved.

...But actually it is interesting to note another difference between your wings: Varinate's flap elements all increase step by step in angle of attack (relative to the ground), whereas yours are much more similar to eachother (the upper element does have a higher angle of attack than the first flap, but Variante's upper element is almost vertical; I'll re-post the image before, which is just an extract from the official images, so he shouldn't complain too much )

Image

Also to mention that some regulations in some series were quite strict allowed volume for profiles, so they tried to find maximum out of such configuration. Also there were main profiles with trimmed trailing edge so flap could fit into that trim, very similar to what you can see on planes' wings.

[LVDH]

Hell, i'm already lagging behind CAEdevice, so i'm not giving away the schematics of my FW

But i can show you how a professional does it:
https://i.imgur.com/OOYPUPI.jpg
(taken from a SimScale webinar).

The way i make my wings is not too different. I find it important to decide a guide line for the low pressure side. It's an arc of circumference in the image here, which i also use for lower DF (and lower upwash) applications; for high DF, i use an arc of ellipse (as Machin essentially noticed).

The aerofoils arrangement, thickness and style from jjn9128 are extremely similar to mine.
CAEdevice's wing shape reminds me of a diffuser!

So the underside of the wing follows an arc (from a circle)? I would never ever start like that. Why would this arc be the best geometry? Do they stretch the geometry after they are done? To me it would more sense to create something like an ellipse and use an optimization algorithm together with CFD to optimize the two parameters of said ellipse. Circles are cool, but they are just a random shape.

[CAEdevice]

A parabolic function looks more reasonable (costant angle increase = constant flow vectorial acceleration), but a circle is easy to draw and for small angles the result is the same (old handmade engineering).

... in modern cars also a linear (constant flow expansion) or even convex shape could make sense.