[MVRC] Mantium Virtual Racecar Challenge 2020 (Grand Prix Cars)

[jjn9128]

Only use known profiles. Never been able to draw something up in sketchup that works. Cant remember which one i started with this time sorry.
I have finished running a case with a sl1223 at an angle similar to the pofile in the image and both downforce and drag are up and the efficiency is only down by 0.5, only seen the numbers so far so once i get back to work and can have a look at the post processing and paraview will i be able to see if i can work the air more with the rear wing..
Cop is now back in the 1.35 range.

Have you seen the benzing aerofoils? Purpose designed for high lift motorsports use. Try either the middle or bottom with the top as a flap, ~60% of the mainplane chord is where I typically start.

[etsmc]

Have seen these and the study that was done to design them but never been able to find a cad file i can use to get all the measurments correct.
If i remember correctly (which is unlikely) the 153-105 was similar to the sl1223.
Will have another look about and see if i can find a way to get these profiles.
But thanks for pointing them out.

[jjn9128]

Have seen these and the study that was done to design them but never been able to find a cad file i can use to get all the measurments correct.
If i remember correctly (which is unlikely) the 153-105 was similar to the sl1223.
Will have another look about and see if i can find a way to get these profiles.
But thanks for pointing them out.

Your cad doesn't have a spline tool?

[machin]

Your cad doesn't have a spline tool?

It’s an impressive car if he doesn’t! It’s really nicely made!

[yinlad]

Slightly off topic, I've made a discord server https://discord.gg/SaWtf7P for people to join if they want. It's a bit better suited for faster flowing conversations and general chit chat. Not officially affiliated to the competition in anyway of course, but I'm happy to transfer server ownership if you guys in charge wanted control of it.

[etsmc]

Spline tool... if i knew what that was i could tell you. But a quick google search shows me plugins are needed i think.
I use sketchup.. but for the wing profiles i was able to use the point data from the airfoil database website and get that in to inventor, from there i could export/convert and get them in to sketchup.

Why dont i use inventor for the whole car.. havent had chance to learn it and i can make the shapes i want in sketchup.

[Joe7218]

Spline tool... if i knew what that was i could tell you. But a quick google search shows me plugins are needed i think.
I use sketchup.. but for the wing profiles i was able to use the point data from the airfoil database website and get that in to inventor, from there i could export/convert and get them in to sketchup.

Why dont i use inventor for the whole car.. havent had chance to learn it and i can make the shapes i want in sketchup.

Inventor has a spline tool, maybe you could use that to make the wing profile then import it to sketchup?

[jjn9128]

Spline tool... if i knew what that was i could tell you. But a quick google search shows me plugins are needed i think.
I use sketchup.. but for the wing profiles i was able to use the point data from the airfoil database website and get that in to inventor, from there i could export/convert and get them in to sketchup.

Why dont i use inventor for the whole car.. havent had chance to learn it and i can make the shapes i want in sketchup.

As Richard said it's some bloody impressive modelling without any splines!

Forgive me for asking so many questions, I'm not familiar with either sketchup or inventor, but what do you use to turn the point data into a wing profile? My point being the aerofoil co-ordinates for the benzing wings are on the image.

[etsmc]

Spline tool... if i knew what that was i could tell you. But a quick google search shows me plugins are needed i think.
I use sketchup.. but for the wing profiles i was able to use the point data from the airfoil database website and get that in to inventor, from there i could export/convert and get them in to sketchup.

Why dont i use inventor for the whole car.. havent had chance to learn it and i can make the shapes i want in sketchup.

As Richard said it's some bloody impressive modelling without any splines!

Forgive me for asking so many questions, I'm not familiar with either sketchup or inventor, but what do you use to turn the point data into a wing profile? My point being the aerofoil co-ordinates for the benzing wings are on the image.

Ahh ok i thought those numbers were to do with lift and drag...
There is something in inventor where you import the points from a csv so i will give that a go. From there i think i was exporting them as a file that i could convert in meshlab to something i could import to sketchup.
Will have a go at it when i get back to work on monday. Thanks.

[Thomas2019]

This little python script I hacked together reads the csv/dat files from the airfoil database

WASP (smoothed)
1.000000 0.000070
0.997540 0.001320
0.990700 0.003920
0.980370 0.006320
0.966980 0.008310
...

and converts them into an obj file

# WASP (smoothed)
v 1.000000 0.000070 0.0
v 0.997540 0.001320 0.0
v 0.990700 0.003920 0.0
v 0.980370 0.006320 0.0
v 0.966980 0.008310 0.0
...

, which you can load into for example Blender. It comes up as a 2D line.

airfoil_file = open("airfoil_wasp.dat", "r")
target_file = open("airfoil_wasp.obj", "w+")
input_line = airfoil_file.read().splitlines()
verts_number = 0
for x in input_line:
print(x)
if verts_number > 0:
target_file.write("v "+ x + " 0.0 \n")
else:
target_file.write("# " + x + "\n")
verts_number += 1

target_file.write("l ")
for verts in range (verts_number - 1):
verts += 1
target_file.write(str(verts) + " ")
target_file.close()
airfoil_file.close()

Maybe useful for some.
Thomas

[AratzH]

How different are your results from the official ones? I am a bit confused. I ran the exact car I submitted with MVRC Long template (5000 iterations) and my results are notably different from the official ones:

Personal Pc:
Cd Cl Cl/Cd Cl(f) Cl(r) CoP Intake Exhaust Cooling
Total 1.305 -2.384 -1.827 -1.179 -1.205 1.718 5.56 -1.2979 3.12139

Official:
Cd Cl Cl/Cd Cl(f) Cl(r) CoP Intake Exhaust Cooling
Total 1.319 -2.431 1.715 4.62 -0.392 2.383

Is there any difference between our solver settings and the official one? This is almost a 1.5s difference in lap time and 4 positions... Still 1.5 seconds off pace though haha

[jjn9128]

How different are your results from the official ones? I am a bit confused. I ran the exact car I submitted with MVRC Long template (5000 iterations) and my results are notably different from the official ones:

Personal Pc:
Cd Cl Cl/Cd Cl(f) Cl(r) CoP Intake Exhaust Cooling
Total 1.305 -2.384 -1.827 -1.179 -1.205 1.718 5.56 -1.2979 3.12139

Official:
Cd Cl Cl/Cd Cl(f) Cl(r) CoP Intake Exhaust Cooling
Total 1.319 -2.431 1.715 4.62 -0.392 2.383

Is there any difference between our solver settings and the official one? This is almost a 1.5s difference in lap time and 4 positions... Still 1.5 seconds off pace though haha

I gained 0.55s in the official run over my simulations, but I use the MVRC template with some mesh simplification to save my poor laptop so some improvement was to be expected. My downforce increased by 0.246, drag by 0.003, my L/D increased over to 1.9 where it had been below 1.8, cooling and balance was about the same (balance is in the margin of error where it just outputs 1.85m).

[MaccaRacing]

I gained 0.55s in the official run over my simulations, but I use the MVRC template with some mesh simplification to save my poor laptop so some improvement was to be expected. My downforce increased by 0.246, drag by 0.003, my L/D increased over to 1.9 where it had been below 1.8, cooling and balance was about the same (balance is in the margin of error where it just outputs 1.85m).

How can you make some mesh simplification with mvrc? And especially what do you make? I have a poor laptop too (4 cores and 8 gb of ram) and I am only able to run fast simulation.. Actually I have to borrow mi brother's PC (6 cores and 16 gb of ram) to run the final standard simulation before submitting the car

[LVDH]

How different are your results from the official ones? I am a bit confused. I ran the exact car I submitted with MVRC Long template (5000 iterations) and my results are notably different from the official ones:

Personal Pc:
Cd Cl Cl/Cd Cl(f) Cl(r) CoP Intake Exhaust Cooling
Total 1.305 -2.384 -1.827 -1.179 -1.205 1.718 5.56 -1.2979 3.12139

Official:
Cd Cl Cl/Cd Cl(f) Cl(r) CoP Intake Exhaust Cooling
Total 1.319 -2.431 1.715 4.62 -0.392 2.383

Is there any difference between our solver settings and the official one? This is almost a 1.5s difference in lap time and 4 positions... Still 1.5 seconds off pace though haha

I always make some small modifications on your cars, depending on how the geometry looks like. The solver settings should be the same. The differences you post here are quite substantial, please send me your logs, so I can have a look.

[variante]

How different are your results from the official ones?

EDIT: i misread your data. Seems like the only significative difference is cooling, so it might be an issue with your control surface mesh. I had some too in the past...
Anyway, i tested my car on Medium settings and my drag, CoP and cooling turned out to be nearly identical, while the official simulation made me gain more than 0.2m² in CLA, so i was half a second faster than expected.

Slightly off topic, I've made a discord server https://discord.gg/SaWtf7P for people to join if they want. It's a bit better suited for faster flowing conversations and general chit chat. Not officially affiliated to the competition in anyway of course, but I'm happy to transfer server ownership if you guys in charge wanted control of it.

Sounds good. I've never used Discord, but i might give it a go.
Anyone else interested?


About airfoils:
I'd say that already existing foils need to be studied and their functioning understood, but then a tailor made wing profile is the way to go, especially when dealing with a wing with multiple flaps.
Even Benzing wings, optimized for racecars, might not suit our cars. They were developed a million years ago, and the needs of those cars might be very different from the needs of our cars.
Splines are not absolutely necessary for CAD. Arcs and ellipses can be enough, which is what i used in the first years of this competition.


@LVDH
The website never gets updated. Do you need help with it? You also mentioned needing some help with renderings. I'm sure that some helper will pop up, if you put the spotlight on such topics.