Sport prototype 3D model

[tomislavp4]

The one you have is a solid. It is a solid made of stitched surfaces so if you need surfaces just tell me and I'll send you the unstitched surfaces.

[Belatti]

Well, in arround a week the i7 processor I bought hopefully will be in my home. I will install windows 7 64 bit and see what I can do, finally...

However, there are still some things I would like to ask to the aero guys from the forum.

The rules states a flat bottom between FW and RW axles, at 40mm static ride height.
We use diffusers at the front and at the rear of the flat bottom, like in any sport proto you can see at European or American LeMans series.

However, there is a tolerance for floor "flatness" that seems pretty wide to me: 5mm. So I was wondering, how would an Aerodynamicist build the "flat" bottom?



Concave or convex?

[wesley123]

i think concave, though you can make it a double shape, maybe experiment a bit with it?

With a double concave you will effectively create 2 tunnels, would be more effective under stall i think

[PNSD]

Would not a concave allow for a less pitch sensitive underbody?

[RacingManiac]

I suppose for your purpose it does not matter, but LMP cars now runs plank and spec tunnels now.

I think even Super GT in Japan runs plank now as well...

[vyselegend]

Wouldn't bending the floor even slightly affect its rigidity?

I guess the concave shape might also hurt packaging of mechanical components which you'll want as low as possible. But since your goal is not building the car but experiment aero, it's worth testing.



I don't know if that can be on any help, but I ran across those blueprints of the legendary Porsche 917:



Here in high reolution (4 867 x 2955) Internet rocks

I was actually searching for much more modern design, even modest ones, like the Norma M20, Juno SSE, Ligier JS51 etc, but unsurprisingly those are hard to find. I remember to have seen a downloadable 3D model of the Norma but can't find it anymore. But I suppose it was "just" an Rfactor mod, not an original...

[wesley123]

Would not a concave allow for a less pitch sensitive underbody?

yep, for the same reason i would head for a dual concave shape a-la the acura, it allows for better flow though the channels under low ride height conditions. I dont know if it has a raised nose wich i doubt, there fore placing such shape in each diffuser section would give better results(i think) What also might be an option is creating a small tip on the edges, maybe sealing the floor by creating an vortex there

[RacingManiac]

I dont know if it has a raised nose wich i doubt,

Yep: http://www.mulsannescorner.com/AcuraARX-01-5.html

[Belatti]

Wouldn't bending the floor even slightly affect its rigidity?

I guess the concave shape might also hurt packaging of mechanical components which you'll want as low as possible. But since your goal is not building the car but experiment aero, it's worth testing.

Remember the tolerance: 5mm

The chasis heigh wont change because of that. It can have 40mm in the center and pass scrutineering with 35mm at the sides.

The floor is a 6mm wood planck bolted to the lower part of the chassis. The way of making the concave/convex is just using spacers.

i think concave, though you can make it a double shape, maybe experiment a bit with it?

With a double concave you will effectively create 2 tunnels, would be more effective under stall i think

Stall? This small car reaches 230Kph at fastest track...

[RacingManiac]

It is a tolerance though....I think Bentley in 2003 at Sebring failed a post quali tech because a section of the floor or something warped due to the temperature.....playing to the mm across something that big is real gambling....

[wesley123]

I dont know if it has a raised nose wich i doubt,

Yep: http://www.mulsannescorner.com/AcuraARX-01-5.html

i was actually talking about the car discussed in the topic, not the acura.

though the acura does got a raised nose, it isnt raised that high, actually it is low compared to the new-breed lmp cars.

[RacingManiac]

My mistake....though the P2 Acura still uses the not-so-new tub from the Courage LC75....The ARX-02a ended having an almost F1 level raise nose...

[Smokes]

hey bellati have you tried simulating the cfd with just half the model which is normal practice for any thing symetrical in 3d CFD, Your probaly better getting hold of a copy of fluent and gambit. Gambit to mesh and state the enviroment for the CFD model and fluent to resovle the model solution.
Please note I only did 6 week at uni with fluent so i don't really know it that well compared to the other guys here.

[Just_a_fan]

Can you run it with 64bit Windows 7

For info, the download is an .iso which you then use to burn a bootable CD. The whole environment is standalone and runs from the CD. I think you can set it up to run from a HD.

[Belatti]

hey bellati have you tried simulating the cfd with just half the model which is normal practice for any thing symetrical in 3d CFD,

Indeed, thats the first thing I tried.