Khamsin Virtual Racecar Challenge 2015

[cdsavage]

The rulebook is closed-wheel and closed-cockpit, but fairly different to the official LMP1 rules. There should be a first public draft of the rulebook and guide files made available in a week or two so that you can get started on a car, but they will probably still be open to changes for a while after that. It should be finalized at least a couple of months prior to the first round.

I can't wait! I think that most of the differences between LMP1 and LMPx will be about floor rules, is this correct?

It won't be based on the LMP1 rulebook, it's written from scratch. Pretty much all areas are different other than the general proportions.

[CAEdevice]

The rulebook is closed-wheel and closed-cockpit, but fairly different to the official LMP1 rules. There should be a first public draft of the rulebook and guide files made available in a week or two so that you can get started on a car, but they will probably still be open to changes for a while after that. It should be finalized at least a couple of months prior to the first round.

I can't wait! I think that most of the differences between LMP1 and LMPx will be about floor rules, is this correct?

It won't be based on the LMP1 rulebook, it's written from scratch. Pretty much all areas are different other than the general proportions.

I think it will be a great effort for the team KVRC. I'm curious about many details, but I'm not going to bother you, so I have only one technical question about the rulebook: flat bottom, "wing-car" or a mix between the two?

It would be possibile to know something about the CFD solver? Still OpenFOAM based? Wich GUI (Khamsin?) It would be great to have a "package" with the virtual wind tunnel included.

[MadMatt]

Sounds really exciting!

Will engine, gearbox, cockpit size, cooling requirements (eg rad/intercooler surface/thickness) be provided?

[cdsavage]

I think it will be a great effort for the team KVRC. I'm curious about many details, but I'm not going to bother you, so I have only one technical question about the rulebook: flat bottom, "wing-car" or a mix between the two?

At the moment we have a flat bottom with room for a large diffuser. With no guarantee that this will change, which would people prefer? Any other comments on detailed regulations are also welcome.

It would be possibile to know something about the CFD solver? Still OpenFOAM based? Wich GUI (Khamsin?) It would be great to have a "package" with the virtual wind tunnel included.

Likely a variation on 2014. We're still undecided on whether we should be making it easy to perfectly replicate the KVRC CFD setup, since this hands a larger advantage to those with more computing power.

Sounds really exciting!

Will engine, gearbox, cockpit size, cooling requirements (eg rad/intercooler surface/thickness) be provided?

Yes, these will all be provided. We won't be simulating internal flows, but we are looking at adding a boundary condition on the inlet and outlet surfaces.

[CAEdevice]

About the floor, I was thinking about these features:

[*] Flat between the axles
[*] Longer diffuser than F1 (starting 300-400mm forward the rear wheels axle, with a similar heigth - 120-160mm at the end)
[*] Inclined surfaces to the side edges (the same as LMP1) and a central step (or a minimum distance from the ground of 40-50mm)
[*] Possibility to include rounds on the edges as possible in F1 (R=50mm or even 100mm)
[*] Frontal area (forward the front wheels or forward and around them) where "cuts" like this ( http://www.mulsannescorner.com/PerrinnLMP1-04.jpg ) and inclined surface are allowed
[*] Possibility to "cut" the floor if there is no bodyworks above (= if we look at the car from anove only the upper surface of the floor could be seen

[Daliracing]

so is it gonna be F1 or LMP?

LMP

well thats a shame for me if it tayed F1 i would have competed. don't know alot of LMP

[CAEdevice]

well thats a shame for me if it tayed F1 i would have competed. don't know alot of LMP

The same for me, but I think I'll re-use most of the concepts I developed for my F1 carshape (consider the aerofoils design of the rear wing as example).

[Daliracing]

well thats a shame for me if it tayed F1 i would have competed. don't know alot of LMP

The same for me, but I think I'll re-use most of the concepts I developed for my F1 carshape (consider the aerofoils design of the rear wing as example).

I might try out something but i don't know if i'll compete i'll see. i guess the rules are totally diffirent so will be a challenge

[MadMatt]

I think starting the diffuser in front of the rear wheel axle isn't a bad idea, but it would be good to know the exact CFD and dynamic simulation settings (if attitude change will be simulated for example), because this will have an effect on ground effect!

Regarding other regulations, if engine and gearbox are provided, it is again good to have a minimum surface for the air intake, as well as the cooling. For sure on a closed cockpit car the flow is more difficult to control towards the openings than it is for the F1 car, but that would prevent people running fully closed (streamlined) bodies.

Regulations on number of elements for the wings, chord length, location of the wing compared to wheel axles would be good addition as well, unless this is some kind of unlimited category (I don't mind but I think people not having too much free time would be happy to already have sort of boxes where to locate their wing).

Minimum cockpit/windscreen width is a good addition as well, besides the obvious overall length, width, wheelbase, wheel dimensions, minimum ride height, front and rear overhang.

[CAEdevice]

About the solver:

It would be possibile to know something about the CFD solver? Still OpenFOAM based? Wich GUI (Khamsin?) It would be great to have a "package" with the virtual wind tunnel included.

Likely a variation on 2014. We're still undecided on whether we should be making it easy to perfectly replicate the KVRC CFD setup, since this hands a larger advantage to those with more computing power.

I'd prefer an official package to concentrate about the car (during the last season I've spent about 30% of the CPU time to make my solver/virtual tunnel work in order to have the same results of the official solver/virtual tunnel), but I would be interesting also to not give any information about the official solver and let the partecipants develop their own. In this second case, it would be necessary that the solver and mesh were very accurate and detailed, so that we can assume it is near to reality (to have an absolute reference: on the contrary it would be a partial guess).

since this hands a larger advantage to those with more computing power.

It reminds me the FIA F1 flops limit

[CAEdevice]

Provided components and internal flows.

Will engine, gearbox, cockpit size, cooling requirements (eg rad/intercooler surface/thickness) be provided?

Yes, these will all be provided. We won't be simulating internal flows, but we are looking at adding a boundary condition on the inlet and outlet surfaces.[/quote]

What about the Center of Mass? It will be imposed or computed?

I think that it would be quite easy to estimate with a CAD package the COM of the provided parts. It would be interested for the partecpiants to have the possibility to choose the position of that components (es. heat exchangers) in order to influence the COM position. To avoid the need of too many verifications and to compute the COM only once, the mechanics components positions should be maintained as provided, or changed and approved only before the first race.

Maybe someone would try a front engine "roadster" LMP, after falling in love with the Panoz LMP-1 Roadster-S

Internal flows: during the last season, I've made some esperiments with the internal flows of the sidepods.
A simple way to consider the internal flows (not very accurate, but interesting because it encourage some "realistic" solutions) was to design a simple sweep between inlets and outlets, with a restricted section and normal (not rounded) connections in order to cause an energy loss.

[CAEdevice]

Last questions for today

How many partecipants do you estimate there will be? If a fee will be required (I hope so), it would be possibile to register two different cars paying a double fee?

[MadMatt]

CAEdevice, you edited your post on diffuser and other aero requirements after my message, so let me answer here. I think these are too restrictive regulations. I think moving away from the usual and well known LMP design is a good thing. As I've read somewhere, they want a mix of group C design, and modern with maybe a bit of F1. I think we have to keep regulations fairly open.

I think on a dimension side of things, what needs to be fixed is:

- maximum overall length
- maximum overall width
- maximum wheelbase
- minimum ride height
- minimum cockpit dimensions (safety cell)
- minimum windscreen width and height
- diffuser starting point
- tyres/wheels dimensions
- maximum height/position of rear wing
- number of elements of rear wing
- chord length of rear wing
- maximum bodywork height at a distance ??mm in front of the front wheel axle (to prevent high nose)

I am however confused about that solver thing. Do we have to do the meshing ourself? I haven't followed last year's competition so pardon me if this question is stupid.

[CAEdevice]

CAEdevice, you edited your post on diffuser and other aero requirements after my message, so let me answer here. I think these are too restrictive regulations. I think moving away from the usual and well known LMP design is a good thing. As I've read somewhere, they want a mix of group C design, and modern with maybe a bit of F1. I think we have to keep regulations fairly open.

I think on a dimension side of things, what needs to be fixed is:

- maximum overall length
- maximum overall width
- maximum wheelbase
- minimum ride height
- minimum cockpit dimensions (safety cell)
- minimum windscreen width and height
- diffuser starting point
- tyres/wheels dimensions
- maximum height/position of rear wing
- number of elements of rear wing
- chord length of rear wing
- maximum bodywork height at a distance ??mm in front of the front wheel axle (to prevent high nose)

I am however confused about that solver thing. Do we have to do the meshing ourself? I haven't followed last year's competition so pardon me if this question is stupid.

Hi, sorry about modifying my previous post, but yesterday I was writing with a small smartphone and I could not express as I wanted.

I quite agree with your opinion. What I'd like to avoid is a "wing car" floor, because it is less influenced by bodywork geoemtry and after one ore two races I fear that it would be completely developed by most of the challengers. A flat floor with some room for creativity (ex. border rounds, cuts, ...) has less DF but gives more opportunities to "differentiate". During (and after) the 2014 KVRC I improved of 40% the floor DF working on the vortex generator of the bargeboards and front wing...

About the mesh: it will not be required to mesh the model for the races, I was talking about the CFD simulation needed during design and development.

PS: I read your blog, I'm sure you would be one of the most competitive teams in the next KVRC

[MadMatt]

I see! Yes I agree, avoiding wing car is important. There is enough development to be made with diffusers (geometry and angle), wings (number of elements, type of airfoil, angle of attack), as you said vortex generators (something quite tricky to do that necessitate access to CFD).

Oh so you meant CFD performed by the designer. Yes indeed, knowing what settings and parameters will be used by the judges to evaluate our car is needed so we can already test our own model a bit before "sending it".

Don't be scared about my blog, I've only scratched the surface with rallycars aero, LMP-like cars is quite different, and I think you have developed your car much more than I did!