[KVRC] Khamsin Virtual Racecar Challenge 2016

[RicME85]

how far away are we from having a finalised rulebook?

[machin]

Looking at Chris' draft rules and the few comments we've had so far on them I don't think we're far off are we?

So far 2 competitors want to keep the current diffuser height, and 1 wants to reduce it.

On the covered suspension rules I think we've had feedback from 3 competitors so far and all three have said to keep the rule but with slight amendments from 2 of those...

Mantium has also suggested increasing the front fender height slightly.

All 3 issues are pretty minor and I would guess shouldn't change the designs too much (assuming that the covered suspension rule stays in one form or other).

[CAEdevice]

I add two other points:

1) The floor distance fron the ground is a bit too much in my opinion, I think LMP1 use a lower ride heigth (even static!). With 25-30mm instead of 40-45mm we would have more realistic diffuser (a lowerd max heigth could help too)

2) Rear wheels are probably too narrow

I agree with Mantium about front (but also rear) fenders.

[variante]

I haven't properly read the draft yet, but i would keep the current diffuser height (-> more room for innovation and greater diffuser variety), and current suspension covers (-> nicely tricky to manage), keeping for next year Machin's idea to get rid of them completely (redbull X1 style).

@CAEdevice: F1 diffusers never go lower than 50mm from the ground; usually more if the car has got some rake. Also, greater distance from the ground translates into greater chances of vortex management (which is very interesting, in my opinion). With lowered distance, diffusers would be more prone to stall.
I would like to have narrower front wheels rather than wider rear.

[CAEdevice]

I haven't properly read the draft yet, but i would keep the current diffuser height (-> more room for innovation and greater diffuser variety), and current suspension covers (-> nicely tricky to manage), keeping for next year Machin's idea to get rid of them completely (redbull X1 style).

@CAEdevice: F1 diffusers never go lower than 50mm from the ground; usually more if the car has got some rake. Also, greater distance from the ground translates into greater chances of vortex management (which is very interesting, in my opinion). With lowered distance, diffusers would be more prone to stall.
I would like to have narrower front wheels rather than wider rear.

Yes, but consider that vortex management would require a much more refined mesh to give the same results with differents software: the actual simulation risks to be a not repeatable cinfiguration. In addition to that, the 2015 ride height would be realistic with a stepped floor, but not reasonable for lmpx cars.

About the wheels: the width used during 2015 is, espcially for the rear wheels, almost impossible to be reproduced in a real car, considering weight and (extremly high) df.

PS: Radillon @ 285-290 km/h would be ok for the Redbull X2010 and GT5 videogames... not for realslistic projects

[machin]

Last idea: I would dedicate a page of the rulebook to the mechanic specifications of the car (not to be changed during the season or established for each race before the first race).

Yeah I can do something for this. However I think it would be fairly meaningless to list all of the mechanical aspects (and to be honest displaying all the tyre characteristics in a useful way which can be audited by competitors would be rather difficult)... As we discussed last year: any change to the mechanical aspects impacts the relationship between Cd.A, Cl.A and lap time, so the important thing is fixing the relationship between Cd.A, Cl.A and lap time (for example two different combinations of power curve and tyre characteristics could result in near identical Cd.A-Cl.A-Laptime relationships).

The difficult thing now is describing in a useful (and not too laborious way) that Cd.A-Cl.A-lap time relationship for each track.

I propose that we define a "nominal car" (currently I have a default Cd.A=1.4m^2 and Cl.A=4.5m^2 on the Virtual Stopwatch page) and then present for each track the lap time for that car, and the effect on lap time of increasing and decreasing drag and downforce by 20% (this data is already presented on the Virtual Stopwatch page in the data window). These figures can be added to the rule book.

This means that any competitor can at any point quickly check that the Cd.A-Cl.A-lap time relationship hasn't changed, just by going to the Virtual Stopwatch page, leaving the default aero coefficients, selecting the track and then pressing the calculate button and comparing the results to the rule book. If the mechanical aspects have changed then this Cd.A-Cl.A-lap time relationship will have changed.

[variante]

Yes, but consider that vortex management would require a much more refined mesh to give the same results with differents software. In addition to that, the 2015 ride height would be realistic with a stepped floor, but not reasonable for lmpx cars.

I was just saying that it's not unreasonable to have such rideheight even at topspeed.
You're right about CFD problems, but i prefer to risk and face a delusion rather than not having the chance to work at a higher level at all.

About the wheels: the width used during 2015 is, espcially for the rear wheels, almost impossinle to be reproduced in a real car, considering weight and (extremly high) df.

Yes, tire degradation would be kinda huge...but we should define the kind of race these car would face before deciding tires "needs". And I think it's not necessary to implement further variables.

[CAEdevice]

Not only degradation, but also pressure difference between cold and hot tyres and handling that would be for... not completely human drivers

Anyway: I am probably too influenced by my other project

[machin]

As I mentioned in a previous post; I've upgraded the tyre model in Virtual Stopwatch this year so it incorporates degradation... (The only impact on the competitor is a change to the slope of the Cd.A-Cl.A-Lap time relationship).

Getting real data for degradation is difficult, but as you all know in F1 Pirelli "engineer" the tyre life to meet the FIA's requirements, so I think what I've done is reasonable...

I do agree with you that I think the top cars in high downforce trim are at the limit of the tyre width; I must admit, I underestimated the level of downforce you guys would achieve last year when we set the tyre sizes... But also bear in mind we're only doing a single lap run and not 20 lap or more stints...

Conversely for the guys in the middle of the field I'd say our tyre size is pretty good... And I think the cars look "about right", and not out of proportion.... So my preference is to keep them as they are...

[variante]

The front wheels wouldn't have much steering angle, that's the only reason why i would like to have them narrower.

BTW that tire degradation you've implemented would be typical of a qualifying compound or a race compound?

[machin]

When you refer to "qualifying" do you mean a qualifying tyre like we had in F1 in the mid 1990's or like we have in F1 today?!

The less facetious answer is that the amount of degradation employed in the KVRC car model is minimal, I think we had pretty good Cd.A-Cl.A-lap time relationships last year (in the second half of the championship we had a good mix of medium and high downforce cars setting similar lap times), so I didn't want to do anything to ruin that, however adding the ability to simulate tyre degradation was something I have wanted to add to Virtual Stopwatch for a while... It made sense to use it in the KVRC championship this year as the facility is available, even if It is only implemented in a minimal way...

I've also made an update to the way KERS is implemented in the model; again, I've selected parameters that don't really affect the Cd.A-Cl.A-lap time relationship too much. The upside is I can now generate some nice KERS energy storage traces as the cars go around the lap!

The final thing I have done is incorporate a "fuel optimisation" regime in which the amount of fuel onboard is optimised to each specific car: the more efficient the car the less fuel you need to start the lap with. As you know Hillclimbing is "my thing" (although I'm currently on an extended sabbatical!) and this was something I wanted to do to help determine the amount of fuel required for each run. Again the impact on the KVRC cars is a really small change to the Cd.A-Cl.A-lap time relationships.

[Gridiot]

Hi everyone

Sorry I don't check the topic more often. I think I agree to the general opinion regarding the new rules: keep the same diffuser height limit and keep the suspension visibility rule as it is (I like how cars look at the moment, and it's an interesting challenge to design the covers trying to minimise negative effects).

I need to have a more comprehensive look at the rulebook, but other new rules (mainly cooling) look OK to me.

[cdsavage]

Thanks everyone for the feedback so far.

Guide files, subclass parts: I am going to be quite busy with a couple of other things for the next week or so, but I'll have plenty of time after that to get these finished and released. I would expect a release of these parts by the end of next week, at the latest.

Front suspension: Still keen to hear from everyone else, but I think it's leaning towards keeping this as-is. If we decide to make no changes, we should keep this option in mind for next year.

Diffuser height: Again, keen for any more input, but if there are no other opinions then we would probably lean towards keeping it unchanged.

The coordinate system is still wrong.

From a CAD standpoint, I think it's maybe "more common" and "less common" rather than "right" and "wrong". Some CAD/modelling packages use Y as the longitudinal axis and some use it as the lateral axis, and I've used one that used Y as the vertical axis (which kinda does seem "wrong" to me).

A bit more space on top of the front fenders would be good. Modeling them was always a tight deal. Having louvers while respecting the 10mm rule was very difficult (for me).

I think raising the top of the bodywork volume slightly in the area above the front wheels is a good idea. I need to have a closer look at the rear wheels, but I would lean towards not making any change at the rear. There is already slightly more space above the rear wheels than above the front wheels, from memory.

The front wheels wouldn't have much steering angle, that's the only reason why i would like to have them narrower.

The fronts were sized based on the front fender size that we were aiming for, keeping in mind that we do not take steering travel into account. The bodywork volume was then built around them. I think it makes sense to make the front wheel parts used in the simulation a bit narrower (without making any changes to the regulations / bodywork volume).

Rear wheel width: It's not a problem to make the rears slightly wider, but for the purpose of the competition there's probably not a compelling reason to do so. What does everyone think about this?

Ride height: probably not a problem from my end to change this, but we will need to see what Julien thinks. It would mean needing to make changes to the bodywork volume in the areas surrounding the wheels. Or, we could keep the bodywork volume unchanged and just move the ground plane upwards so that a larger region of the bottom of the wheel is "chopped off" below the ground plane.

[CAEdevice]

Hi, is there a reason for the different area of the "template surface" (Cooling option 1, 200000mm2) and the "heat exchanger surface" (Cooling option 2, 250000mm2)?

[RicME85]

Heat exchanger is larger but has less rules (is what I take from Chris' post on Jan 20th)