Khamsin Virtual Racecar Challenge 2015

[cdsavage]

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

The floor on LMP cars doesn't feature a step like in F1, and we don't have this feature either at the moment. Ground clearance, as in 2014 and 13, won't be something open to modification, it will be a fixed value.

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

I'd encourage you to have a good look at the rulebook when we release the draft, hopefully most F1-related concepts should still be applicable.

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.

All of this is included in the rulebook. Rather than rules on windscreen width, we have a template to represent the minimum volume of the cockpit which bodywork must enclose.

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.

Including some input from center of mass in the laptime calculation based on the position of heat exchangers is a possibility, but probably less than 50/50 chance of going ahead with this.

I'll have a think about it, but I would expect that we won't be allowing front-engined cars - this introduces a whole set of extra challenges in allowing free positioning of the cockpit templates.

For heat exchangers, there won't be any simulation of internal flows. Any change here, if there is any, will be in CFD on the KVRC side.

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?

I believe Julien is keen to do away with the entry fee, but I don't think this is fully decided yet. Difficult to tell how many participants we will get, but we are making some efforts to attract new entrants from outside F1technical too.

[cdsavage]

In 2015 we will be releasing more detailed technical images of the best entries each round, both of the base geometry, and of the CFD results. What does everybody think about going further than this, such as releasing images of cross-sections of the diffuser and wing profiles?

[CAEdevice]

I'm in favour of more detailed images of the geometry (sections and rendering included) but I have doubts about publishing pictures of the CFD post processing.

[variante]

I've got no objections. I doubt that a cross section would allow for an actual comprehension of each car's "secrets", so no problem for me.

[MadMatt]

I think cross section would not really be useful but detailed pictures would be nice, that's for sure!

[cdsavage]

Here is a first public draft of the rulebook for next year. A few things to be aware of before reading through it:

• -We will try to commit to not changing wheelbase and (hopefully) wheel size, but otherwise this draft is completely open to change. Please keep this in mind if you are starting on your design at this point. This release is mainly so that we can receive some feedback, rather than to give an indication of what the final rulebook will look like.
  
  -We have yet to add images and extra explanatory text for each rule. This will be done before the final draft is released, with an aim of defining the more complex rules in a less rigid way, guided with examples of what is and isn't acceptable.
  
  -There's a minus sign missing in rule K4.1, "Rotation of between 10 and +20 degrees in X" is supposed to be "between -10 and +20".

It can be found here: https://www.mediafire.com/?ryr199su882m527

We will aim to finalise the rulebook by around the end of the year so that you have at least a couple of months to work on your designs.

[CAEdevice]

Thanks! This is the news I've been waiting since the end od KVR2014!
During the weekend I'm going to take a look.

For the moment I have only one request: it would be possibile to have the template geometry in STEP format (not only SKP)?

[CAEdevice]

here's a first observation after a quick look: the flat floor template appears very small, especially in the X direction. In the area between 650mm and 1000mm from the centerline (X direction) there is much room for... everything. The "rear body work rear template" is quite high too (360mm). I have the impression that a big DF will be easily obtained by everyone and the differences between the first 3 or 4 teams will be small.

[variante]

I have to say that i do like it! The formula is similar to what i expected, if not better.

But here some constructive (hopefully) criticism:

First of all: it looks like the rule boxes have been determined by either random coordinates (i would have chosen more measures that are multiples of 10, for example) or unnecessary complex schemes (like the curvature determining the rear wing box, or the combination of curves and angles backwards of the front wheels). This condition increases the chances of error while designing our cars...and since not all of us is using parametric softwares...

Also:
K2.3 -- is this rule necessary? Why not leaving this aspect as a free choice?

K3.1 -- it isn't specified the distance from FWCentreLine of that section.

K3.5 -- this is one option. The other one is the minimum area section: wouldn't this one work better?

K3.7 -- again, why not leaving this as a free choice?

[cdsavage]

STEP file here - https://www.mediafire.com/?8xgf5f2uyj5682s

here's a first observation after a quick look: the flat floor template appears very small, especially in the X direction. In the area between 650mm and 1000mm from the centerline (X direction) there is much room for... everything. The "rear body work rear template" is quite high too (360mm). I have the impression that a big DF will be easily obtained by everyone and the differences between the first 3 or 4 teams will be small.

There was a deliberate decision to leave the outer regions of the floor fairly free. As for the longitudinal position and height, this can certainly be changed easily, these were mostly just arbitrary dimensions. With that said, I'm not sure whether allowing large diffusers necessarily means there will be small differences between teams.

First of all: it looks like the rule boxes have been determined by either random coordinates (i would have chosen more measures that are multiples of 10, for example) or unnecessary complex schemes (like the curvature determining the rear wing box, or the combination of curves and angles backwards of the front wheels). This condition increases the chances of error while designing our cars...and since not all of us is using parametric softwares...

The cockpit templates and footbox template are taken straight from the LMP1 regulations with only small modifications. The visibility template is taken from the LMP1 regulations but with a few more modifications.

I'm guessing most of the dimensions you're referring to are to do with these parts? If it's somewhere else, let me know where and I'll look at changing it, since I did make an effort to choose multiples of 5 or 10 for most dimensions.

I can replace the rounds with flat chamfers if this makes things easier. It should decrease the file size, at least.

For later releases of the rulebook, we do plan on releasing a template which serves as a measuring tape, with markings at relevant distances from the wheel centerlines.

K2.3 -- is this rule necessary? Why not leaving this aspect as a free choice?

We wanted the cars to have at least some resemblance to prototype sports cars from the past couple of decades, and all cars from this period were required to cover the wheels.

K3.1 -- it isn't specified the distance from FWCentreLine of that section.

This dimension was specified relative to the front of the bodywork volume, which is itself 1000mm forward of the FWCL. I will change this to read "between 700mm and 1000mm forward of the front wheel centerline".

K3.5 -- this is one option. The other one is the minimum area section: wouldn't this one work better?

The goal here is not really the same as with the sidepod shape in 2014, the intention with this rule is to keep the appearance of the cars more like real-world prototype sportscars. There are rules very similar to these in the LMP1 rulebook. A minimum cross-section area is something we can include, but I'm not sure it's necessary, and I imagine that this is more difficult to check in some modelling packages.

As indicated in the draft, we might end up leaving out K3.5, K3.6 and K3.7 completely.

K3.7 -- again, why not leaving this as a free choice?

As above, the intention is just there to keep the cars looking more like their real-world counterparts, since a rule like this has existed in LMP1 for a number of years, but we might not end up using this.

Any other comments on the general direction of the rulebook? Too restrictive, or not restrictive enough? Are the rules on the cooling inlets OK?

[MadMatt]

I have few questions but mostly because my English is not so good:

1) 2.5: I don't understand the 3rd point.
2) 3.3: I don't understand this one either. Does it mean no bodywork can sit higher than the orange plane?
3) When you mention "must point directly rearwards (or forward)", does that mean the surface that has to point rearwards has to be normal to the X axis or can there be an angle?

[cdsavage]

1) 2.5: I don't understand the 3rd point.

Don't worry too much right now about the rules on bodywork intersecting the suspension volumes, there will be images added here to make this much more clear.

2) 3.3: I don't understand this one either. Does it mean no bodywork can sit higher than the orange plane?

It means that any bodywork which is visible from below cannot be higher than the orange plane. There can be bodywork higher than this, but any such bodywork mustn't be visible when viewing the car from underneath.

3) When you mention "must point directly rearwards (or forward)", does that mean the surface that has to point rearwards has to be normal to the X axis or can there be an angle?

Directly rearwards = surface normal of Y, no rotation allowed.

[MadMatt]

Thank you! Yes of course Y axis, not X (I usually use X for longitudinal and Y for lateral hehe).

For the 2nd point I was mentioning, what is considered as bodywork? Is the diffuser part of the bodywork? I am not sure I see the meaning of this rule, or what it tries to cover

[cdsavage]

Thank you! Yes of course Y axis, not X (I usually use X for longitudinal and Y for lateral hehe).

For the 2nd point I was mentioning, what is considered as bodywork? Is the diffuser part of the bodywork? I am not sure I see the meaning of this rule, or what it tries to cover

Anything which you model will be considered as bodywork, so this is meant to govern the height of the diffuser. This is pretty much the same as how the height of the diffuser is regulated in F1. At the moment it's easy to get around this rule since we have nothing preventing holes or slots - this will probably change.

[MadMatt]

Oh I see now, yes of course it makes sense! My English is always under pressure when reading regulations!