Khamsin Virtual Racecar Challenge 2014

[astracrazy]

so....conversations seem to of gone dead so how bout we talk about next year/season

My proposal:
more open rule book, based on something (open wheel/closed wheel leading to LMP style or F1 style) but less restrictive rules made more open to ideas. At the moment basing it purely on f1 (or any other particular formula) we are restricting what can be done and where the downforce can come from. Perhaps we should aim for the idea of a formula but write the rulebook from scratch.

an idea, for example, could be a closed wheel LMP style rule book but much more open. Even allowing engine placement to allow for different packaging ideas (front, mid, rear)

lets brainstorm for now. after this season we will home in on some things

[CAEdevice]

Hi astracracy,

in addition to the car type I would have to discuss some other general ideas, tell me if I can do it here or if it would be off topic.
About the car, this are my thoughts:

1) F1 (from my point of view) has a more general attraction and it is more likely to find possible competitors (and, why not, sponsors). Obviously there are many other raxcing categories that can be technically interesting: previously somebody wrote about up hills races. If you consider that I've been passionate about the history of Trento-Bondone since I was 14 you can imagine how good my opinion on this type of racing is

2) The point is: indipendently from the car type, I think that is important (even essential) that we remain near to reality. This means that the rules should be very realistic and very similar to the category we will choose. Less rules don't mean more fun. In my opinion it is funny to design once a sort of flying saucer, but I find t much more funny to work looking for small improvements on my f1 car this year (or LMP/formulaX next year)

3) Why don't think about an improved KVRC F1 based and a second (shorter) challenge with a different approach? The KVRC lasts a few months and there is almost half year for other races.

[astracrazy]

It would be 100% still realistic.

3) is not a bad idea. It's something which could be looked at and might help KVRC to be more appealing overall. Perhaps in the first half of the year it would be f1 and 2nd a closed wheel. It would be a lot of work though really. My only concern would be time. Setting up this year took, roughly, 2 months prob slightly more. There would be many things we need to improve so this would increase. My concern would be it would get on near a 9 month part time job.

If people want more, i'd rather increase the championship by two races with a break in the middle or something.

[machin]

Aero Coefficient vs Lap Time chart for the Silverstone round:-

[cdsavage]

Thanks

[julien.decharentenay]

Sorry for being out of touch recently. The CFD models are now running with very little input at the moment - which is great for me... CFD software and models: there are many difference between software and models itself - none the least associated with the person that does the model. I read an article a while back where they got 30 people to model a building (not CFD, but another simulation tool) to predict energy performance. They had a large variety of results. Another good initiative study is the blood flow CFD round-robin study by the FDA, which followed the same principle but with comparison to experimental results.

There is an obvious difference in mesh resolution. The computational resources are quite limited, when compared to a F1 team. Other aspects to consider is that we are not modelling internal flows or exhausts, and wheel rotation is reasonably crude.

Important: I have altered a bit the settings used in the mesh cleaning step (ie netfabb) that will be used in the next race. It is not a CFD related item, but may have an impact.

[julien.decharentenay]

By the way, I am looking at moving back from Australia to the UK... If you know of CFD related job opportunities, I would appreciate if you could let me know...

[CAEdevice]

hi julien, if you wrote a solidworks version of khamsin plugin, possibly with a post processing tool, you could sell it all over the world

[julien.decharentenay]

I would rather focus on 3D packages that do not have an existing integrated CFD simulation package. Soliworks has already got this aspect covered https://www.solidworks.com/sw/products/ ... lation.htm... SpaceClaim, which you suggested earlier, is probably a better option (if only they were in the UK).

[CAEdevice]

They are both based in Boston actually. Anyway: the commercial space of a third party plugin for SWX depends on the final price. Also consider that open foam solver has larger field of applications than FloEfd/FloWorks and that SWX users are so many all over the world.

Spaceclaim (I worked for SC two years) is a fantastic tool to prepare CFD geometry (I'm using an old SC release for the KVRC, it also export to sketchup).

Sorry for the OT, if you prefer we could talk elsewhere.

Now let's wait for Monza results, even if (after receiving the cfd report) I think my race was nothing special

[UlleGulle]

so....conversations seem to of gone dead so how bout we talk about next year/season

My proposal:
more open rule book, based on something (open wheel/closed wheel leading to LMP style or F1 style) but less restrictive rules made more open to ideas. At the moment basing it purely on f1 (or any other particular formula) we are restricting what can be done and where the downforce can come from. Perhaps we should aim for the idea of a formula but write the rulebook from scratch.

an idea, for example, could be a closed wheel LMP style rule book but much more open. Even allowing engine placement to allow for different packaging ideas (front, mid, rear)

lets brainstorm for now. after this season we will home in on some things

Unfortunatly my CAD-skills are way to inadequate to ever take part in the Khamsin competition. However, I really like this idea. My humble suggestion would be to try to get hold of a rulebook from 1982, one of the last seasons to have a really liberal approach to car construction. To simplify things a standard engine with set dimensions and a output of 1000 hp and attached gearbox would be supplied to the teams. One off-season race, set at imola for example.

It would be really exciting to see what the combination of a modern comprehension of aerodynamics and fixed skirts and low ride-heights. It would also be a interesting piece of alternative history, how would F1 today be if the FIA would have gone a more laisse faire way?

[CAEdevice]

It a difficult question to answer...

From a technical point of view I consider less interesting a wing car campared to a flat or stepped floor car (even if the first could be much faster... but in a numerical simulation speed is only a parameter).

For this reason my proposal is to mantain the present version of the KVRC, eventually including a final super race with double assigned points (Spa? Old Nurburgring? a special fantasy track designed by an expert as Machin?) and some simulation improvements (i.e. better inlet/outlet simulation, non necessary simulating internal flows).

In addition to this, after a couple of moths or more, it would be interesting to organize a 24h (Le Mans?) with LMP cars and a simulation engine that could take into account also the fuel consumption, in order to give the right importance to the aero efficiency.

[machin]

and a simulation engine that could take into account also the fuel consumption, in order to give the right importance to the aero efficiency.

Not wanting to get too off topic, but actually, in a race car, aerodynamic efficiency has little effect on fuel consumption.... The more aerodynamically efficient the car is the faster it will be for a given power output, but if you give a race car to any race driver he will attempt to maximise power output at all times since more power = more acceleration. Now, fuel consumption is a direct result of power produced by the engine (which is controlled by the throttle pedal) and the engine's fuel efficiency; BSFC (brake specific fuel consumption, measured in grams per kilowatt hour). So the race driver who is trying to get the most power out of the engine at all times, is effectively trying to use fuel as quickly as possible....

Interestingly, this is no more evident than in the 2014 Le Mans rules where each car is given a maximum fuel consumption per lap (hence maximum average power output over that lap) and each driver will drive to achieve that. It is up to the teams to design a car that is faster than their rivals for the same fuel consumption.

This is totally different to how we drive on the road, where we're not driving to maintain a specific power output (and therefore fuel consumption), instead, we're driving to maintain a specific speed (mandated by the local speed restrictions)... and in that instance lower drag will decrease fuel consumption, since power (hence fuel) required to move the car is proportional to car speed (cubed) and drag....

[CAEdevice]

and a simulation engine that could take into account also the fuel consumption, in order to give the right importance to the aero efficiency.

Not wanting to get too off topic, but actually, in a race car, aerodynamic efficiency has little effect on fuel consumption.... The more aerodynamically efficient the car is the faster it will be for a given power output, but if you give a race car to any race driver he will attempt to maximise power output at all times since more power = more acceleration. Now, fuel consumption is a direct result of power produced by the engine (which is controlled by the throttle pedal) and the engine's fuel efficiency; BSFC (brake specific fuel consumption, measured in grams per kilowatt hour). So the race driver who is trying to get the most power out of the engine at all times, is effectively trying to use fuel as quickly as possible....

Interestingly, this is no more evident than in the 2014 Le Mans rules where each car is given a maximum fuel consumption per lap (hence maximum average power output over that lap) and each driver will drive to achieve that. It is up to the teams to design a car that is faster than their rivals for the same fuel consumption.

This is totally different to how we drive on the road, where we're not driving to maintain a specific power output (and therefore fuel consumption), instead, we're driving to maintain a specific speed... and in that instance lower drag will decrease fuel consumption, since power (hence fuel) required to move the car is proportional to car speed (cubed) and drag....

Yes I agree, but I was assuming the in a CFD simulation of a 24h the "ideal drivers" could drive in the same way of a qualifying lap in F1. Consider that in our case alle engines and drive style are equal (the same for the car mass) and only aero efficiency can differetiate fuel consumption (so it has more importance than in real races).

[machin]

I'm not sure I follow... If the cars have the same mass, the same drivers, the same chassis/tyres and the same engine, with only aerodynamics being a differentiator, there are two extremes:-

1, The average power (and hence fuel consumption rate) is the same for all cars and better aero means faster lap time.
2, The lap times are the same and the car with the better aero requires less power (lower fuel consumption rate) to achieve that time.

Case 1 reflects a qualifying situation, case 2 represents a safety car situation.....