Khamsin Virtual Racecar Challenge 2014

[CAEdevice]

Sure, but I was looking at the values of Cd.A of Monza 2013, and they are higher than I would expect (also considering a 20% more drag for the diffrent rules).

It is worth remembering that Cd.A is a function of the car design, not a direct function of the track design; i.e. if Cd.A values were higher than expected at Monza last year then there is only one reason for it: the car's that were submitted had high Cd.A values. I think that we are only just seeing that everyone has previously been working with Cd.A values that were too high; as per graph above, we should be aiming to see Cd.A values in the region of 0.8 to 1.2, maybe even lower, whereas previously we were seeing Cd.A values of the submitted cars in the range 1.2 to 1.5.

I think it is good that we are seeing a progress in the design of the cars.

I agree! Thanks for the explanation (and for the Monza detalied chart of the previous post).

Just a curiosity: wich is the value of engine(s) power I should consider to extimate the maximum speed of my car just before the first chicane ("prima variante")?

[machin]

The 1.6T power curve I have used on Virtual Stopwatch is very similar to the chart below:-



I have used a curve between the red and white lines to account for the fact that the car's cannot use the full MGUK all of the time (as per the regulations).

If you do want to work out a top speed then it is quite a long winded process to get a good accurate figure... the process being:-

1.First choose the starting road speed* (This being the speed at which the car exits the previous corner)
2.Determine the engine's speed, RPM, in each gear for the road speed in step 1 using the gear ratio, final drive ratio and the rolling radius of the driven wheels.
3.Using a look-up table of the engine's power output curve and the RPM's calculated above, determine the engine's power output in each gear, choose the gear with the highest available power.
4.Multiply the flywheel power by the transmission efficiency to determine the motive power available at the tyre contact patches. Note, Virtual Stopwatch adds an additional calculation to take into account the effect of the driver’s ability to slip the clutch. This only applies below 30mph.
5.Determine the maximum motive power that can be transmitted by the front and rear wheels (separately) using static mass distribution, downforce/lift generation, and the maximum load transfer due to CG height, wheelbase length, mass and tyre grip coefficient. Since the tyre’s grip coefficient is dependant on the vertical load placed on it this step is iterated several times to determine a final figure. Apply a “grip factor” to the result of the above based on the road bumpiness and the suspension’s compliancy and damping.
6.Find the maximum accelerative power that can be transmitted by the car, based on step 5, where:- Rear wheel drive = Rear grip only, Front wheel drive = Front grip only, 4 wheel drive = Front and rear grip.
7.Find the actual maximum motive power which is the lower value of step 4 or step 6.
8.Determine the power absorbed by resistive forces, where Total resistance = Air drag + Rolling resistance + Gradient “resistance”.
9.Determine the power available for accelerating the car by taking the value from step 7 and subtracting the power absorbed in step 8.
10.Convert the power remaining to a force using Force = Power / velocity.
11.Determine the acceleration at the chosen road speed by applying the equation F=mA, where m includes the car’s mass and an allowance for the inertia of the car’s rotating parts.
12.Determine the time taken to accelerate 1 mph using the result of step 11. If there has been a gear change between the last mph and this one, add in the time required to change gear.
13.Determine the distance covered whilst accelerating the 1 mph based on the average speed and the time calculated in step 12.
14. Repeat the above steps for the next mph, until either the car reaches the desired speed (in the case of say 0-62mph), or when a specified distance is covered (for example in the case of 1/4 mile calculation)..
15. Add up all of the individual times calculated at step 12 to determine the time taken to arrive at the braking zone*

*The cornering speed and length of the braking zone is determined by the characteristics of the track and the vehicle.

All of the above steps are calculated by Virtual stopwatch for every straight on the course and combined with a cornering calculation and a braking calculation to arrive at a final lap time.....

I presume that you are just doing this study for a bit of fun (which is pretty much the reason why I wrote Virtual Stopwatch in the first place!)????

[CAEdevice]

Thank you for the detailed answer!

Yes, I'm just extimating the maximum speed for fun (to compare my car to the real 2014 GP cars). I mean an absolute max speed (imagine to have an infinitely long straight and flat road).

I used to extimate it with this formulas:

Power@MaxSpeed = Drag_Force * MaxSpeed (I should consider also a trasmission/wheels efficency, about 90%)
Drag_Force = 0.5 * Cd.A * MaxSpeed^2

MaxSpeed = (Power@MaxSpeed / (0.5 * Cd.A))^(1/3)

Considering that Monza principal straight segment is very long (and the initial speed, after the Parabolica, is quite high) I wondered if real F1 will plan to use the electric power at the end of this straight segment or during the acceleration.

[RicME85]

FYI, Netfabb's .STL file cloud repair service has been taken over by Microsoft and is now called Microsoft Model Repair. Turnaround times are faster thanks to Microsofts Azure Cloud - https://netfabb.azurewebsites.net/

[andylaurence]

Is there a chance we might see more data than the lap time? What's the chances of a speed/acceleration trace being made available? Admittedly, it doesn't tell more than the graphs you've produced, but it's some data to mull over.

[Schifty]

I have a big concern about this competition, i saw almost of the car... and they are almost really poor, i mean about modelling. A lot of designer have not a lot of 3D skill to modelling properly a car and surely the one have a step higher in 3d skill will automatically win it and not because hes design is the most performant....

I suggest for next years juste to make a big one modelling designer group. Try to modelling the most perfect F1 car and try to beat performance of a real F1 team.

Also tried to find a good Modeller for this challenge i propose.

I'm not telling that because i'm beater, juste only i know how its not easy to modelling and i guys like me, or someone else who participate to the actual challenge, like if he good brillant idea for aero of his car, to reproduce it on a 3d model lets him not showing hes real skill. for now its mostly a 3d modelling skill challenge instead of aero and car concept skill challenge

[CAEdevice]

I have a big concern about this competition, i saw almost of the car... and they are almost really poor, i mean about modelling. A lot of designer have not a lot of 3D skill to modelling properly a car and surely the one have a step higher in 3d skill will automatically win it and not because hes design is the most performant....

I suggest for next years juste to make a big one modelling designer group. Try to modelling the most perfect F1 car and try to beat performance of a real F1 team.

Also tried to find a good Modeller for this challenge i propose.

I'm not telling that because i'm beater, juste only i know how its not easy to modelling and i guys like me, or someone else who participate to the actual challenge, like if he good brillant idea for aero of his car, to reproduce it on a 3d model lets him not showing hes real skill. for now its mostly a 3d modelling skill challenge instead of aero and car concept skill challenge

I think that race after race the model quality will improve: in my case after a simple initial design, I'm modelling a totally new car body for the next race.

[astracrazy]

I have a big concern about this competition, i saw almost of the car... and they are almost really poor, i mean about modelling. A lot of designer have not a lot of 3D skill to modelling properly a car and surely the one have a step higher in 3d skill will automatically win it and not because hes design is the most performant....

I suggest for next years juste to make a big one modelling designer group. Try to modelling the most perfect F1 car and try to beat performance of a real F1 team.

Also tried to find a good Modeller for this challenge i propose.

I'm not telling that because i'm beater, juste only i know how its not easy to modelling and i guys like me, or someone else who participate to the actual challenge, like if he good brillant idea for aero of his car, to reproduce it on a 3d model lets him not showing hes real skill. for now its mostly a 3d modelling skill challenge instead of aero and car concept skill challenge

I think your wrong if you think the best designed car would win regardless of its performance. I've seen every car and i can tell you some are better than others and not always the best designed finish at the top - in fact sometimes the opposite. And besides there is such a range already of different levels yet not much different in projected time.

We could create some "group" but what would be the point? We'd only model a poor car....

The whole purpose of this was to be open to anyone, which is why we suggest sketchup for people to use. Yes the standard might not be high but it doesn't matter. People enjoy themselves (the number 1 goal). If a pro designer wants to join next year, be my guest, but i don't think they would get the result you think.

I'd be more than happy to be proved wrong but does it matter? People have fun. No offence but i think you maybe miss understand the purpose of the challenge.

[Schifty]

If its was free... yes you are right... but ask to pay 50$ to join the competition when some of them will surely not win because to have not a lot of 3D skill when they have great design idea its a bit shameless for them i think.

By the way, i know you got some challenges maded, 2012-2013 and this one, may be tried to make it one fantasy, i mean choose your proper rules for next competition and let more time to prepared their car. May be write the rules before the end of 2014 challenges

[CAEdevice]

Nobody asked you to pay and take part to the challange.

I paid for it and I'm having fun: what's the problem?

PS: I'm not sure they win at last

[RicME85]

The fee isnt just for the sheer hell of it, the fee is to cover the cost of the computational time to run the simulations and any money left over goes into a prize fund.
To me that is reasonable.
If the money was to secure a spot and that was all then I would agree its not on.

Seems to me that you just do not understand what this is about.

There is a lot more to it than just 3D modelling skill. IMO my car looks better modelled than some of my competitors but it hasnt performed as well.

If you don't like it, don't join, simple.

[astracrazy]

who had to pay $50? It was £20 to cover costs purely so this could continue

You don't even know what your on about at all - so just button it. You've come in here, told people there models are crap and now called them shameless. In what way does any of it have anything to do with you or why do you think people care about your opinion?

People are having fun and thats what matters. Your simply proving you have no idea what this challenge is about.

[Schifty]

The fee isnt just for the sheer hell of it, the fee is to cover the cost of the computational time to run the simulations.

Its is really computational time.... or just paid he's own time to calculate everything. He said just before its for fun, if its for fun... why he need to get paid, why its needed to get prize ?

Why he wasnt able to get sponsor like 2013 challenges? May be he's sponsor know he was need to get money to run his challenges. Every designer here put more time to design a car than beeing check on Khamsin.... so thats my point.

I just want to make sure hes not stealing your money to after that gave a licence key ( if its always that ) of Khamsin CFD plugin from Hibou Software when this key is free..

[RicME85]

yes it is for CPU time, the time to run the cars costs.
dont need a prize, the only way there is a prize is if there is money left over from paying for CPU time.

[CAEdevice]

The fee isnt just for the sheer hell of it, the fee is to cover the cost of the computational time to run the simulations.

Its is really computational time.... or just paid he's own time to calculate everything. He said just before its for fun, if its for fun... why he need to get paid, why its needed to get prize ?

Why he wasnt able to get sponsor like 2013 challenges? May be he's sponsor know he was need to get money to run his challenges. Every designer here put more time to design a car than beeing check on Khamsin.... so thats my point.

I just want to make sure hes not stealing your money to after that gave a licence key ( if its always that ) of Khamsin CFD plugin from Hibou Software when this key is free..

Just to let you know how different is my approach from yours: if I won (I'm working for that) I would let the prize as sponsorship for the next edition... so I can enjoy the challange again.