The aerodynamics of 'dirty air'

[jjn9128]

I agree. I think it was a rumour started about 20 years ago that one of the teams (Ferrari?) were using the wake offensively. Within the regulations of F1 it's very difficult to fundamentally alter the shape of the wake of the car, while remaining competitive. You could maybe increase the negative wake effect a little, but the drag penalty would make it self defeating.

[Shakeman]

There is no such thing as mechanical grip - it's a made up term - if there were tin top series like Aussie V8s or BTCC would be as quick as F1 cars through trick suspension and sticky tyres. Lateral loads are increased because of downforce. Don't believe me here's Frank Dernie https://www.motorsport.com/f1/video/mai ... 94939/?s=2

Hogwash, if mechanical grip isn't a thing then why did we have grooved tyres to reduce mechanical grip?

The tyres we have today are designed to degrade at a predetermined rate to supposedly spice up the show, they don't. When drivers push it takes them away from their precalculated optimal race strategy which is a sad state of affairs, it leads to pit lane over takes as part of the show.

A combination of better tyres, active suspension and ground effect and doing away with wings as much as possible and what's left making them active would improve the ability of the cars to follow closely. There's no reason why tyre manufactures could not produce sticky tyres that would last a race weekend if the rules allowed and with a car body shape that allowed close racing fake racing through DRS and passing in the pit would be a thing of the past.

BTW, how on earth do you 'open up multiple racing lines' when there's one fastest line? How do you open up lines when f1 is increasingly being taken to city centre tracks and who is going to pay to make changes to existing permanent race circuits? I rather doubt the cash strapped circuit owners would be too pleased to re-engineer their circuits when the real issue is the rules that have led to these types of cars being produced.

[Just_a_fan]

Hogwash, if mechanical grip isn't a thing then why did we have grooved tyres to reduce mechanical grip?

They were intended to reduce grip. Not "mechanical grip", just grip. Doing so limited corner speed which was something the FIA was concerned about following some nasty accidents.

[jjn9128]

Hogwash, if mechanical grip isn't a thing then why did we have grooved tyres to reduce mechanical grip?

BTW, how on earth do you 'open up multiple racing lines' when there's one fastest line? How do you open up lines when f1 is increasingly being taken to city centre tracks and who is going to pay to make changes to existing permanent race circuits? I rather doubt the cash strapped circuit owners would be too pleased to re-engineer their circuits when the real issue is the rules that have led to these types of cars being produced.

I don't claim to be an expert in kinematics, which is why I linked to Frank Dernie talking about it - a true expert. If you won't take his word on it then I don't know what to suggest.

I would open up racing lines exactly as I suggested a few posts back. No re-engineering of circuits required. A car behind is normally trying to overtake because they are faster than the car ahead. So taking a 'slower' line to lose less in the wake should have a net benefit.

Going to my stock answer on 'ground effect' - F1 cars produce as much of their downforce (if not a bit more) in ground effect as Indycar (the floor is ~65% + front wing 15-20% and the rear wing is both assisted by and assists the floor). Indycars only produce ~3/4 of the total downforce of an F1 car, so F1 cars generate more absolute downforce from the floor than Indycars do (~17% more). Is the racing in F1 better than Indycar? Probably not. So why is increasing the underbody downforce always touted as the cure to processional races?

[Vyssion]

I think part of the problem with this discussion is that people are combining "mechanical grip" as being purely "tyre grip"... Grooved tyres weren't aimed to reduce the "mechanical grip" they were implimented as a quick and dirty way to slow the cars down as the "mechanical system" was improved with the current batch of tyres. Cars going too quick? Add another groove to slow them down due to the reduced contact patch area (simplistically).

"Grip" is dependent on downforce, vehicle weight, weight transfer, camber, toe, caster, stiffness, track camber, temperature, kinematic friction, slip angle, track surface, air pressure, etc etc etc.... The cars have four wheels which have four contact patches. There is only one load path for all the variables together and that is through the tyre contact patch. So you cannot claim that aero and mechanical are mutually exclusive, because they just simply aren't.

And as for increasing "overall grip" past the mechanical theoretical maximum, here is a post I made a while back showing you the link of how pure downforce factors in 9 yes, an oversimplification, but it gets the point across).

Essentially, the generation of downforce is the way that allows for the car to (in lamans terms) "be heavier than it actually is, without the bad stuff that comes with an increased weight".

The downforce and the normal (weight) force of the vehicle is the simplified mechanism by which the tyres gain their grip. And again, over-simplifying things for a purely aero discussion, the more grip you have, the faster you can theoretically corner at.
(Can't display an actual 'mu' symbol so will refer to it as C_f from here)

The "N" denotes normal force which is made up of the vehicles weight force and any downforce currently being produced.


If you combine this equation with the formula for centripetal acceleration (which could be adapted to fit a corner if a constant radius)

and rearranged to give:


Then you get the following formula:


This then shows that for a constant coefficient of friction, that velocity is proportional to (meaning that an increase in the right hand side of the equation will increase the left hand side). If this is differentiated to get this in terms of time, it shows that time is proportional to (or simply that it is inversly proportional).

The important term here is this which is often referred to as the "specific downforce" of the vehicle. So if we are to increase this term, by means of increasing downforce or reducing the cars mass, the theoretical maximum velocity we can corner at will increase and hence the time taken to travel the corner will decrease. Add in that since you can carry more speed through the corner, braking time is reduced in the lead up to it and the acceleration beyond it begins from a higher speed, and you can begin to see the benefits.

By increasing mass initially, this would have the effect of decreasing this term, which would be counter productive.

This argument here is purely from an aerodynamic standpoint (and extremely simplified!!!) though and doesn't even mention things like the weight transfer or suspension changes and other vehicle dynamic effects that would be required to handle the higher initial weight during a race. But hopefully it helps explain why it is the way it is!!

[trinidefender]

As far as my understanding goes, for 2009 the main changes that were made to move the wake away from the following cars was the neutral central section and the having the rear wing placed higher up and be made narrower.

For 2017 onwards we still have the neutral central section however the rear wing was made lower and wider, and most likely not allowing the wake to clear the following car. I suggest moving the rear wing up a bit to ensure that the wake clears following cars.

Pit stop overtaking for me has always been boring. I want to see drivers pursuing different strategies in the race and be able to change them mid race to adapt to changes in the race. I'm in agreement that making the tyres last longer to make more racing lines be closer to optimum is a good idea.

In addition what about active suspension, teams spend vast swathes of money developing these very complicated passive systems which have no road relevance what so ever. An active system could in all probability be cheaper to produce and not require new pieces every single race reducing manufacturing costs for smaller teams. More to the point, as far as overtaking goes, active suspension will allow the car to be optimised for the condition. I.e. The ride height of a trailing car can be raised or lowered so it loses the least amount of downforce while following further allowing closer following and easier setups for overtaking.

Secondly what about partially fairing the rear wheels we get no reduction in downforce, maybe even a slight downforce gain in the diffuser, and a smaller wake, again, helping closer racing and increasing challenges for overtakes.

I think looking at the number of overtakes as the determining factor alone is wrong. For me it has always been about the overtaking challenges. A driver challenging another driver is what is exciting even if no overtake happens. The more times a driver can challenge another driver, the more likely someone is going to make a mistake and ergo the more overtakes that will happen.