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Aerodynamic Drag - F1 cars


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#1 blueprint2002

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Posted 11 July 2020 - 14:44

Happened to be reading Arthur Mallock’s article about his FJ car of 1960, and was intrigued by this statement:

Drag: Anything approaching “lamina flow” is impossible, on an open-wheeled car, so the object should be to keep down the overall frontal area and minimise air disturbing projections. In 1960 Coopers proved that cutting down the body width doesn’t help a lot, their “full width” Formula 1 car having a lower drag than the much narrower Lotus.

I am not certain whether he is referring to the results of wind tunnel tests, or to speeds measured at fast circuits (Spa? Reims? Monza?), and am wondering if anyone knows the basis of the last statement? The latter seems  more likely to me, for 1960.

(Although the Cooper of that year was the famous “Low Line” model, noticeably lower and narrower than its immediate predecessor, it was most certainly wider than the Lotus 18).

Interestingly, Colin Chapman would continue to pursue low drag by narrower, lower bodies and by moving suspension units inboard, despite the results obtained by the 1956 Lancia Ferrari and the 1958 Vanwall, both unusually “full width” cars. And again, in the mid-seventies, the similarly “full width” Ferrari 312T series would triumph over the notably slim Lotus 72/76/77 as well as others of the same ilk.

There is nothing quite so baffling as aerodynamics, is there? Even when you have accounted for other factors such as weight, power, handling, tyres etc which also play a major role.



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#2 Charlieman

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Posted 13 July 2020 - 12:47

There is almost nothing so baffling as aerodynamics, I agree.

 

I suspect that Arthur Mallock was influenced by Laurence Pomeroy in ideas expressed in 'The Grand Prix Car' volumes. Pomeroy attempted to measure frontal area and used measurements/calculations of top speed or engine power output to create a performance rating.

 

Arthur Mallock: Drag: Anything approaching “lamina flow” is impossible, on an open-wheeled car, so the object should be to keep down the overall frontal area and minimise air disturbing projections.

 

It is ironic that a multitude of projections are present on a current F1 car, designed to disturb air in ways which create downforce.

 

Inboard front suspension: I refer you to 1970s experiments with production racing cars, non venturi tunnel types. I'd suggest that there is no conclusion. For a racing car run (sub-optimally) by a small or amateur team, simplicity of outboard suspension has to be counterbalanced against any potential benefits.



#3 blueprint2002

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Posted 13 July 2020 - 15:01

There is almost nothing so baffling as aerodynamics, I agree.

 

I suspect that Arthur Mallock was influenced by Laurence Pomeroy in ideas expressed in 'The Grand Prix Car' volumes. Pomeroy attempted to measure frontal area and used measurements/calculations of top speed or engine power output to create a performance rating.

 

Arthur Mallock: Drag: Anything approaching “lamina flow” is impossible, on an open-wheeled car, so the object should be to keep down the overall frontal area and minimise air disturbing projections.

 

It is ironic that a multitude of projections are present on a current F1 car, designed to disturb air in ways which create downforce.

 

Inboard front suspension: I refer you to 1970s experiments with production racing cars, non venturi tunnel types. I'd suggest that there is no conclusion. For a racing car run (sub-optimally) by a small or amateur team, simplicity of outboard suspension has to be counterbalanced against any potential benefits.

Thank you, C'man.

The profusion of projections on the current F1 cars would have been unimaginable, to me at least, even 10 years ago. 

And while they are all there to "manage" the air flow, one way or another, they must each add to the drag, even if only in a small way. It would seem that there is so much power available that some can be squandered, if that is the right word. 



#4 Bikr7549

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Posted 13 July 2020 - 16:20

And drag is the least important aspect, down force (which wasn't realized till later in the decade) is king. I have been reading the Katz book on aerodynamics to try and get past the baffling part, pretty interesting.

 

 

I am not certain whether he is referring to the results of wind tunnel tests, or to speeds measured at fast circuits (Spa? Reims? Monza?), and am wondering if anyone knows the basis of the last statement? The latter seems  more likely to me, for 1960.

 

 

I would be very surprised it there was any wind tunnel work done on these cars in this period-maybe the big automotive manufacturers (MB) due to finance issues. 



#5 gruntguru

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Posted 14 July 2020 - 03:23

Thank you, C'man.

The profusion of projections on the current F1 cars would have been unimaginable, to me at least, even 10 years ago. 

And while they are all there to "manage" the air flow, one way or another, they must each add to the drag, even if only in a small way. It would seem that there is so much power available that some can be squandered, if that is the right word. 

I am sure a significant proportion of the "protrusions" are there to reduce drag. Some (most) are purely to generate DF and some help with both.



#6 blueprint2002

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Posted 14 July 2020 - 05:31

I am sure a significant proportion of the "protrusions" are there to reduce drag. Some (most) are purely to generate DF and some help with both.

 

Thanks, gg. You're probably right.

Wish someone like Peter Wright would write a book about F1 Aerodynamics.



#7 GreenMachine

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Posted 14 July 2020 - 08:04

I am sure a significant proportion of the "protrusions" are there to reduce drag. Some (most) are purely to generate DF and some help with both.

 

I'm not so sure about that.

 

As I understand it, those protrusions are there to control the airflow downstream to increase the efficiency of the aerodynamics generally, not necessarily to generate DF or reduce drag themselves.  This seems to mean increasing downforce firstly, and reducing drag (or at least minimising the increase in drag) as a secondary consideration.  The only other consideration that springs to mind might be to improve cooling by better managing the entry and exit of external air to the various heat exchangers.



#8 desmo

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Posted 14 July 2020 - 13:54

The protrusions are purely there to increase the L/D, most of the crazier ones in what used to called the 'bargeboard area' trying to tame the turbulent wakes caused by the front wheels and vortices coming off the transition between the loaded outer portion of the front wing and the mandated central neutral part. Maximizing DF by itself isn't the point really, if it were they'd run Monaco settings at Imola. F1 has painted itself into a corner as the "pinnacle of motorsport"; any changes to significantly reduce the reliance on aero DF will necessarily render what are today minor formula cars capable of lapping faster than F1 cars. That won't work I don't think.



#9 gruntguru

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Posted 14 July 2020 - 21:25

I'm not so sure about that.

 

As I understand it, those protrusions are there to control the airflow downstream to increase the efficiency of the aerodynamics generally, not necessarily to generate DF or reduce drag themselves.  This seems to mean increasing downforce firstly, and reducing drag (or at least minimising the increase in drag) as a secondary consideration.  The only other consideration that springs to mind might be to improve cooling by better managing the entry and exit of external air to the various heat exchangers.

I can only think of four goals for race car aero. DF, Drag, Cooling and interaction with competing cars.


Edited by gruntguru, 14 July 2020 - 21:46.


#10 Greg Locock

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Posted 14 July 2020 - 23:17

Sensitivity to cross winds, sensitivity to ride height, pitch moment would be sub attributes of the aero task.



#11 GreenMachine

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Posted 15 July 2020 - 00:27

I can only think of ... interaction with competing cars.

 

Is this really a thing?  I know it has been talked about, but surely energising the wake is going to use energy than can more effectively be used to reduce drag/increase DF?  No free lunches, and all that. 

 

The wake problem is real enough, but to deliberately use energy from your car to make it worse seems misguided to me.  I had always assumed that this was a red herring put about to either distract from something, or to get others to waste time and resources chasing down a blind alley.



#12 gruntguru

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Posted 15 July 2020 - 04:03

A following car can be affected in either DF terms, drag terms or both. Reducing the following car's ability to slipstream might involve modifications that also reduce drag.


Edited by gruntguru, 15 July 2020 - 04:03.


#13 GreenMachine

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Posted 15 July 2020 - 08:25

Lets try and nail this one.  My working hypothesis is that both the leading and following cars have their aero set up to maximise performance (fastest lap time).
 

A following car can be affected in either DF terms, drag terms or both. 

 
 Surely it can only be both?  The very qualities which reduce the following car's drag (enabling it to approach the car in front at a greater rate than in 'clean' air) must also reduce its DF?  The converse also surely holds - a car with lower DF must have lower drag (assuming unchanged aero setup)? 

 

and ...
 

Reducing the following car's ability to slipstream might involve modifications that also reduce drag.

 

If the aero has been optimised for lap time, the implication is that all the components, and the car overall, has been optimised for efficiency and/or effectiveness.  Change anything, and you are making the car slower, because it/its components are no longer operating as efficiently/effectively.  That is, energise the leading car's wake/slipstream to make the wake more turbulent, or change the location or size of the wake area, will require the energy to be taken from the leading car.  This can only make the leading car slower - law of conservation of energy IIRC.  Note also, this penalty will be felt for the whole race, not just when a car is following closely.

 

Reducing drag will of course make the leading car go faster, meaning the need for reducing a following car's ability to slipstream is also reduced.  To do both sounds like there is a free lunch in there somewhere, and as we all know, there are no free lunches.

 

I may be missing something.  Maybe someone can point out what I am missing and I'll have to eat my words, but until then I am on the 'furphy' side of this one.



#14 Charlieman

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Posted 15 July 2020 - 09:30

I am sure a significant proportion of the "protrusions" are there to reduce drag. Some (most) are purely to generate DF and some help with both.

Perhaps we can simplify the debate by considering the protuberances as elements to manage air flow. Given that laminar flow is an impossibility over the length of a car, the elements exist to manage turbulent air. If we go back to the 1980s and earlier, there would have been insufficient knowledge of turbulent flow even if wind tunnel testing was available. Wind tunnel testing would have largely focused on laminar-ish flow except for occasions when an engineer spotted that something strange was going on...

 

Today we have three(?) main reasons for the additional elements:

1. Maximisation of downforce.

2. Minimisation of drag.

3. Creation of smooth airflows for cooling.

 

When considering overall performance of a racing car, 1 and 2 are part of the same equation. We have to go back to cars like the Lotus 78 for one factor to be rated significantly more than the other -- and Lotus were determined to put that right.

 

Creating an unpleasant wake for a following car? I can believe that designers have experimented with the idea but like the other sceptics here I find it difficult to accept that it might work in practice. Fancy ideas have this habit of banging their heads against reality. But sticking a fan on the back of a car to extract air -- you can hardly go wrong!

 

Greg Locock suggested three other factors. I wonder if cross wind sensitivity is a problem on most of the circuits used for single seater racing; noting that Indy car/oval racing creates a new set of scenarios. Ride height and pitch moment sensitivity seem to be related problems. Are they mitigated by the short extractor/venturi length on modern single seaters and the greater proportion of downforce generated by upper body wings?



#15 DogEarred

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Posted 20 July 2020 - 12:05

I think you are all correct in one way or another.

 

An F1 wind tunnel model run involves cycling through pitch, roll, yaw, ride height, steering angle & even tyre 'squidge' & exhaust blow.

 

So a huge amount of aerodynamic information is extracted from an 8 minute run and each run involves changing at least one component for comparison.

 

How that data is used is down to the general design philosophy but generally speaking, an increase in down force  and/or drag reductionis a 'win'.



#16 Charlieman

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Posted 23 July 2020 - 10:22

Protuberances seem to have arrived in F1 with Gerard Ducarouge's Lotus 97T in 1985. It introduced vertical vanes just behind the front suspension, midway between chassis and wheel. The intent was to minimise turbulence between front wheel and sidepod area of the car. They seem to have been used throughout 1985 and other teams tried them, but the idea fizzled out. The Lotus 97T also used winglets mounted on the back of the side pods, variants of which have been seen over the years.

 

According to Wikipedia, bargeboards appeared at South Africa 1993 on a McLaren. The Lotus vane was inspired by CART cars, according to Doug Nye, History of the GP Car. Can any CART enthusiasts provide further information?



#17 blueprint2002

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Posted 23 July 2020 - 10:40

Protuberances seem to have arrived in F1 with Gerard Ducarouge's Lotus 97T in 1985. It introduced vertical vanes just behind the front suspension, midway between chassis and wheel. The intent was to minimise turbulence between front wheel and sidepod area of the car. They seem to have been used throughout 1985 and other teams tried them, but the idea fizzled out. 

 

Correct me if I'm wrong, but those vertical vanes were of aerofoil cross-section, not just curved plates, and they were set at a large angle of incidence to airflow from straight ahead. If so, they would shed a strong tip vortex off both upper and lower ends: perhaps the lower one was intended to seal off the  outer edge of the sidepod underfloor, with some gain in downforce. That was only the third year of flat-bottom regulations.



#18 Charlieman

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Posted 23 July 2020 - 11:43

Correct me if I'm wrong, but those vertical vanes were of aerofoil cross-section, not just curved plates, and they were set at a large angle of incidence to airflow from straight ahead. If so, they would shed a strong tip vortex off both upper and lower ends: perhaps the lower one was intended to seal off the  outer edge of the sidepod underfloor, with some gain in downforce. That was only the third year of flat-bottom regulations.

 

I've not seen the perfect photo of the Lotus 97T, but I think the vanes were aerofoil section at about 30 degrees outwards from the car's longitude line (i.e. air flow). There seems to be a flat element to the vane (parallel to the road) as well.



#19 gruntguru

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Posted 23 July 2020 - 21:44

Correct me if I'm wrong, but those vertical vanes were of aerofoil cross-section, not just curved plates, and they were set at a large angle of incidence to airflow from straight ahead. If so, they would shed a strong tip vortex off both upper and lower ends: perhaps the lower one was intended to seal off the  outer edge of the sidepod underfloor, with some gain in downforce. That was only the third year of flat-bottom regulations.

Or the angle was simply to align with airflow around the sidepod.



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#20 blueprint2002

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Posted 24 July 2020 - 00:45

I've not seen the perfect photo of the Lotus 97T, but I think the vanes were aerofoil section at about 30 degrees outwards from the car's longitude line (i.e. air flow). There seems to be a flat element to the vane (parallel to the road) as well.

Indeed there is, thanks for pointing it out. Unlike the usual wing endplates, it is only to one side of the vane, the "pressure" or concave side, and it extends well forward, near the lower wishbone. It would not stop the tip vortex forming at the trailing edge, but it can't happen further forward. Maybe it has another function. 

 

Or the angle was simply to align with airflow around the sidepod.

Could be, but why bother to make it aerofoil section?



#21 Charlieman

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Posted 27 July 2020 - 11:17

Could be, but why bother to make it aerofoil section?

The first time that people try things they tend to get it about right but not quite there. Think about how long it took Peter Wright to develop an aerofoil on the side of a car into ground effects. I'd like to know what Ducarouge and his aero team thought the Lotus 97T vane achieved and why motor sport abandoned it so quickly. Lotus may not have had the money to develop the concept but it surprises me that something which is now so important took seven or eight years to re-emerge.

 

Over the weekend I saw a photo of the 1967 Chaparral sports car with a high variable pitch wing. But it was a high wing of extended teardrop form rather than aerofoil section, and no end plates. Aah, the glories of hindsight.



#22 GreenMachine

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Posted 27 July 2020 - 13:36

Small detail CM, extended teardrop IS an airfoil section.  Providing the wing chord is not parallel to the airflow, lift/DF will be generated by a symmetrical airfoil (high performance aerobatic aircraft use(d?) symmetrical airfoils, so they must have something going for them).  OTOH, when the chord is parallel to the airflow, lift/DF will be negligible and so will drag, desirable when the DF is not required and the wing is trimmed out for top speed.

 

If the airfoil is fixed, non-symmetric is usually the way to go.

 

End plates would be a good idea though.