DOF_power

Effective Aerodynamic Solutions

12 posts in this topic

In the late 1930s the germans from Auto Union and MB had crazy ideas on aerodynamics. What began with wind tunnel testing for reducing drag on their GP car ended with some ground braking ideas and the discovery of negative lift aka downforce.

A certain Professor Eberan-Eberhorst, from experience gained by recent wind tunnel experiments, rebuild an AU car destined for breaking speed record. The Auto Union technicians had, by covering the underside of the car with "skirts", in fact created a ground effect car only ~40 years before the Lotus 78/79.

rm3.gif

Unfortunately german ace Bernd Rosemeyer was killed in this monster.

MB on the other hand decided to take another path, inverted airfoils, the result being the T80 record car.

MHV_MB_T80_World_Record_Car_1939.jpg

Briliant revolutionary work, decades ahead of its time. But came WWII and all this interest in downforce and drag would be lost till the 1960s.

Now onto Can-Am and F1:

a few clarifications (witch I posted before on other treads)

image025.jpg

image054.gif

As you can see there is blue beneath and above the car. Blue is downforce, red is drag.

The diffuser is usually found on each side of the central engine and gearbox fairing and is located behind the rear axle line as seen in Figure.

As seen in Figure , the diffuser consists of many tunnels and splitters.

It is designed to carefully guide and control airflow underneath the racecar.

Essentially, along with the flat bottom (and previously the big and low front wing now gone), it creates a suction effect on the rear of the racecar and pulls the car down to the track.The suction effect is a result of Bernoulli's equation, which states that where speed is higher, pressure must be lower.Therefore the pressure below the racecar must be lower than the pressure at the outlet since the speed of the air below the racecar will be higher than the speed of the air at the outlet. Racecar engineers must carefully design the diffuser, since its dimensions are limited by the racing regulations and its angle of convergence is somewhat restricted.If the angle of convergence is too great then the flow will separate because of the adverse pressure gradient.

The problem with downforce is that it comes with drag so there 2 solutions for creating "downforce on demand"

1] the Chaparral movable aero/wing.

Basicaly the wing moves to switch between low drag and high downforce.

2] the active suspensions

http://youtube.com/watch?v=sjbc1tmKi6g

Basically car goes up air goes freely underneath drag is reduced, car goes down the air is compressed/accelerated (by the flatbottom and diffuser) the pressure drops (Bernoulli's principle ) resulting downforce.

Today, in F1, the time between a wing is conceived and until it becomes a museum piece is just 6 week. And will be used for at least 1 race to a maximum of 3 races.

Every track demands modifications or downright redesign of aerodynamics, suspension (along with these maybe even brakes), and even some weight tweaking, all very costly and time consuming.

So why not use these "ancient" solutions ?!

Edited by DOF_Renault_BMW

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I always enjoy reading your more technical posts DOF. Good post young man! As to your question at the end, I suspect it wouldn't help all that much. F1 is such a high profile big business now that the teams will have large budgets and so will always do a lot of fine-tuning and development work. Wherever you have development/research and technical freedom/innovation you will have costly time-consuming work (and unequal teams!).

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I think getting rid of the front wing would solve the problem of cars not being to follow each other closely round a fast bend. But I'm no aero wizard so maybe my solution is pure rubbish.

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Interesting posting... well don't forget the infamous BT46B "fan-car" from Brabham in 1978, where they attached a fan to to the back of the car driven by the engine (and which won a race for Niki Lauda before being banned). It was this, incidentally which brought in the rule against moveable aerodynamic devices.

My recollection of the active suspension cars was that they were so successful at creating downforce that car speeds went up dramatically. The FIA banned them on the basis of speeds becoming dangerously high, as well as the cost of implementing - many of the poorer teams could not afford to develop systems of this nature. Williams used it to greatest effect - the funniest thing though was when it failed on a car and you really see the performance difference as it crabbed around the circuit with other cars rocketing by. As I recall McLaren dabbled with active suspension too but never got it hooked up quite as well as Williams did.

I still think one of the simplest ways to encourage more overtaking is the "boost" button as used in A1GP or "Power to Pass" as it is known in Champcar, where pressing this gives an extra 30 or so BHP. Although I think F1 purists and the FIA would not go for this - admittedly there would be policing problems, esp. as the series that use it have standard engines. In F1, how could one be sure that the boost was being used fairly/equally? etc

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I think getting rid of the front wing would solve the problem of cars not being to follow each other closely round a fast bend. But I'm no aero wizard so maybe my solution is pure rubbish.

Not true.

Because the front wing in the last 15 seasons was both reduced in size and lifted higher the car lost front ground effect downforce witch made the front very sensitive to turbulence thus contributing in a large amount to the impossibility to overtake of today.

Pat Symonds of Renault F1 in a podcast recognized this problem as did Sam Michael of Williams F1. Ofcourse it took them a while, Montoya on the other hand recognized this in an instant an was qquite furious about the lifting of the front wing.

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Not true.

Because the front wing in the last 15 seasons was both reduced in size and lifted higher the car lost front ground effect downforce witch made the front very sensitive to turbulence thus contributing in a large amount to the impossibility to overtake of today.

Pat Symonds of Renault F1 in a podcast recognized this problem as did Sam Michael of Williams F1. Ofcourse it took them a while, Montoya on the other hand recognized this in an instant an was qquite furious about the lifting of the front wing.

I say put the front wing back down on the ground!!

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Interesting posting... well don't forget the infamous BT46B "fan-car" from Brabham in 1978, where they attached a fan to to the back of the car driven by the engine (and which won a race for Niki Lauda before being banned). It was this, incidentally which brought in the rule against moveable aerodynamic devices.

Nope, I haven't forgot it. Just thought (after numerous reconsiderations) that it would be too extreme.

My recollection of the active suspension cars was that they were so successful at creating downforce that car speeds went up dramatically. The FIA banned them on the basis of speeds becoming dangerously high, as well as the cost of implementing - many of the poorer teams could not afford to develop systems of this nature. Williams used it to greatest effect - the funniest thing though was when it failed on a car and you really see the performance difference as it crabbed around the circuit with other cars rocketing by. As I recall McLaren dabbled with active suspension too but never got it hooked up quite as well as Williams did.

Yes active suspensions were very effective.

McLaren were also successfull with them in 1993, the MP4-8. Senna won 5 victories with it and came second in the championship despite a severly underpowered engine.

As to the costs:

after the ban the aero needed to be modified/redesigned for every track, ditto for the passive suspensions witch can sometimes imply brake modifications, and the weight balance also has to be tweaked by playing with super-expensive materials (advanced alloys and/or composites), dependece on anti-wheel spin and anti-lock has increassed, and all of these have made costs explode far beyond the levels in the days of the active rides.

Not to mention all of these provided low gains/advantages vs. costs when compared to active suspensions.

So the proposed costs cuts turned into an explosion of costs.

I still think one of the simplest ways to encourage more overtaking is the "boost" button as used in A1GP or "Power to Pass" as it is known in Champcar, where pressing this gives an extra 30 or so BHP. Although I think F1 purists and the FIA would not go for this - admittedly there would be policing problems, esp. as the series that use it have standard engines. In F1, how could one be sure that the boost was being used fairly/equally? etc

With restricted engines this will be a necesity. It the unrestricted engines you'd have button to increase the rev limit and improve the air-fuel mixture witch worked as sort of an F1 "push to pass".

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.........With restricted engines this will be a necesity. It the unrestricted engines you'd have button to increase the rev limit and improve the air-fuel mixture witch worked as sort of an F1 "push to pass".

Great posts Dof_Renault, they're always a great read.

With the above in mind re: restricted engines and the rev limit, I really hate the way this affects slipstreaming - no boubt there's some draft, but nothing like the engine revs taking off as they hit the sweet spot. I think they (FIA) shot themselves in the foot, definately a move against overtaking :wacko:

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Well I belive that everything since the ban of the active rides was a mistake. Sam Michael from Williams goes even further to the ban of the ground effects.

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Because the front wing in the last 15 seasons was both reduced in size and lifted higher the car lost front ground effect downforce witch made the front very sensitive to turbulence thus contributing in a large amount to the impossibility to overtake of today.

Pat Symonds of Renault F1 in a podcast recognized this problem as did Sam Michael of Williams F1. Ofcourse it took them a while, Montoya on the other hand recognized this in an instant an was qquite furious about the lifting of the front wing.

From what you say, wouldn't it then make sense then to drop the noses back to the way they used to be? If dropping the nose as well as the front wing increases aerodynamic efficiency to the front of the car why hasn't any team ditched the raised nose/wing apporach?

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From what you say, wouldn't it then make sense then to drop the noses back to the way they used to be? If dropping the nose as well as the front wing increases aerodynamic efficiency to the front of the car why hasn't any team ditched the raised nose/wing apporach?

The lift of the nose isn't a problem, but the wing is.

Their reason was "to reduce downforce = improve safety and overtaking".

Witch actually decreased safety (front wheels now lose all contact with ground is the driver doesn't back off) and decreased overtaking.

Ofcourse it would make sense to lower the front wing and make it bigger, but Max/FIA isn't known for resonable decisions.

Edited by DOF_Renault_BMW

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So why not use these "ancient" solutions ?!

No idea. Probably something to do with the FIA's general incompetence.

Anyway, great post(s)/thread DOF and once again impressive technical knowledge & understanding, I award you an A*.

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