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DRS/f-duct debate


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#1 IPBushy

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Posted 23 March 2012 - 11:08

I've been away a couple of days, so have I missed the great debate over whether Mercedes' DRS operated f-duct is legal?

IMHO it's got to be illegal. If the driver didn't do anything it wouldn't work, so if the driver has to activate something to make it work....

I mean, if there was a system that changed the aerodynamics to assist braking and was operated when the driver pressed a button, that would be obviously illegal. If the system operated only when the driver operated the brakes, then it would surely still be illegal?



Have I missed something?!!! :confused:



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#2 Joe Bosworth

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Posted 23 March 2012 - 11:17

Yeah, I think that you missed something.

A driver activated DRS is legal. DRS moves the major element of the rear wing so air can be dumped in a lap time enhancing manner.

There are no rules controlling where that air goes.

Brawn has figured a way of having the air to dump to a location that is more enhancing than the other guys.

End of arguementation.

Regards



#3 GeoffR

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Posted 23 March 2012 - 11:29

From what I have read Charlie Whiting has declared it legal, so it is legal. Watch the race now for everyone else to develop a similar system.

#4 IPBushy

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Posted 23 March 2012 - 12:59

Thanks for the insight guys. I must pay more attention. Trouble is, I can't hear much from the back of the class, and this dunce's hat keeps falling over my eyes...!!!

#5 jatwarks

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Posted 23 March 2012 - 13:06

From what I have read Charlie Whiting has declared it legal, so it is legal. Watch the race now for everyone else to develop a similar system.

Can't argue with that.

Various reasons for its acceptance have been given;

Charlie doesn't want to stifle all innovation, and its fairly simple to copy, so won't favour the front-running teams.

Ross Brawn has mused that a lot of the complaints from other teams, whilst they quickly develop their own versions, draws attention away from their questionable exhaust systems.

As far as I'm concerned, it's a storm in a teacup. The "primary function" of the DRS button is to reduce the drag of the rear wing in order to allow a higher speed. The "secondary function" of the DRS button on the Mercedes is to reduce the drag of the rear wing in order to allow a higher top speed.

Given that a driver needs to carefully select his gear ratios, for the best compromise between running with and without DRS activated, I don't think the tweak, available only when DRS is activated, is a major advantage; remember, Mercedes were quick on the straights anyway.

I can't see that the small advantage offered to Mercedes, only in overtaking in the DRS zone remember, would be of much greater value than a driver that is more skilled in overtaking!

Given the choice between Kobayashi in the driving seat, or the DRS F-duct, I'm not sure which I'd prefer!

#6 munks

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Posted 23 March 2012 - 13:54

As far as I'm concerned, it's a storm in a teacup. The "primary function" of the DRS button is to reduce the drag of the rear wing in order to allow a higher speed. The "secondary function" of the DRS button on the Mercedes is to reduce the drag of the rear wing in order to allow a higher top speed.


I think you meant front wing in the second sentence.

But point taken: as Whiting said, DRS stands for "drag reduction system" ... while its activation mechanism is by rule the rear flap, it doesn't say jack about how exactly the airflow should reduce drag.

Given that a driver needs to carefully select his gear ratios, for the best compromise between running with and without DRS activated ...


That's an especially good point. Mercedes' speed gain with DRS is so significant (I think I read something like 20kph?) that I wonder how close they are to making 6th gear the top "non-DRS" gear.

Edited by munks, 23 March 2012 - 13:58.


#7 jatwarks

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Posted 25 March 2012 - 21:52

Clearly, the main advantage of the Mercedes DRS F-duct is to give MSC and ROS false grid positions.

Fine during qualifying, when DRS use is unrestricted. But, when it can only be used to overtake in the official DRS zone, and then only when within one second of the car in front, it offers nothing to a car hurtling towards the rear of the field.

#8 GreenMachine

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Posted 26 March 2012 - 07:19

It may be a neat device, but at what cost?

Whether because of how it works, or the diversion of effort into getting it to work, or something, Saturday speed is not being reflected on raceday. I wonder if someone has taken their eye off the ball, the one that says that the name of the game is finishing the race before everyone else - or at least regular podiums and wins. Not fast practice times, or even good grid slots.

Brawn had a good breakthrough with the DD, I wonder if he is throwing everything at finding another 'secret weapon'?

#9 MatsNorway

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Posted 26 March 2012 - 13:48

Most cars on the grid now is supposedly focusing on maximum reduction in drag from the DRS not best compromise between drag and df without DRS.

By doing this F-duct thingy right you can focus more on drag without drs activated. This should give better times in the race.

If its overall worth it i don`t know.. But i doubt it. The grid slot is worth a lot of time. Espesially in a rain race or at street courses.





#10 ray b

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Posted 26 March 2012 - 15:59

do we ''know'' if it acts on the front or rear wing

or both ?

#11 jatwarks

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Posted 26 March 2012 - 22:13

do we ''know'' if it acts on the front or rear wing

or both ?

Almost certainly the front wing. DRS acting on both front and rear is far more useful as it allows both the front and rear of the car to rise slightly with reduced downforce.

Adding to the effect at the rear wing only may give beneficial rake angles, but if you're still trying to push the full front wing through the air then drag is still high.

#12 GreenMachine

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Posted 26 March 2012 - 22:29

do we ''know'' if it acts on the front or rear wing

or both ?


Scarbs reckons the front linky

#13 GreenMachine

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Posted 26 March 2012 - 22:39

Almost certainly the front wing. DRS acting on both front and rear is far more useful as it allows both the front and rear of the car to rise slightly with reduced downforce.

Adding to the effect at the rear wing only may give beneficial rake angles, but if you're still trying to push the full front wing through the air then drag is still high.



I don't think the ride heigth is a benefit in itself, more the reduction in drag (part of which comes from increasing the ride heigth), and the reduction in front DF. In practice, when DRS is free, you can use DRS anywhere you do not need max DF, as the balance of the car is unaffected by opening/closing the DRS (assuming you have it tuned properly, and the act of transitioning to/from DRS does not unsettle the car - ie one end comes on/off quicker than the other).

I think Scarbs gives some good reasons why you can't blow the rear wing, but those regs do not apply to the front wing (yet  ;) )

#14 gruntguru

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Posted 27 March 2012 - 01:24

more the reduction in drag (part of which comes from increasing the ride heigth

Increasing ride height usually increases drag AFAIK.

#15 GreenMachine

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Posted 27 March 2012 - 01:39

Increasing ride height usually increases drag AFAIK.


... in which case the 'blowing' of the FW would need to eliminate any increase in drag from the FW being higher, and then provide a further drag reduction on top of that. This might be drag arising from the FW itself, and/or drag arising from the attitude (aka 'rake') of the car.

Thanks GG, I assumed that as the FW becomes less efficient (effective) as it rises out of ground effect, both lift (DF) and drag would drop.

#16 jatwarks

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Posted 27 March 2012 - 11:42

I'm no expert, clearly, but it seems to me that raising the car would / could stall the diffuser, reducing downforce generated by ground effect. That's why teams like Tyrrell were so keen to introduce active ride at the front only, to bring the nose up on straights. I remember Gerhard Berger crashing his Ferrari accelerating hard out of the pits; by all accounts the active ride cut in when the car reached a pre-determined speed, the nose lifted and the car headed straight across the track at the pit exit, into the barrier on the other side. I'm not suggesting that the amount of movement achievable with DRS would match that of active ride, but ride height is still considered just as critical.

And, if activating DRS has no effect on downforce, why do drivers spin if they open it too soon when exiting corners in qualifying?



#17 jatwarks

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Posted 27 March 2012 - 12:31

... in which case the 'blowing'...

I feel compelled to make sure that you're not confusing DRS effects with blown diffusers. They are totally different.

Apologies if I've made too many assumptions.

#18 ray b

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Posted 27 March 2012 - 16:26

would not the reduced DF
directly result in a higher ride height

do the M-B CARS GAIN height IN FRONT WHEN THE DRS is used

#19 cheapracer

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Posted 27 March 2012 - 18:02

Stalling the front wing in conjunction with DRS makes the car stable in high speed turns by balancing the downforce front to rear (or lack of it). Apparently with just DRS and full front downforce (throw in rake as well), the car was a bit nervy with the light rear making high speed turns tricky and that's why they are qualifying well now but can't use it on race day.

yes ray
they
gain ride height
at the front
because of
lost
DF


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#20 Ross Stonefeld

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Posted 27 March 2012 - 18:07

Increasing ride height usually increases drag AFAIK.


When the DRS is activated the rear ride height increases, so you get rake. And that becomes a bit draggy.

#21 MatsNorway

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Posted 27 March 2012 - 18:14

When the DRS is activated the rear ride height increases, so you get rake. And that becomes a bit draggy.


Sounds reasonable

#22 GreenMachine

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Posted 27 March 2012 - 21:32

I feel compelled to make sure that you're not confusing DRS effects with blown diffusers. They are totally different.

Apologies if I've made too many assumptions.



No apologies necessary, I used that term illadvisedly. I wasn't confusing the two, as I put the word in quotes. I was clumsily trying to make a point that as soon as the rulemakers make a rule, the teams work on how to avoid its impact and recover what has been lost by the imposition of the rule. But that is a discussion for another thread ...;)

Following on from the comments above about the nervous rear end with just DRS on the RW, another benefit might be reduced consumption of rear tyres. With a fixed tyre allocation, you would not want to take more out of your tyres than was necessary, and the better balance of the car would make life a lot easier for the rears.

However, I come back to my earlier comment about the price that might be paid for these (non-raceday) gains. A front-of-grid start is only of benefit if you have the raceday pace to maintain that position. Without that, all you are doing is diverting resources from the ultimate objective - building the fastest racecar.

(edited - spelling)

Edited by GreenMachine, 28 March 2012 - 03:24.


#23 cheapracer

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Posted 28 March 2012 - 05:40

When the DRS is activated the rear ride height increases, so you get rake. And that becomes a bit draggy.


So we have less twitchy through high speed turns, less drag down the straight and add to that, less tyre rolling resistance (less DF distorting the tyre).